i,; ! LEA}CAGE TESTING HANDBOOK Revised Edition July 1969 NATIONAL Prepared for LIQUID PROPULSION SECTION JET PROPULSION LABORATORY AERONAUTICS AND SPACE ADMINISTRATION PASADENA, CALIFORNIA CONTRACT NAS 7-396 REPRODUCED BY NATIONAL TECHNIC.&L INFORMATION SERVICE U. S. DEPARTMENT OF COMMERCE SPRINGFIELD, VA. Z2161 GENERAL _ ELECTRIC $CH[NECTAOY, NEW YORK S-69-1117 https://ntrs.nasa.gov/search.jsp?R=19690029458 2020-03-23T20:12:39+00:00Z LEAKAGE TESTING HANDBOOK Revised Edition July 1969 NATIONAL Prepared for LIQUID PROPULSION SECTION JET PROPULSION LABORATORY AERONAUTICS AND SPACE ADMINISTRATION PASADENA, CALIFORNIA CONTRACT NAS 7-396 GENERAL 0 ELECTRIC SCHENECTADY, NEW YORK At S-69-II17 FOREWORD This is a revised edition of the Leakage Testin_ Handbook originally written by J.W. Marr and issued as NASA Report No. CR-952 in June 1967. Both the original and revised edi- tions have been prepared at the General Elec- tric Company Research and Development'Center under National Aeronautics and Space Admini- stration Contract No. NAS7-396, between the Jet Propulsion Laboratory and the Missile and Space Division of the General Electric Company. The work of revising and updating the Leaka@e Testin@ Handbook was performed by Dr. Philip H. Peters, Project Manager, and Mr. Everett E. Stone and Mr. A.J.Bialous, members of the engineering staff of the General Elec- tric Research and Development Center. The NASA Project Manager is Mr. F.E. Compitello, Code RPL, Liquid Propulsion Tech- nology, Office of Advanced Research and Tech- nology. The NASA Technical Manager is Mr. R.S. Weiner, Liquid Propulsion Section, Jet Propulsion Laboratory. TABLE OF CONTENTS Section FOREWORD i Part I: THEORY AND FUNDAMENTALS 1 1.1 1.2 1.3 2 2.1 2.2 2.3 2.4 3 3.1 3.2 3.3 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 5 5.1 5.2 5.3 6 6.1 6.2 6.3 6.4 6.5 6.6 INTRODUCTION ................ Background .............. Scope ................. Leakage Test Categories ........ REASONS FOR LEAKAGE TESTING ........ Material Loss ............. Contamination ............. Leakage and Reliability ........ Sensitivity .............. CHOICE OF PROCEDURE FOR LEAKAGE TESTING . . Introduction ............. Leakage Measurement .......... Leakage Location ........... TESTING FUNDAMENTALS ............ Dimensions of Leakage Units ...... Conventional Leakage Units ...... Leak Conductance ........... Sensitivity and Testing ........ Leakage Measurement Testing .... Tracer-accumulation Testing ...... Leak Location Techniques ....... Sealed Unit Testing .......... PLANNING LEAKAGE TESTS ........... Design for Accessibility ....... Examples of Typical Test Aids and Fixtures ........... System Cleanliness .......... FLOW CHARACTERISTICS ............ Gas Flow ............... Permeation .............. Liquid Flow ........... Correlation of Leakage Rates ..... Anomalous Leaks Leak Clogging iii Precedingpageblank 1-1 1-1 1-2 1-3 2-1 2-1 2-1 2-2 2-3 3-1 3-1 3-2 3-6 4-1 4-1 4-2 4-4 4-5 4-5 4-14 4-18 4-22 5-10 5-26 6-1 6-1 6-9 6-13 6-13 6-16 6-22 TABLE OF CONTENTS(Cont'd) Section 7 7.1 7.2 7.3 7.4 7.5 SOME GUIDELINES FOR WRITING SPECIFICATIONS Introduction ............. Specifying Maximum Allowable Leakage Rate .............. Instrument Qualification ....... Testing Technique, Safety, and Design . General Leakage Test Specifications . . 7-1 7-1 7-1 7-3 7-4 7-5 Part II: TESTING METHODS 8 8.1 8.2 8.3 8.4 8.5 9 9.1 9.2 9.3 9.4 9.5 9.6 i0 I0.i 10.2 10.3 10.4 10.5 10.6 ii ii.i i1.2 11.3 11.4 12 12.1 12.2 12.3 12.4 MANUFACTURED LEAKS ............. 8-1 Common Types of Manufactured, or "Standard," Leaks ........ 8-1 Errors in Leakage Measurement .... 8-5 Availability of Standard Leaks .... 8-8 Leak Qualification Techniques .... 8-10 Positioning of Test Leak ....... 8-17 MASS SPECTROMETERS AND LEAKAGE TESTING 9-1 9-1 9-2 Introduction ............. Sensitivity ............ Characterization of an Ion-deflecting Mass Spectrometer ........ 9-2 Typical Mass-spectrometer Leak Detector . 9-9 Leakage Testing .......... 9-15 Operation and Maintenance ...... 9-21 HEATED-ANODE HALOGEN LEAK DETECTOR .... 10-1 Introduction ............. i0-i Sensitivity ............ i0-i Description ............. 10-2 General Characteristics ........ 10-5 Leakage Tests ............. 10-8 Safety ................ 10-11 PRESSURE CHANGE METHOD OF LEAKAGE TESTING . . ii-i Introduction ............. ll-i Sensitivity .............. ii-i Description of Test Equipment ..... ii-i Leakage Testing Methods ........ ii-i FLOW MEASUREMENT METHOD OF LEAKAGE TESTING . 12-i Introduction ............. 12-1 Sensitivity .............- 12-1 Description of Equipment ....... 12-1 Leakage Testing Methods ........ 12-2 iv TABLE OF CONTENTS (Cont'd) Section 13 13.1 13.2 13.3 13.4 14 14 .i 14.2 14.3 14.4 14.5 15 15.1 15.2 15.3 15.4 16 16.1 16.2 16.3 16.4 17 17.1 17.2 17.3 17.4 18 18 .i 18.2 18.3 18.4 19 19.1 19.2 19.3 19.4 19.5 Page BUBBLE EMISSION METHOD OF LEAKAGE TESTING . . 13-1 Introduction ............. 13-1 Sensitivity 13-1eoomeloeeooI*o Description of Equipment ....... 13-1 Leakage Testing Methods ........ 13-1 USE OF RADIOACTIVE TRACERS IN LEAKAGE TESTS . 14-1 Introduction ............. 14-i Sensitivity .............. 14-1 Equipment and Materials ........ 14-1 Radiflo Method ............ 14-2 Other Methods of Leakage Testing . 14-6 USE OF THE HALIDE TORCH IN LEAK LOCATION . . 15-1 Introduction ............. 15-i Sensitivity .............. 15-1 Description of Equipment ....... 15-1 Leakage Testing Method ........ 15-2 SONIC DETECTION OF LEAKAGE ........ 16-1 Introduction ............. 16-1 Sensitivity .............. 16-1 Description of Equipment ....... 16-1 Leakage Testing Method ........ 16-1 LEAKAGE DETECTION BY ABSORPTION OF ELECTRO- MAGNETIC ENERGY ............ • • 17-1 Introduction ............. 17-1 Sensitivity .............. 17-3 Description of Equipment ....... 17-3 Leakage Testing Method ........ 17-3 LEAK LOCATION BY MEANS OF CHEMICAL INDICATORS ................. 18-1 Introduction ............. 18-1 Sensitivity .............. 18-1 Materials Available .......... 18-1 Leakage Testing Methods ........ 18-2 LEAK LOCATION BY HIGH-POTENTIAL DISCHARGE . . 19-1 Introduction ............. 19-1 Sensitivity ............. 19-I Description of Equipment ....... 19-1 Leak Testing - Spark Discharge .... 19-2 Leak Testing - Corona Discharge . . . 19-2 V TABLE OF CONTENTS (Cont'd) Section 2O 20.1 20.2 20.3 20.4 20.5 21 21.1 21.2 21.3 21.4 21.5 22 22.1 22.2 22.3 23 23.1 23.2 23.3 23.4 23.5 23.6 23.7 23.8 23.9 IONIZATION-GAGE LEAKAGE TESTING Introduction ..... • o . • • • • • Gage Response in Leak Sensing ..... Improving Sensitivity ........ Discharge Gages and Ion Pumps in Leak Sensing ............. Applicability of Method ........ 20-1 20-1 20-2 20-6 20-10 20-12 LEAK DETECTION WITH THERMAL CONDUCTIVITY GAGES ................... 21-1 Introduction ............. 21-1 Application to Leak Detection ..... 21-2 Sensitivity .............. 21-2 Operating at Atmospheric Pressure . . . 21-2 Leakage Test Methods ......... 21-4 LEAK DETECTION BY GAS-TO-PARTICLE CONVERSION ................. 22-1 Introduction ............. 22-1 Typical Particle Counter ....... 22-1 Gas-to-particle Version ........ 22-2 MISCELLANEOUS LEAKAGE TESTING METHODS . . . 23-1 Introduction ............. 23-1 Combustible Gas Detectors ....... 23-1 Analytical Mass Spectrometer ..... 23-2 Gas Chromatograph .......... 23-2 Gas Capacitance Leakage Test ..... 23-2 Propellant Leak Detector ....... 23-3 Hydrogen Leak Detectors ........ 23-3 Oil Leak Detector ........... 23-3 Biological Techniques Adapted for Leakage Testing ....... 23-3 Part III: CHARACTERISTICS AND SOURCES OF COMMERCIALLY AVAILABLE LEAK DETECTORS 24 24 .i 25 26 COMMERCIAL LEAK DETECTORS ......... 24-1 Arrangement of Tables ......... 24-1 MANUFACTURERS OF LEAK DETECTING EQUIP- MENT -- MAILING ADDRESSES ......... 25-1 CODE SYMBOLS FOR PRINCIPLES USED IN LEAK DETECTING EQUIPMENT ............. 26-1 vi TABLE OF CONTENTS (Cont'd) Section 27 28 29 3O MANUFACTURERS OF LEAK DETECTING EQUIP- MENT -- PRINCIPLES USED .......... TYPES OF LEAK DETECTING EQUIPMENT -- MANU- FACTURERS AND TRADE NAMES ......... GENERAL SUMMARY OF CHARACTERISTICS FOR LEAK DETECTOR TYPES .............. LEAK DETECTORS -- THEIR CHARACTERISTICS . . 27-1 28 -1 29-1 30-1 REFERENCES Appendix A B C PROPERTIES OF TRACER GAS ......... PRECAUTIONARY MEASURES FOR USING VARIOUS TRACER GASES ............... LEAK TESTING SPECIFICATIONS ........ DISTRIBUTION LIST ............. A-I A-2 B-1 C-1 vii LIST OF ILLUSTRATIONS Figure 2-1 2-2 3-1 4-1 4-2 4-5 4-6 4-7 4-8 4-9 4-10 4-11 5-1 5-2 5-3 Ease of Operation Versus Procedure Sensitivity ................ Effect of Required Sensitivity on Leak Detection Equipment Cost ......... Typical Step-by-step Procedure for Choice of Leakage Test ............... Leakage Measurement Modes Using the Dynamic Testing Technique ............. Leakage Measurement Involving the Use of an Auxiliary Pump .............. System Response Time ........... Response Nomograph for a Leakage Detection System .................. Alternate Sites for Leak Detector on Vacu- um System ................. Bubble Formation at a Leak Site ...... Leak Location Techniques ......... Detector Response for a Unit Sealed with Tracer Gas ................ Relation of Leak-rate Signal to Leak Con- ductance for Back-pressurizing Technique . . Computed Relation of Leak-rate Signal to Leak Conductance for a Particular Set of Conditions ................ Required Values of PEtE Calculated for Q = 2.5 x i0 _ Torr Liter per Second . . Sketch of Typical Series Leak Path .... Tank Pressure Versus Energy Equivalent . . Diffusion of Tracer Gases in Blind Ducts. Time Required to Reach One-tenth the Orig- inal Tracer Gas Concentration at End of Duct ................... ix 2-3 2-5 3-3 4-6 4-8 4-11 4-13 4-15 4 -19 4-21 4-23 4-24 4-26 4-27 5-2 5-7 5-12 Precedingpageblank Figure 5-4 5-5 5-6 5-7 5-8 5-9 5-10 5-11 6-1 6-2 6-3 6-4 6-5 6-6 6-7 8-1 8-2 8-3 8-6 8-7 LIST OF ILLUSTRATIONS (Cont'd) Typical Setup for Hood Testing ....... Typical Manifold for Rapid Testing of Small Parts ................... Reliable Test Fixture for Leakage Measure- ment .................... Split Fixture for Parts Testing ...... Vacuum Box for Weld Testing ........ Use of Vacuum Box for Weld Testing ..... Detector Probe for Leak Location ...... Self-extracting Tracer Gas Probe ...... Laminar Flow in a Typical Hardware Leak . . Permeation Rate Versus Time of Rubber Gasket for a 4 x 4 mm Cross Section ........ Gas-liquid Leakage Nomograph ........ Check-valve Effect in a Hardware Leak . . . Geometry Change in a Gasket Leak ...... Self-cleaning Effect in Leaks ....... Bubble Clogging ............... Helium Permeation Leak ........... Reservoir Leak with Leak Factor Gage .... Variable Leakage Source Heated-anode Leak Detector .................. System for LS20 Variable Leakage Source . . Comparison of Leakage Values for Leaks Supplied by Various Vendors ........ Correlation Between Actual and Measured Leakages .................. Leak Qualification by Isobaric Volume Change . 5-14 5-16 5-17 5-19 5-20 5-22 5-25 5-26 6-3 6-12 6-15 6-18 6-19 6-20 6-23 8-2 8-4 8-6 8-7 8-II X LIST OF ILLUSTRATIONS (Cont'd) Figure 8-8 8-9 8-10 8-11 9-1 9-2 9-3 9-4 9-5 9-6 9-7 10-1 10-2 10-3 10-4 10-5 10-6 ll-i Leak Qualification by Pressure Rise Technique ................. Leak Qualification by Pressure Drop Across a Known Conductance ............ Leak Qualification by Pressure Measurement at Constant Pumping Speed ......... Alternative Positions for a Qualified Leak on a System ................ Schematic Diagram of an Ion-deflecting Mass Spectrometer ............... Mass-spectrometer Leak Detector Pumping System .................. Analyzer Tube of a Modern Mass-spectrometer Leak Detector ............... Operation of Modern Mass-spectrometer Ana- lyzer Tube ................ Exposed View of a Diffusion-pump Isolation Valve ................... Effect of Probing Speed and Probe Distance on Sensitivity .............. Response and Cleanup Time Versus Probe Length for a Mass-spectrometer Leak Detector . . . Heated-anode Halogen Leak Detector .... Detector Element of Heated-anode Halogen Leak Detector ............... Basic Circuit of Heated-anode Halogen Leak Detector ................. Controlled Atmosphere Test Booth ..... Fresh-air Ducting for a Proportioning Probe . Diffusion of Halogenated Hydrocarbon R-12 in a Blind Duct ............. Effect of Leakage and Outgassing on a Pres- sure Versus Time Curve ......... 8-12 8-14 8-14 8-18 9-4 9-10 9-11 9-12 9-14 9-18 9-19 10-3 10-3 10-4 10-7 10-8 10-10 11-3 xi LIST OF ILLUSTRATIONS (Cont'd) Figure 11-2 11-3 11-4 11-5 12-1 12-2 12 -3 13-1 14-1 15-1 16-1 17-1 19-1 20-1 20-2 20-3 20-4 21-1 22-1 22-2 Test Setup for Pressure Change Testing, Using a Vacuum Hood ............ Volume Sharing Technique of Leakage Mea- surement ................. Pressure Change Procedure, Using a Carrousel Vacuum Lock ................ Differential Pressure Change Method of Leak- age Measurement .............. Flow Observation in Sealed-volume Leakage Measurement ................ Delta-Vee Meter for Leakage Measurement . . Pumping Technique of Leakage Measurement . . Pressure Versus Temperature for a Fixed Volume .................. Unit for Radiflo Testing ......... Halide Torch for Leak Location ...... Block Diagram of an Ultrasonic Leak Detector ................. Infrared Leak Detector .......... Discharge Tube Audible Leak Locator .... Idealized System for Vacuum Gage Response Testing .................. Null Balance Circuit for Leak Location . . Response of Ion Pump Current to Various Gases ................... Ion Pump Leak Detector .......... Thermal Conductivity Leak Detector .... Condensation Nuclei Counter ........ Gas-to-particle Conversion Concept .... ii-5 Ii-6 11-7 ii-8 12-2 12-3 12 -4 13-4 14-5 15-1 16-2 17-i 19-2 20-2 20-7 20-i1 20-12 21-3 22-1 22-2 xii LIST OF TABLES Table 4-1A 4-1B 4-2 5-1 6-1 6-2 7-1 8-1 9-1 i0-i ll-1 12-1 13-1 14-1 15-I 16-1 17-1 19-1 20-i Leakage Conversion Factors ......... Leakage Conversion Factors (Weight) .... Signal Responses as a Percentage of Final Signal Strength .............. 4-12 Diffusivity of Tracer Gases in Air ..... 5-11 Viscosity of Gases at 0°C ......... 6-4 Mean Free Paths and Molecular Diameters for Various Molecules ........... 6-5 Molar Heat Capacity of Gases ........ 6-8 Permeability of Polymeric Materials to Vari- ous Gases ................. 6-11 List of Leakage Test Specifications .... 7-6 Precision Leaks Commercially Available . . 8-9 Commercial Mass-spectrometer Leak Detectors . 9-15 Sensitivity of Heated-anode Halogen Leak Detectors to Various Halogen Compound Gases . 10-2 Commercial Pressure-change Detectors .... 11-2 Commercial Flow Measurement Detectors . . 12-1 Commercial Liquid-application Fluids for Bubble Testing ............... 13-2 Materials Used for Radioactive Leakage Testing .................. 14-3 Characteristics of Halide Torch Detectors . 15-2 Characteristics of Sonic Leak Detectors . 16-3 Characteristics of Light Absorption Leakage Detectors ................. 17-4 Discharge Colors in Gases and Vapors at Low Pressures ............... 19-4 Leakage Testing Substitution Factors @ . . . 20-5 4-3 4-3 xiii LIST OF TABLES (Cont'd) Table 21-1 22-1 23-1 Thermal Conductivities of Tracer Gases . . . Some Gases Detected by Gas-to-particle Con- version .................. Characteristics of Combustible Gas Detectors . 21-5 22-4 23-1 xiv k Section i Section 2 • Section 3 Part I THEORY AND FUNDAMENTALS Section 4 Section 5 Section 6 Section 7 _Y Section 1 INTRODUCTION i.i 1.2 1.3 BACKGROUND ................. SCOPE ................... LEAKAGETEST CATEGORIES .......... I-i 1-2 1-3 Section 1 INTRODUCTION I.I BACKGROUND Systems which contain liquid or gaseous fluids vary widely in size, complexity, function, and application. At some point in manufacture, there is concern about the degree to which a system is free of paths through which fluid leakage could oc- cur. Methods and procedures must then be chosen or devised for testing for leakage, taking into account the amount of leakage that can be tolerated, the levels of working pressure which will prevail on the faces of container boundaries, and the means by which leaks may be located once they are sensed. Numerous meth- ods are available for detecting, measuring, and locating fluid leakage across a containing boundary. Often only a few of these methods are applicable for testing an apparatus in a given situ- ation after factors such as sensitivity of the test, time required to perform the test, and the cost, weight, and size of testing equipment are considered. It is desirable to specify in advance the maximum allowable leakage rate and the methods and procedures which should be followed in performing leakage testing. Usually a manufacturer of equipment must develop standards and procedures for measuring fluid leakage which are appropriate to the particular type of equipment he manufactures and to the application in which the equipment is used. He may decide to in- clude a listing of his specifications with the operating instruc- tions for testing the system or unit before it is placed in use. Several military agencies and a few industrial groups have devel- oped specific methods and procedures for performing leakage tests. Societies such as the American Society for Testing and Materials (ASTM), the Society for Nondestructive Testing (SNT), and the American Vacuum Society (AVS) either have established or are in the process of establishing standards for qualifying testing meth- ods and procedures. More is said about this subject in Section 7, "Some Guidelines for Writing Specifications°" When a purchaser of an equipment places leakage test speci- fications in his requisition he may not be fully acquainted with the details of the method and procedures which he is in effect asking the supplier of the equipment to follow. As a result his specifications can easily be impracticable if not inordinately expensive to guarantee. To offset a high testing cost the pur- chaser can take advantage of statistical sampling techniques, where applicable,to reduce the number of units which actually need to be tested. In any event, it is not uncommon to specify maximum allow- able leakage rates which are unnecessarily low and require high test sensitivities. Subsequently the manufacturer is asked to i-i prove that the specified sensitivity is in fact present in his test instruments. Serious problems can arise in obtaining ac- ceptance of equipment by the purchaser under these circumstances. Programs may be slowed or brought to a halt until the specifica- tions are met or until a new agreement is reached which reflects a more thorough appraisal of the level of allowable leakage and the sensitivity which is required to achieve an acceptable level of test accuracy. More importantly, if test sensitivity is in- adequately prescribed, leakage of such magnitude may be found in a terminal test that the equipment must be scrapped or completely rebuilt. Potential hazards to personnel may also arise. 1.2 SCOPE This handbook has been written to unify and consolidate in- formation and, hopefully, to prevent discrepancies in understand- ing which can develop between the person preparing a specification and the one responsible for complying with it. It is expected to serve as a reference to persons who design equipment and write specifications, as well as to those who perform the leakage tests. The book covers fundamental concepts of leakage testing, leakage phenomena often encountered during testing, and testing methods. This handbook is divided into three parts: • Part I (Sections 1 through 7) describes the funda- mental concepts and theories of leakage testing. • Part II (Sections 8 through 23) describes methods of leakage testing, their limitations, sensitivi- ties, and use. • Part III is a comprehensive review of leak detectors which are commercially available in the world market. Characteristics and sources of each equipment have been compiled and are presented in tabular form on individual data pages. Contributions from 128 ven- dors are included. Twenty-nine different principles of measurement are being used by these vendors. Several cross-indexing tables have been developed to serve as guides to information concerning speci- fic types of leak detecting equipment and their manu- facturers. The reader desiring to become familiar with leakage testing can study Part I of the book to gain an understanding of the gen- eral subject, and can then select individual sections of Part II for the various methods which are appropriate to his application. He can refer to Part III to learn about equipment which is cur- rently available for performing leakage tests. 1-2 1.3 LEAKAGE TEST CATEGORIES Leakage testing can be divided into three categories: • Leakage measurement • Leak location • Leakage monitoring Leakage measurement is the measurement of the total leakage of a system or subsystem; it is the only method which reliably determines that a leak exists. Leakage location is the procedure of pinpointing the precise locations of individual leaks. It is extremely important that leakage measurement techniques and leak location techniques not be interchanged indiscriminately. In testing a system, the most reliable sequence is the measure- ment of total leakage and then, if necessary, the location of individual leaks. Leakage monitoring is the continuous measurement of contam- inants entering or leaving an enclosed system. The major dis- tinction between leakage monitoring and the other two leakage testing techniques is that monitoring is usually performed over extremely long periods of time during system storage or opera- tion. Leakage monitoring equipment differs from the equipment used for leak detection in that it usually consumes less power and is designed to operate stably over long periods of time. Many of the instruments used for leakage measurement may be adapted for continuous use. 1-3 Section 2 REASONSFOR LEAKAGETESTING 2.1 2.2 2.3 2.4 2.4.1 2.4.2 2.4.3 2-1 _TERIAL LOSS ................ 2-ICONT_INATION ................ LEA_GE AND _LIABILITY ........... 2-2 2-3SENSITIVITY ............... Opt_um Sensitivity Value and Testing 2-3Difficulty ............. 2-4Cost Considerations ......... 2-4Zero Leakage .............. k Section 2 REASONS FOR LEAKAGE TESTING Rapid, nondestructive methods for the detection of gas and liquid leakage in sealed systems are of great industrial and military importance. The operational reliability of such systems is greatly increased when considerable attention is paid to the leakage testing of individual components as well as that of the final assembly. Leakage testing is performed for three basic reasons: i. To prevent material loss by leakage. , To prevent contamination, creation of hazardous conditions, or disfigurement by leakage. , To detect faulty components and control the re- liability of the product (Ref. 2-1). 2.1 MATERIAL LOSS The first consideration in specifying the leak-tightness of a system is that the system must not leak sufficient material to cause system failure during its useful life. The allowable leak- age rate is simply the allowable total leakage divided by the use- ful life of the system. Material leakage can constitute a hazard to personnel during system operation. Tolerable concentrations must be known or es- tablished_ These are often reported in the literature (Ref. 2-2). The maximum tolerable equipment leakage can be calculated from given allowable concentration, taking into account effects of dilution, ventilation, etc. 2.2 CONTAMINATION Contamination of a system may be caused by material leaking either into or out of the system. For example, damage may be caused in the system of a liquid rocket motor when the oxidizer leaks out of the storage tank and reacts with parts of the motor. Electronic components may fail when air or water vapor enters a sealed protective container. Often very small amounts of _nater- ial can cause contamination failure; it thus becomes difficult to predict accurately the conditions under which a failure may occur. In any event, if some decision can be made as to the amount of reaction product which may be allowed to develop be- tween an oxidizer and part of a rocket engine, a total amount of leakage and an allowable leakage per unit time can be designated. Again, failure of a sealed semiconductor component usually follows when a monolayer of water vapor, corresponding to i0 _5 molecules per square centimeter, has been absorbed on the surface 2-1 of the semiconductor (p. 381, Ref. 2-3). An allowable leakage rate for such a component can be calculated in terms of the maxi- mum life time which is required of the component for a given mission. If failure results from a pressure rise, then the max- imum allowable pressure, the planned system operatlng time, and the system volume are all that are necessary for calculating the allowable leakage rate. Neilson (Ref. 2-4) has demonstrated such a method for calculating the allowable leakage into small sealed electronic components. Appearance may often be a factor in setting a leakage speci- fication, since leakage which spoils appearance eventually may lead to a failure of the equipment or otherwlse render the equip- ment less acceptable for use. Rusting or corrosion of the exter- nal surfaces of valves, fittings, piping, panel-mounted switches, and nameplates are examples where loss of appearance affects utility and safety. 2.3 LEAKAGE AND RELIABILITY Leakage testing may be employed to assess the reliability of a system by pinpointing sources of fluid leakage in the sys- tem and its components which may later affect the operation of the system deleteriously. High values of leakage where none is expected can serve to identify errors of installation, such as the improper alignment or absence of a gasket. Such errors generally result in leakage rates of 10 -2 to 10 -5 atmosphere-cubic centlmeters per second. Of course, the absence of high leakage does not necessarily in- dicate that a connection has been properly made. Leak-tightness can be obtained with misaligned parts as well; however, if parts are misaligned, leakage is likely to occur. Many leaks are caused by material flaws such as cracks and fissures. Some of these flaws can be detected by leakage mea- surement. Even more can be detected by x-rays. But neither tech- nique will detect all flaws. Leak detection is therefore comple- mentary to other detection techniques in finding basic material flaws. Occasionally it is desirable to locate very small leaks, be- low 10 -_ atm-cc/sec. Such leaks, if they remain small, would not be objectionable in an equipment. However, operating stresses can cause the size of a leak path to increase with time, a_d leaks which are negligibly small at room temperature will enlarge ±_ the component in which the leak path exists must eventually operate at a high temperature. Temperature cycling can cause permanent en- largement of a leak path which is initially very small. The reliability of a system may be thought of in terms of the maximum rate of leakage which can be tolerated from or into that system. Test procedures are designed to determine that the leakage rate is in fact no greater than this maximum value. A 2-2 system or component is deemed unreliable if testing shows that the leakage exceeds this level. The sensitivity of the test needs to be only high enough to measure leakage rates between one-fourth and one-half of the leakage reliability level. 2.4 SENSITIVITY In specifying a leakage test, a procedure with an optimum sensitivity value in the correct leakage range should be chosen. Large deviations from this optimum value increase the time and the difficulty of performing the measurement. Any increase in the sensitivity specified for a particular test automatically increases the cost of testing. Therefore, a compromise has to be reached between testing cost and leakage tolerance. For example, if a leakage rate of 10 -4 atm-cc/sec is allow- able in an equipment, it is unnecessary to perform a test sensi- tive to much less than that value, even though the actual leak- age rate of the equipment is in fact well below 10 -4 atm-cc/sec. The chief concern here is not with the actual leakage rate, but rather with meeting the requirements of the application. From this viewpoint testing costs may be minimized; design of the equipment also can be influenced resulting in the use of lighter weight materials, and in a reduction in weight, size, and cost of manufacture as well. 2.4.1 Optimum Sensitivity Value and Testing Difficulty The procedure employed with a given method of testing for leakage has an optimum value of sensitivity at which it is most easily used. Deviation from this optimum value makes it more difficult to perform the measurement and decreases confidence in the results. Figure 2-1 is a diagram showing the influence of Z O n- uJ Q. 0 u. 0 Figure 2-1. PROCEDURESENSITIVITY Ease of Operation Versus Procedure Sensitivity 2-3 increasing sensitivity on the ease of operation of the equip- ment. In most cases, after reaching a plateau, further increase of sensitivity rapidly decreases the ease of operation. Bubble testing by immersion in water provides an example of how the optimum value of sensitivity affects the ease of perform- ing the test. This testing method has a sensitivity range be- tween i0 -l and 10 -4 atm-cc/sec. In measuring for i0-" atm-cc/sec leaks, a component may be placed in water and quickly removed. With immersion, bubbles will evolve from the pressurized compo- nent at such a rapid rate that there is no question of the exis- tence of a leak. In checking for leaks in the range of 10 .2 to 10 -3 atm-cc/sec, care must be taken that the immersed component is submerged long enough for any bubbles coming from around crev- ices to collect and rise. In the measurement of leaks near l0 -_ atm-cc/sec, the compo- nent, after being immersed, has to be completely stripped of at- tached air bubbles so that the formation of bubbles of leaking gas may be detected. The i0 -_ atm-cc/sec range is near the limit of detectability of this method, although higher sensitivity should result if longer waiting periods are used. If the rate of bubble evolution approaches the rate at which the gas dissolves in the testing fluid, no gas will be seen and the sensitivity will decrease rapidly as will the ease of operation. A somewhat higher sensitivity may be obtained by saturating the liquid with the gas. Evidently bubble testing becomes exceedingly difficult to employ if a leakage rate much less than 10 ..4 atm-cc/sec is speci- fied. It would be better to change to a test procedure which is more effective at that higher sensitivity. In the same manner, trying to check leaks larger than i0 -l atm-cc/sec becomes diffi- cult because of rapid gas evolution and rapid decay of pressure in the system. However, the difficulties in the lower range of sensitivity are usually not so great as in the maximum sensitivity range of the method. 2.4.2 Cost Considerations The cost of leakage testing increases as the required sensi- tivity increases. Figure 2-2 illustrates this increase in cost. The investment for a leakage determination of 10 -3 atm-cc/sec is negligible, perhaps a few dollars for the apparatus involved in a bubble test. The investment for testing at 10 -12 atm-cc/sec may well be in the order of $50,000. An increase in the sensi- tivity of a test with a given instrument will result in an in- crease in measurement cost. Such an increase is usually caused by the additional test complexity. This cost increases more rapidly when the level of sensitivity is located at the right of the sensitivity plateau of Figure 2-1. 2.4.3 Zero Leakage Nothing made by man can be considered to be absolutely leak- tight. Even in the absence of minute porosity, the permeation of 2-4 50,000 5,000 o 0 t-- 0 I-- Z r_ Z 5OO 5O 5 RADIOACTIVE TECHNiQdES MASS SPECTROMETER HALOGEN HEATED ANODE \, U BBL E TESTING I I i0 -3 i0 -6 i0 -9 LEAKAGE MEASUREMENT SENSITIVITY, otto cc/$ec Figure 2-2. i0 "12 Effect of Required Sensitivity on Leak Detection Equipment Cost. (Reprinted from J.W. Marr, "Leakage Phenomenon," Valve Technology Seminar, Midwest Research Institute, Kansas City, Mis- souri, October 1965.) 2-5 certain gases through metals, crystals, polymers, and glasses still occurs. Leak-tightness is, therefore, a relative term. In setting the upper limit on allowable leakage, it is necessary to establish a practical leakage level for any given component under test below which the component may be considered to ex- hibit leak-tightness. The importance of leakage in the specific type of equipment or component may often be used as a practical guide. Increasing the sensitivity of a testing method brings with it an increase in the time required and the cost of perform- ing a test. Cost reaches a maximum level when the specifications read in one of the following ways: • No detectable leakage No measurable leakage • No leakage • Zero leakage Such specifications are ambiguous and impose an unattainable standard on any type of equipment. Their use is to be avoided. With specifications such as the above the operator will be continually forced to operate his equipment at maximum sensitiv- ity and will always have to decide whether the signal output is due to system noise and drift or to actual leakage into the de- tector. In essence, if there is to be no leakage, there can be no signal to detect. It is much easier to discriminate a leakage signal against a reference signal generated through a leak whose leakage rate is known than it is to discriminate against system noise. It is therefore suggested that the term "zero leakage" be used only if it is defined as the measurable value of leakage below which the satisfactory operation of the system to be tested is in no way impaired. The Jet Propulsion Laboratory, for example, has used this concept in defining a level for zero liquid leakage into or out of a system in terms of a measurable level of tracer gas leakage (Ref. 2-6). 2-6 3.1 3.2 3.2.1 3.2.1.1 3.2.1.2 3.2.2 3.2.2.1 3.2.2.2 3.3 3.3 .i 3.3.2 Section 3 CHOICE OF PROCEDUREFOR LEAKAGE TESTING INTRODUCTION ................ 3-1 LEAKAGEMEASUREMENT ............ 3-2 Units Accessible on Both Sides ...... 3-3 Unit8 Which May Be Euaauated ..... 3-4 System8 Leaking to Atmospheri_ Pre88ure .............. 3-4 Simultaneous Testing of Sealed Units . . 3-5 Testing Euaauated Unit8 ....... 3-5 Testing Unit8 Sea_ed with Traaer GaS • . 3-6 LEAKAGE LOCATION .............. 3-6 Detector Probe Procedure ........ 3-6 Tracer Probe Procedure ......... 3-6 {% % Section 3 CHOICE OF PROCEDURE FOR LEAKAGE TESTING 3.1 INTRODUCTION The method to be used in conducting a leakage test must be chosen with considerable care. A correct choice of method will optimize sensitivity, cost, and reliability of the test. One way to approach the problem of selecting a preferred method is to rank the various methods which are available for the test according to test sensitivity. Then, one has only to decide what degree is required and choose the method from those offering adequate sensitivity. It is important to distinguish between the sensitivity associated with the instrument which is to be employed in mea- suring leakage and the sensitivity of the test procedure which is to be followed in using the instrument. The sensitivity of an instrument influences the sensitivity which can be attained in a specific test. The range of temperatures or pressures and the types of fluids involved influence both the choice of instru- ment and the choice of test procedure. Each test procedure may have a different sensitivity. For example, a test utilizing a mass spectrometer leak detector will usually have a sensitivity of 10 -I° atm-cc/sec when the procedure involves the measurement of a steady-state gas leakage rate. Under special conditions the sensitivity of the test may be in- creased to I0 -i_ atm-cc/sec by allowing an integration of the leakage to occur in a known volume before a measurement of the leakage is made. Thus, in the first case the sensitivity of the test equals the sensitivity of the instrument, whereas in the second case the sensitivity of the test is ten times greater than that of the instrument. On the other hand, if the test pro- cedure utilizes a mass spectrometer operating in the detector- probe mode, the sensitivity of the test can be 102 to 104 smaller than that of the spectrometer alone. Comparison of the sensitivities of any two instruments must be made with one particular type of test situation in mind. If the helium mass spectrometer leak detector is compared with the heated-anode halogen leak detector in detecting the presence of a leak into an evacuated vessel, it will be found that the mass spectrometer is at least 1000 times more sensitive. On the other hand, if these two instruments are both used for locating a leak from a pressurized environment into atmospheric air, the sensi- tivity of the heated-anode halogen detector is greater by at least a factor of ten. Thus, the manner in which an instrument is employed in a test affects its basic sensitivity and, thereby, the overall sensitivity of the test. 3-1 In view of these facts, the choice of the test method and procedure should be made by following a step-by-step process such as that outlined in the chart of Figure 3-1. Note that the numbers assigned to the headings of this section are repeated on the chart for reference purposes. The chart is entered on the left at "Leakage" with the ques- tion: Should this test reveal the presence of a suspected leak(leakage measurement) or show the location of a known leak (leak location)? One then proceeds along the chart according to the features of the particular type of system to be tested in order to select an optimum testing method. A number of the most commonly used leakage test methods are listed on the chart, showing the range of leakage sensi- tivity over which each method is applicable. Any practical leakage testing program will utilize several different leakage test methods, progressing from those with lit- tle sensitivity to those of higher sensitivity as the leak-tight- ness of the object or system is proved. A systematic program must be employed for leakage testing in large complex systems(Ref. 3-2). In general, it is necessary to correct the large leaks before the small leaks can be evaluated. There are special cases, usually mass production items, where it is advantageous to make fine leakage tests prior to the gross leakage tests(Refs. 3-3, 3-4, and 3-5). 3.2 LEAKAGE MEASUREMENT The leakage measurement procedure involves covering the whole of the suspected region with tracer gas, and establishing a pressure differential across the system by either pressuriz- ing the tracer gas or evacuating the opposite side. The pre- sence and concentration of tracer gas on the lower-pressure side of the system are then determined and measured. The objects of leakage measurement fall into two categories: i) open units which are accessible on both sides, and 2) units which are sealed. The second category usually consists of mass- produced items which are to be tested in large quantities. These include transistors, relays, ordnance units, and instruments. 3.2.1 Units Accessible on Both Sides Either evacuation or pressurization of one side of a unit which is accessible on both sides may be employed to test for leakage across the unit. If one side is evacuated the tracer gas leakage into the vacuum will reach the detector quickly, since there is essentially no possibility of stratification. However, evacuation does not always allow the most sensitive and reliable measurement. If the evacuation system is extremely large, high pumping speeds will be involved and can often re- sult in a substantial reduction of the amount of tracer gas which 3-2 - 'o _,_,% i - q - 'o- -- - ,_- .,¢e: _ 7 _._ ,,c i -T-- :-T--I _[-]-- I I I_l ,,a iI- I la-t I I I_j i - _ g _- -- _ i i - i t - o J ° _ _ l z.. _i .! i _u _ ._. _'. ! i °! _g 01 I11 I1) 0 .,-t O O O O D_ I I D-, (D ,-.I .M O., I -M 3-3 reaches the detector. Aside from sensitivity, evacuation of one side to low pressure may not be possible if the equipment is not strong enough to withstand the pressure differential. 3.2.1.1 Units Which Ma_ Be Evacuated. The first approach to testing units which may be evacuated is to determine whether there is an inherent tracer in the system. Perhaps during nor- mal operation the system contains one of the tracer gases (e.g., helium or halogenated hydrocarbon). If so, the use of a testing method specifically for that gas might be preferred, since con- siderable savings can be realized if the system need not be filled with a tracer gas. If no inherent tracer is available, the next approach should be to consider whether there is a gage already present in the sys- tem which might be used for leakage measurement. This gage might be simply an ionization gage or, in some fortunate circumstances, a mass spectrometer which is in the system as part of the analyt- ical instrumentation. Not only gages which are normally used for leak detection should be considered: any equipment for detecting gas concentration which happens to be available may be used for leakage measurement. Even equipment not originally intended for pressure measurement may be used. For example, it is possible to detect the pressure rise in a leaking vacuum tube by operat- ing the grid at a positive and the anode at a negative potential, and noting an increase in anode current with time. If there is not an inherent tracer or gage within the sys- tem, then some testing method must be chosen which has the desired sensitivity. In the order of increasing sensitivity for testing an evacuated system, these include: flow measurement, pressure measurement, heated-anode halogen detector, and helium mass spec- trometer leak detector. In most cases, all the possible methods should be considered. A more sensitive procedure may represent a higher initial invest- ment, but will usually provide test results of greater relia- bility. Once the method has been chosen, it is necessary to decide on the testing procedure to be followed. Since it is usually preferable to perform the tests in the shortest possible time, a dynamic (steady-state) testing procedure should be tried ini- tially. A static (accumulative) testing procedure of leakage testing yields a higher sensitivity but requires a much longer testing time. In some cases it will be necessary to resort to static testing if the dynamic test fails to reveal any leakage and the desired test sensitivity is above that provided by the dynamic test. For example, leaks in ceramic-to-metal seals may be so small that accumulative testing is required to de- tect them. 3.2.1.2 Systems Leaking to Atmospheric Pressure. The choice of testing method for systems leaking to atmospheric pressure should 3-4 be made in the same pattern as suggested for evacuated systems. The first point to be considered is the possibility that there is an inherent tracer in the system. It should then be determined whether a gage exists in the system which may be used to measure pressure or tracer gas concentration. Again, this might not necessarily be the original purpose of the particular gage, but it may be adapted to this use for the leakage measurement. If a tracer or a pressure monitoring device is not inherent in the unit being tested, then one of the standard methods of making leakage measurements must be employed. These are, in the order of increasing sensitivity: flow measurement, pressure mea- surement, bubble testing (immersion), and the use of a helium mass spectrometer, infrared analyzer, heated-anode halogen de- tector, or radioactive tracer. (Note that the helium mass spec- trometer method is not the most sensitive when the measurement is to be made at atmospheric pressure.) Whenever applicable, dynamic testing should be used. Static testing techniques will increase testing time, but they will also increase test sensitivity. 3.2.2 Simultaneous Testing of Sealed Units Sealed units which are made in large quantities present several specific problems in testing. It is imperative that a large number of units be tested rapidly. It is also imperative that no defective units be allowed to pass. Most of the testing procedures for sealed units involve par- tial evacuation. If the leak in the unit is exceptionally large, the tracer gas will escape rapidly from the unit during this par- tial evacuation. Consequently, high-sensitivity tests will be ineffective since they cannot be usefully employed if the tracer gas has already escaped from the system. It is therefore recom- mended that all parts be tested for large leaks after the high sensitivity tests that are described below have been conducted. This is because the standard way of performing large-leak test- ing is by the bubble-testing procedure; and since liquids are involved, smaller leaks can easily become clogged and may not be detected during a subsequent high-sensitivity test. In the testing of sealedunits, applicable testing methods are, in the order of increasing sensitivity: bubble testing, flow measurement, pressure measurement, infrared analyzer, heated- anode halogen detector, helium mass spectrometer, and radioactive tracer. The last four methods are applicable to a back-pressur- izing testing procedure. 3.2.2.1 Testing Evacuated Units. With evacuated units the choice of testing procedure is relatively simple. If the system contains a gage which may be used to show the presence of gas contamination, it is the first testing method to be tried. If such a gage does not exist, a flow measurement procedure may be 3-5 considered. Finally, if this is not sensitive enough, the back- pressurizing procedure must be used. The only other considera- tion in the choice of a procedure is that, after testing, the units should be passed through a bubble test to locate the excep- tionally large leaks. 3.2.2.2 Te8ting Units Sealed with Tracer Gas. Units sealed with tracer gas may be tested for leakage of the gas out of the unit by dynamic or static precedures. Generally, the partial pres- sure of tracer gas inside a unit will be higher than it would be if the tracer gas were forced into an evacuated unit through a small leak, as is done in the back-pressurizing procedure. Thus presealing with tracer gas leads to a more sensitive, lower-cost leak test procedure involving fewer steps. As in the case with the other methods a final inspection must be conducted by means of a bubble test procedure to locate exceptionally large leaks. 3.3 LEAKAGE LOCATION Leakage location can be subdivided into a tracer probe pro- cedure and a detector probe procedure. The tracer probe procedure is generally used when the sys- tem is evacuated and the tracer gas comes from the outside. The detector probe procedure is used when the system is pressurized with tracer gas and testing is done at atmospheric pressure. Usually tke tracer probe technique is more rapid because the gas reaches the detector at a higher concentration than with a detector probe. In the detector probe procedure a pressure dif- ferential higher than one atmosphere across the system may be used, and therefore leaks of a smaller conductance can be found. In using either procedure it is important that leak location be attempted only after the presence of a leak has been ascertained. 3.3.1 Detector Probe Procedure In testing a system which is leaking into atmosphere the first consideration is whether or not the leaking fluid may be used as a tracer. This will always be the procedure when using either the sonic method or the bubble-testing method. However, the tracer might be of a composition which will also prove satis- factory for use with the other testing methods. In order of in- creasing sensitivity these methods of leak location are: chemical testing, gage response, infrared gas analyzer, mass spectrometer, and heated-anode halogen detector. 3.3.2 Tracer Probe Procedure In the location of leaks in evacuated systems the first item to consider is whether or not there is an inherent detector with- in the system. This may be a pressure gage of some type or, more desirably, a gage which is specific for a tracer gas which may be used. If such a gage does not exist, the methods to use in the order of increasing sensitivity are: sonic, pressure change gage 3-6 response, high voltage discharge, heated-anode halogen detector, infrared detector, and mass spectrometer. These methods must be individually examined to see if their limitations and advantages are suitable to the particular system being tested. Radioactive gases are not generally employed as a tracer for routine leak location because of the hazards asso- ciated with their use. 3-7 Section 4 TESTING FUNDAMENTALS 4.1 4.2 4.3 4.4 4.5 4.5.1 4.5.2 4.5.3 4.6 4.7 4.7.1 4.7.2 4.8 4.8.1 4.8.2 4.8.2.1 4.8.2.2 NOMENCLATURE DIMENSIONS OF LEAKAGE UNITS ........ CONVENTIONAL LEAKAGE UNITS ......... LEAK CONDUCTANCE .............. SENSITIVITY AND TESTING .......... LEAKAGE MEASUREMENT TESTING ........ Magnitude of Response ......... System Response Time .......... Detector Location ............ TRACER-ACCUMULATION TESTING ........ LEAK LOCATION TECHNIQUES .......... Bubble Testing ............. Probe Techniques ............ SEALED UNIT TESTING ............ Unit Sealed With Tracer Gas ..... Back-pressurizing Technique ....... Molecular Flow Leaks ......... Laminar Flow Leak8 .......... 4-i 4-2 4-4 4-5 4-5 4-8 4-9 4-14 4-14 4-18 4-18 4-20 4-22 4-22 4-22 4-25 4-28 NOMENCLATURE FOR SECTION 4 a C CA e g h K P PE Po PI P2 Po Q QE Qi r S S E S d t t E Current Conductance Conductance of tracer gas Base of natural logarithms Standard gravity Height Multiplication factor Pressure Pressure of tracer gas Atmospheric pressure Upstream pressure Downstream pressure Initial partial pressure of tracer gas Leakage rate, pressure-volume per unit time Leakage rate, tracer gas Indicated leakage rate Bubble radius Capillary radius Pumping speed, volume per unit time Pumping speed, tracer gas Pumping speed of detection instrument Time Time of exposure to tracer gas t R V O V P T Residence time after pressurizing Volume Leakage rate, volume per unit time Ratio of length of circumference of a circle to its diameter Density Surface tension Time constant, volume per unit time Section 4 TESTING FUNDAMENTALS The fundamental concepts involved in leakage testing with a tracer gas are presented in this section. These concepts govern the preparation for a particular leakage test and guide in the selection of the necessary testing equipment. For example, the effects on detector sensitivity and response time of the in- ternal volume of a container relative to the internal volume of a leak detector used to measure leakage from that container can be evaluated from the principles set forth in this section. 4.1 DIMENSIONS OF LEAKAGE UNITS The dimensions of the rate of gas leakage are Pressure x Volume Time O sometimes written as PV. The leakage rate is proportional to the mass flow of a given gas at constant temperature. If the nature of the leaking gas and the temperature are known, it is possible to use the formula for an ideal gas to determine the actual mass leakage. A wide variety of units for leakage are in common use. The units always represent pressure multiplied by volume per unit time. For example, an operator may have a gas tank whose volume is known in cubic feet. The tank is fitted with a pressure gage calibrated in pounds per square inch. If the gage is read daily, it is convenient for him to express the leakage as the product of the change in pressure which occurs during one day and the cylinder volume. He will then express the leakage as psi-cubic feet per day. Suppose leakage occurs from the atmosphere into an evacu- ated chamber and increases the pressure in the chamber. The increase in pressure is determined by the number of molecules entering the chamber. The number of molecules entering the chamber depends not only on the volume flow rate of the gas but also on its pressure. The product of the volume flow rate and the external pressure is equal to the change in pressure Inside the system times the system volume. Thus, it is not fully de- scriptive of the leakage rate to state that so many cubic centi- meters per second of a gas are entering the chamber. Unless the entrance pressure is given, it will be assumed to be equal to one atmosphere. On the other hand, the volume of a given mass of liquid is invariant over a very wide range of pressure; hence, liquid leakage may be expressed in terms of volume flow. Considerable confusion can arise in performing calculations if the dimensions of gas and liquid leakage are not clearly set forth. 4-1 All equations used in this book express gas leakage rates in volume multiplied by pressure per unit time, and liquid leak- age rates in volume per unit time. 4.2 CONVENTIONAL LEAKAGE UNITS Lists of conventional sets of units used to express leakage rate and factors for converting from one set to another are given in Tables 4-1A and 4-1B. In leakage work, mass flow is usually expressed in atmosphere-cubic centimeters per second (atm-cc/sec) at 25 degrees C. Sets of units for leakage rate are commonly employed as follows: • Military standards are written in atmosphere-cubic centimeters per second. . The Atomic Energy Commission specifies leakage rate in standard cubic centimeters per second, defining a standard cc as the volume of a gas at zero degrees centigrade and one atmosphere of pressure• • The George C. Marshall Space Flight Center of the Na- tional Aeronautics and Space Administration defines leakage rate in units known as SCIMs. A SCIM is a standard cubic inch per minute at one atmosphere pres- sure. • The English term lusec is another unit for leakage rate. A lusec is a micron-liter per second, a micron being defined as i/i000 torr. • The tort-liter per second is in common use in America in preference to the less popular micron-liter per second° • Refrigeration servicemen define their leakage speci- fications in ounces per year of refrigerant• This standard is rational, since refrigeration systems are charged with several ounces of refrigerant and the sys- tems must operate for years. A leakage of an ounce per year of refrigerant is equlvalent to a helium leakage of 1.8 × i0 -_ atm-cc/sec. Attempts have been made to initiate a clear, concise and exact form of describing leaks for use in specifications and other documents (Ref. 4-1). Roberts (Ref. 4-2) suggested a nomenclature which eliminates the exponent and units• For example, the desig- nation 2-8G 50-15/2 would signify the following: 2-8 Maximum leak size permitted is 2 x 10 -8 atm-cc/sec G Gas leakage (for liquid leakage: L followed by viscosity in centistokes. Example: L (80), 80 being viscosity of light oil at 20°C) 4-2 Table 4-1A LEAKAGECONVERSIONFACTORS Tort i/sec Micron [/sec (lusec) I Arm cc/sec Psi co/see Tort cu in./sec Micron cu £n./sec Arm cu in./sec I [ Psi cu ;n./sec l 1 * [0 i 1.316 1.934 * 10 I 6.i03 x 10* 6.103 _ l0 _ 8.030 x 10 -_ i 1.180 1 * 10 -a i 1.316 × I0 -a 1.934 x i0 _ 6.103 _ i0 z 6.103 x l01 3.030 x 10 .5 1.180 x i0 -_ 7.60 _ I0 -_ 7,600 x L0 a 1 1.470 _ i0 z 4.638 _ i0' 4.638 * I0 _ 6.103 * i0 "z 8.969 x i0 s 5.171 * 10 _ 5.171 _ l01 6.805 × i0 : 1 3.156 3.156 x 10) 4.153 • i0 "_ 6.103 _ 10 -z 1.638 _ 10 _ 1,638 _ i01 2.156 x i0 2 3.168 _ i0 z 1 1 * i0 _ 1.316 _ lO 3 1.934 x i0 -2 1.638 _ i0 "_ 1,638 w i0 z 2.156 x i0 "s 3.168 x I0 _ i w 10 _ i 1.316 " l0 ¢ 1.934 _ i0 s 1.245 x i0 z 1.245 _ I0 _ 1.638 _ I0 I 2.408 _ i0 _ 7.60 • 10 z 7.60 x I0 s I 1.470 _ i0 z 8.474 * I0"* 8,474 _ I0 a 1.115 1.638 _ i0 z 5.171 . 10 s 5.171 x I0 * 6.805 x 10 -z 1 To change the time base from seconds: To Multiply Value by Minutes 60 Hours 3600 Days 8.640 x I0 _ Weeks 6.048 • 10 s Months 2.417 x l0 6 Years 3.154 x i0 ? Table 4-1B LEAKAGE CONVERSION FACTORS (WEIGHT) Tort liters Molecules Gram-moles Kilogr am-moles Ounce-moles Pound-moles 0.76 2.7_i0 L_ 4.5_I0 _s 4.5xi0 -m 1.6 x I0 "_ 1.0.i0 "7 1.3 3.5xi0 l_ 5.9,i0 -I 5.9xi0 "i 2.1xlO "_ 1.3xl0 "? 3.7 _ i0 "z° 2.8 _ I0 "z" 1.7 < i0 "2_ 1.7 x i0 "n 5.9x10 -2m 3.7xI0 a7 2.2.10 _ 1.7x10" 6.0.i0 _s I0 _ 3.5x10 _ 2.2x10 * 2.2_10' 1.7 . 10' 6.0x10 z* i0 ) 35 2.2 6.4x10 s 4.8 x 10 s 1.7 i0 zs 28 2.8_i0 -_ 6.3xi0 2 l. OxlO _ 7.7 _ lO t 2.7_i0 z_ 4.5 . iO a 0.45 The weight leakages are stated in welght-mole units; i.e., the num_oer of moles of the material expressed in the stated weight unite. To obtain the weight of material, mul- tiply the weight-mole by the molecular weight of the material. The conversions between volume and weight or molecular numbers are made for a gas temperature of 0ec. TO convert volume to • weight at any other temperature, multiply result of calculation at 0eC by 273/(273 + T}, where T is the temperature in de_rees centigrade. Example: Convert 5 × 10 "_ a_m-oc of air at 100"C to grams: (5 x 10 "_) x (4.5 x i0 "_ ) x 29 x {273/373) = 4.78 x 10-TGrams (Gram-molesl x (Molecular Weight) x (Temperature Correction) m {Grams)(Arm-co) _ (Atm-cc) 4-3 50-15 High-side pressure, psza; and low-side pres- sure, psia /2 Maximum accuracy factor of detection method. Here it is required that the demonstrable accuracy of the leak detector -- leak tracer -- leak standard system fall within the range of 1 _ i0 -_ to 4 _ i0 -_ atm-cc/sec. 4.3 LEAK CONDUCTANCE In vacuum technology, a leak is a hole or porosity in the wall of an enclosure capable of passzng gas from one side of the wall of the enclosure to the other when a pressure or con- centration differential is established across the wall (Ref. 4-3). Unless a leak is intentionally manufactured in an item, the dimensions of the leak will generally be unknown and indeter- minate. As a result, it is not possible to calculate in advance the flow of a fluld through the leak under a given pressure dif- ferential. It becomes necessary, rather, to characterize the leak in terms of an extrinsic property known as conductance. The conductance of a leak zs determined by applying a mea- sured differential pressure across the wall in which the leak is located, and measuring the rate at which fluid passes through the leak. The conductance is given by the following ratio be- tween the two measured quantities: C = Q (4-1) PI - P2 Thus conductance is the (volume flow rate) tlmes (pressure) per (pressure difference). In a conventional set of units, conduc- tance is measured in atm-cc/sec/atm. Conductance is also the ratio of the volume of a gas that enters a leak at one atmosphere of pressure and exits from that leak to vacuum per unit of time. In this case the dimensions of conductance are volume per unit time, or cubic centimeters per second in the units above. The conductance is dependent upon the mode in which the fluid flows through the leak, and may often be found to be dif- ferent at different levels of absolute pressure, especially when the average value of the inlet and outlet pressures in one situ- ation is greatly dlfferent from that in another sltuation A large change in conductance can be observed when the average pres- sure is close to a transztion region between two modes of flow. The transition from laminar to molecular flow with decreasing average pressure is a common instance of a mode change. It is zmportant to specify the average pressure at which the conductance is measured. In fact zt is helpful to measure the flow rate versus dlfferential pressure over the same range of ab- solute values of pressure which is expected to prevail in the equipment in which the leak is located. An average value of 4-4 conductance can then be determined from data obtained in this way and any large changes in conductance observed. Changes in conductance due to a change in the area of the cross section of the leak with pressure will be taken into account. An abrupt increase in the cross section at high pressure would abruptly increase the conductance, and would reveal the presence of an incipient leak path which might not be noticed in a test at a lower pressure. 4.4 SENSITIVITY AND TESTING The sensitivlty of a detector is determined by the minimum concentration of tracer gas which will produce a measurable sig- nal at the detector. An increase in the pressure of tracer gas applied in the region of a leak will increase the flow of tracer gas through the leak and Into the detector. The minimum level of leak conductance which can be detected with a detector of fixed sensitivity will decrease as the pressure of tracer gas at the entrance to the leak is increased. Thus, holes of smaller size can be found if a higher entrance pressure is employed. For example, a small increase in pressure on the detector side of the leak will not affect the sensitivity of a detector of the mass spectrometer type. Factors affecting detector sensitivity are presented in more detail in sections dealing with specific instruments, their operation, and use. The above brief discussion shows how the sensitivity of a test can be increased by changing a parameter external to the detector. In dynamic (steady-state) testing a pressure increase is effective in increasing test sensitivity. In static (accumu- lation) testing an increase in testing time accomplishes a similar increase in test sensitivity. In both cases the detector or in- strument sensitivity would remain the same. 4,5 LEAKAGE MEASUREMENT TESTING The leakage measurement technique involves a sampling of the total leakage from a closed system or from a region of a closed system which requires leakage testing. Use of the technique re- sults in an indication of a leak if it is present, but not in the identification of particular locations where leakage occurs on the object being tested. Tests using the leakage measurement technique can be con- ducted in two ways, as shown in Figure 4-1. By one method, the object to be tested is pressurized with tracer gas and placed inside a closed container, to which a leak detector is attached. The external container may be filled with normal air or any gas other than the tracer gas to which the detector is sensitive. The detector must be of a type operable at or near atmospheric pressure in this case. Alternatively, the container may be evac- uated and a vacuum type of instrument employed. Evacuation of the container increases the differential pressure across any leak- age path in the wall of the test object by one atmosphere for the same pressure of tracer gas that was used in the first instance 4-5 f ° ENV F'LOI_E ' • • °, • = .,, °o , o • ° ° °. o 4 • . , o • • • '.°o ., SYSTEM " i ..• .,. TEST",:. !.'.':':':..:.:::. • # 1 [o r---1o ILEAKDETECTOR PRESSURIZED SYSTEM MODE '.;"i-:'._NV'E!LOPE:."':':"_ "i:.",':' TEST" [.:'.."i': . ...:.. lo r--n o ILEAKDETECTOR PRESSURIZED ENVELOPE MODE r 1 Figure 4-1• Leakage Measurement Modes Using the Dynamic Testing Technique 4-6 above. The sensitivity of the vacuum type of detector may be higher than that of the detector operating at atmospheric pres- sure, with the same differential pressure across the leak. A second approach is to pressurize the container and evac- uate the test object. In this situation a vacuum detector is located in the vacuum line to detect inward leakage from the pressurized container. The tracer gas flows to the detector, where its concentration is measured when equilibrium is estab- lished. The equation for the response of the detector is: Q = PS (4-2) Here it is assumed that the only gas in the detecting system is tracer gas. The test sensitivity should be the same for either direction of flow through the leak paths, providing the same levels of ab- solute pressure and differential pressure of tracer gas are em- ployed. The choice between the above two approaches might be based on the ability of the test object or the container to with- stand pressure in one direction in preference to the other, or on the ease with which tracer gas may be applied to one side of the test object. Some of the factors which affect the sensitivity and re- sponses of the detector when the leakage measurement technique is employed are: l. Physical properties of the particular tracer gas which is used. These govern the rate at which gas will traverse a leak path. • Speed at which tracer gas is removed by the vacuum pump in comparison with the volume of the test ob- ject. . Sensitivity of the detector for the particular tracer gas used. • Position of the tracer sensing element in the pump- ing system. It is also possible to test and measure gas leakage from a pressurized test object by building a frame to support a plastic bag or tent which surrounds the test object. The bag is filled initially with atmospheric air (Refs. 4-4 and 4-5). The rate of change of tracer gas concentration is determined on a compara- tive basis against a known rate of tracer leakage into the bag. The method is especially useful in testing very large objects, perhaps ten to twenty feet high and several feet in diameter. References 4-4 and 4-5 discuss the accuracy of this method of measuring leakage. Measured values are within about 10 percent of the expected values on the basis of tests with calibrated leaks. The method does not appear to be useful for measuring 4-7 leakage rates less than I0 -s atm-cc/sec, but may be entirely adequate in some testing situations. Certainly this level of test sensitivity is comparable with that attainable with bubble testing. The method has none of the disadvantages of bubble testing in that the test object is not wetted or contaminated and a large tank filled with heavy liquid is not required. 4.5.1 Magnitude of Response The magnitude of the response in the dynamic (steady-state) method is dependent on the sensitivity of the detector to the tracer gas used and the speed at which the gas is removed by the pump. In most cases, where the tracer-gas partial pressure is converted by the instrument to a current which is proportional to pressure, Equation 4-2 can be expressed in the following form: Q = Sd(Ka) (4-3) In this form, the product Ka has dimensions of pressure. Instru- ment sensitivity can be affected by changing either K or a. The multiplication factor K can be increased to a limit generally imposed by electronic instrument noise; a can be increased by increasing the tracer-gas partial pressure within the system through a decreased pumping speed. Thus the sensitivity of the method increases with a decrease in pumping speed. Unfortunately, this increase in sensitivity brings with it a decrease in the speed of response. There are times, however, when it becomes necessary to em- ploy additional pumps in the evacuation system being used for testing. This is particularly the case when the detector must operate at a low pressure. The additional pumps are necessary to remove gas arising from both leakage and outgassing at a rate sufficient to keep the pressure at the detector at a suitably low level. The manner of connecting an additional pump to the detec- tor system is shown in Figure 4-2. This pump increases the total i _'::'.'ENv EL'OPIE}'.";':_;. ...... ..!:: 0 IoF--1olLEAKDETECTOR Figure 4-2. L I I Leakage Measurement Involving the Use of an Auxiliary Pump 4-8 pumping speed of the system and reduces the partial pressure of the tracer gas at the detector. The sensitivity of the measure- ment is thereby reduced. 4.5.2 System Response Time Although the pumping speed of a dynamic leak detecting sys- tem determines the magnltude of the response at equilibrium (Equa- tion 4-2), several other factors influence the system response time. System volume is the most important of these factors. The complete subject is discussed in detail in several papers (Refs. 4-6, 4-7, 4-8, and 4-9). The discussion here shows the fundamental points involved. The response time of a leak detection system may be deter- mined by considering a system with leakage rate of tracer gas QE, an evacuated volume, V, and an internal partial pressure of tracer gas PE. This system is evacuated by external pumps, and a portion of the tracer gas passes through the leak detector (see Figure 4-2). The pumping speed at the outlet of the vol- ume to be tested is called SE. A mass balance on the system at constant temperature requires that the rate of tracer gas ac- cumulation within the system be equal to the rate of tracer gas leaking into the system, less the rate at which tracer gas is pumped out of the system, or: dP2 V _ = QE - PESE (4-4) When this equation is integrated with the initial condition that at t = 0 the tracer gas partial pressure is P0, there results: QE - PESE SEt Zn = (4-5) QE - PoSE V or, QE - PESE = e-SEt/V QE - PoSE (4-6) If the pumping speed S is the same for all gases, then S = S E, and the subscript may be omitted. Two special cases of Equation 4-6 are of interest. First is the case in which the system has been pumped for a long time and the partial pressure of the tracer gas in the system is ini- tially zero (P0 = 0). Equation 4-6 then becomes: QE -St/V) (4-7) PE = S-- (1 - e After a long exposure time the exponential term approaches zero, and PE = QE/s (4-8) 4-9 For example, a leak detector may be pumping on a 10-1iter system with a one-liter-per-second pump. The response of such a system is plotted as Curve 1 in Figure 4-3. In ten seconds, the detector responds with 63 percent of the ultimate signal. The equilibrium signal is attained in approximately one minute. If the system to be pumped is i00 liters, the response time is considerably longer. As seen on Curve 2 of Figure 4-3, in i0 seconds only about 10 percent of the total response is observed. The equilibrium value is not reached for i0 minutes. Such a response time might not be acceptable for leakage measurement, and is of dubious value for leak location. It is possible to decrease the response time by increasing the pump- ing speed of the system. In Curve 3 of Figure 4-3, the pumping speed for the 100-1iter volume has been increased from one liter per second to five liters per second. This, however, decreases the magnitude of the signal. It may be observed that in this particular case the response rates for Curves 2 and 3 are simi- lar at the beginning of the test. The second special case of Equation 4-6 is that in which the pumps continue evacuation and gradually reduce the tracer gas concentration in the system. This condition corresponds to QE = 0 in Equation 4-6. The equation thus becomes: PE = P0e-St/V (4-9) Curves 1 and 3 of Figure 4-3 indicate that the tracer gas is pumped rapidly from the system once it is removed from the vicinity of the leak. However, in Curve 2, the gas remains for a considerable period. The important factor in determining the shapes of these curves is the ratio S/V. The reciprocal quan- tity V/S, having the dimensions of time, is generally called the time constant of the system, T. A long time constant re- sults in a large indicated partial pressure change during the probing time. A short time constant permits rapid removal of search gas from the system when probing has ceased. If the requirements of rapid response and clean-up times are not met, the leak-testing process is delayed to a large and sometimes intolerable extent. As an example, consider the case of a section of weld being probed at a constant rate. If the response is poor, the leakage indication will appear after the probe has moved well beyond the leak, and the path will have to be retraced slowly until a second signal is obtained. The second signal cannot be observed distinctly until the first signal has dropped to a low level. Therefore, the decay or clean-up time is equally as important as the response time. Once the time constant V/S (volume/pumping speed) of the system has been calculated, and the equilibrium response is known, 4-10 I! i i I"" I,,61 _ _2 _ B-_\ 8_ II II - \ _ I I 1 Jo o Io I / -" "" "" // 83_. 3_. _-_-'8_,== = ¢o Q_ Qo n oO n _ cd ¢y ¢Y ¢Y i I _' ....---4-'"i \ I i I \ \ / i/ o " 0/ I ! I I I I I I I I I I I I I I 6_ I! -I ml wl e,-I I I I I ! ! I 0 Z 0 0 cn 0 I-- 0 0 8 8 8 _J E_ _J 0 0 0 4o o') I B4 -)=4 0 SIINfl ' 3SNOdS3_ NOIIO313G 0 4-11 it is possible to construct response curves similar to those shown in Figure 4-3. Table 4-2 shows signal response as a per- centage of final signal strength for several different time con- stants. Table 4-2 SIGNAL RESPONSES AS A PERCENTAGE OF FINAL SIGNAL STRENGTH Percent of Final Si@nal Signal Signal Time Constant Increasin@ Decreasin@ 0.5 39.4 60.6 1 63.2 36.8 2 86.5 13.5 3 95.0 5.0 4 98.2 1.8 The response of the detector in a leak detecting system relative to the equilibrium response may be estimated with the aid of the nomograph shown in Figure 4-4. Pumping speed, sys- tem volume, and the time which has elapsed from the moment tra- cer gas was applied to or removed from the system must be known. The nomograph consists of the following parallel axes: I. System volume, V 2. Pumping speed, S 3. Reference 4. Elapsed time, T 5. Relative response, Scales A, B, and C A straight line is drawn connecting the two points repre- senting values of S and T. This line intercepts the Reference axis. A line is then extended from the volume axis at the value of V, through the intercept on the Reference axis, and is ter- minated on the Response axis. Scale A on the Response axis re- presents the number of elapsed tlme constants before the signal is read. Scale B represents the response relative to the equil- ibrium signal after the tracer gas has been removed. Scale C represents the response relative to the equil_brium signal after the tracer gas has been applied. The utility of the nomograph can be extended to any range of values by multiplying only the V, S, and T values by ten raised to an appropriate power. The response axis need not be so modified. 4-12 200G 1500 I000 9O0 600- 500 - 400- b-- ._ 300- > 250- 200 - JO0 9O 8O 70 6O SO t 500- PARAII_T[R A T : St/V 400- e [e'a], REFER Eg 4-9 c [,-e'a],.EVER eO 4-7 300_ 260- S ZOO tSO IO0 90- gO- 70- -tOO f' 0 -,0 - 90 -60 i ._. sst / I j/ 30- :t_ w..- Z5 > -- "" _ 15-- r_ iO" i5 11_ 7- 6- 10 5 _,# A B C 4 -_ - 0.018_?. 0.98167 3 - - 0.0490 0.9501 - 0.1353 O.0647 l- - 0.3670 0.632t 0.5" 0.6060 0.3940 Figure 4-4. Response Nomograph for a Leakage Detection System 4-13 4.5.3 Detector Location In recent years, many papers dealing with dynamic (steady- state) leakage measurement have been published. To increase the sensitivity of this method, it is often suggested that the detector be connected between the diffusion pump and the fore- pump (see Figure 4-5). While some authors conclude that such an arrangement does not show any improvement (Refs. 4-6 and 4-7), or that an improvement may be obtained under certain conditions (Ref. 4-8), others assert that by this procedure the change in probe pressure in the forepressure line can be considerably great- er than in the test chamber (Refs. 4-9, 4-10, and 4-11). These differences in interpretation form the basis for extensive dis- cussions in current technical periodicals (Refs. 4-7, 4-12, 4-13, " 4-14, and 4-15). D.J. Santeler (Ref. 4-16) summarizes these discussions by stating that whether or not an advantage is gained depends on the factor that is limiting the ultimate sensitivity of the test. In a clean system, the ultimate sensitivity may be limited by the partial-pressure sensitivity of the detector. In this event, the pressure amplification obtained on the forepressure side will result in a sensitivity gain. In a contaminated system, or in a search for extremely small leaks in the presence of large leaks, the sensitivity is frequently limited by the resolution of the detector in distinguishing tracer-gas partial pressure from the background. In this event, forepressure leak detection results in amplification of both tracer signal and background and unless selective pumping means are employed, no gain in the concentra- tion ratio is realized. When the leak detector is connected on the forepump side of the diffusion pump, the forepump removes gas from the system by a batch process and the pressure of its inlet side tends to fluc- tuate. These fluctuations contribute to the noise level of a sensitive detecting element if it is directly connected to the mechanical pump. The effect can be greatly attenuated by locat- ing the detecting element in the line between two diffusion pumps connected in series. An alternative approach is to place a bal- last tank or a throttling valve between the forepump and the de- tector (see Figure 4-5). 4.6 TRACER-ACCUMULATION TESTING When the tracer-accumulation technique is used, the device to be tested is pressurized with the tracer gas and placed in a leak-tight chamber. The concentration of tracer gas in the cham- ber is then monitored as a function of time. Depending on the instrument being used for monitoring, the chamber can either be evacuated or remain at atmospheric pressure. The important charac- teristic which defines accumulation (static) testing is the con- centration of the increased tracer gas in the test chamber during the testing period. In general, accumulation testing can be more sensitive than steady-state testing, since the sensitivity can be 4-14 _ _NvE!°_!1 C) ._ I.":k u_°_. U L".:;_-:.;.]_ o_.,o. DIFFUSION PUMP I°r--lol_=LEAKDETECTOR VACUUM SIDE r' 1 ' 1%_r=_11o_ o ON FORE PUMP rA i0i ,--, I i J I JFORE PUMP [ Fzgure 4-5. Alternate Sites for Leak Detector on Vacuum System 4-15 increased simply by increasing the accumulation time, assuming that outgassing and leakage into or out of the test chamber are negligible. The governing equation for leakage measured by accumulation testing is dP Q = V _-_ (4-10) Consider, then, a test object of volume V_ at initial pressure PI - Pl 0 , placed inside a chamber, with V2 as the volume of the chamber not occupied by the test object° The chamber is evacuated and sealed off at an initial pressure P2 = P20 = 0. A gage at- tached to the chamber measures the pressure P2. Applying Equation 4-10 to both volumes Vl and V2 results in I dP_ _ 1 V_ dt -Q 2 +Q V_ From these can be written dP dP2 Vl _-_ = -V2 d--_- (4-11a) (4-11b) (4-11c) integrating so that P: P2 Pl_ P_0 -V2dP_ (4-11d) Vl (P, - P: u) = -V2 (P2 - P2_) For a leak having a conductance C and a flow rate Q, Q = C(PI - PI 0) = C(P2 - P_0 ) (4-11e) (4-11f) Combining Equations 4-11e and 4-11f, Q = C [P:0 - P_ (i ÷ V2/V:) ] (4-11g) But Q is also equal to (V2) dP2/dt from Equation 4-11b. Substituting Equation 4-11b in 4-11g and simplifying gives Rearranging and integrating with respect to P2 and time t, [°cvivlIin - IVI+V VI = -Ct V2 (4-11i)ic I V_ P20 4-16 Now, since P20 is zero, the conductance of the leak can be calculated in terms of elapsed time T and the pressure P2 in the outer chamber. (It is here assumed that PI 0 was known when the object was placed in the chamber and, therefore, that the change in PI 0 before testing began was negligible.) This calculation, of course, is based on the assumption that the total conductance of all leaks in the object is relatively small. Equation 4-11i may be expressed in exponential form to show how P2 varies with time for a given leak conductance and initial pressure. Thus, ll (VIV2(vl(IP2 = VI_92 P1° - e (4-11j) P2 approaches (Vl/(Vl + V2)) P*0 with time. The above analysis is also applicable when the outer cham- ber is not evacuated but contains an atmosphere in which there is no tracer gas. In this case, P2 represents the partial pres- sure of tracer gas in the chamber. The accumulation technique is useful when l . 2. • • A reading of total leakage is desired. The leak to be measured is smaller than the maximum sensitivity of the leak detector in the steady-state mode. The background contamination is severe, making it difficult to stabilize the leak detector for ordinary steady-state testing• There are surfaces or a number of possible leak points not feasible or economical to check individ- ually. The accumulation chamber should be made reasonably tight to prevent loss of tracer gas by direct leakage. The accumu- lation chamber should also be made of nonpermeable material, to minimize losses by permeation. If the accumulation chamber has an unsymmetrical shape, some means should be provided to circulate the air within the chamber. This will tend to prevent an uneven concentration of tracer gas. Circulation is also necessary when the chamber is of a large volume or when a high-density tracer gas (that tends to stratify) is used. A shortcoming of this method is that during the period of waiting for the tracer gas concentration to increase, it is also possible for adsorbed gases to be released. Frequently this out- gassing will interfere with the detection of the tracer gas, re- sulting in biased leakage values. The use of a partial-pressure analyzer will identify the various gases present and allow virtual leaks to be distinguished from real leaks. 4-17 4.7 LEAK LOCATION TECHNIQUES Although there are numerous techniques which can be used to locate leaks, bubble emission, tracer probe, and detector probe are the methods most frequently used. Techniques involving sonic energy, high potential discharge, and chemical reaction are use- ful under rather specific conditions. 4.7.1 Bubble Testing The immersion or covering of a leaking part by a liquid leads to the formation of bubbles at the source of the leakage. Bubbles are emitted from a leak when the internal pressure ex- ceeds the external liquid-head and surface-tension forces. Bubble size and frequency are functions of gas flow rate, leak size, and surface tension; these effects are discussed in References 4-17 and 4-18. In the simplest example, that of a single cylin- drical capillary, the equilibrium bubble pressure is given by 2o P = P0 + pgh + _-- (4-12) representing the atmosphere pressure above the liquid, the grav- itational head of the liquid, and the pressure due to surface tension of the bubble as it begins to form at the liquid end of the capillary. As the gas flows through the capillary (leak), each bubble forms and expands, ultimately being attached to the rim of the leak by a neck, as illustrated in Figure 4-6 for the case of liquid wetting the leak channel. Assuming that the bubble formed at the end of a tube is part of a sphere, then as the bubble is being generated, its radius R first decreases, as indicated by Figure 4-6(a), until it reaches its minimum value r, corresponding to the radius of the capillary as shown in Figure 4-6(b). Thereafter the radius RB increases to form the expanding bubble shown in Figure 4-6(c). This vari- ation implies that the term 2_/R in Equation 4-12 has a maximum value, 2o/r, corresponding to the maximum value of excess pres- sure. When the bubble buoyancy exceeds the surface tension re- straint at the neck, the bubble is detached and rises to the surface. Bubble detachment occurs when 4z R_pg = 2zro (4-13) Equations 4-12 and 4-13 present almost the total picture of bubble formation and growth. In more rigorous equations, viscosity affects the bubble size; however, this is considered negligible (Ref. 4-18) in most leaks. With an increase in vis- cosity there will be a small increase in bubble size. 4-18 LIQUID BUBBLE Z.--LIQ U IO-- - ---LIQUID--_ , ...,., .-'... : (o) (b) (c) Figure 4-6. Bubble Formation at a Leak Site (Reprinted with permission from J.G.S. Biram and G. Burrows, "Bubble Tests for Gas Tightness," Vacuum, Vol. 14, June 1964, p. 223.) The external pressure may be regarded as constant; there- fore, there is a critical value of the pressure inside the bubble which must be reached if the bubble is to expand beyond the hemi- spherical stage. This condition imposes a limit on the applica- tion of bubble testing. For example, if the end of the capillary is just submerged in water, _ = 73 dynes per centimeter, and the capillary is supplied with gas at a differential pressure of one atmosphere (i.01 x 106 dynes per square centimeter), than 2 × 73 r = = 1.45 x 10 -4 cm 1.01 x 10 _ This is the smallest capillary radius that could be detected by means of a bubble for the given pressure difference. If, however, a liquid of lower surface tension were used, such as methyl or ethyl alcohol, then the same differential pressure would allow a bubble to be formed at the end of a cap- illary of radius 2 x 23 = 4.5 x 10 -5 cm. 1.01 x 106 This radius is less than one-third of the smallest radius of a capillary which can be detected when water is used. With liquids having lower surface tensions, leakage rates 1/50 to i/i00 of the lowest rate detectable when the bubbles are formed in water can be detected. Another factor which affects the sensitivity of bubble test- ing is the average size of the bubbles evolved. It may be seen by an examination of Equation 4-13 that the size of the bubble 4-19 increases with an increase in surface tension. Therefore, the generation of a large number of bubbles requires the use of liquids having a small surface tension. Bubble size is influenced by mechanically vibrating the test object. If the test object is vibrated, the bubble breaks off before it would if the test piece were stationary. This can be useful, as it increases the bubble rate for a given leak rate. If the pressure over the liquid is reduced below atmospheric until bubbles just emerge from the end of the leakage path, lim- itations are imposed by the tendency of a liquid to degas and boil under conditions of reduced pressure. A comparatively high boiling point permits reasonably low pressures to be realized without boiling. To enable the smaller leaks to be detected it is desirable to use liquids having low values of surface ten- sion; but such liquids also have correspondingly lower boiling points. These liquids may boil spontaneously before the pres- sure over the liquid can be reduced sufficiently to increase the rate of bubble formation significantly. Therefore, the choice of liquid for these tests must be very carefully made. In summary, it is desirable to use a liquid of low surface tension and low viscosity. Pressure has to be higher with capillaries of small diameter. Finally, the use of a low-vis- cosity, low-molecular-weight gas will increase the flow rate through the capillary. 4.7.2 Probe Techniques There are two distinct techniques for locating leaks with instrument probes. One employs a tracer probe and the other a detector probe, as shown in Figure 4-7. By the former tech- nique, a fine stream of tracer gas from the tracer probe is played over the suspected leak area. Tracer gas is drawn into the interior of the test object if a leak is present, and is discovered by the leak detector. For the detector probe, tracer gas blankets one side of the system being tested. The detector probe is then passed over the suspected area to determine if tracer gas is leaking through to the detector side of the system. The response equa- tions given in Section 4.5 for steady-state testing apply to both probe techniques. (A detector probe is also known by such names as sniffer probe, pressure probe, sampling probe, and re- verse probe.) Selection of one or the other methods depends on several factors. For example, the detector probe technique of leak location should be used if the system must be tested in a pres- surized condition, or the tracer gas is readily absorbed on the leak surfaces. If a tracer probe is used and the gas is absorbed in the leak, small leaks will go unnoticed since an equilibrium 4-20 PROBE SYSTEM UNDER ' TEST ' TRACER PROBE TECHNIQUE !o r-I ol LEAK DETECTOR I"'1 PROBE :':".'UNDER "::Jl !i:. DETECTOR PROBE TECHNIQUE [o r-7 o I LEAK DETECTOR Figure 4-7. Leak Location Techniques is not quickly established between the leak surfaces and the tracer gas. (See Section 6.5 for details.) The detector probe technique may also be used if the detector has a sensing ele- ment that operates unde_ atmospheric pressure. Leak location by means of the tracer probe technique is usable on systems which can be evacuated or otherwise subjected to pressures below atmospheric. It is necessary that a port or aperture be available for attachment of the detector. Other factors affect the choice of one technique over the other. • It may be desirable to check for leakage in one specific direction where the existence of check valve leaks is suspected (see Section 6.5) • The system might have long, narrow passages, so that it will be prefereable to pressurize rather 4-21 than evacuate them. This is because the rate of travel of molecules in narrow evacuated passages is slow and a long time is required to reach the operating pressure of the leak detector. 4.8 SEALED UNIT TESTING Two methods of testing sealed units are: • Fill with tracer gas under pressure during manufac- ture. Test for gas leaks. • Seal the unit, subject to high-pressure tracer gas, and remove tracer gas from the outside envelope. Test for gas leaking from the sealed unit. This technique is called "bombing" or "back-pressurizing". 4.8.1 Unit Sealed With Tracer Gas For the first of these systems, the effect of leak size on detector signal may be represented in the generalized graph of Figure 4-8. Here the leak rate, derived from the signal of the detector, is plotted against the leak conductance. The curve represents the situation where the pressure of the tracer gas is initially atmospheric and where a fixed time elapses be- tween manufacture and testing. Because of the time lapse, the curve departs from the line of unit slope, reaches a maximum, and falls for larger leak conductances. This is caused by the diffusive loss of gas from a leaking specimen. The minimum de- tectable leak is thus fixed by the detector, and the maximum detectable leak by the time lapse before testing (among other factors such as the internal geometry of the unit and the rate of release of absorbed tracer gas from the internal surfaces). It follows from this description that extremely large leaks cannot be detected by this procedure. Some independent method of testing, such as immersion bubble testing, must be used to detect extremely large leaks. It also follows that this method will not be quantitative on large leaks. The leak size at which this method ceases to be quantitative may be calculated from the magnitude of tracer-gas loss prior to leakage measurement. 4.8.2 Back-pressurizing Technique Back-pressurizing is a term coined by Howl and Mann (Ref. 4-19). Their article is the most comprehensive treatment of this technique. The test unit is held for a period in a pressure vessel con- taining tracer gas at a high pressure. The gas enters the unit through any leak and is detected when the unit is taken out of the pressure vessel and the gas issues from the leak. The rate of the flow depends not only on the conductance of the leak but on how much gas has entered during the pressurizing period. 4-22 _J o= > _3 / / _,/_, _ LIMITING SENSITIVITY OF DETECTOR LEAK CONDUCTANCE Figure 4-8. Detector Response for a Unit Sealed with Tracer Gas (Reprinted with permission from D.A. Howl and C.A. Mann, "The Back-pressurizing Technique of Leak-testing," Vacuum, Vol. 15, No. 7, 1965, pp. 347-52; Pergamon Press Copyright 1965 (Ref. 4-19) .) The leak-conductance signal-response curve for the back- pressurizing process is shown in Figure 4-9. For very small leaks, where the final signal is a function of the leak conduc- tance and the partial pressure of the tracer after pressurizing, itself a function of leak conductance, the curve is concave and tangential to the x-axis. The curve crosses the line of unit slope where the leak conductance and pressurizing conditions are such as to raise the pressure of the tracer to one atmosphere. The curve remains above this line for a range determined by these two factors and, in addition, by the time lapse before testing. The physical significance of this curve being above the unit slope is that the pressure of the tracer in the specimen is above atmos- pheric at the time of test. The curve subsequently falls, as in Figure 4-8. 4-23 T .J Z m O9 ri- O I-- I-- W 0 n- It. > Q W t.O v L_ ._J / / / / / / / / / / / / / LIMITING SENSITIVITY OF DETECTOR LEAK CONDUCTANCE Figure 4-9. Relation of Leak-rate Signal to Leak Conductance for Back-pressurizing Tech- nique (Reprinted with permission from D.A. Howl and C.A. Mann, "The Back- pressurizing of Technique of Leak-test- ing," Vacuum, Vol. 15, No. 7, 1965, pp. 347-52; Pergamon Press Copyright 1965 (Ref. 4-19).) Although the minimum and maximum detectable leaks are shown as greater in Figure 4-9 than in Figure 4-8, this is not of gen- eral significance. Back-pressurizing may be more or less sensi- tive than a test with previous filling with tracer, depending on the pressurizing and test conditions. The discussion which follows indicates how the sensitivity may be determined or the conditions specified for a given sensi- tivity. The discussion includes the effect of absorbed tracer gas on the outside of the test specimen, which can be one of the main practical disadvantages of the method. The back-pressurizing technique of leak testing is carried out in three distinct steps: 4-24 i , . . A tracer gas at high pressure is applied to the ex- ternal surface of the test specimen, causing inflow of the tracer gas through any leak. A period ensues following the removal of the source of tracer gas during which some tracer gas is lost from the test specimen through the leak. A test for leakage is performed on the test speci- men. Consider the application of the back-pressurizing technique to leaks through which the flow is either purely molecular or purely laminar (see Section 6). In leak-testing practice the leak with molecular flow is the more important, since it is necessary to detect leaks down to 10 -_ torr liter per second or less, although leaks of 10 -3 torr liter per second may still show molecular flow characteristics. For capillary leaks it can be shown that the leakage rate must be less than 10 -6 atm- cc/sec for purely molecular flow and greater than i0 -_ atm-cc/ sec for purely laminar flow. 4.8.2.1 Molecular Flow Leaks. Assuming that the flow in and out of the system is molecular, the equation derived (Ref. 4-17) for the measured flow after performance of the three-steps de- scribed above is: Q = CA PE 1 - exp exp - V (4-14) Figure 4-10 shows a plot of the measured leakage Q against leak conductance CA for typical values of PE, V, tE, and t R. Most leak detector systems using tracer gases are designed to detect leaks very much smaller than i0 -s torr liter per second. An assessment of the smallest detectable leak must therefore be based upon the molecular flow e_uation. Furthermore, for the very small leaks (less than i0 -_ torr liter per second) it is possible to reduce this equation to a very simple form: PEtE 2 (4-15)Q = V CA This may be rewritten: Qv PEtE = _--r (4-16) CA The smallest detectable leak CA depends upon the minimum leak rate Q, which gives a signal on the detector appreciably above the background. Equation 4-16 defines the value of the product PEtE necessary to detect leaks as small as CA on a system with a background signal appreciably smaller than Q. Figure 4-I1 shows the product of PEtE plotted against CA for various values of system volume, the minimum detectable sig- nal being taken as 2.5 × 10 -8 torr liters per second. 4-25 10-2 PLOTTED FOR : PE = 8 otrn V = 2 cm 3 tE = 2h t R = IOmln I I i0 "5 10-4 10-3 LEAKAGE CONDUCTANCE, C A , TORR L/sec otto Figure 4-i0. Computed Relation of Leak-rate Signal to Leak Conductance for a Particular Set of Conditions. (Reprinted with permission from D.A. Howl and C.A. Mann, "The Back-Pressurizing Technique of Leak-Testing", Vacuum, Vol. 15, No. 7, 1965, pp. 347-352; copyright 1965 Pergamon Press (Ref. 4-19).) It is common for the noise level or background signal of the detector to result mainly from the presence of tracer gas which has been absorbed on the surface of the system during pressurizing. The amount of this absorption, and of the sub- sequent desorption during the leak test, is dependent on the gas used and on the material of the outer surface of the speci- men and its finish. Generally, bright metal surfaces absorb least, oxidized metal surfaces absorb significantly, and such porous materials as graphite absorb excessively. As a first step in any back-pressurizing test, the signal from desorbed tracer gas should, if possible, be measured experimentally, using a specimen of the material which will be used. The effect of significant absorption can be _educed by heating the specimen. This can be done either after pressur- izing or, to minimize delay before testing, by heating while pressurizing. While hot, the tracer gas desorbs rapidly. In tests on nuclear fuel elements using helium (Ref. 4-19), tem- peratures in the range 200 - 400oC have been found satisfactory ,_r 4-26 F':_gur e 4-J.i. ' l I 1 I I0 :O0 ,0_,0 PRODUCT PETE, olm-H i'.,-.quz:e'lValues of _,_:tE C,:_ic'._'._%<:_i-c: Q -= 2.5 i0"" To_'t LJter uer Scce,;d. iReFrznt_! '..:!th permLa:_1o:_ f_em D.A. ,[owl al_d C-;,. :.'.z:t:_.,"The Rac_-p._css_,r - lzlng Te.cl nzque <.f Leal:.-tusr_ng," Vacua.t,, Vol. 15, : "2 p_ _ . This imF, i-e" that EquatJo_ 4-17 is valid for leaks greotcr thin th,._ range of i0 -'_ tort liters per se=c::d per atmo_p]:ere, if the volume of the s:/stum is in t_,e cubic c_ntimet ar r_n,ie. Equation 4-1.7 for laminar flow ]ed]:_; breaks down ".:h,_:., in the seco._d staqe, with the _est soot_men in the :_tmos:sheI_, .-_._-.,-a_ainst t:,.: outflow the diffusion of air into t'ne test 5?c ....._ ..... of gas bccc, mes appreciatie- This is areitlari!y ass_ed to occur when the pres[:ure in the system is less than tv.lce atmos- pheric pressure. Calculations using E__uation 4-17 for laminar rio'.-, are co:<-- pared with the results when using Equation ,,-14 for _m].ecular flow on Figure 4-10. Equation 4-17 .s plotted oi:iy between 4 x i0-_ and 8 × i0 -_ tort ]iters Fer second per atmospner _, the range in which It is applicable. In gen-_¢al, the size of the leaks which may be detected de- pend om loss of gas during the seccnd stage. Th_ range of detec- table leaks can onl,." :_e extended app_eciab!y hi' r_ducing tR, the time m__tween back-pressu=.'zing ;_no leak tes_:ing. NOT REPRODUCIBLE Section 5 PLANNING LEAKAGE TESTS 5.1 5.1.1 5.1.2 5.1.3 5.1.3.1 5.1.3.2 5.1.3.3 5.1.3.4 5.1.4 5.1.4.1 5.1.4.2 5.1.4.3 5.2 5.2.1 5.2.1.1 5.2.1.2 5.2.1.3 5.2.1.4 5.2.2 5.2.2.1 5.3 NOMENCLATURE 5-I ACCESSIBILITY ......... DESIGN FOR 5-1 . • • • • • Leaks in Series ....... 5-2 Testing ........... Component 5- 4 safety Considerations .... 5-5 • • • • • Flammability .... 5-6 Asphyxiation ....... 5-6 . i • " " " • Explosion ....... 5-8 • • • • • • • Implosion ...... 5-8 Effects of Gas Properties ....... 5-8 . • • • • • • Gas Concentration " • 5-9 Stratification ............ 5-10 . • • • • • Diffusion ......... EXAMPLES OF TYPICAL TEST AIDS AND FIXTURES • 5-10 5-13 . • • • • Leakage Measurement ...... 5-13 . I • " • • " Hood Testing ...... 5-15 small Component Testing ....... 5-20 Weld Joint Testing .......... 5-21 Testing Pipe and Fittings ...... 5-21 . • • • • Leak Location ......... 5-24 Design of Probes ........ 5-26 SYSTEM CLEANLINESS ............. J,k Secti on 5 PLANNING LEAKAGE TESTS 5.1 DESIGN FOR ACCESSIBILITY If a system is to require leakage testing, such a requirement should be given consideration during the design period. Too often a system is completely constructed before any thought is given to the need for leak testing. At the end of construction, it may be impossible either to pressurize the system with tracer gas or to make connections to the system for evacuation. Therefore, if leakage testing is to be required, a system should be accessible by which it may be pressurized or evacuated. Well-designed test connections should be used. Such connec- tions can be a major source of difficulty on account of leakage, excessive tracer gas contamination, and dirt. Minimum amounts of elastomers and plastic should be used. Rubber and plastic tubing should be avoided because they will often absorb tracer gas which is difficult to remove by pumping. Only the shortest lengths of rubber tubing should be used. A light film of good, low-vapor- pressure grease should be applied to gaskets. Any excess should be removed since large quantities of grease act as a source of tracer-gas contamination and as a dirt catcher. The system may become so dirty because of excess grease that a good vacuum can- not be attained. 5.1.1 Leaks in Series It has long been recognized (Ref. 5-1) that for a device which will require leak testing, no design which may develop voids in series with possible leak paths is acceptable. For example, if two heavy plates are to be welded together along mating edges, it is best to make either a full penetration weld or a partial penetration weld from only one side. It is undesirable to allow partial penetration welds from opposite sides since a void can be left between the welds. It would then be difficult to check and assure that there is not a leak through both welds because the speed of response to leakage from the void would be very slow. The leak path (Figure 5-1) may consist of one or more small chambers connected by very fine capillaries. The pressure in a chamber (the intermediate volume) is atmospheric immediately af- ter pressurization of the system, and the driving force (or pres- sure difference) between the chamber and the outside atmosphere is zero at this time. As the inner capillary (between the sys- tem and the chamber) conducts tracer gas to build up the pressure in the chamber, the pressure difference between the chamber and the outside atmosphere increases. With this increased pressure difference there is a slow increase in the flow rate to the out- side. There will be a delay in time before atmospheric air is removed from the leak path and the path becomes filled with tracer 5-1 gas. The presence of the leak will not be detected until tracer gas issues from the outside surface of the wall. Thus, consideration of the time delay in leak detection is important when an intermediate volume is present in the total leak path, since a time lapse may prevent a leak from being detected. A review of leak-test procedures is necessary to establish the time lapse to be expected between component pressurization and measurable leakage. This can be accomplished by solving the de- rived equations for typical values of parameters associated with a particular configuration (Ref. 5-1). °°._[ ° ° ; • ._ ._. J," • °',° _' ' " 'Z 'INSIDE OF;" ,': SYSTEM ":: "' • ", .... a" .'-TRACER ' '2 "::"..:'::."-..".i . - .*.'." .'. I ", . .,. , • :..-... • o WALL OF SYSTEM INNER OUTER CAPI LLARY CAPILLARY ATMOSPHERE Figure 5-1. Sketch of Typical Series Leak Path Testing of a fluid handling system will be greatly facili- tated if the ports or gasketed openings which are provided for leakage testing are made large enough to permit rapid evacuation or pressurization. Large openings are especially desirable when the system is to be evacuated for leakage testing. Vacuum pump- ing of a vessel having a volume of several cubic feet through a valve having an orifice diameter of only one-eighth inch requires a pumpdown time which is not only excessive but also very costly. Instructions for welding without enclosing sealed voids may be found in current publications (Refs. 5-2 and 5-3). 5.1.2 Component Testing When a vacuum system is to be constructed, it is advisable to test each individual component for leakage prior to assembly. If this procedure is followed, any leaks indicated during a final test of the assembled system should be located only at the joints, unless a component has been damaged during assembly by the appli- 5-2 cation of excessive torque or thermal stress, for example. As a further safeguard, the vacuum tightness of the system can be checked as each component is added and assembly proceeds. It is always good practice in repairing leaks found during leak hunting to make permanent repairs whenever possible. Tem- porary repairs should be made only if the system must be operated, for a limited length of time, before permanent repairs can be made. A permanent repair means reworking the part involved or replacing the part. Some common sources of leaks and possible methods of repair are indicated below (reprinted with permis- sion, from Vacuum Technology, by A. Guthrie; John Wiley and Sons, Inc., New York, 1963, pp. 500-501) (Ref. 5-4): l • Static _asket seals • Tighten seal but not too much • If tightening does not work, shut down the system and examine the gasket and gasket surfaces. • Replace any damaged gasket and smooth rough sur- faces (fine emery cloth). • When the gasket is not damaged, clean (acetone, etc.), coat with light film of good-quality vacuum grease (when permitted), and reassemble seal. • Do not use sealing materials such as Glyptal* to stop the leak. This procedure is temporary and the gasket cannot be used again. • Movable, @asketed seals (Wilson, chevron, etc.) • Add a small quantity of good-quality vacuum grease to the moving member and operate this member a few times through the seal. • If vacuum grease does not work, try tightening the retaining rings on the seal. • If tightening does not work, dismantle the seal and examine the component parts• Replace all damaged parts. • Flare fittin@s (and similar metal-to-metal seals) • Tighten the compression nut moderately. Too much tightening is likely to twist the tubing passing through the fitting. • If tightening does not work, take the joint apart. • Try annealing the copper flare. • If annealing does not work, use a thin coating of a suitable sealant (Glyptal*, etc.) on the surfaces that make contact• *Registered trademark of the General Electric Company. 5-3 4. Soldered, brazed, and welded _oints • For temporary repair, use a cement. This method works for small leaks where the diffusion pumps are in their operating range. A "thin" cement (clear Glyptal, Eastman Kodak Resin 910, etc.) can be used for the smallest leak. For somewhat larger leaks use a more viscous cement, such as red Glyptal. • For permanent repair, rework the joint or replace the part. 5. Leaks throu@h metal parts • For temporary repair use a cement, as in the case of soldered, brazed, and welded joints. • For permanent repair, rework the part involved (as appropriate) or replace the part. • Peening the leak is not reliable. 6. Glass-to-metal seals • A temporary seal can be made with a cement or wax. • Rework wax seals• • For permanent repair, replace the seal. • Glass-to-@lass _oints, cracks, and pinholes in a @lass system • For small leaks, use a cement (at room temperature) or heat the glass and apply a suitable wax (picein, sealing wax, etc.). • For a large leak, rework the glass or replace the part of the system where the leak is located. 5.1.3 Safety Considerations Potential hazards to personnel safety must be taken into account when designing the leakage test. These are: the flam- mability of the tracer gas, the possibility of asphyxiation or poisoning, and the danger of explosion or implosion of a pres- surized system• As long as the designer is aware of these con- siderations from the beginning, it is possible to test with lit- tle inconvenience or danger• Included in Appendix A, along with physical properties of tracer gases, is a list of the safety precautions to be observed with the following gases: ammonia, argon, carbon dioxide, dichlorodifluoromethane, helium, hydrogen chloride, hydrogen, krypton, methane, neon, nitrogen, nitrous oxide, oxygen and sulfur dioxide. 5-4 5.1.3.1 Flammability. Hydrogen, methane, butane, and many of the liquids used in leakage testing are flammable. When these tracer fluids are used they are usually mixed to some extent with air. These potentially explosive mixtures are dangerous, and pro- cedures should be taken to provide adequate ventilation and to prevent accidental ignition. The precautions listed below will apply in all cases of flam- mable gases. Use of hydrogen enhances risk, and the precautions given are essential (Ref. i-6)_ i. Before hydrogen is admitted the system under test should be evacuated or purged with nitrogen. This will avoid an air-hydrogen mixture anywhere in the explosive range (4 percent to 74 percent of hydrogen in air, by volume). The same should be done with a rigid hood. With flexi- ble hoods the volume between hood and vessel under test can usually be made very small - much less than the i0 cubic feet referred to below. If this is done, evacua- tion or purging is not essential. A hydrogen/nitrogen mixture is safer than pure hydrogen, if it can be used. . • Testing should be done in a well-ventilated place, iso- lated as far as practicable from other processes. A room with a high roof, adequately vented at its apex, and with enough low-level air inlets is desirable. A small room with low roof and a minimum of openings for ventilation should not be used for testing with hydrogen. Special precautions will be necessary when the volume between the hood and system under test approaches i0 cubic feet, as there is then risk of a major explosion. Safety can then be insured only by testlng the system in a blast enclosure, or cell. This should have strong walls and a light roof; persons should not be allowed to enter during a test. For safety, and to avoid hav- ing to provide a test cell unnecessarily, the volume between a hood and the enclosed system should be as small as possible• Test areas, particularly test cells, should be free from obvious sources of ignition• Smoking must be prohibited, particularly when hydrogen is used. Electrical equip- ment may pose a hazard. If there is a possibility that, in the event of a leak, such equipment will be in an explosive atmosphere, then either the equipment must be repositioned outside the danger area or special equip- ment must be used. Such special equipment is either pressurized with inert gas or is intrinsically safe. A discharge of static electricity is a possible cause of ignition• Therefore all metal parts liable to be- come charged should be grounded, and any flexible non- metallic hood should be made of "anti-static" material. 5-5 This would mean that the resistance of the leakage path from any point on the hood would not exceed l0 T ohms. It is advisable for personnel, when testing with hydro- gen, to avoid wearing clothing liable to produce static charges, and to wear shoes with conducting soles. An- other precaution is to use tools which cannot produce sparks. • If possible, hydrogen cylinders should be in a storage area separate from any occupied building. The storage area should be well ventilated. Permanent piping should be provided to convey hydrogen to the test area. The above precautions are also relevant where other flam- mable tracer gases are used, although hydrogen easily presents the greatest risk. Where a large system is be- ing tested, or large volumes of hydrogen used, it may be advisable to provide monitoring equipment giving a con- tinuous indication of the hydrogen-in-air content in the test area. Intrinsically safe detectors are available. 5.1.$.2 Asphyxiation. Most tracer gases are not toxic. However, if a question exists about the toxicity of any particular gas, a competent authority should be consulted (Ref. 2-2). Toxicity of some tracer gases is given in Appendix A. None of the tracer gases will support human life. That is, if they replace oxygen in a volume, this volume cannot be entered without proper respiratory equipment. In this case, proper equip- ment is a gas mask which contains its own oxygen supply. The oxygen required for breathing might be accidentally re- moved from an area. For example, if one of the halogenated hydro- carbons is used as a tracer gas, it will stagnate and settle to the lowest area in the system. If an operator is attempting to use a detector probe in this low area, the tracer gas which set- tles may eventually displace enough of the air to produce asphyx- iation. In this case, adequate ventilation is necessary. Such ventilation, however, must be performed carefully. If the tracer gas is dispersed too rapidly from the place where it is escaping from the system, leak location will be difficult. 5.1.3.3 Explosion. If the system is pressurized with tracer gas, the rupture of its walls can produce considerable damage from release of the stored energy. It might seem that little pre- caution is necessary in pressurizing a small system; however, the damage from the rupture of a gas-filled volume results from the total mass of gas. Therefore, a small system at high pressure and a large system at low pressure may be equally dangerous. Large systems need proof-testing prior to leakage measure- ment. The proof-test may be performed by pressurizing with gas to a high pressure while the test area is evacuated, or by a hydro- static test using water. The disadvantage of the gas proof-test is that considerable damage can result if the system bursts dur- ing testing. On the other hand, should hydrostatic testing be 5-6 performed, any small leaks in the system will become clogged with water. Therefore, if at all possible, hydrostatic testing should not be performed on systems where the allowable leakage must be less than 10-6 atm-cc/sec. The American Society of Me- chanical Engineers code for unfired pressure vessels specifies that a hydrostatic test at 1.5 times the working pressure shall be performed on all code fabricated vessels (Ref. 5-5). When a system is to be pressurized a pressure regulator fitted with a safety over-pressure device should be included, so that a pressure in excess of the design pressure can never be applied to the system. Olson (Ref. 5-6) has related the hazard potential associated with a volume of compressed gas to its TNT equivalent. Figure 5-2 is a logarithmic plot of tank pressure versus the energy equiva- lent in pounds of TNT per cubic foot of tank volume. The explo- sion hazard can be readily seen. For example, a tank at i00 psia contains the energy equivalent of 0.023 pound of TNT per cubic foot of tank volume. A 10-cubic-foot tank under those conditions has the explosive potential of 0.23 pound of TNT. O'3 a. UJ n_ OO n_ 10,000 I000 I00 t0 O.OOI ,,- I I I I I I 11 L- I I 1 I 1 Ill I I I 1 I III 0.01 0.I 1 I I I I 1 I I I I I fill I I I I I II I0 ENERGY EQUIVALENT, LB TNT/FT 3TANK VOLUME Figure 5-2. Tank Pressure Versus Energy Equivalent 5-7 5.1.3..4 Implosion. Although they are not pressurized, glass bell jars which are evacuated can be a dangerous source of flying glass from implosions. Should a crack occur in the bell jar, an unequal force distribution can shatter it. Pieces of flying glass, propelled by a pressure difference of approximately 15 pounds per square inch, will travel great distances unless they should happen to meet a safety shield or glass coming from the other direction. This is particularly serious when the capacity of the vessel exceeds approximately one cubic foot. For this reason all evacuated bell jars should be enclosed in some safety shield. Safety shields should be used on bell jars under all condi- tions. One mistake often made is to omit them unless the system is to be evacuated to a high vacuum. The increase of the pressure on the bell jar from one torr to 10 -3 torr is negligible. The major part of atmospheric pressure is exerted on the jar when rough evacuation takes place; the increase in pressure difference by evacuating the bell jar further is very small. 5.1.4 Fffects of Gas Properties Various properties of tracer gases affect the results of leak- age testing. Gas density has an effect on the tendency of the tra- cer gas to stratify, or form layers, in the test volume, giving uneven readings for various leak locations. The diffusion rate of a tracer gas has an important effect on test results, particu- larly if there are restrictions or long, narrow, blind passages or crevices in the test volume. Variations in tracer-gas concen- tration can give varying leak indications. 5.1.4.1 Gas Concentration. In many leakage measurements, it is desirable or necessary to dilute the tracer gas used. Diluted tra- cer gas might be dictated by: 1. Expense involved in the use of pure gas. 2. More linear or more stable response obtained at lower gas concentration. 3. Pure gas producing a sensitivity much greater than needed. 4. Danger of fire or explosion with a flammable tracer gas (a dilute gas mixture reduces danger). 5. Inability to completely evacuate the system prior to filling with tracer gas, so that a dilute tracer is obtained during the pressurizing process. Concentration of tracer gas in the system depends on its partial pressure. Total system pressure is the sum of the par- tial pressures of the gases in the system. Thus, P = PA + PB + PC + .... (5-1) Using Equation 5-1, the fractional concentration of gas A in the system is: 5-8 PA "A (5 "' - = ?C 'A P :'A + P + ÷ ....B A special tracer-gas mixture is often prep,lred by co:;_U_n_ng volumes of dlfferen_ gases havlng uqual partial press_res. A tracer qas such as helium is often m_xed with nitrogen for use in leakage testlng of large systems. Most leak detectors are to some extent specific to a partic- ular tracer gas. As a general and approximate rule, the response of a leak detector _o a measured dilute tracer-gas concentration is proportional to the concentration of the tracer. For example,tracer .which leaks ,ixture containing one percent c,f a with a gas r., - . ,_-_ ...... /sec -* . the leak detector at an actual rate ot i _ _u _'_" _' _ " _ _ _n 4 _,__cc/sec-: • id indicate a leakage rate or onxy • _Y_ =_'". %.... A_ signal wou . - • .... _ _ ._nv deviation _rom tnls rule u_F=,,,-,_ The magnituae ana ul_uu_u,. _ - _ The on the predominant flow mode for the tracer gas in nhe leak. expected predominant flow n_odes are d_scussed in Section o, "Flow Characteristics- " If the leakage is laminar, the flow will be inversely pro- portional to the viscosity of the gas mixture. The mixture -.till _,_av_ a vi_cosit'." proport_onai to the viscosity of the individual species iF a relatiol%" _, mlxture = NA qA + _B nB + NC _C + ' (5-3_ The estimated leakage for pure _zacer gas, Qest, may be cal- culated from the relationship: Qindica ted tracer _mixture %5-4) Qest, pure tracer = Ntracer ntracer The calculations are usually slmpl_ fled by the fact that the vls- comities of most gases are similar (Table 6-i, Section 6.1). Therefc_re, the measured leakage for laminar flow is approximately related to the total leakage by the equation: Qindicated tracer (5-5i Qest, pure tracer = Ntracer If the flow in the leak is molecular, leakage of the tracer gas can be calculated from the measurement of leakage of the fol- lowing m_-x ture : Qindicated tracer I Mmixturel:/2 (5-6) Qest, pure tracer = Ntracer \Mtracer $. ]. 4. 2 Sfp,It_%On. If a tracer gas is added to air already in the system, a" uniform mixture is not readily achieved. The tra- cer gas will rise toward the top or settle toward the bottom of the system, according to its density. This stratification is 5-9 more pronounced with hich-molecular-_.'elght gases a_:,_ '..'ith ,_asc._ efa low diffuszon ceefficiena. precautions should be taken to m..ix the tracer wlth the d_lu- ent (Tas _urlng pressurlzatlon of the s:,,ste,_. T.hls z:ay ke dor-_ b':' provlding some means of cJLculatlng t_,e gases within the system. Alternatlvely, both the tracer and diluent cases nay be _d_:d simultaneously tl_rough a rake or screened auerture. There should be no stratiflcation problem inslde the system prcvidzi_g precau- tions are taken to mix the tracer thorouqh:y with dil_,cnt gas In pressurizing _he system. When the mzxture _=: in equllzbrluun the concentration at height h above the bottom w!ll vary as: Ch/C O = exp :-Mhg/R:T) (5-7) _.._. 4.,_ ;'_'C_'uz'cr.. A tracer gas of low diffus_vlty speeds iuak location because the tracer gas remains close to the leak exlt and allows accurate location of the !oak wlth a detector probe. Scan- ning of the suspected area must be done thoroughly, however, to avoid passing over the leak. A tra z_r g_s _f high diffusiv_._y i_ necessary to fill _':_'- ,_e-sac& or blind passages within a reasonable time. A low diffu- sion rate _,ould n<;t allow tracer gas to traverse a tortuous leak passage; hence would make ?.__ak detection unreliable. (Table 5-I gives the diffusivlty of certain gases used In leak dctectxcn work. ) The time required for a gas to diffuse Into or out of a blind duct is given by: t ~ _.--_ Zn _ -:.: /'N (5-8) " L uj Figure 5-3 is a plot of diffusion t1_.e in a blind duct for a n_n- ber of tracer gases, usirg Equation 5-_. Two procedures may be used to fill a duct wlth tracer gas. If the duct can be opened (perhaps by a valve) at the end remote from the gas source, filling the duct with tracer gas w111 be ex- pedited. The other procedure, which is much more diif_cult, zs to evacuate the system prior to admission of tracer gas. 5.2 EXAMPLES OF TYPICAL TEST AIDS A_D FIXTURES Two types of test procedure are discussed here: leakace mea- surement and leak location (by probe techniques). Although there are many simiiarities in principle, each procedure al,_ows for in- dividual equipment and operating peculiarities. Many of these are demonstrated on the following pages. 5-10 Table 5-1 DIFFUSIVITY OF TRACER GASES (i arm, 0-C) Chemical Gas Formula Acetylene C2H2 Ammonia NH3 Argon A Benzene C6H6 Butane C_Hl0 Carbon dioxide CO2 Carbon disulfide CS2 Carbon monoxide CO Carbon tetrachloride CCI_ Ethane C2H6 Ethyl alcohol C2HsOH Ethylene C=H_ Halogenated hydrocarbon F-If** CCI_F Halogenated hydrocarbon F-12** CCI2Fz Halogenated hydrocarbon F-21** CHCIzF Halogenated hydrocarbon F-22"* CHCIF2 Halogenated hydrocarbon F-II2** CCI2F-CCI_F Halogenated hydrocarbon F-II4** CCIFz-CCIFz Helium He Hydrogen H2 Hydrogen Sulfide H2S Krypton Kr Methane CH_ Neon Ne Nitric oxide NO Nitrogen N2 Nitrous oxide NzO Oxygen Oz Propane C3Ha Sulfur dioxide SO2 Water H20 Xenon Xe IN AIR Molecular Wei@ht 26.0 17.0 39.9 78.1 58.1 44.0 76.1 28.0 154. 30.1 46.1 28.0 137. 121. 103 86 5 204 171 4 00 2 02 34 1 83.8 16.0 20.2 30.0 28.0 44.0 32.0 44.1 64.1 18.0 13.1 Diffusion Coe f flcient* (Sg ft per hr) 0.55 0.66 0.61 0.30 0.33 0.52 0.36 0.67 0.28 0.49 0.38 0.52 0.30 0.32 0.33 0.37 0.25 0.28 2.7 2.6 0.53 0.51 0.72 i.i 0.70 0.68 0.52 0.68 0.39 0.42 0.85 0.42 * Values calculated from empirical equation of J.C. Slattery and R.B. Bird (AIChE Journal, vol. 4, No. 2, 1958, pp. 137-42.) **ASHRAE Standard Designation 5-11 i I ! I o. o,i ,\ \ o. _o \ \ 0 =d \ U'3 aD \ \ \ \ 0 san0H- 3fl11 \ \\ "r"- \\ \\ Q 0 \ o. 0 U O. O_ "0 0 OJ -,-I I_ o. Eo •_.1-,-I _4a 0 I_ t,4 ,._ m -I.J 0 I'- _ 0 Ola,I i o,.-I -_1 0 ¢n I-'- Z r_ o, ._ _._ E_ u_.c: 0 O_ O_ 0 q_ I E30 o 0 0 I L_ _n °M 5-12 5.2.1 Leakage Measurement On large systems, where rapid testing of a large number of objects is required, testing time can be reduced by the use of a testing hood to surround the entire test object with an atmos- phere of tracer gas. This eliminates probing time and gives a response proportional to the total leakage if several leaks exist; the possibility of missing leaks by careless probing is also re- moved. After the location of leaky test objects the hood may be removed and the leaks accurately located by probing with a small jet of tracer gas. A valuable adjunct to the testing hood is a thermal-conductivity gage, calibrated to read directly the con- centration of tracer gas in the hood. 5.2.1.1 Hood Testing. In hood testing, the form of hood used depends on the task at hand. In a semipermanent assembly designed for routine overall testing of large numbers of components, the hood may be a metal chamber or bell jar. When testing one object of a type almost any item can be accommodated in a polyethylene bag. It can be dangerous, however, to use flammable or explosive tracer gases in conjunction with plastic hoods which can acquire an electrostatic charge. A typical hood setup is shown in Figure 5-4. For small ob- jects several manifolds are attached to one pump-leak detector combination; this allows the objects to be set up or taken down on one manifold while the units on another are under test. For larger equipment individual pump-leak detector combinations are required. The test is made in the following manner: • With the valve leading to the calibrated leak in an open position, tracer gas is forced into the hood un- til its concentration there is sufficient to give a reading on the leak detector. This reading (A) is proportional to the total leakage, which consists of unknown vessel leakage and known leakage from the cal- ibrated leak. • The valve leading to the calibrated leak is then closed, and a second reading (B) taken. This reading is, of course, proportional to the unknown leakage alone. The unknown leakage may be calculated from these two readings. Thus, unknown leakage = readin 9 (B) /conductance of reading(A) - reading(B) X kcalibrated leak/ x I pressure >difference (5-9) • Equation 5-9 gives the unknown leakage in terms of the two readings and the leakage through the calibrated leak. Knowledge of tracer-gas concentration in the hood is not necessary. The only requirement is that 5-13 ,° FAN CRANE --_HOOK ° ° _ ° • . • °o • . o • • o° . • " • • • ° ° " G • • - • ° • • ms • I • °. " • • • _•t° • o ooo - • j. SYSTEM. • '" "• ._. UNDER• • "'"" i:'[" TEST N HOOD • " •Z• • ':i • • i i , i • • I!' o • Q • • I i • • o* • t • o • b • o J• • t • • • o • • _ e° , I "STA N DA R D" LEAK ! uSiON I, ! Io J---'io I_= LEAK DETECTOR t "I | I Figure 5-4. Typical Setup for Hood Testing 5-14 this concentration remain substantially constant while the readings are taken. Normally, this requires from five to ten minutes. Well-constructed hoods show prac- tically no decrease in tracer-gas concentration for considerably longer periods. Figure 5-5 illustrates a type of manifold which allows con- tinuous testing of a number of small vessels. The three testing lines make possible three simultaneous operations: loading and unloading, rough evacuation, and leakage measurement. Measure- ment of leakage can be performed individually on each vessel, or several vessels may be grouped in a single test. These measure- ments are made by the hood method. If rejected vessels are set aside for later attentlon, testing may be as rapid as the loading and unloading can be performed. The calibrated leaks shown serve both to test the effectiveness of the testing manifold and as a reference standard. 5.2.1.2 Small Component Testing. For rapid testing, components are sometimes leak-tested on a rubber pad on a base plate, by sealing the component to the pad (usually with the help of vacuum grease) and spraying some tracer gas around the component. If leakage is indicated, the experimenter must determine whether the component or the grease seal between pad and component or pad and fixture is leaking. Furthermore, vacuum grease absorbs and re- tains tracer gas. This produces a changing background signal due to tracer gas in the setup which must be compensated for in ana- lyzing the test results. Duxseal and Apiezon Q are putties which can be used for sealing in rapid testing. The component is sealed to a fixture with the putty and pumped down. The system is then allowed to stabilize at its maximum sensitivity. Tracer gas is passed over the entire surface of the part, and then lightly over the joint. If a leak is observed in the seal area, the setup is dismantled and reassembled, using new putty. Seal material is used only once and then discarded because the material may absorb tracer gas and allow permeation by tracer gas. The time constant for Duxseal exposed to helium has been determined as 20 minutes; hence, a test should be terminated within that period of time. A good discussion of fixtures for leak testing is given by Smith in Reference 5-7. Every fixture has two sealing surfaces: where it is sealed to the detector and where the component to be tested is sealed to the fixture. Figure 5-6 is an example of such a test fixture. The seal between the envelope and the base plate does not have to be leak-tight. Flexible gaskets made of elastomers and certain other mater- ials should be used sparingly since they easily absorb helium. During the first few minutes that helium is entering one side of such a gasket, no helium leaves the other side. However, leakage starts after a few minutes and quickly builds up to a steady value. Because of permeability, the use of elastomers and similar ma- terials is limited to the sealing of test setups for the measure- 5-15 TESTING OUTLETS ISOLATION VALVES CALIBRATED LEAKS DIFFUSION PUMP BALLAST TANK io r--n o IILEAKDETECTOR ROUGHING PUMP J BACKING PUMP Figure 5-5. Typical Manifold for Rapid Testing of Small Parts 5-16 ENVELOPE TEST PIECE , :"'.",':"' .': i :" :,";': :,' i :' :" ELAST'OM'ER. ''_ ;:,', ": • " "0" RING .-7". _[gll::':!il _ _. ,. :: .... ... ,. , • , , , _,_ --ADAPTER• ' • • i • o ' / " ' " .. ELASTOMER _'' ,::.': .",','."•.'I_[_.TII ":.:' BASEPLATE LEAK DETECTOR I" 1 I I Figure 5-6. Reliable Test Fixture for Leakage Measurement (Reprinted with permission from G.C. Smith, ISA Journal, Vol. 10, November 1963, pp. 55-60; copyright 1963, Instrument Society of America, Pittsburgh, Pa. (Ref. 5-7).) ment of leaks larger than 5 x l0 -_ atm-cc/sec unless special fix- turing and pumping techniques are used at the seal. If, however, rapid testing is essential and if long-term measurements are not required, elastomers can be used when detecting leaks as small as 1 x 10 -9 atm-cc/sec. (Details on permeation are given in Section 6.2). The size and type of leaks which must be detected are major considerations in the design of fixtures. In the region i0 -_ atm- cc/sec to 5 x 10 -7 atm-cc/sec, elastomers and flat gaskets are the easiest and most practical to use. Common elastomers used in O-ring configurations are made of viton or butyl rubber; flat gas- kets are made of neoprene. O-rings are mainly used for sealing between a base plate and a test fixture. When sealing around a circular part, the fixture must incorporate a means of holding the O-ring radially against the part. One way to accomplish this is to use a retainer ring in the fixture to hold the O-ring in place. Without the retainer, the O-ring tends to spread or roll away. 5-17 Sealing surfaces should be of good quality and have a 64 RMS minimum finish. Shaft surfaces should not have longitudinal marks or scratches. Tooling marks which are so oriented that they bridge the sealing interface are harder to seal than marks which are per- pendicular to the shortest leak paths. To reduce the problem of sealing it is better to provide a good surface rather than to try to fill a rough surface with vacuum grease. Metal gaskets are often used for sealing in tests for leaks smaller than 5 x i0 _ atm-cc/sec. These gaskets are usually made of copper or aluminum and heat-treated to a dead soft condition. Tests, lasting 24 hours, performed on these gaskets show their permeability rate for helium is far below the above leakage rate. The big disadvantage in using metal gaskets is in the large forces required to assure sealing. Fixtures can be designed to withstand these forces, but many components do not have the phy- sical strength to resist them° Therefore the dimensions of a component, and the mechanical properties of material used in it, must be known when designing fixtures. The surfaces which metal gaskets seal against must be of much better quality than those used with elastomers. Surface finishes of 16 RMSor better are required for repeatable sealing. The split-type fixture makes possible the use of elastomers and neoprene gaskets for leak testing in the realm of 5 × 10 -9 atm-cc/sec. Design of the fixture is such that any leakage of tracer gas through seals will be to the atmosphere and will not be sensed by the detector. Detector seals (Figure 5-7) between the test piece and the detector base plate do not have to seal against the tracer gas since they are not in contact with it. Therefore any tracer gas entering the detector must come through leaks in the test piece. This method is generally more practi- cal than metal-to-metal seals, and it does not impose severe me- chanical loads on the test piece to secure good sealing. The shape of test pieces, however, sometimes prohibits its use. Considerable test time can be saved by keeping the internal volume of the fixture as small as possible, and avoiding materi- als of construction which have high vapor pressures or high out- gassing rates. This reduces the time required to evacuate the fixture to the operating pressure of the detector. Additional time can be saved by using a pump of ample capacity for evacu- ating the fixture and component. The time required to perform the actual leak test is largely determined by the test specifications. Response time of a de- tector to tracer gas leakage in small parts, such as are considered here, is usually very rapid. The fixture designer should see that nothing impedes the flow of tracer gas to the detector tube and thereby adds to the testing time. Fixtures should be small. This allows the use of a small envelope containing the tracer gas, and a saving in cost of the 5-18 i--T 1 HELIUM ATMOSPHERE ,. TUBING ;-.. o I°'D TESTg 1 PYf_/_ '_ TRACER GASSEALS SEALS / °,rLEAK DETECTOR Figure 5-7. Split Fixture for Parts Testing. (Reprinted with permission from G.C. Smith, ISA Journal, Vol. 10, 1963, p. 56, Instrument Society of America, Pittsburgh, Pennsylvania., Copyright 1963.) 5-19 fixture, envelope, and tracer gas results. In addition to re- quiring less storage space, small fixtures save time during evac- uating and backfilling. Before a finished fixture is released for use, it should be thoroughly inspected visually, and leak-tested. Leak testing is done by substituting a solid metal replica for the component which will be used with the fixture. If any leaks are found, they will be in the fixture, providing the sealing surfaces are of good quality. If the fixture leaks, it can be repaired until the leakage is much smaller than the maximum allowable leakage for the component. 5.2.1.3 Weld Joint Testing. Testing of individual welds in large systems is discussed in Reference 4-10. The test method is illustrated schematically in Figure 5-8. A vacuum box which temporarily covers the section of weld under test is evacuated by a pump and also connected to the mass-spectrometer leak de- tector. Helium is maintained near atmospheric pressure on the opposite side of the weld under a cover of sheet polyethylene, fastened at its edges to the steel plate by suitable adhesive tape. If a leak is detected, it can be located by progressively reducing the surface enclosed by the plastic cover. The leak is finally isolated by means of a fine tracer probe. / k_qWELD BEINGTESTED_ | i •.,..,.,,¢.:_..,.,. H TEST ENVELOPE [oC:] o / LEAK DETECTOR AUXILIARY PUMP Figure 5-8. Vacuum Box for Weld Testing (Reprinted with permission from R.I. Garrod and J.F. Nanki- vell, Vacuum, Vol. ii, No. 3, 1961, pp. 139- 145; copyright 1961, Pergamon Press, Inc. (Ref. 4-10).) The major design requirements for the vacuum boxes may be summarized as follows: 5-20 l • 2. • Working pressure in a box should not exceed 10 -I torr. Attachment of a box to any welded section should be an easy, reliable, and relatively rapid process. Design should aim for a minimum number of different box types and sizes to cover all types of weld. The principal difficulty in meeting these requirements is in making a satisfactory seal between the box and the section of the system under test. The surface of the steel plate is usually pitted, and generally has a poor finish compared with normal vacu- um engineering standards. Furthermore, the welds often impose a relatively abrupt change in contour on the seal where the two ends of the box cross the weld. The method adopted, which has proven satisfactory in opera- tion, is illustrated schematically in Figure 5-9. The vacuum box consists of a flexible metal plate, to which are cemented two rectangular rubber gaskets. The gaskets are made from non- interconnecting cellular rubber. This material provides suffi- cient sponginess to effect a satisfactory seal with the steel plate and across the weld, but at the same time is nonporous• The section of the box inside the inner gasket is connected via flexible neoprene hose to the leak detector, which also contains the roughing pump for evacuating this volume. The annular space between the two gaskets is connected to a second rotary pump. By this means, leakage across the inner gasket is reduced suffi- ciently to allow the inner volume of the box to be maintained at a pressure, in most cases, of about 10 -2 torr. Air is admit- ted to each section of the box, through driers and inlet valves to release the box from the welded plate after a leak test. For transportability and convenience in use, the rotary pump and the air inlet system may be mounted on a trolley• 5.2•1.4 Testin_ Pipe und Fittings. The vacuum box can take any convenient form that makes a reasonably tight seal to the pipework. The box or shroud case consists of two brass half- shells with silicone rubber seals molded to them• The offset clamp can have an over-center lock with adjustable tension simi- lar to a pair of "vice-grip" pliers (Ref. 5-8). Different sizes and configurations would be needed for various fittings• Such a fitting may be used to hold the tracer gas or as the detector connector. 5.2.2 Leak Location The location of leaks is usually accomplished by the detec- tion of gas leakage• A hand-held probe is most frequently used to search for leakage which is first detected by chemical or other means• Where less sensitive detection methods can be tol- erated it is possible to use audio or visual methods such as ultrasonics or bubble formation. Probing is performed with either a detector or a tracer type probe• Certain precautions are necessary when using any probe. 5-21 /_/_ GUARD VACUUM rJ ii I DIFFUSION PUMP I I t MOUNTED ON i TROLLEY I I I WELD BEING TESTED II I =t o r---i o I LEAK DETECTOR DIFFUSION PUMP Figure 5-9. Use of Vacuum Box for Weld Testing.(Reprinted with permission from R.I. Garrod and J.F. Nankivell, Vacuum, Vol. Ii, No. 3, 1961, pp. 139-145; Copyrzght 1961, Pergamon Press, Inc. (Ref. 4-10}.) I I i I l I I I I I I I l l I l l l I l I I I 5-22 Too rapid a search may miss very small leaks. If this risk is to be avoided, the speed at which the probe is moved must be in pro- portion to the minimum leak tolerance. In testing equipment for a leak specification of the order of i0 -s atm-cc/sec, the travel can be one to two inches per second; but probe speed should be reduced to one-half inch per second for smaller leaks. If the tracer gas escapes into the room after the test has been completed and the test piece opened, sufficient time must be allowed to permit the amblent to again become free of tracer gas. If the waiting period cannot be tolerated, there are two alternatives that may be employed: • The test piece can be removed to an outside area be- fore the gas is permitted to escape. • A vacuum system can be used to remove the gas before opening the test piece. The use of the vacuum system has proved the more satisfactory. Although some gas usually remains in the test piece after evacu- ation, and therefore tends to contaminate the alr, the time lost in reestablishing tracer-free air is relatively small. If large volumes are to be tested, it is possible to recom- press the tracer gas for reuse. The degree of mechanization employed in a testing setup is dependent upon the production rate, the uniformity of test pieces, and the total time available for hand work by the operator. It is usually not possible to depend on natural dissipation of escaping gas in a high-speed production test; it therefore be- comes necessary to remove gas in the shortest possible time. The design must include adequate vacuum lines to remove the gas from the test piece after testlng; and proper forced ventilation must be employed to clear the surrounding air. A hood has been found suitable for this purpose. When sufficient incoming airflow is used to clear away leak- ing gas, steps must be taken to properly direct the air so that it does not remove the gas at the point of the leak, before the detector has had time to acquire a sample of tracer gas and in- dicate the leak. It is suggested that due consideration be given to the fol- lowing points. i. If the tracer gas is lighter than air, the system should be probed from the upper parts of the test object to the lower. In this way the tracer gas, which rises, will flow back only over areas already tested. Of course, the reverse is true if the tracer gas is heavier than air. 2. For tracer probe testing of individual joints, time may be saved by using a generous flow of tracer gas 5-23 •• • . . . from a flexible rubber tubing (1/4 inch ID). When a leak is indicated, its exact location can be determined by means of a finer probe. On the other hand, with large leaks in the system, enough tracer gas may en- ter the system to saturate the leak detector for a while. With many small leaks, diffusion of tracer gas to these small leaks may make leak location difficult. The use of a fine probe will narrowly limit the area covered by tracer gas. A very large leak will register on the detector, even when the probe is some distance from it. The leak should be located and repaired (permanently or tem- porarily). Vacuum putty may be used for temporary repairs. When a point appears to leak but does not give a con- sistent response, a large leak in some other location is possible. To distinguish between two possible points of leakage, close to one another, one of them can be covered (with tape, for example). A fine probe and a minimum flow of tracer gas will help. If a liquid tracer is to be employed, there is less likelihood of blocking a leak if a pad of cotton is moistened (but not saturated) with the liquid and used rather than a liquid spray. The probe should be moved over the test area at a speed consistent with the time constant of the sys- tem (see Section 4.5.2). When a detector probe is used, response and cleanup time constants depend on the length of tubing connecting the probe to the de- tector. As the length of tubing is increased, both response and cleanup time increase. In detector probe testing, if large leaks are known to be present, it is wasteful of search gas to use a high pressure. Furthermore, the space outside the test vessel in the neighborhood of a large leak will become flooded with search gas, which will give con- fusing results when adjacent areas are probed. It is advisable, therefore, to pressurize the test vessel cautiously, watching the pressure gage for an Indica- tion of the presence of large leaks. 5.2.2.1 Design of Probes. The "sniffer", or detector pro•e, can be a simple device when it is to be connected to a leak de- tector with a pumping system, since the pumps provide the suction necessary for drawing a gas sample through the sniffer into the leak-detecting element. Figure 5-10 shows the Atlas-MAT "Schnuf- felsonde" (Ref. 5-9) with a screw adjustment for controlling the gas throughput. The important points in this design are that a sleeve on the end of the probe collects the gas which will travel to the detec- 5-24 SCREW FOR ADJUSTING Figure 5-10. Detector Probe for Leak Location. (Reprinted with permission from H.W. Drawin and K. Kro- nenberger, Vakuum-Technik, Vol. 8, 1959, p. 128, Rudolf A. Long-Verlag, Wiesbaden, Ger- many (Ref. 5-9).) tor; and that the flow is controlled at the entrance to the probe, i.e. there are no blind ducts at the entrance. When tracer probe techniques are employed to locate the exact position of small leaks in equipment having re-entrant cavities, difficulties arise owing to the escape of search gas from the area under test. Under extreme conditions the whole region may become charged with search gas, which by its entry through neighboring leaks makes localization almost impossible. Fans which remove excess search gas from the region where the test is conducted effect only a partial improvement, and their installation is costly. Pacey (Ref. 5-10) described a probe design which overcomes this difficulty. It consists of two coaxial stainless-steel tubes, search gas being supplied through the inner, and the ex- cess being removed through the outer by means of a small vacuum pump which is vented outside the test region. The flow of search gas is adjusted to provide coverage of leaks without exceeding the capacity of the extraction pump. Standard hypodermic needles provide a ready source of suit- able tubes. Size 0 is used for the outer, and size G for the inner, both having Luer type fittings. The arrangement adopted is shown in Figure 5-11. The outer needle is softened by heat- ing in a small gas-air flame; when cool it is bent through an 5-25 angle of about 30 degrees, after the removal of most of the fit- ting to provide an attachment for the flexible tube leading to the vacuum pump at D. A hole is made at the bend to allow inser- tion of the inner tube. Concentricity at the probe end is brought about by winding a five-turn helix, shown at B, of 0.25-millimeter- diameter wire around the inner tube. D '_TRACER GAS OUT Figure 5-11. Self-extracting Tracer Gas Probe. (Reprinted with permission from D.J. Pacey, Journal of Scientific Instruments, Vol. 41, 1964, p. 398, Institute of Physics and The Physi- cal Society, London (Ref. 5-10).) After the helix is sprung into place in the outer tube, the inner is inserted through the hole already made and soft-soldered in position, using a zinc chloride flux. This allows a fillet of solder to form at C to provide adequate mechanical strength. The probe is attached to a suitable tubular holder by a taper engaging with the fitting of the smaller needle, through which search gas is supplied. If a leak closes at atmospheric pressure, and thus does not exist under ordinary testing conditions, it is very difficult to locate. A device (Ref. 5-11) has been developed to locate such leaks by applying gas pressure to selected small portions of the surface. By application of this device to successive small por- tions of the system the leak is localized. 5.3 SYSTEM CLEANLINESS The need for cleanliness of the system as a whole, including the test object, cannot be overemphasized. The larger the sys- tem the more important is cleanliness. Tracer gas accumulation in surface dust and oil may cause false but large leak signals. Excessive amounts of rubber -- for example, gaskets and rubber tubing -- should not be used, since they absorb tracer gas. When a large leak is encountered, appre- ciable amounts of tracer gas are absorbed by the rubber and give false leak indications on succeeding tests. Lubricants and vacuum greases should be minimized, since they, too, have an affinity for tracer gas. Good vacuum seals are obtainable without the use of greases. Greases are dirt catchers and, as such, will contaminate the vacuum system. 5-26 Outgassing properties of leak detection systems are described in numerous books on vacuum technology. A pressure rise in a sealed vacuum indicates a leak, but so does outgassing. Pressure rise caused by a leak will be a straight line when plotted against time. Outgassing will graph differently because it gradually de- creases with time. The practical aspects of this are dlscussed in Section 11.4. It is possible for a system to exhibit the symptoms of a leak when it is in fact vacuum-tight. Virtual leakage, as it is called, is often due to the presence of a condensable vapor in the system. For example, if water vapor is present in a system equipped wlth dry-ice traps, the system pressure will approach a limit of 10 .-3 torr, the vapor pressure of water at the temperature of solid carbon dioxide. This is the simplest form of virtual leak. In a liquid-nitrogen-cooled trap, the vapor pressure of water is about i0 -Is torr, which is negligible by present-day standards. If, however, some of the water vapor has been condensed as ice just below the refrigerant level, then, as the liquid nitrogen evaporates and its level falls, the temperature of this ice will rise until it begins to sublime, producing a virtual leak. This effect will not occur, of course, in a trap in which the refrlg- erant level is automatically maintained. In the presence of virtual leaks the system pressure is raised to a particular value which tends to be constant. When a virtual leak is indicated, volatile material may be present in the vacuum system. The use of a dry-gas bleed in vacuum systems and leak detec- tors is a highly recommended procedure (Ref. 5-±2). The purpose of the gas bleed is to create a laminar flow of gas through the entire system during those periods when the equipment is not in active use. This aids the outgassing of condensable materials, such as water vapor, by preventlng readsorption. It also m_ni- mizes the back-migration of both hydrocarbons from the mechani- cal pump and condensables evaporating from the trap. In the case of mass-spectrometer leak detectors, the background signal will be lowered and maintenance reduced. A gas such as nltrogen is generally employed. When installing a dry-gas bleed system, the point of connec- tion is chosen so that the gas flows from the cleanest parts of the system, past any traps or baffles, and then through the vacu- um pumps. In the case of the leak detector, locating the bleed between the spectrometer tube and the inlet cold trap, and leav- ing the inlet valve open to the manifold and its pump during the bleed operation, permits gas flow toward both pumps. In this way the inlet trap can be cleared of condensables without passing them through the spectrometer tube. Gas flow is adjusted to main- tain the vacuum system pressure between 0.2 and 0.5 torr. This can best be accomplished by collapsing a piece of i/4-inch copper tube until the vacuum pressure is in the proper range. A good vacuum valve between the vacuum system and the restriction can be used to turn the bleed off and on. 5-27 When the gas bleed procedure is employed on a vacuum system, the cold traps, if any, should not be maintained cold but allowed to warm to room temperature. Diffusion pumps should be shut down before the bleed gas is applied, leaving only the mechanical pump(s) operating, since the required system pressure for effec- tive bleeding is above their normal operating pressures. 5-28 Section 6 FLOWCHARACTERISTICS 6.1 6.1.i 6.1.2 6.1.3 6.1.4 6.1.5 6.1.6 6.2 6.3 6.3.1 6.3.2 6.4 6.4.1 6.4.2 6.5 6.5.1 6.5.2 6.5.3 6.5.4 6.6 6.6.1 6.6.2 NOMENCLATURE GAS FLOW ................. Poiseuille Flow ............ Knudsen or Molecular Flow ....... Transition Flow ............ Turbulent Flow ............ Choked Flow .............. Distinguishing Between Modes of Flow . . • PERMEATION ................ LIQUID FLOW ............... Laminar Flow ............. Turbulent Flow ............ CORRELATIONOF LEAKAGE RATES ....... Gas-to-gas Flow Correlation ...... Gas-to-liquid Correlation ....... ANOMALOUS LEAKS ............. Check-valve Leaks .......... Geometry Changes in Leaks ....... Self-cleaning Leaks .......... Surface Flow Leaks ........... LEAK CLOGGING .............. SurfaceTension Effects ........ Vapor Pressure, Viscosity, and Particu- late Effects ............. 6-1 6-i 6-4 6-6 6-7 6-7 6-8 6-9 6-13 6-13 6-13 6-13 6-13 6-14 6-16 6-16 6-17 6-17 6-21 6-22 6-22 6-24 l Ao A Co c d d m F f g K Kp £ M m N K NRe n P Pa PT _P Q,Qg Q£' Qv NOMENCLATURE FOR SECTION 6 Area Avogadro's number (number of molecules per mole) Coefficient of discharge, dimensionless Specific heat (Cp, c v, value at constant pressure and constant volume respectively) Diameter Molecular diameter Average velocity in flow channel Fanning friction factor, dimensionless Standard gravity Constant Permeation coefficient or permeability Length Molecular weight Mass Knudsen number, dimensionless Reynolds number, dimensionless Number of molecules per unit volume Pressure (PI, P2, upstream and downstream pressure respectively) Average pressure Pressure at throat of a nozzle or orifice Pressure differential Leakage rate, pressure-volume per unit time Leakage rate, volume per unit time , j qR R0 r c T V V a W Z 7 n P o Permeation rate, volume per unit time Radius Gas-law constant Critical pressure ratio Absolute temperature Volume Sonic velocity Mass flow rate, weight per unit time Function given by the argument of Equation 5-13 Specific heat ratio, Cp/C v Viscosity (qa, n£, viscosity of gas and liquid respectively[ Mean free path Density Surface tension Contact angle, liquid to wall Section 6 FLOWCHARACTERISTICS 6.1 GAS FLOW Mass transfer due to gas leakage across a boundary proceeds in one or more of three basic modes of flow. These modes of flow are classified as • Poiseuille, or laminar, flow • Knudsen, or molecular, flow • Transition flow, which is a mixture of laminar and Knudsen flow • Turbulent and choked flow The rate of transport in each mode is a function of several fac- tors associated with the leak channel and the gas involved. The total pressure gradient is common to all modes of flow. 6.l.l Poiseuille Flow Isothermal streamline motion in round tubes under conditions such that the velocity distribution is parabolic with the maximum velocity at the axis characterizes the laminar type of flow. At sufficiently high values of velocity the motion becomes turbulent and is characterized by the existence of eddies or vortices in the flow channel. Turbulent flow is rarely encountered in leak-de- tection work. Streamline or laminar-flow leakage rate through a straight capillary of circular cross section can be calculated from Equation 6-1: (_I _ Pa ( )-- PI - P2 (6-i)Q = _ n£ PI + P2 where P = a 2 The equation is applicable where the length and diameter of the flow passage are known. The equation may be rewritten as follows: Q = K a i 2 (6-2) n where K represents the constants in Equation 6-1. The constant K includes the two geometry factors of diameter and length, which are generally not known. Thus, = Laminar flow occurs under conditions determined by the average velocity of flow across a plane transverse to the leakage path, 6-1 and by the density of the gas and its viscosity.* A dimension- less ratio called the Reynolds number may be used to express the conditions for laminar flow as well as other types of flow. The Reynolds number is the ratio of the inertial to the viscous forces in a flowing fluid. It is expressed as: = 0 d F NRe n (6-4 ) Substituting the value of the density in Equation 6-4, the ideal gas equation gives the following expression for the Rey- nolds number for an ideal gas: Q 4M NRe = _ z _ RoT (6-5) The critical value of the Reynolds number defining the re- gion between laminar and turbulent flow has been shown to be dependent upon the entrance conditions, roughness of the walls, and the shape of the flow path. In general, for smooth tubes with well-rounded entrances, the critical value is about 1,200. For flow corrections necessitated by turns, constrictions, and surface roughness see Reference 6-1. The two most important characteristics of laminar leaks are: i) flow is proportional to the difference between the squares of the pressures upstream and downstream of the leak; and 2) leakage is inversely proportional to the leaking gas viscosity. Table 6-1 shows that the viscosities of many gases are similar. Therefore, a change of gas will not markedly in- crease the sensitivity of the leak-detection method unless this change of gas implies a change of instrument sensitivity. However, as shown in Figure 6-1, increasing the pressure dif- ference across the leak by a factor of a little more than three will increase the flow rate through this leak by a factor of ten. Obviously, then, when the leaks to be measured are in the laminar flow range, the simplest method of increasing de- tection sensitivity is to increase the pressure across the leak. The average velocity dividual molecules is m *From kinetic theory the viscosity of a gas is: mF n = 3 /_d 2 m RoT/_M ) z12 and the mass of the in-is (8 = Thus, 2 (MRoT) z/2 3_; 2 _ d 2 m This equation shows that the viscosity of a gas is independent of pressure and is proportional to the square root of temper- ature. 6-2 U9 E 4to- O W _9 uJ _J Figure 6-1. HELIUM GAS BROKEN LINES INDICATE THEORETICAL LAMINAR FLOW SLOPE 4 6 8 I0 20 40 60 80 I00 PRESSURE ACROSS LEAK, psi 200 Laminar Flow in a Typical Hardware Leak. (Re- printed from J.W. Marr, Study of Dynamic and Static Seals for Liquid Rocket En@znes, Final Report Phase If, Contract NAS 7-102 (Ref.6-2).) 6-3 Table 6-1 VISCOSITY OF GASES AT 0°C (Ref. 6-1) Gas Viscosity, Centi_oises Acetylene 0.0092 Air 0.0169 Ammonia 0.0094 Argon 0.0208 Benzene 0.0069 Carbon dioxide 0.0135 Carbon disulfide 0.0089 Carbon monoxide 0.0171 Ethane 0.0085 Ethyl alcohol 0.0082 Ethylene 0.0093 Halogenated hydrocarbon F-If 0.0103 Halogenated hydrocarbon F-12 0.0118 Halogenated hydrocarbon F-21 0.0108 Halogenated hydrocarbon F-22 0.0120 Halogenated hydrocarbon F-If3 0.0098 Helium 0.0178 Hydrogen 0.0083 Hydrogen sulfide 0.0118 Methane 0.0100 Nitric oxide 0.0178 Nitrogen 0.0168 Nitrous oxide 0.0133 Oxygen 0.0191 Propane 0.0077 Sulfur dioxide 0.0116 water 0.0088 Xenon 0.0210 6.1.2 Knudsen or Molecular Flow Molecular flow occurs in a duct when the mean free path is greater than the largest dimension of a transverse section of the duct (Ref. 6-1). In such flow, each atom moves independently and randomly. Net flow is in the direction of a concentration gradient. The mean free path is the average distance that a molecule travels between successive collisions with the other molecules of an ensemble; it is given by the following equation: 1 = (6-6) /2_nd 2 m 6-4 OIf n = (mA)/(V × M) becomes and V = m/M [(RoT)/P] then Equation 6-6 l = RoT (6-7) m In Equation 6-7, the mean free path at constant pressure is proportional to temperature. However, if the amount of gas in a volume is kept constant, the mean free path is independent of temperature (Equation 6-6). The magnitude of molecular diameters and mean free paths is shown in Table 6-2. As a convenient calculation guide, the mean free path of air at room temperature is: l = 5 × l_ 3 centimeters (6-8) air P when P is expressed in torr (about one millimeter of mercury). Table 6-2 MEAN FREE PATHS AND MOLECULAR DIAMETERS FOR VARIOUS MOLECULES (Ref. 2-3) Mean Free Path Molecular Diameter Molecule (cm × i_ _ at 1 torr and 25°C) (cm × 10 _) Hydrogen 9.3 2.75 Helium 14.72 2.18 Neon 10.45 2.60 Argon 5.31 3.67 Oxygen 5.40 3.64 Carbon dioxide 3.34 4.65 Water 3.37 4.68 Benzene 1.34 7.65 Methane 4.15 4.19 Ethane 2.53 5.37 Propane 1.82 6.32 n-Butane 1.46 7.06 n-Pentane 1.19 7.82 n-Hexane 1.03 8.42 Knudsen or molecular flow exists when the expression (I/d) (8/_) *a is greater than i. The flow rate in long cir- cular tubes under these conditions can be calculated from: /_ _-_ d 3Q - 6 _-- (Pl - P2) (6-9) 6-5 In the case of an orifice or aperture in a flat plate the flow rate in torr-liters per second is: _d2 IT1 _2Q = 3. 638 -T- M AP (6-10) These flow-rate equations include the terms of length and diameter of the flow channel. In most cases the leak channel is irregularly shaped and the values of length and diameter are not known. Using these equations, an estimate of leak size must be made to calculate leakage. Again, when experimental data on leakage rate are available a value of the ratio (d3/£) or of d 2 may be obtained if the other constants and conditions are known. Thus the equations can be used to evaluate effects on mass flow rate of other gases and other temperatures and pressures. When the mean free path is large relative to the size of the effective leak diameter, the gas flow is limited by molecular collisions with the channel wall. There are comparatively few intermolecular collisions (the molecules act independently of each other), and the molecular momentum interchange with the wall causes molecules to travel in a direction opposite to that of the net mass flow. For example, when an ultra-high-vacuum system at 10 -9 torr is leak-tested by a mass-spectrometer leak detector operating at I0 -? torr, some of the tracer gas will arrive at the leak detector because of migration in a direction opposite to the concentration gradient. 6.1.3 Transition Flow where The transition from laminar flow to molecular flow occurs over a pressure range of about two orders of magnitude, rather than at any set pressure value (see Section 6.4,"Correlation of Leakage Rates"). Transition flow can be described by an empirical equation formulated by Knudsen (Ref. 2-3): Z i+2Rf lj2 _-- _Ro_ Pa 1 + 2"47RI RoT)Pa (6-11) (6-12) Equation 6-11 is useful over a wide range of pressures for flow in long cylindrical tubes where the flow is laminar, molecular, or transitional. Another empirical equation suitable for estimating purposes was derived by Burrows (Ref. 6-3) by assuming that the total flow rate can be represented by the sum of the laminar and molecular flows (Equations 6-1 plus 6-9). The following equation was ob- tained in this way for the flow of air at 20°C from atmospheric pressure to a high vacuum (zero pressure): 6-6 where meters. Q = 2 31 x i0_ R3 [ ]. -_ 3.55 x i0 _ R + 3.18 (6-13) Q is in torr-liters per second, with R and £ in centi- This equation is an adequate representation of the events occurring in the leak. Both laminar and molecular flow always occur together in a leak. However, laminar flow is insignifi- cant at small values of R and the molecular flow mode contrib- utes little to total flow at large values of R. A simple graphical solution is described in Section 6.4.2 to calculate laminar flow through one section of a tube and molecular flow through another to approximate the behavior in the transition region. 6.1.4 Turbulent Flow As mentioned, above a Reynolds number of about 2100 in the case of circular pipe, flow becomes unstable, resulting in the development of innumerable eddies or vortices. The laws for turbulent flow are quite different from the laws for laminar flow. The equation relating flow rate (Q) times volume/time may be written: gRoT(Pl _ - P2 L 64 fM£Q in units of pressure 2)11_ (6-14) where f, the fanning friction factor, is a function of the Rey- nolds number and depends on the roughness of the channel walls. The Reynolds number can be considered approximately constant in fully developed turbulent flow. Turbulent flow, because of its associated high velocity, occurs only in large leaks. 6.1.5 Choked Flow Choked flow, or sonic flow, as it is sometimes called, occurs under special conditions of pressure. Assume a passage in the form of an orifice or a nozzle, and assume that the pres- sure upstream is kept constant. If the pressure downstream is gradually lowered, the fluid velocity through the throat of the orifice or nozzle will increase until it reaches the speed of sound in the fluid. If the downstream pressure is brought below this pressure, no further increase in fluid velocity will occur, and the mass flow rate will have reached a maximum or critical level. This is the condition known as choked, or sonic, flow. The ratio of the throat pressure to the upstream pressure when maximum flow occurs is called the critical pressure ratio (rc) ; this is related to y by the following equation: re = y+-_[] (6-15) 6-7 The maximum, or sonic, velocity for an ideal gas is given by V a = _Yg RoT (6-16) Based on knowledge of only upstream conditions of temperature and pressure, the maximum mass discharge under critical flow conditions is calculated as W = ----4-- CoPI__,,.o._ 1 (6-17) For an ideal monatomic gas, the value of 7 is 1.67. For poly- atomic molecules, the heat energy supplied is used for increas- ing not only the kinetic energy of translation but also the kinetic energy of rotation and vibration. Since the same amount of extra energy is required at both constant pressure and con- stant volume, y decreases with molecular complexity. Charac- teristic values of 7 are shown in Table 6-3. Additional values may be calculated (Ref. 6-4) or obtained from other references (Ref. 6-5). Table 6-3 MOLAR HEAT CAPACITY OF GASES Calories per Mole at 25°C and 1 Atm C C Cp/Cv- YGas __2__ v _ Argon 4.97 2.98 1.67 Helium 4.97 2.98 1.67 Hydrogen 6.90 4.91 1.41 Oxygen 7.05 5.05 1.40 Nitrogen 6.94 4.95 1.40 Carbon dioxide 8.96 6.92 1.29 Ammonia 8.63 6.57 1.31 Ethane 12.71 10.65 1.19 Propane 17.60 15.60 1.13 Because of the special conditions, choked flow is seldom encountered as the predominant flow mode, except in very large leaks. 6.1.6 Distinguishing Between Modes of Flow Equations have been presented for the various possible modes of flow that can prevail in a leak. The following sum- mary indicates the manner in which it is possible to determine the mode of flow in any situation. 6-8 The dimensionless ratio of mean free path to a character- istic lateral dimension of the flow channel is known as the Knud- sen number : NK = I/d (6-18) Laminar flow exists for values of NK < 0.01 and molecular flow exists for values of NK > 1.0. The region of transition from one mode to the other lies between values of 0.01 and 1.0. The Reynolds number (Equation 6-4) can be used to distin- guish between turbulent and laminar flow. Turbulent flow exists at values of NRe > 2100; laminar flow exists for values of NRe < 1200. For values of 1200 < NRe < 2100 the flow mode can be either turbulent or laminar, depending upon the channel rough- ness. As a rule of thumb, it is possible to predict the mode of flow through a leak channel from a knowledge of the rate at which a gas passes through the leak under a differential pressure in the order of one atmosphere (Refs. 5-4, 6-3, 6-6, and 6-7). Leakage Rate Mode (atm-cc/sec) Turbulent > 10-2 Laminar 10 -I to 10 -6 Transition 10 -_ to 10 -7 Molecular < 10-_ 6.2 PERMEATION Permeation is the passage of a fluid into, through, and out of a solid barrier having no holes large enough to permit more than a small fraction of the molecules to pass through any one hole. The process involves adsorption, diffusion, dissociation, solution, migration, and desorption. The rate of flow by permeation is given by the following equation: q = Kp A _--_P£ (6-19) The AP in this case represents the difference in the partial pressures of the leaking fluid on the two sides of the barrier. The permeability coefficient, Kp, is defined as the product of the diffusion coefficient and the solubility coefficient of the permeating fluid in the barrier material. In a porous ma- terial in which the ratio of the volume of an average pore to the surface area of the pore is large, fluid transport from pore to pore is governed largely by diffusion processes. 6-9 Values of the permeability coefficient for a few polymeric and ceramic materials are shown in Table 6-4. The literature reference (Ref. 6-8) should be consulted for permeability values at other temperatures, or with other materials, or for differ- ent permeants. If any system is to be relatively leak-tight, the materials of construction must have a very low permeability. For example, the permeation rate at room temperature of a natural rubber gas- ket 0.i inch thick, 0.I inch wide, and 5 inches in diameter with a one-atmosphere hydrogen pressure differential is 6 × 10 -6 atm- cc/sec. In some uses, this permeation might represent an unac- ceptable leakage rate. Permeation presents a problem to leakage checking equipment where the construction materials have a high permeability to the tracer gas. If a component containing a rubber diaphragm one millimeter thick and one square inch in surface area is leak-checked with helium gas, a leakage of approximately 2 × i0 -s atm-cc/sec will be measured across the diaphragm. This leakage is due to permeation of helium through the diaphragm; not to any actual holes. It represents the maximum sensitivity of helium leakage testing that can be performed on this component. However, if the component is to be used with another fluid, to which the membrane is impermeable, the leakage due to helium permeation measured during leakage testing is misleading. Another example of this type of false reading is that ob- tained from a rubber O-ring. Depending on the particular mate- rial being tested, an O-ring will have a permeability of approxi- mately 10 -_ atm-cc/sec-atm per linear inch of exposed surface. Figure 6-2 illustrates the permeation rates of O-rings to helium; it also shows the time lag which depends upon the diffusion con- stant (Ref. 6-9). This permeability does not have to be taken into consideration during routine leakage checking if the leakage measurement can be performed before helium saturates the O-ring. To eliminate permeability as a factor in leakage measure- ment, one of three possible procedures may be used. i. The leakage measurement may be taken rapidly, not allowing the material to be saturated with gas. This is only possible if the material is relatively thick. For example, a very thin rubber diaphragm will rapidly saturate and almost immediate show leakage. On the other hand, O-rings are relatively thick and will nou saturate rapidly enough to give a reading within a rea- sonable period of time (five minutes). If the diffu- sivity and solubility of the fluid in the material are known, it is possible to calculate the rate of increase of leakage (Ref. 6-10). However, in many cases (where the leakage path is long) this calculation is not neces- sary. An experimental check can be made to determine very quickly if leakage through a thick gasket is incon- sequential for short-time periods. 6-10 Table 6-4 PERMEABILITY OF POLYMERICMATERIALS TO VARIOUS GASES (Ref. 6-8) std cc cm × 108 (Note: 1 bar = 10_ dynes per sq cm) sq cm sec bar Carbon Dioxide Helium Hydroqen Nitrogen Oxygen Type or Trade Name Suna S 92.8 17.3 30.i 4.7 12.8 Butad lene-acryloni tr ite copolymer Cellulose acetate Cellulose acetate butyrate Cellulose nitrate Ethyl cellulose Hydropol Mlpolam MP Neoprene G MEM-II3 Polycarbonate* Nylon 6 Polybutadlene polychlorotrlfluoroethyle,e Perbunan 18 12.7 18.9 1.89 G.12 German _rbunan 9.20 11.3 0.84 3.0 Hycar - OR - 15 5.13 5.35 0.178 0.72 Hycar - OR - 25 7.40 8.05 0.45 1.76 Celanese P-912 6.6 0.01 Kodapak II lO. 8 15.8 1.1 2.8 5.1 1.48 Etbo¢el 810 KeI-F TritheRe Alathon 14 Polyethylene terephthalate Mylax A polypropylene (0,907 g/_ J Polystyrene Dow 0641 polyv_nyl chlorlde-dloctyl phthalate IOI°EF-100 31.6 22.4 5.5 17.9 36.3 11.0 3.0 8.5 3.85 4.3 0.2 0.69 19,2 3.30 10.2 0.88 3.0 713. 90. 150. 75. 128. 0.92 0.0063 0.023 103.9 31.6 4.05 14.3 0.73 0.0025 0.02 25.5/30C 0.73 0.0079/23C _._ 3.7 5.88 0.73 1.65 0.00| 0.73 0.44 0.0031 0.019 0.33/30C 2.72/30c 5.63/20C G7.6 5.0 18.3 0.765/30C 2,0/30c Propane Water 2.0/31c 0.0057 40.5 900. 4740. 9750 750. 53 0.22/30c 97.8 36.8 Polyv_nyl_dene chloride Saran S17 _uDbec. butyl OppanoI-B-200 Rubber, hydrochloc_de Rliofllm 140-N2 Pllofllm FMI Rubber, methyl Rubber, natural Rubber, polysulflde Rubber, dimethyl silicone Teflon GLa_s Thiokol B FEP TFE 0.024 0.01 0.05 4.8 0.22 0.0018 0.89 0.48 1.20 0.70 0.109 0.40 0.3 10.9 12.0 0.36 1.6 105. 25.0 38.3 7.4 17.5 2.37 1.2 0.22 2030. 263 • 495. 210. 450. 7.51 30.1 9.88 1.44 3.37 523. 17.0 2.4 7.5 FUSed silica 0.75 0.00011 Vy¢or 1.13 0.00030 Pyrex 0.0_ Soda llme 0.00056 X-ray shield 0.000 000 31 0,480 0.00027 126. , 3080 7.4 2570 28500. 'Information furnished by the Medical Development Operatlon of the General E1ectrlc COmpany's Chemical and Medical Division. 6-11 SILICONE** 0 1 i I I I I 30 60 90 120 150 180 TIME, minutes Figure 6-2. Permeation Rate Versus Time of Rubber Gasket for a 4 × 4 mm Cross Section. (Reprinted with permission from I. Kobayeshi and H. Yada, "Leak Test of Rubber Gaskets," Fundamental Problems in Vacuum Techniques, Vol. I, Per- gamon Press, London, 1960, p.248 (Ref. 6-9).) . . The maximum permeability of all components and the re- sulting mass transfer produced during leakage testing may be calculated by Equation 6-19. Then the differ- ence between the total measured leakage and the per- meation will be the actual gas leakage. The last method and the most difficult one to perform, is to quantitatively measure the leakage at several pressure differentials. If the flow is solely due to permeation the leakage will be directly proportional to the difference in permeant concentration across the leak. A flow through a hole or a porous barrier will exhibit a leakage that is proportional to the differ- ence in the squares of the pressures on each side of the barrier under laminar conditions. In this way, the presence of holes in the component can be differ- entiated from permeation. 6-12 6.3 LIQUID FLOW The flow mode of a liquid through a leak or capillary chan- nel at low flow rates will be laminar; at high flow rates the flow mode will be turbulent. The value of the dimensionless Reynolds number for the liquid is again the criterion for deter- mining which mode prevails (see Section 6.1.1). 6.3.1 Laminar Flow 6.3.2 Poiseuille's equation for laminar liquid leakage flow is QV = • Iz) nZ Turbulent Flow The turbulent flow equation for liquids is sh , / (P1 - P2)g Qv _- d V (6-21)= 2pf£ Turbulent flow occurs only in very large liquid leaks. 6.4 CORRELATION OF LEAKAGE RATES It is often of interest to find the leakage rate of a gas or liquid through a given leak channel when the leakage rate for a particular gas through that channel is known from a previous measurement. Under certain conditions it is possible to cor- relate leakage values between different gases and between a gas and a liquid without a knowledge of the actual dimensions of the leak channel. Variations in the leakage rate with molecular weight, temperature, and pressure may also be calculated as long as the mode of flow remains the same. It does not appear pos- sible to predict a leakage rate if the mode of flow changes or if, more specifically, a knowledge of the geometry of the leak- age path must be known (Ref. 6-11). 6.4.1 Gas-to-gas Flow Correlation If the flow is laminar, Equation 6-2 may be used to calcu- late a new flow rate relative to a known flow rate for two gases having different viscosities, or for different levels of inlet and outlet pressure for the same or two different gases. The geometrical factor K is common to the equations for the known and calculated flow rates. For the same levels of pressure, the flow rates for two gases of different viscosity are related: QA nB QB nA (6-22) 6-13 In general, QA _ nB 2 _ P2 (6-23) QB _ - P_ where (P:, P_) and (P3, P_) are two pairs of inlet and outlet pressures. The subscripts A and B represent two different gases. if a single gas is involved, the viscosity ratio is unity in Equation 6-23. A change in flow due to a difference in tempera- ture is accounted for by the effect of temperature on viscosity. The footnote in Section 6.1.1 indicates that the viscosity of a gas varies as the square root of temperature. As shown in Table 6-1, the viscosity of gases at constant temperature varies by less than half an order of magnitude between the most viscous and the least vzscous. If the flow is molecular, and the leakage path is long com- pared to the length of its effective diameter, Equation 6-9 can be used to generate a similar proportionality: QB x × 3" p_ (6-24) It is assumed in going from one set of pressures to the other that the flow mode remains unchanged in both laminar and molecular flow. When there is reason to believe that the flow will change in going to a different level of pressure the following pro- cedure is recommended: • If pressure is increased, correlate as laminar. • If pressure is decreased, correlate as molecular. • If gas is changed, correlate as molecular. 6.4.2 Gas-_o-llquid Correlation It is possible to predict liquid leakage on the basis of leakage measured under other known conditions. This method is generally applzcable to a leak or series of leaks which have a conductance between 1 and i0 -s atm-cc/sec-atm. An equation which relates the laminar flow of a gas to the laminar flow of a liquid through the same leak is readily 9b- tained by dzviding Equation 6-1 by Equation 6-20. The equation is independent of the geometry of the leak and is n£ Pa Solution of this equation is easily accomplished by use of the nomograph in Figure 6-3. One line connects the viscosity axes with a reference axis (I). A second line connecting the average 6-14 '2 @ 2 r r I T I I'I TII S }1_.*/ii_ ']gVIW]'I (]111011 _ _ ,_ _ '_, ,o ,,:, i r l I I I 1 1 I ] I I I i i i _I b i I _ i _ 1 [ I I I I l ISd ']_l/ISS]lld S_/9 391/_]/_I T _' _ T _T,T_ o -,=1' m m o 0 Z I _D I _D S]SlOdlLII]:} 'A IISO_Sl/_ $1/_ I I I I I ! I I [i I I I I I t I I_' I I I I I 1 I I I I I I I I I I I S3SlOdhLld]3 "_,LiS03SI^ 0_non 6-15 pressure axis with axis (I) locates a point on axis (II). Third- ly, a line connecting the point on axis (II) with the gas leakage value also intersects the liquid leakage axis at a value which is the solution to Equation 6-25. This correlation proceduze is accurate only for laminar flow leaks. Should the measured leakage be molecular rather than laminar, the error introduced in the calculation will pre- dict a greater liquid leakage than will actually be found. The equation may therefore be used with confidence, since any error will add a margzn of safety to the results. It is also necessary that: • Leakage be the result of a finite hole or holes, and not of permeation_ • Gas flow be laminar; i.e. the flow through the leak is in the range of 1 to 10 -3 atm-cc/sec or is made up of a number of leaks in that flow range. • Calculatzons should at best be considered accurate to only a factor of two. Error in both the measure- ments and the deviat±ons from the flow equations pre- clude a more accurate solution. In experiments performed to check the validity of the above correlation (Ref. 6-12) liquid leakage was measured for leaks with previously measured gas leakage rates. It was found that leaks having a gas conductance in the 10 -3 atm-cc/sec range had a liquid leakage approximately one-half that predicted by Equa- tion 6-25. Leaks in the 10-" atm-cc/sec range leaked liquid at a rate approximately one-tenth the rate predicted. Liquid leak- age in leaks in the i0 -_ atm-cc/sec-atm range were approximately one-twentieth of that predicted by the above equations. It would appear that Equatlon 6-25 for correlation will produce conservative answers; i.e. the actual liquid leakage will always be smaller than that predicted by theory. It is believed that the liquld flow was lower than calculated for two reasons. Fizst, no correction was made for any molecular flow component of the measured gas leakage. Secondly, the ef- fective diameter of the leak channel was reduced in size by an immobile layer of liquid adjacent to the leak wall. 6.5 ANOMALOUS LEAKS Some leaks which occur in practice exhiblt a flow behavior quite unlike that of an ideal smooth-bore capillary. Such leaks are called anomalous leaks, and include check-valve leaks, geo- metry-change leaks, self-cleaning leaks, and surface-flow leaks. 6.5.1 Check-valve Leaks Reference 6-2 contazns examples of check-valve and geometry- change leaks found during a study of leakage phenomena. 6-16 Figure 6-4 is a plot of the leakage-pressure differential obtained on a damaged needle valve. It was observed that al- though the typical laminar flow curve was obtained at a high pressure differential, below this pressure the leakage abruptly stopped. With increase of the pressure, the leak reappeared. This phenomenon was repeatable. This type of leak would be particularly hard to find, since it would not be detected below a critical pressure value. 6.5.2 Geometry Changes in Leaks The shape of a leak may change with variations in tempera- ture or pressure. Either a liquid or a gas under pressure can cause a change in leak size. Change of leak size will affect a prediction of flow based on either Equation 6-23 or Equation 6-24. Each of these equa- tions has been derived on the basis that the geometry factor re- mains invariant with changes in the other variables. Each of the equations correlates a new flow and a new pressure differ- ential with an old flow and an old pressure differential. If the new pressure differential is higher than the old, the leak size may be caused to increase. If so, the actual leakage will be greater than that predicted by the correlation calculation. The influence of temperature on leak size is somewhat unpre- dictable. For example, either an increase or a decrease in temperature can open up a leakage path, depending upon the stress distribution in the material near the leak wall. 6.5.3 Sel f-cleanin 9 Leaks Quantitative determination of the leakage of helium across gaskets under compression was observed to consist of a series of discrete laminar flow steps (Ref. 6-2). Figure 6-5 shows the data plotted in logarithmic form along with theoretical laminar flow lines. Since the step-like increases in flow rate could result from a permanent deformation of the gasket, an experiment was run using an aluminum gasket too sturdy to be deformed. Figure 6-6 shows the data obtained from this experiment. During the original increase in pressure, the leakage increased at a rate greater than the square of the pressure increase. However, upon release of the pressure, the leakage decrease was proportional to the square of the pressure decrease. A second increase in pressure produced an increase which retraced the leakage en- countered during the pressure decrease. It is believed that the original pressure increase cleaned the leakage passages. Further pressure cycling did not effect the maximum leakage. This suggests that whenever possible leak- age testing should be done at the proposed operating pressure, in order that potential leaks may be formed and observed. 6-17 163 U E O t9 uJ I i0-6 Figure 6-4. LEAKAGE DROPS TO LESS THAN I0 "8 otto cc/$ec 2 4 6 8 I0 20 40 60 80 I00 200 PRESSURE ACROSS LEAK, psi Check-valve Effect in a Hardware Leak. (Re- printed from J.W. Marr, Study of Dynamic and Static Seals for Liquid Rocket En@_nes, Final Report Phase II, Contract NAS 7-102 (Ref.6-2).) 6-18 ,d5 i06 U9 t_ E 4-" O W _9 UJ -J 10.7 Figure 6-5. BROKEN LINES INDICATE THEORETICAL LAMINAR FLOW SLOPES I0 3 PRESSURE ACROSS LEAK, psi IO 4 Geometry Change in a Gasket Leak (Reprinted from J.W. Marr, Stud_ of D[namic and Static Seals for Liquid Rocket Engines, Final Report Phase II, Contract NAS 7-102 (Ref. 6-2).) 6-19 id4 i0-5 U U U E 4-- O W t9 w -- 0-6I IO"7 I0 0 INITIAL PRESSURE INCREASE 0 PRESSURE DECREASE & SECOND PRESSURE INCREASE BROKEN LINES INDICATE THEORETICAL MOLECULAR 8= LAMINAR FLOW SHAPES Figure 6-6. 20 40 60 80 1(30 200 400 600 I000 PRESSURE ACROSS LEAK, psi / / Self-cleaning Effect in Leaks. (Reprinted from J.W. Marr, Study of Dynamic and Static Seals for Liquid Rocket Engines , Final Report Phase II, Contract NAS 7-102 (Ref. 6-2).) 6-20 6.5.4 Surface Flow Leaks The flow of gases and noncondensing vapors through fine capillaries and micropores cannot be dealt with by simple meth- ods analogous to those applicable to molecular and laminar flow. Because of the narrow passages and large surface areas involved, surface adsorption and surface flow become important factors. The adsorption may be physical where only relatively weak van der Waals attractions are involved; or the adsorption may be re- garded as chemical where the surface of the solid provides bind- ing sites for the atoms, and the electronic structure of the solid permits the formation of a chemisorption bond. The nature of the binding sites, the bonds between the gas atoms, and the surface influence the degree of surface migration of the atoms. The flow along a fine capillary or micropore is assumed to consist of two mechanisms worklng simultaneously: I. Molecular flow along the bore of the capillary, whereby molecules are supposed to collide with the wall, rebound, and collide with the wall again without intermolecular collisions. 2. Surface flow along the wall of the capillary, whereby molecules are adsorbed and diffuse along the surface of the wall. Both of these mechanisms promote gas flow from regions of higher gas concentrations to regions of lower gas concentrations. For a given set of conditions, the proportion of molecules that follow the above mechanisms depends on a variety of factors. These factors include: • Sticking probability (the probability that a molecule striking the surface will become adsorbed) • Length of time the molecule remains adsorbed (the mean surface lifetime of the molecules) • Coefficient of surface diffusion of the molecules Such features are, in turn, influenced by other characteristics -- the number of sites occupied by the adsorbed molecules and wheth- er a complete monolayer has been formed. The nearer the properties of a gas approach those of a con- densable vapor the greater the proportion of surface flow. There- fore, a reduction of temperature or an increase of pressure may sometimes promote a total flow in excess of that predicted by the laminar theory. Although the final leak rate achieved with a condensable gas will be higher than predicted from flow theory, Hayashi (Ref. 6-13) showed that there will be an initial delay of flow due to condensation of the tracer gas on the leak surfaces. Consideration of this delay is important if a tracer probe tech- nique is used for testing. For example, if butane, a readily 6-21 condensable gas, is used in a tracer probe, some small leaks will be missed because of the time delay caused by the adsorption. Two remedies can be suggested to counter this problem: i. Use of a noncondensable gas 2. Use of a detector probe where the gas is continually in contact with the leak and an equilibrium flow rate is established 6.6 LEAK CLOGGING 6.6.1 Surface Tension Effects Very small holes that may give rise to appreciable leakage rates of gas under high vacuum conditions are sometimes partially or wholly blocked by solid particles having sizes in the micron range, or by liquids as a result of surface tension effects. The blockage may be of a temporary nature, and so give rise to misleading test results. Until leakage testing has been performed, the system should be kept out of contact with atmospheric or other vapors and par- ticulates that may cause blockage. However, this condition can- not always be met in practice. It is frequently observed that if a container to be tested for leaks has been in contact with a liquid at any time after manufacture, no leaks of small size (i.e., I0 -_ atm-cc/sec or smaller) will be found. Small leaks are clogged with liquid because of surface tension. If water has entered a capillary tube, the pressure necessary to force it out of the tube is given by the following equation: p = 40 cos_ d (6-26) A leak with a diameter of 1 × i0 -_ centimeters will have a leak- age rate for helium of approximately 1 × 10 -6 atm-cc/sec. If water, with a surface tension of 72 dynes per centimeter, enters such a leak, the pressure required to force it out is approxi- mately 2.8 atmospheres (cos _=i). Since the pressure differen- tial during leakage testing is only one atmosphere, this leak is essentially clogged by the water. Clogging is more likely to take place under actual conditions than in the above example. Most leaks are neither circular nor regular in diameter; they usually contain constrictions and occasionally consist of slits. Figure 6-7 shows an example of surface-tension clogging by a slug of liquid in the leak path. The cross section of the leak channel increases to the right. Gas pressure from the left has forced all liquid out of the leak but that in the slug. With no change in cross section, the adhesive forces acting at the liquid-wall interface would be equal and opposite in direc- tion, and surface tension would not affect the ability of the applied pressure, P, to force the liquid out of the hole. How- ever, the increase in cross section on the right reduces the 6-22 I ]P>2o" rl r2 Figure 6-7 Liquid in Nonuniform Channel force of surface tension directed to the right, so that the liquid resists any attempt to force it out. In some cases, pressures of many atmospheres are required to free a leak path of a liquid slug. This type of clogging effect will be greatest at the exit of a leak path, and the eventual removal of the slug may depend mainly on evaporation. Conversely, if the gas pres- sure forces the slug to the left, the net surface-tension force will aid such flow, and the slug will pass all the more easily into the smaller cross-sectional region. If the cross section again increas- es on the left, the slug will re- main locked in the constriction until it is removed by other means. If the liquid does not wet the wall, the curvature of the meniscus on each side of the s--_ug is reversed, and the slug will be easily forced toward the larger cross section, but not as easily toward the smaller cross section. Liquid clogging is not generally permanent in nature. If the temperature of the container is raised, the surface tension of the liquid will decrease or the liquid inside the leak will evaporate. However, if the entering vapor c_ntains a dissolved salt, solid particles will remain after evaporation and cause permanent blockage. Gas leakage much smaller than 10 -8 atm-cc/sec is rarely seen, even though it is in the range of detectability. Such small leaks are found on new systems which have never been in contact with liquid. These leaks have to be carefully treated or they will clog during normal handling. It may be calculated that a leak 10 -8 atm-cc/sec has a diameter in the order of i0 -s centimeters. To place this number in dimensions of atomic size, its diameter is about 1,000 Angstrom units.* Molecules of liquid contaminants (for example, either hand or machine oil) are in the order of 100 Angstroms in length. Should these molecules be held by surface tension, they could reduce the size of the hole and therefore reduce the leakage rate to a point of clog- ging. Molecular flow, which should predominate in this range, is proportional to the cube of the leak diameter. Therefore, a small decrease in leak diameter will produce a drastic decrease in gas leakage. *One centimeter = 108Angstrom units. 6-23 6.6.2 Vapor Pressure, Viscosit X, and Particulate Effects A pressurizing test may suffer some restriction in its ap- plication to certain types of vacuum equipment, because the de- sign may permit the use of only small overpressures. In these applications the presence of water may easily block a leakage path owing to its high surface tension. For example, when a particular capillary has absorbed water that wets its wall, this capillary can become completely blocked against a gas pressure difference of 1-1/2 atmospheres. A thin mineral oil in the cap- illary has a lower surface tension and would be more easily moved, requiring only about one-half atmosphere. Even though the applied pressure difference may be sufficient to move the oil, the viscosity of oils is relatively high. Therefore, in practice, the oil will usually permanently block a capillary of any appreciable length. This is due to the extremely slow rate of flow of oil. Oil is also difficult to remove thermally, and a deposit is generally left in any leak pore. Consequently, oil should not be used for pressure testing before leakage testing with a tracer gas. Water will evaporate much more readily at reduced pressures than will a mineral oil, because of its higher vapor pressure. The rate of evaporation is accelerated if the temperature is raised. For leakage testing of evacuated systems, a number of points should be considered. • A preliminary water-pressure test is permissible, but not recommended. • Oil should never be used for overpressure test. • A compressed-air test should never follow a water- pressure test before vacuum testing for leaks. This is because the residual water that is held in small capillaries maybe forced back by the compressed air into larger voids. Under vacuum conditions, the liquid would evaporate slowly through the capillary restriction. • Even a preliminary water-pressure test is inadvisable for an ultrahigh-vacuum system. In such a system de- tection of very small leaks through fine capillaries becomes essential and the time required to ensure clearance of such capillaries (by evaporation of the residual water) may be unduly prolonged. To summarize, when a liquid is in a capillary, the liquid that has the lower surface tension is more readily moved by a gas-pressure difference, while a liquid that has a higher vapor pressure is more readily evaporated. As a consequence, capil- laries that may be blocked by water under the conditions of an overpressure test may often be cleared by evaporation of the water into a vacuum. Moreover, apparatus which must undergo a rigorous check for leaks must be dried in a vacuum because small leaks are readily closed by the water adsorbed on the walls. 6-24 Following the general rule, it is preferable that the ves- sel or component to be tested should be kept out of contact with sources that may cause blockage, until after leakage testing and leak repair have been completed. Components should be kept in a dry box to prevent absorption of water vapor from the at- mosphere. Solid particles in the millimeter size range are not, in general, a source of trouble. But solid particles in the mi- cron range may enter and temporarily block a capillary. They may subsequently be displaced, giving rise to an intermittent leak that is difficult to establish and locate. Blockage by solid particles may occur, for example, if the fluid used in con- nection with magnetlc crack-detection work is applied before testing for leaks. Magnetic fluld contains iron particles, of which the greater proportion are usually in the 2 i/2-to-10-mi- cron size range and are, therefore, comparable with the cross- sectional dimensions of small leaks. One of the disadvantages of porosity will be understood by considering the effect of a hypothetical condition of a thousand capillaries, one-fourth inch long, situated close together in parallel, each having a radius of i0 -s centimeter. The total leakage rate through this assembly would be approximately 1.3 x 10 -_ torr liters per second -- that is, about the same order of leakage as a single capillary of 10-2 centimeter radius. How- ever, if water has access to the porous assembly, the pressure difference required to remove it from the capillaries would be (from Equation 6-26) 14 atmospheres, or 210 pounds per square inch. This is ten times the pressure difference needed to re- move such blockage from a capillary of i0 -_ centimeter radius. Small holes in mild steel vessels or components may become permanently blocked by "rusting up" caused by moisture. In practice it is usually impossible to prevent atmospheric mois- ture from entering capillaries. Most metals are attacked to some extent by water in the presence of air; such an action gives rise to an oxide film that has a greater specific volume than the metal. This effect applies particularly to mild steel, where the oxide film has a specific volume about seven times greater than that of the parent metal. Consequently, the smal- ler capillaries, which have the greater tendency to retain water, readily rust up. Stainless steel is less likely to be affected in this way. When a liquid blocks a capillary its removal from the capil- lary may be influenced by such factors as: • Wetting combined with surface tension, which resists motion • Viscosity, which controls the tendency to flow • Vapor pressure, which controls the tendency to evap- orate. 6-25 In addition, there are situations where factors such as soluble contaminants, polarization in the liquid, ionic solutions of the wall material, electrokinetic forces, and temperature can affect the leak rate. Reference 6-3 is an excellent article dealing with the flow of liquids and the effect of evaporation on fine capillary tubes. Under certain special conditions it is possible for large leaks to become plugged. The expansion of liquids from below their triple-point pressures will result in freezing of the liq- uid to a solid. The buildup of a solid can temporarily plug leaks (Refs. 6-14, 6-15, and 6-16), and it is possible that such leaks might not be detected in the course of testing for leakage. 6-26 7.1 7.2 7.3 7.4 7.4.1 7.4.2 7.5 Section 7 SOMEGUIDELINES FORWRITING SPECIFICATIONS INTRODUCTION ................ SPECIFYING MAXIMUM ALLOWABLE LEAKAGE RATE . . INSTRUMENT QUALIFICATION .......... TESTING TECHNIQUE, SAFETY, AND DESIGN • • • Safety Statement ........... Design for Leakage Testing ...... GENERAL LEAKAGE TEST SPECIFICATIONS .... 7-1 7-1 7-3 7-4 7-5 7-5 7-5 b Secti on 7 SOME GUIDELINES FOR WRITING SPECIFICATIONS 7.1 INTRODUCTION This section discusses factors to be considered in specify- ing a maximum allowable leakage rate or a total level of leakage for a component or system. A leakage rate or leakage specifica- tion should be determined from an analysis of the effect of leak- age on the system as well as on the mission or application in which it is to be used. At the outset, good design and fabri- cation techniques are requisite to assure proper and safe per- formance. Long-term storage of the system may be necessary; this should be taken into account. A leak-detection procedure requires careful planning in advance, with consideration of the test sensitivity and response time that will be required in test- ing the system for leakage. It may be preferable to specify a level of maximum toler- able leakage rather than maximum allowable leakage rate. The maximum tolerable leakage usually can be obtained by multiply- ing the maximum allowable leakage rate by the length of time a system is expected to be usable, including the period during which it is to be in storage. However, if fluid is not to be introduced into the system until it becomes operational, the maximum tolerable leakage need be specified only for the dura- tion of the mission. The level of the maximum tolerable leakage should be specified when the total amount of leakage is more im- portant in its consequences than is the rate at which it is dis- pensed. 7.2 SPECIFYING MAXIMUM ALLOWABLE LEAKAGE RATE One approach to the determination of maximum allowable leakage rate is to determine the leakage rates which apply to the following situations: • System failure during the operational life of the system • Hazard to either equipment or personnel • Unacceptable appearance of the system • Assurance of adequate design and good construction on the part of the manufacturer The smallest leakage rate assigned to the above listing is taken to be the maximum allowable leakage rate on which specifi- cations will be based. If the fluid in the system is to be a liquid, it is necessary to correlate the above maximum liquid leakage rate to the leakage rate of a tracer gas. Leak testing can then be conducted with a gas-sensitive leak detector of high sensitivity, using a calibrated gas leak as a standard. 7-1 The accuracy of calibration of a qualified or reference leak and the overall accuracy of the leakage test are such that it is advisable to specify a level of leakage rate which is at least a factor of two lower than the maximum allowable leakage rate as chosen above. It is much better to add the safety factor to the maximum allowable leakage rate than to require that measurement of the leakage rate be performed with high accuracy. Setting the maximum allowable leakage rate should also include the following considerations: • Is the cost involved in performing the leakage measurement reasonable? If the requirements are set so high that the unusual techniques and/or equipment are necessary to perform the measurement, it might be prudent to reevaluate the specified maximum allowable leakage and lower the requirements. • Is the maximum tolerable leakage less than the in- herent or otherwise unavoidable, leakage normal to the operation of the system? If this is the case, the leakage standard should be revised upward. For example, if the allowable leakage specified is less than the leakage expected from permeation there is not much point in assigning more stringent leakage specifications. If requirements are relaxed, re- liable leakage measurements can be made more quickly and at less cost. The allowable leakage rate should be specified for the gas used in the operation of the system. The value should be given in units of pressure multiplied by volume per unit time at a specified pressure differential across the leak. Gas leakage tests can be performed with gases other than the one designated if a formula is specified for correlation between the gases. A correlation which produces conservative values should be used. It is very important to specify the pressure difference across the leak. This should be at the highest operating pres- sure of the system. Whenever possible, leakage measurements should not be performed at low pressures only. A test must be made at the maximum operating pressure to reveal any self-clean- ing leaks, check-valve leaks, and leak expansion. The testing should be done both at maximum operating pressure and at one or several pressures below this maximum to completely eliminate the possibility of check-valve leaks. However, leakage at maxi- mum operating pressure must be measured first. The temperature for the leakage test should be specified as the operating temperature. Changes in the dimensions of the leak due to thermal expansion or contraction can affect measured levels of leakage. 7-2 7.3 INSTRUMENT qUALIFICATION The sensitivity of a test instrument must be determined be- fore it is used in testing equipment for compliance with a set of leakage-testing specifications. When this is done, it is suggested that the instrument should be said to have been quali- fied rather than calibrated. The term oalibrated implies that a given reading on the in- strument corresponds to a leakage rate known to a certain accu- racy. Actually, all that is known is that the indication bears a proportional relationship to the leakage issuing from the test leak. The calibration of the test leak is then a matter of com- paring its conductance with that of one or more other leaks whose leakage rate is known, presumably with greater accuracy than is the conductance of the test leak. The actual conductance or leakage rate must depend on the accuracy with which pressure, differential pressure, and volume flow rate can be measured. Alternatively, it is possible to measure and calibrate the mass flow rate by measuring the change in the buoyancy of a gas environment caused by leakage into that environment in a given period of time. A change in buoyancy in- volves units of mass, length, and time, each of which can be measured and defined with high accuracy. The leakage through a "standard" leak used by one organi- zation may be different from that through a "standard" leak used by another organization even though both groups claim that their respective leaks have the same value of conductance. These dis- crepancies arise because of errors in leak calibation, the cali- bration and stability of the instruments used, the purity of test gases, etc. They are troublesome and difficult to resolve, es- pecially when specifications requiring high accuracy of leakage measurement have been accepted and must be met. The accuracy with which leakage can be measured need not be made of prime importance however, in qualifying a testing in- strument or system. Most practical situations require that some particular level of leakage not be exceeded. It need only be established that the leakage in the tested system is less than the allowable maximum. This can be done without requiring high accuracy of the testing instrument or of the test, simply by lowering the maximum allowable leakage rate and increasing the tolerance to which the rate needs to be measured. An alternative and more certain approach is to specify that a set of leaks, all calibrated at the same time and under the same conditions, be supplied and used in all leak tests made on a system and its components. If the item is shipped to a distant location the leak used to test it should be shipped with it. This procedure will improve the consistency in the measurements made at the point of manufacture and at the point of use, although it is impractical to follow when many units are involved. Two leak detectors at two different locations can be calibrated 7-3 against one another with better accuracy if the same test leak is employed. In any event, the accuracy with which the leakage rate of a test leak is known should be higher than the accuracy required for qualifying a piece of test equipment in terms of a given set of leakage specifications. To qualify the instrument, the test leaks and their method of use should be carefully detailed. Test leaks may be supplied by the manufacturers of the leak detector or by the specifier's laboratory. If the leakage measurement is to be performed on several pieces of equipment in various locations, the test leaks used for the various equipments should be similar and procedures should be standardized. The leakage of the test leak should be in the range of the specified leakage. A qualifying test shows that, under the conditions of leak- age measurement, it is possible to determine that a certain leakage rate is not exceeded. It is important in detailing the procedure that the test is being qualified and not the in- strument itself. For highest accuracy, the same gas should be used for qualifying the. test leak that is used for measuring the leakage rate of the system. The gas should be introduced at the same pressure and in the same concentration into the qualifying leak as into the system being tested. If leaks smaller than 10 -6 atm-cc/sec are to be measured, it should be specified that the system should not be cleaned prior to leakage testing. Cleaning fluids will clog the smal- ler leaks in the system, and thus prevent their detection. 7.4 TESTING TECHNIQUE, SAFETY, AND DESIGN Providing the allowable leakage is specified and an accept- able correlation is given between the various test gases, it should not be necessary to specify the exact equipment to be used in the test. However, it is necessary to state in some manner whether leakage measurement or location is required. Leakage measurement rather than location is the only reliable method of testing to determine the maximum leakage. It might be necessary to specify the use of an enclosure to ensure that all gas leaking from the system is collected by the leakage-mea- surement equipment. These specifications should be written to ensure that all of the gas which leaks out of the system is being measured. Only under unusual circumstances should leakage-location techniques be used for leakage measurement. This method will drastically affect the credibility of the test. When a leakage- location technique is used, the sampling speed should be spec- ified and extremely rigorous methods of qualifying the technique (not the equipment) should be used. 7-4 7.4.1 Sa fetj, Statement Some statement must be made as to the safety precautions necessary while tests are being performed. If large pressur- ized vessels are being used, warning concerning proof-testing must be given. Decision must be made by the designer as to whether it is permissible to test at high pressure prior to proof-testing. Proof-testing using a hydrostatic test will clog most small leaks. It is, therefore, necessary to weigh the relative importance of leakage and the other factors that are involved in determining the overall safety of the system. 7.4.2 Design for Leakage Testin 9 Testing requirements should be considered early in the design of the system. System design should take into consid- eration such items as location of ports or connections for leak- age measurement. The system must be capable of being tested quickly. It should not, for example, contain sealed voids which could greatly increase the testing time. 7.5 GENERAL LEAKAGE TEST SPECIFICATIONS Several technical societies and certain Government agencies introduced approved leakage testing procedures for specific types of equipment. These tests provide both the equipment manufacturer and the user with uniform methods for conducting leakage measurement. For example, the tests detail the data to be recorded, calibration of the test, and the computation of leakage rate. Table 7-1 lists some of these tests and their originating societies, along with the number which identifies each document. 7-5 _4a _ _ .,_ _o ,_ < --_ E • 0 _0 o T H r- H ° il* Z I ,c f._ o ,"'u 0 0 _ ,_ o_ H ? ? I'_ I'_ _,_ : _ .., Ill 4-11_ = ,-I .la •, ®® -: _ >= • U-,,4 _; • ,_ =. . ,_® =,_ _ _.,., _ _,_ _ u ° _ _ _ o o _ _"_ '_:3 _n. ZQ_ :3 =' :D =1 _: 0 m O r. • '_o ? ° ='_ e- • o ._ ,-4 _.,._ U _.,_ X _._ 3 _ 0_ II1 =0 _ _ _d_ _0 .,._ .,.4 C _JE I "_ U_U 0"_ _ _ _J 0 ..... _ _ _0 ,uOC_ _;_ _.,_ . m _0_ 7-6 Section 8 Section 9 411 Section i0 -ql Section Ii Section 12 -IK Section 13 Part II TESTINGMETHODS Section 14 Section 15 Section 16 Section 17 Section 18 _& Section 1% Section 20 _e Section 21 Section 22 Section 23 Section 8 MANUFACTURED LEAKS .,q 8.1 8.1.i 8.1.2 8.1.3 8.1.4 8.1.5 8.2 8.3 8.4 8.4.1 8.4.2 8.4.3 8.4.4 8.4.5 8.4.6 8.5 NOMENCLATURE COMMON TYPES OF MANUFACTURED, OR "STANDARD, " LEAKS .................... 8-1 Permeation Leaks ............ 8-1 Porous Plug Leaks ........... 8-3 Capillary Leaks ........... 8-3 Variable-leakage Sources ........ 8-3 Variable Conductance Leaks ....... 8-5 ERRORS IN LEAKAGE MEASUREMENT ........ 8-5 AVAILABILITY OF STANDARD LEAKS ....... 8-8 LEAK QUALIFICATION TECHNIQUES ........ 8-10 Isobaric Volume Change ......... 8-10 Pressure Rise Method .......... 8-12 Pressure Drop Across a Known Conductance . 8-13 Pressure Measurement at Constant Pumping Speed .................. 8-13 Change in Intensity of Alpha Radiation . . 8-15 Mass Leakage Analysis .......... 8-15 POSITIONING OF TEST LEAK .......... 8-17 8,1.2 Porous Plu 9 Leaks Porous plug leaks are cited in the literature (Refs. 8-3, 8-4, 8-5, 8-6, and 8-7). A leak of this type consists of a metal, ceramic, or glass plug containing extremely fine pores. Flow through the plug is molecular. Therefore, the change of flow which will result from a change in the type of gas may be calculated from Equation 6-24. Such leaks can be made as reser- voir or non-reservoir types, and can be calibrated against an- other reference leak or by absolute measurements of flow and dif- ferential pressure. 8.1.3 Capillary Leaks Another type of leak which can be calibrated is made from fine capillary tubing of glass or metal, such as Pyrex and hydrogen- fired nickel. The capillary is constricted over a short region to the extent required to limit the flow of gas to a desired value. The capillary is mounted within and attached to one end of, a strong metal tube, to prevent breakage during normal handling. Such leaks can be made with leakage rates from about 5 × 10 -_ atm-cc/sec upward. Although smaller-sized leaks of this type can be made, they become extremely difficult to use because of clog- ging. These leaks can be calibrated with one or with a mixture of gases. They are normally made to be used with a separate sup- ply of gas at a known differential pressure and are calibrated at the same pressure. 8.1.4 Variable-leakage Sources A variable leakage source for a given gas may be made from a single capillary leak of fixed conductance by simply changing the differential pressure across the leak. If the leak is to supply gas at atmospheric or any other fixed pressure, the amount of leakage can be controlled by changing only the input pressure. A calibrated variable leakage source can be made by the use of a pressure gage on the input side of the capillary. The gage can be calibrated in leakage rate rather than in units of pressure. A capillary leak may be connected to a small reservoir of tracer gas with a pressure gage, to form a calibrated variable leakage source. Figure 8-2 shows such a device, which is called a leak factor gage. Its scale is marked in multiples of the leak- age rate of the capillary when measured from atmospheric pressure to vacuum. Provision is made for altering the pressure applied to the input side of the capillary. The General Electric Type LS20, shown in Figure 8-3, is an example of another variable leakage source. Figure 8-4 is a schematic diagram of the system used. The unit includes a reser- voir of halogenated hydrocarbon which is valved into a ballast tank in gaseous form. Also connected to the ballast tank is a glass capillary tube and pressure gage. The amount of leakage through the calibrated capillary is dependent on the amount of pressure in the ballast tank. Because the flow through the leak 8-3 Figure 8-2 Reservoir Leak with Leak Factor Gage. (Reprinted with permission of the Instrument Department, General Electric Company. West Lynn, Massachusetts.) Figure 8-3 Variable Leakage Source Heated-anode Leak Detector. (Reprinted with per- mission of the Instrument Department, General Electric Company, West Lynn, Massachusetts.) TRACER GAS SUPP_ (PRESSURE INCREASE) [_RESERVOIR _ FILL BALLAST QUALIFIED PROBE VENT (PRESSURE DECREASE} Figure 8-4. System for LS20 Variable Leakage Source 8-4 is laminar the gage is marked in units proportional to the square of the pressure drop. It is an excellent standard to use with probe-type instruments, such as the heated-anode halogen leak detector. The probe may be placed directly in the leak exit; the calibration approximates operating conditions. 8.1.5 Variable Conductance Leaks A leak whose conductance can be changed is called a variable leak. It can be fashioned so that the conductance can be pre- cisely set and reset many times. Such a leak takes the form of an elegant needle valve, or a mechanical means for flexing a piece of crushed metal tubing so as to slightly alter the size of the leak path. The accuracy with which the conductance can be set has been improved greatly over the past few years. Never- theless, a variable conductance leak should not be used as a re- ference for calibrating a leak detector to be used in checking equipment-leakage specifications unless it is calibrated after each adjustment of its conductance. 8.2 ERRORS IN LEAKAGE MEASUREMENT The principal errors contributing to the inaccuracy of leak- age measurements are: l. 2. 3. • 5. Inaccuracy in calibrating the leak Nonlinearity of the leak-detection instrument Variation in pressure differential applied across the leak Impurity of gas applied to the leak Variation in the amount of gas reaching the detector Comparisons between leaks of various manufacturers (Ref. 6-2) have shown that their accuracies do not agree to more than plus or minus fifty percent of a mean value. This may be seen by the experimental plot of Figure 8-5, which shows the calibrated leak- age readings as plotted to the response of a very linear mass spectrometer. The straight line drawn in the graph is the least- mean-square value of leakage versus spectrometer response. This line does not imply the correct value, but the general pattern around which the values of the leaks congregate. Even the leaks of a single manufacturer vary by approximately ten percent. This is usually the guarantee which is presented upon purchase of the permeation-type calibrated leak. Leaks of a variable type -- for example, the General Electric LS20 -- are claimed to be accurate only to plus or minus twenty percent. Most commercial leak detectors display the response to a detected leak as a current reading on a sensitive microammeter. It is usually assumed by the operator that a current reading twice the magnitude of a previously observable one represents a two-fold increase in leakage. This is not necessarily correct, 8-5 lo' i02 io3 io4 ¢J ¢p ¢J (J iO-5 0 n GE-ATL • CEC e VEECO & WORK • VIC o ELION x GE- LYNN ,/ / / / / jo-9 -IO I0 io',4 io-'3 Figure 8-5. i_'z i_'t i_iO i_ 9 i0 "e ION CURRENT, Amperes Comparison of Leakage Values for Leaks Supplied by Various Vendors (Ref. 6-2) I0 "7 8-6 because of nonlinear properties associated with the structure of the pumping system or the electronic circuitry. A typical correlation is shown in Figure 8-6. The confi- dence range is a fan-shaped area which converges on the mean values of actual and measured leakages. The tightest confidence range for a fixed amount of data is obtained when the points are grouped evenly at the extremes of the actual leakage range. Un- less linearity of the correlation has been established it is best to have the data evenly distributed throughout the leakage range. Because such deviations exist it is recommended that when a leak- age measurement is made to a closer tolerance a qualified leak of that specific value should be used. _U t9 X _J UJ u_ CONFIDENCE RANGE OF CORRELATION ACTUAL LEAKAGE Figure 8-6. Correlation Between Actual and Measured Leakages Leakage is dependent on the pressure differential across the leak. When leak detection is done by a tracer probe, the pressure differential is usually one atmosphere, the gas being sprayed over the suspected area without the aid of additional pressure. Should leak detection be performed at high altitudes, the atmospheric pressure is less than one standard atmosphere; the magnitude of this reduction is as much as twenty percent in such places as Boulder, Colorado. If the leaks which are being located are of a laminar nature, the flow through the leak is proportional to the square of the pressure differential. There- fore, a leak measured at atmospheric pressure in Boulder, Colo- rado, will be approximately forty percent lower than one in Cape Kennedy, Florida. 8-7 As has been mentioned, certain calibrated leaks contain their own gas supply, whereas others have the tracer gas sprayed on the leak at one-atmosphere pressure differential during use. Calibrated leaks wlth a self-contained gas supply always deliver to the detector a fixed amount of gas which is interpreted as the sensitivity of the leak detector. On the other hand, leaks where gas is added during use produce the calibrated amount of leakage only when a one-atmosphere pressure differential is sup- plied. The latter leaks, therefore, deliver less than the cali- brated amount of leakage when used at high altitudes, where the atmospheric pressure is lower. Another source of inaccuracy is the impurity of the tracer gas used for leakage measurement. If a tracer probe is used for leak detection, the gas is sprayed over the suspected area, in which case it is quite posszble that the tracer gas is diluted with air as it approaches the leak. Therefore, the response of the leak detector will be reduced by the amount of air impurity entering the detector with the tracer gas. The use of a cali- brated leak with a self-contained gas supply is thus undesirable, since it would not reproduce the leakage measurement method. In other words, the gas should be sprayed on the calibrated leak in the same manner as on the tested leak. Tracer gas traveling to the detector may be absorbed on system surfaces. This would decrease the response of the de- tector. For accuracy, therefore, calibrated leaks should be positioned on the system as near as possible to suspected leak sites. Alternatzvely, they may be positioned as far away from the detector as possible to show minlmum sensitivity. Because of the variations discussed in this section, a mea- sured leakage value is probably only withzn a factor of two from the true value. Thls implles that if a leak is measured as 1 x i0 -s atm-cc/sec! the actual value of that leak is between 2 x 10 -s and 0.5 x 10-= atm-cc/sec. Therefore, if the maximum allowable leakage of a particular system is 2 x 10 -S, the speci- fication may be wrztten wzth a leakage not to exceed 1 × i0 -s, with the knowledge that the accuracy of this measurement is a factor of two. There is reasonable assurance that if the mea- sured leakage is no higher than the one stated on the specifzca- tion (i × 10-s), the actual system leakage will be no greater than the allowable one (2 x 10-s). This method of speczfying leakage is much more sensible than specifying a slightly hzgher leakage value with an unreasonable accuracy. 8.3 AVAILABILITY OF STANDARD LEAKS Typical of the precision leaks commercially available are those shown in Table 8-1. Only a limited number of gases may be used with such leaks. Only one type of leak is designed to deliver gas at atmospheric pressure; that is the General Electric LS20 leak for the heated-anode halogen leak detector. Some manu- facturers will produce precision leaks on request. One of these is Hastings-Raydist, Incorporated, formerly the R.H. Work Company. 8-8 _m 0 0 0 0 0 _) _J _ 4J 4J _0 •._ 0 C _ 0 • _ qJ >_ = < Z = c3 0 0 ,-I ? 0 ,-I 0 c_ I 0 ,-I o ! I IO ¢D 0 0 ,'--4 ,.-I ,-I ,-i 0 0 0 0 4J 4_ .U 0 0 0 0 0 0 O • 0 "._ 4J_" .-_ e_ •,-_ _) U ,-_ _) W :Z: ¢n < H < O0 U 0 0 U t£/ e. d._; d d d _; d *01= * • * _ * _G < Z 0 U_ _) c_ t_ I_ _: I I I •._ _ _ W {J U L) I r_ m :>', 0 0 _'_ 0 CU _ W _ _ W U U _ _ U I_ IN ,,-I I= I 0 •,.-I I..I ,u I_I IE .,=I I.I n. 0 .=4 4J 0 0 °1 ° _ O_ _O _.,I 4..I g_,l .,,.t -,-I I_ O'_ m_ e_m Om ,3 C 4-I ® :3 .,u W '_W .u U m 0 ¢)0 0 _ _ I I O_ 0 _0 _ m • o _=. ® _ o_ o _ _=Z W _ e'_ _G =4 *'"_ " " "_ 83 _ _;_ _W _0 O_ _ ®,,_ ®_ ,_ o.._ _O.E G WG _ 0 _0 _ 0 OZ O _O _ mG wm _N _o ! _._ _o _ mN m m W U m W W m 0 U 4-i H $i el 04 8-9 8.4 LEAK QUALIFICATION TECHNIQUES Qualified precision leaks are available covering a range of eight decades of leakage values. Leakage rates are determined by methods such as the following, which are described in this sub- section. • Isobaric volume change J Pressure rise method • Pressure drop across a known conductance • Pressure measurement at constant pumping speed • Change in intensity of alpha radiation • Mass leakage analysis 8.4.1 Isobaric Volume Change A schematic diagram of the equipment used in the determina- tion of leakage rates by isobaric volume change is shown in Fig- ure 8-7. One side of the leak is attached to a vacuum system; the other side is attached to a gas reservoir at atmospheric pressure. To this reservoir is attached a capillary of known cross section, in which a slug of indicating fluid is placed. As gas leaks from the volume into the vacuum the slug of fluid travels down the capillary, to keep the pressure in the reservoir constant. As stated in Equatlon 8-1, the leakage rate is deter- mined by measurement of the volume displaced by the travel of the slug down the capillary: Q = P(v2 - v_) (8-1) t The primary limitation of thls method is the size of the capillary involved. It is difficult to obtain a liquid which can be placed in one end of a small capillary tube and subse- quently forced out the other end. For this reason, the _rac- tical limitation of such a method ls in the range of 10 -_ atm- cc/sec. It would be theoretically possible to use a slightly larger capillary, and to take longer periods of time between readings. However, the errors might arise from gas permeation through the liquid slug or through the walls. An error might also be introduced by a change in barometric pressure or a change in ambient temperature. This becomes particularly crit- ical in the qualification of small leaks, since a slight tem- perature change might produce a volume change greater than that due to the efflux of the gas. It is desirable to use a fluid with a low vapor pressure so that the leak is not contaminated by the vapor of the fluid. Unfortunately, most liquids of low vapor pressure are also of high viscosity, making it difficult to obtain an accurate mea- surement of the flow of liquid displaced in the capillary. 8-10 GRADUATED _ LEAK f - '"" ::" "PRESSURE! "--_ .........ATMOSPHERIC_:_ I I- -I (a) INDICATING FLUID METHOD VACUUM VACUUM PUMP DIFFERENTIAL PRESSURE II {.'::::_ PISTON LEAK /,, _ _',:r -u .......... _ ,,,,,,,,,,,,,,,, ,,I;:_;5":C::,1 I "GAS AT ATMOSPHERIC PRESSURE (b) MOVABLE PISTON METHOD I VACUUM J ! ! VACUUM PUMP Fzgure 8-7. Leak Qual_fication by Isobaric Volume Change. %Repranted from J.W. Marr, Study of Static and D_nam_c Seals in Liquid Rocket En@ines, F_nal Report Phase II, Contract NAS 7-102 _Ref. 6-2).} 8-11 Such fluids also tend to form bubbles at the end of the capil- lary. The added pressure necessary to remove the bubble of liquid from the end of the capillary prevents the experiment from being isobaric. Haywood (Ref. 8-8) overcame the need for an indicating fluid by the use of a piston to replace the effluxing gas. In this method, a differential pressure gage is used to measure the pressure in the gas volume, and the piston is pushed into the volume at a rate to keep the pressure constant. The pressure gage need not be calibrated. This method can readily measure leakage as low as 10 -6 atm-cc/sec. 8.4.2 Pressure Rise Method The second method of qualifying leaks is the pressure rise technique (Ref. 8-9). A leak and its gas supply are attached to an evacuated chamber of known volume (Figure 8-8). The leak- ing gas is allowed to accumulate in this volume, and the pres- sure rise is measured at various intervals. The leakage may then be computed by the equation: Q = vP Laufer (Ref. 8-10) describes this procedure in detail, claim- ing an error of less than i0 percent. The major difficulty with •_,ATMOSPH ERIC.",: '',.. PRESSURE"" J, * .• • ,• ,.-,, - - .'.'.',.. t LEAK VACUUM PRESSURE GAGE Figure 8-8. VAC.UUII pump Leak Qualification by Pressure Rise Technique. (Reprinted from J.W. Marr, Study of Static and Dynamic Seals in Liquid Rocket Engines. Final Report Phase II, Contract NAS 7-102 (Ref. 6-2).) 8-12 this type of qualifying technique is in the measurement of pres- sure. The pressure in an evacuated system usually does not stay constant, but gradually increases because of outgassing of the walls of the chamber. The pressure rise due to this desorption must be taken into account in the calculations. A second difficulty in pressure measurement is the lack of a suitable gage. A McLeod gage may be used, but is suitable only for the higher pressure ranges. If a long period is used to ob- tain a readable pressure change, outgassing becomes a particu- larly difficult problem. Ionization gages are difficult to use for this work, because of lack of adequate calibration and be- cause of outgassing at the low pressures at which they work. Another alternative is the use of a mass spectrometer as the pressure gage (Ref. 8-11). In this case the effect of outgas- sing may be overlooked, since the desorbing gas is usually not the one being measured. Fisher (Ref. 8-12) has described a "calibrated" leakage rate system suitable for use on large vacuum chambers which is not limited by the usual difficulties. Known leakage rates of a gas enter an evacuated chamber to which a mass spectrometer is coupled. Leakage rates of the actual substance are thereby de- termined, obviating the need for an inert tracer gas. An ac- curacy of plus or minus twenty percent is claimed for the method. 8.4.3 Pressure Drop Across a Known Conductance A third method of determining leakage rates is measurement of the pressure drop across a known conductance. This technique is illustrated in Figure 8-9. The pressure drop across a known conductance is proportional to the flow. As previously stated, Q = C(PI - P2) (8-3) In molecular flow the conductance C may be determined from theory using known dimensions of the leak. Again, the major difficulty is in obtaining accurate measurements of pressure. Ionization gages have been used for pressure measurement, but their readings are often questionable. With the use of a pre- viously qualified leak, this type of measurement can also be used to calibrate ionization gages (Ref. 8-13). 8.4.4 Pressure Measurement at Constant Pumping Speed A fourth method of qualifying a leak is measurement of the pressure which results when a vacuum system is pumped at a known speed (Figure 8-10). The equation then used is: Q = sP (8-4) The system is usually constructed so that the pumping speed is controlled by an orifice and may be rigorously calculated on theoretical grounds. The disadvantage of such a method is, again, 8-13 Figure 8-9. PRESSURE GAGES CONDUCTANCE ! ! Leak Qualification By Pressure Drop Across a Known Conductance. (Reprinted from J.W. Marr, Study of Static and Dynamic Seals in Liqui_ Rocket En@ines, Final Report Phase II, Contract NAS 7-102 (Ref. 6-2) .) "";""::";":""'"""::"":" LEAK ' PRESSURE GAGES CONDUCTANCE | ! Figure 8-10. Leak Qualification By Pressure Measurement at Constant Pumping Speed. (Reprinted from J.W. Marr, Study of Static and Dynamic Seals in Liquid Rocket En@ines, Final Report Phase II, Contract NAS 7-102 (Ref. 6-2).) 8-14 that the pressure of the system must be accurately measured. If the leakage Q and the pumping speed S are known, P can be derived using the above Equation 8-4. This type of system has also been used to calibrate pressure gages (Ref. 8-14). Some accuracy is gained if a mass spectrometer is used as the pressure gage since the error due to outgassing may be eliminated. 8.4.5 Change in Intensity of Alpha Radiation A type of standard for leak qualification is described in Reference 8-15. Radioactive polonium is used as an alpha emit- ter (alpha particles are helium atoms stripped of their elec- trons). When alpha particles come in contact with other atoms, they acquire the necessary electrons to become helium molecules. Since the radioactivity of the polonium sample can be measured accurately, the number of alpha particles evolved is known. Therefore, the amount of helium gas formed is also known. In this way pressure-measuring instruments may be accurately cali- brated. The only source of error is possible absorption or en- trapment of the helium within the leak. This may be _revented by good design and/or the establishment of steady-state condi- itions. The above technique is limited to helium gas calibration. It can be used effectively only in the low-leakage ranges _ 10 -8 atm-cc/sec) because of the shielding that would be necessary in its use at higher concentrations of radioactive material. How- ever, the technique is an excellent supplement to the other me- thods described, and it is most effective in the range which is difficult to measure by other techniques. 8.4.6 Mass Leakage Analysis A novel method of measuring the mass of a gas in a chamber, as well as its rate of change with time, has been demonstrated at TRW Systems, Inc., by R.J. Salvinski (Ref. 8-16). The meth- od has the advantage that measurement is theoretically indepen- dent of the type of gas, the ambient pressure in the chamber, and the gas temperature. However, these parameters do affect the accuracy of the measurement as they affect, for example, the sensitivity of the test and the size of the chamber. The meth- od may be used to calibrate the conductance of a leak in terms of the fundamental units of mass, length, and time. A sensitive electrobalance is placed within an evacuated chamber. A spherical glass ball of known volume V B is attached to one end of the electrobalance and suitable counterbalancing weights to the other. An electrical signal is generated which is proportional to an unbalance in the force moments about the fulcrum of the electrobalance. This signal is fed back through an amplifier to an actuator which restrains any deflection of the arm of the electrobalance by applying a counter torque. A meter reads a voltage that is proportional to the countertorque. 8-15 The system can be used to measure a mass of gas admitted to the chamber through a leak. When the gas enters the chamber, the density of molecules in the chamber increases and causes the buoyant force FB on the ball to increase. The arm becomes un- balanced and a countertorque is applied to compensate it. The buoyant force is equal to VBPAg. The gas density PA is equal to MA/Vc, where MA is the mass of the gas and Vc is the chamber volume less that of the ball. Thus: VB g (8-5)FB = MA V c The meter reading will therefore be proportional to the mass of the gas, the known volumes, and the gravitational constant, g. The reading should be independent of the type of gas, its temper- ature, and its pressure. It is assumed that the measurement is made after leakage has been stopped, that there is no outgassing or absorption of gas; and that the sizes of the chamber and ball have not changed, because of a change in temperature, for example. It appears that the conductance C of the leak can be found as follows. As leakage proceeds, the pressure P in the chamber increases toward the pressure P I as P = PI i - e (8-6) Since the mass in the chamber is proportional to the pressure P, PV c M A = _ (MW) (8-7) If the time constant of the electrobalance is short compared to that of the leak, Vc/C , it is now possible to determlne the rate of change of the buoyant force with respect to time, from data on the variation of the force itself with time. Recall that F B is proportional to the output reading of the electrobalance. A differentiator placed in series with the output will produce a reading directly proportional to FB" As derived from the previous equations, FB = _ VB (MW) and the rate of change of buoyant force is: FB = e _-_ (MW) If P_ and T are now constant, then: vetl - e cJ V B _8-8) (8-9) 8-16 Ct V _B = C e c (KI) (8-10) and Zn (FB) = Zn K1 C- (Tc) t (8-ii) A semilog plot of in (FB) versus t is then a straight line of negative slope (C/Vc). Since Vc is known, the desired conduc- tance of the leak may be calculated. The conductance has thus been determined from the data without a knowledge of the en- trance pressure, the gas temperature, or the molecular weight. The leakage rate Q0 of the leak with a forepressure PI and and afterpressure of zero is simply (C) (P,). Here the type of gas and its temperature are the same as were used in determining the conductance, so as to account for the effects of these para- meters on viscosity and the mode of flow. The sensitivity of the mass leakage analyzer is determined by the ratio of the volumes and the sensitivity of the balance. In the first demonstration leakage rates of 10 -2 atm-cc/sec could be measured. Leakage rates near 10 -5 atm-cc/sec have been mea- sured in improved models of the system. 8.5 POSITIONING OF TEST LEAK Since there are many variables which can affect the sensi- tivity of testing, it is necessary that leakage calibration or qualification be frequently performed. Locating a calibrated leak close to a suspected undesired leak will result in test measurements that most nearly reflect the actual leakage rates. Figure 8-11, for example, shows two methods which might be used for leakage measurement. Method 1 gives better assurance that the concentration of tracer gas is the same in all phases of the test than does Method 2. These methods are only as accurate as the linearity of the detector response. Either method will show whether the system leakage rate is greater or less than the reference leak. In practice, Method 1 is easy to incorporate in a rigid hood in a permanent test position. It is not always easily arranged with a flexible hood. It is extremely important when establishing sensitivity that the tracer gas be applied to the leak for the same period of time as it will be applied to each suspected area. This will take into account the effects of absorption on the walls and the effect on the time constant volume of the system. For accurate results the unknown leak should be placed in the same port of the detector as the qualified leak, and under 8-17 _) = . ":"'1 UNDER" ! " " i";: REFERENCE LEAK METHOD ITRACER GAS QUALIFIED LEAK Ioc-nol LEAK DET ECTOR VACUUM PUMP .'.; :.: ._ ..'.'. SYSTEM •i_-:__%_ .:....: REFERENCE LEAK METHOD 2 TRACER GAS QUALIFIED EAK I° r-t°l_ =LEAK DETECTOR r"l | ! VACUUM PUMP Figure 8-11. Alternative Positions for a Qualified Leak on a System 8-18 identical conditions. In calibrating, if the object to be tested is located immediately adjacent to the inlet of the detector, the known leak must be placed in that position. If the object to be tested is a vacuum chamber or an object to be located in a vacuum chamber, and the leak detector will be connected to the chamber foreline, the known leak must be located away from the foreline in the vacuum chamber. In this case, output versus time must be known. When a glass qualified leak is placed inside a vacuum cham- ber, the helium permeation through the glass envelope of the qualified leak as well as that through the quartz membrane may be significant. The rate given by the manufacturer is for heli- um permeation through the quartz membrane only. When a system is calibrated by using a pure helium leak with a one-atmosphere pressure differential across it, the rate obtained during an actual test must be that for pure helium across a one-atmosphere pressure differential. If, in the ac- tual test, the helium is reduced in concentration by being mixed with another gas, the calibration must be adjusted accordingly. The reference leak should have a leakage rate approximately equal to the permissible leakage rate, particularly if the re- sponse of the detector to leakage is not linear. The smaller the reference leakage rate the greater the difficulties associ- ated with its use. Two standards are available for the calibration of mass- spectrometer leak detectors. American Society for Testing and Materials standard F78-67T covers a procedure using qualified leaks (Ref. 8-17). American Vacuum Society standard AVS 2.1, which is reproduced in Appendix B, determines the significant performance characteristics in addition to the calibration (Ref. 8-18) . 8-19 Section 9 MASSSPECTROMETERSAND LEAKAGETESTING 9.1 INTRODUCTION The mass spectrometer is a device which identifies atomic or molecular species by their mass-to-charge ratio. The opera- ation consists of ionizing the sample, separating the different ion species, and detecting the separated species. A mass spec- trometer that is built for leak detection is usually limited to the detection of helium. Other small mass spectrometers, called residual-gas analyzers, are built to scan over a range of masses and are useful in partial pressure measurements of residual gases in a vacuum. Different schemes are employed for separating the ions ac- cording to their mass-to-charge ratios. A deflection type of mass spectrometer accelerates the ions and effects a separation by passing them through a magnetic or electrostatic field, or both. A time-of-flight mass spectrometer separates the ions by their different speeds over a fixed path. Several varieties of this latter type are available, namely the pulsed-beam, omega- tron, and radio-frequency mass spectrometers. J.B. Farmer sur- veys the various types of mass spectrometers and discusses the outstanding properties of each type in Chapter Two of Mass Spec- trometry (Ref. 9-I). The deflection type of mass spectrometer is most commonly used in leak-detection work. 9.1 .l Application Mass spectrometers for use in leak detection have been devel- oped commercially by many firms throughout the world (see Part III). This type of instrument has proved to be highly versatile in its application to many different situations. It has gained wide acceptance, largely because of its high sensitivity and specificity to a single tracer gas helium, which has a very low concentration in earth's atmosphere. Applications also cover a considerable range of size in electronic components. The same instrument can be adapted to test upwards of 1200 individual parts per hour or to test the integrity of large vessels such as are used for the storage of cryogenic liquids. A residual-gas, or partial-pressure, analyzer can also be used to determine the leak-tightness of a system (Ref. 9-2). For example, it is possible to differentiate between outgassing, pump-oil backstreaming, and air leakage of an evacuated system from a scan of the first seventy mass numbers. When an air leak is indicated, by the presence of a nitrogen-oxygen signal, the i 9-1 instrument can be adjusted to respond only to helium. A helium probe is then used to locate the defect. Briefly, some of the responses and their diagnoses are: Gas Present in System Probable Cause Oxygen, nitorgen and argon Nitrogen Water Hydrocarbons Air leak Leak in liquid-nitrogen baffle Virtual leak, leak in coolant lines Ineffective baffling of pumps 9.2 SENSITIVITY The sensitivity of a mass spectrometer depends upon several factors, some inherent in this instrument and others dependent upon the response to different gases. A helium leak detector will usually have a minimum-detectable concentration ratio of about one part of helium in ten million parts of air, or about 10 -I° atm-cc/sec. The method by which ions are detected has the greatest ef- fect on the sensitivity of the instrument. There are two common- ly used methods for detecting the ion current: I) by an electro- meter, and 2) by an electron multiplier. The electrometer collects the ion current directly on an electrostatically shielded plate. This current establishes a voltage across a resistor of very high resistance which then is amplified by a high-gain DC amplifier. In the second method the ions are collected on the first of several dynodes of the electron multiplier. An ion striking the first dynode releases an electron, which travels to the next dy- node; there a larger number of electrons are released. The pro- cess continues and the number of electrons is increased from stage to stage for as many times as there are stages in the de- vice. The response of an electron multiplier which is exposed to a vacuum system (as opposed to one sealed in its own envel- ope) depends upon the condition and past history of the multi- plier. For example, poisoning of the dynodes by some contami- nant in the vacuum system will change the electron yield for tracer-gas ions. In fact the contaminant may be any gas other than the tracer, such as oxygen, hydrogen, or carbon monoxide. When using such a detector, it is advisable to calibrate ±re- quently the output reading of the instrument, keeping a record of the sequence in which gases or vapors have been introduced and removed from the system being tested. Sensitivity of a helium spectrometer is also a function of both total pressure and helium concentration. If excessive out- gassing or leaks in the system under test raise the system pres- sure above approximately 10 -2 torr, the sensitivity decreases rapidly. In this case, auxiliary pumping may be used to reduce 9-2 system pressure. Such pumping, however, will also reduce sen- sivity; also, if too large an opening is used in the detector probe, sensitlvity decreases rapidly because pressure within the mass-spectrometer detector will rise to the 10-2 torr region. A compromise must be sought between too large a probe opening, which reduces sensitivity, and too small an opening, which does not allow entry of enough helium for detection. Present-day mass spectrometers actually have higher sensi- tivities to masses 30 - 50 than to mass 4 for helium. By the use of a tracer having a molecular welght in the above range, the sensitivity of a leakage test may be increased by about three orders of magnitude over that obtainable with helium (Ref. 9-2). 9.2.1 Ratings Helium mass spectrometers are usually rated by their sensi- tivity. Sensitivity is determined by the level of gas flow which produces the minlmum detectable slgnal. The American Vacuum So- ciety has promulgated a procedure for making such measurements (Ref. 8-18). A copy of this standard (tentative), AVS 2.1, is included in Appendix B. The sensitivities are usually expressed in terms of helium (atm-cc/sec), although a value for air will occaszonally be used. For conditions of molecular flow the conversion to helium is ob- tained by multiplying the air value by 2.7. 9.3 CHARACTERIZATION OF AN ION-DEFLECTING MASS SPECTROMETER Figure 9-1 shows schematically the basic elements of an ion-deflecting spectrometer. Singly ionized molecules or atoms are produced by a stream of electrons in a small ionizing cham- ber. The ions are drawn from the chamber and formed into a beam of constant velocity. This beam passes into a magnetic field in an electrlc field-free reglon. The beam interacts with the magnetic f_eld and moves in a circular arc untll it leaves the field. The beam then passes through a slit in a grounded electrode, to an ion collector. The radius of curvature of the beam while it is in the magnetic fleld is proportlonal to the function M_-_ /B, where M is the mass of the ion, V is the beam voltage, and B is the strength of the magnetic field. Only ions having masses lying within a particular, narrow range will reach the collector for a given setting of the voltage and magnetic field strength. Other ions are collected on the grounded elec- trode. A mass spectrometer designed expressly for use in a leak de- tector that is operated with a single tracer gas does not have to be capable of scanning a mass spectrum. Beam optics and para- meters such as the beam voltage and magnetic field are set to de- tect the mass of the particular tracer gas with the highest pos- sible sensitivity. Provision is made for fine tuning of the re- sponse, by an adjustment of the electric field, for example. 9-3 IONIZING CHAMBER_ t+V ELECTRON EMITTER_ i _1 %- --2 ION BEAM MAGNET B® TRACER IONS ION COLLECTOR Figure 9-i. + .-r Schematlc Diagram of an Ion-defiect!ng Mass Spectrometer 9-4 The electrometer stage of the DC amplifier is usually mounted inside the mass-spectrometer tube. This keeps the input resistor and other input connections dry, to minimize leakage currents. It also makes the leads as short as possible from the ion collector to the input element of the amplifier to prevent electrostatic pickup. The random noise level at the output of the amplifier is de- termined largely by the resistance of the input resistor and the bandwidth of the input circuit of the amplifier. The output noise voltage varies as the square root of the product of the in- put resistance and bandwidth. The average value of this noise is zero. Superimposed on the noise will be small signal fluctuations which are the result of energetic ions in the collector chamber which strike the collector and are neutralized by electrons which flow through the resistor. This type of fluctuation can occur in the absence of the main ion beam. Lastly, there can be a DC drift in the balance of the amplifier's output circuit, which of- ten results in a slow, monotonic change in the meter reading. Thus, in some instruments the zero balancing adjustment must be reset from time to time to keep the meter on scale. DC drift does not limit the sensitivity of the detector. Drift and noise must be considered when quantitative values of a leakage rate are being sought. Frequent checking of the re- sponse with and without tracer gas is required when the magnitude of the leakage is very small. Flushing of the system with an inert gas other than helium is sometimes employed to remove mem- ory effects, so that the leak signal will be as large as possible against the noise background. In some instruments it is possible to use tracer gases other than helium. However, helium is most often chosen for the pur- pose because: i. Helium diffuses through a leak more rapidly than any other gas except hydrogen. 2. Normal concentrations in the atmosphere are only one part in 200,000 parts of air (Ref. 9-4). In most cases the presence of tracer helium is clearly dis- tinguishable from atmospheric helium. The latter is sometimes found to add to the background level when a spectrometer is operated at maximum sensitivity. 3. Except in systems which may contain deuterium gas, there is little possibility that another gas will give an indication that can be mistaken for helium. 4. Helium is inert and forms no compounds from which it can be released by dissociation. Helium is absorbed by elastomers. O-ring gaskets can become saturated with helium and raise the background level in the mass spectrometer. Helium is pumped in Penning discharge gages by an ion burial process; since it forms no true compound it can be released by regurgitation mechanisms. Helium entrap- 9-5 ment in ion pumps is also not permanent; in fact its use as a tracer gas in an ion-pumped system is to be avoided. (Fortu- nately, these effects are not present in a system pumped by an oil or mercury diffusion pump.) If a Penning gage is present in a mass-spectrometer leak detector, it should be cleaned and baked periodically to remove sorbed helium. The gage should be off when the spectrometer is operating at maximum sensitivity. In principle, it should be possible to convert a commercial helium leak detector so that it will detect some other gas such as argon, hydrogen, or neon. In practice, however, this can prove to be expensive and unsatisfactory. The problems encoun- tered stem from the higher concentrations of these other tracer gases in the atmosphere and from the difficulty in distinguish- ing the mass spectrum of the desired ion from the spectrum of an unwanted ion. Hydrogen and argon have been used fairly extensively with mass spectrometers. However, their normal concentrations in air are about one part in i0,000 and one part in 100,respec- tively. Consequently, the background due to air seeping into the system is considerably higher with these gases. Suitable means must be used to compensate for this. Hydrogen is more widely available and costs less than he- lium. It is more readily ionized than helium, yielding a high- er sensitivity for leakage measurements. But it is also formed in the spectrometer ion source as a breakdown product of hydro- carbons and water vapor, especially when these come into con- tact with the spectrometer filament. In a mass spectrometer for hydrogen special precautions must be taken in the construction of the ion source. Vapor con- tamination from the equipment under test is kept out of the spec- trometer by a liquid-nitrogen trap in the inlet line to the ion source. The ion-source construction is "clean," in that organic materials are avoided and the demountable seals use metal foil gaskets. Finally, the mass spectrometer pumping system comprises a mercury diffusion pump with its own liquid-nitrogen trap. The result is a significantly lower hydrogen background. Cossutta and Steckelmacher (Ref. 9-5) have attained a sen- sitivity of 4 x i0"1° atm-cc/sec on a lens mass spectrometer using hydrogen as the tracer gas. With helium the sensitivity was about half that for hydrogen. The background stability was greater in the mass-4 than in the mass-2 region. Therefore, the limiting sensitivity was about the same for both helium and hydrogen. Argon can be used as a substitute for helium, but will re- duce the sensitivity of the spectrometer. It retains many ad- vantages such as high ionization efficiency, chemical inertness, and low cost. It has a relatively high background in air. The principal disadvantage is that argon at mass 40 is difficult to 9-6 resolve from the background peaks. Both the nitrogen and oxygen peaks of air and hydrocarbons normally present in the vacuum system increase the general background in the mass-40 region. Thus argon is difficult to detect and measure_ Some of these background difficulties may be overcome by use of the doubly ionized argon peak at mass 20, although this produces a lower sensitivity than measurements near mass 40. The mass-20 peak appears ±n a relatively clean region of the spectrum. Thus background ceases to be a problem. Slow diffusion of argon through leak passages limits to some extent its use for leak location. The variable pressures and atmospheres associated with leak detectors are factors contributing to the unpredictable life of analyzer tube filaments. Occasional bursts of gas bring the system up to high pressures. Even with protective circuits to take care of these bursts, tungsten filaments will have a very short life. It is possible to increase filament life (Ref. 9-6) by coating it with thoria. Most commercial leak detectors are now sold with spectrometer tubes containing thoria-coated or ir- ridium-tungsten filaments. Some leak detectors are built with dual filaments; if one filament burns out, the second can be quickly put into operation. Ionization of the tracer gas varies with electron-emission current. Therefore, the emission must be kept constant with an automatic regulator. Contamination of the ion source can result in low sensiti- vity or unstable operation. One commercial helium leak detector contains a self-cleaning ion source in the mass spectrometer head. In that instrument, the ion repeller is a grid which runs red-hot, to burn off contamination deposits which try to form on the electrodes (Ref. 9-7). On other instruments, the ion repel- ler is platinum-clad and may be cleaned by immersion in a soft flame. 9.3.1 Some Other Ion Spectrometers Ion mass-spectrometers other than the magnetic sector type may be used for leak detection. For example, Varadi (Ref. 9-8) describes a radio-frequency mass-spectrometer leak detector. In this type of analyzer tube ions are accelerated by a direct-cur- rent voltage, and then sent through a series of grids which have a radio-frequency (RF) voltage applied to them. If the transit time of the ions in going through the grid structure is in prop- er phase with the frequency of the applied RF voltage, the ion will gain energy. A repelling potential placed on a grid be- tween the RF structure and the collector prevent all but those ions which have gained a maximum energy from reaching the col- lector. This type of tube does not require a magnetic field. It requires a large amount of electronic circuitry. Barrington (Ref. 9-9) developed an inverted magnetron type of ion detector. In this tube, the anode is mounted centrally inside a grounded cylinder which acts as the cathode. A magnetic 9-7 field of about i000 gauss is applied axially. A discharge is initiated on application of a potential difference of about 1500 volts between the electrodes. The electrons, trapped by the magnetic field, circulate around the anode. Positive ions are accelerated radially towards the cathode and, because of their much larger mass-to-charge ratio, are deflected only slightly by the magnetic field. A small exit hole is provided in the cathode. Ions emerge through the hole at angles and with velocities which vary ac- cording to the mass of each species. The ions continue to trav- el in the fringing magnetic field, and some spatial separation is achieved as a function of ion mass. The sensitivity of the device is in the order of 10-:° atm-cc/sec for helium. It does not appear to have sufficient resolution to be useful as a gas analyzer, however. Basically the magnetron interaction space may be thought of as an ion source. Collislonal processes im- pair the formatlon of an ion beam at the exit hole where the angle is strictly a function of the mass of the ions contained in it, however. An omegatron leak detector is described by Nicollian (Ref. 9-10). The omegatron is basically a small, compact cyclotron. The electron beam produces ions of the residual gases in the volume, and the magnetic field causes these ions to move in circular paths at their cyclotron frequency. When the applied radio-frequency voltage is in resonance with the cyclotron fre- quency of a particular ion, the ion will gain energy and move out in a spiral path, eventually striking the collector. Any mass spectrometer may be used as a leak detector. How- ever, those designed for leak detection are portable, rugged, and must have the ability to remain tuned to the tracer gas signal. Reference 9-i1 describes a mass spectrometer using two ion- deflecting analyzers in series. Those ions which are gas-scat- tered in the first analyzer, and which would produce a broad- ened peak in a single-stage instrument, are resolved into sep- arate peaks by the second analyzer. With operating pressure in the spectrometer tube in the region of 10 -s to 10 -_ torr, the background was three orders of magnitude less than in a commer- cial single-stage mass spectrometer. It was therefore possible to use an electron multiplier as an ion detector. A leak de- tector which employs this principle has recently been manufac- tured. The smallest detectable leak in this detector is in the range of 5 x i0 -I_ atm-cc/sec. Unusual problems are encountered with higher mass-specro- meter sensitivity. Residual background from atmospheric helium, diffusion of helium through glass, helium holdup from previous testing, and helium accumulation in the associated vacuum-mea- suring gages can present serious limitations. One of the most significant problems is the handling of the item to be tested. Leaks which a new machine would be capable of detecting can be 9-8 easily - though temporarily - sealed by the grease and moisture from a fingerprint. One approach to the problem of reducing background signals is embodied in an ion detector described by Daly in Reference 9-12. It can distinguish between helium ions and unwanted "air" ions. This detector is used with a conventional single- stage mass spectrometer. Its operation depends on the fact that the penetration of low-energy-charged particles in aluminum is proportional to the energy and inversely proportional to the square root of the atomic number of the ion. The metal thickness can be chosen so that the helium ion penetrates just to the back and releases there a secondary electron, which may be used to record the arrival of the helium ion in the foil. No signal will be ob- tained from the N+ and N_ ions because of their failure to pene- trate a foil of this thickness. A great reduction of background can be achieved by this technique. This detector is not commer- cially available at present, however. 9.4 TYPICAL MASS-SPECTROMETER LEAK DETECTOR A mass-spectrometer leak detector comprises the following major components: i. High-vacuum pumping system for the analyzer system 2. Analyzer tube and its associated electrical circuits 3. Low-vacuum pumping system for roughing out the test item 4. Cold trap for removing condensable vapors 5. Appropriate couplings or flanges for the attachment of a test piece and qualified leak 6. Valves to control the flow of gases through the de- tector 7. Leak indicator, such as a meter or audible signal, or both 8. Vacuum gages A typical vacuum system is shown in the functional diagram of Figure 9-2. 9.4.1 High-vacuum Pumping System A forepump and a diffusion pump are used to maintain a vacu- um of i0 -_ torr or less in the analyzer tube. Since hot organic diffusion-pump oils decompose near atmos- pheric pressure, the system must be exhausted to a pressure less than 10-* torr before the diffusion pump is turned on. Similarly, it is important to shut off the diffusion pump first, and then allow the oil to cool before turning off the mechanical forepump or venting the diffusion pump to atmosphere. 9-9 ROUGHING i MANIFOLD _ GAGE CONTROL I---I i 'N TI I I ROUG,,NG ) /_ TEST INLET ROUGH PUMP TEST STATION DIFFUSION PUMP ISOLATION VALVE DIFFUSION PUMP COLD TRAP VENT SCREW SPECTROMETER TUBE IN LET THROTTLE VALVE LIQUID NITROGEN ! COLD TRAP OUTER CASE SPECTROM ETER TUBE CASE VACUUM GAGE LEAK DETECTOR Ficure 9-2. Mass Spectrometer Leak Detector Pumping System. (Reprinted with permission from Analytical Measurement Business Section, General Electric Company, Schenectady, New York.) The forepump, diffusion pump, and blower should be inter- locked for maximum protection of the diffusion-pump oil. The diffusion pump then cannot be turned on unless the forepump is started. A thermal, self-restoring circuit breaker should pro- tect the forepump while providing intermittent operation to maintain vacuum in certain instances. The blower should be fused in conjunction with the diffusion pump so that a failure of the blower fuse will disrupt heating power to the diffusion pump. One manufacturer uses a detector with a novel pumping sys- tem. Instead of a diffusion pump, chemical gettering is used. It is claimed that by the preferential chemical reaction of the residual gases, the concentration of helium in the analyzer tube is increased. This is supposed to increase the inherent sensi- tivity of this type of leak detector. 9.4.2 Analyzer Tube The modern mass-spectrometer tube operates in a chamber con- nected to a cold trap. Usually, the entire tube and detector assembly is completely self-contained on a single, easily de- mountable flange (Figure 9-3). All elements of the tube, in- cluding magnets and filament, are self-aligning, eliminating critical alignment problems. The entire assembly can be lif- ted out for cleaning and parts replacement. _ 9-10 £/ Figure 9-3. Analyzer Tube of a Modern Mass-spectrometer Leak Detector. (Reprinted with permission of the Analytical Measurement Business Sec- tion, General Electric Company, Schenectady, New York.) Design of the tube is shown in Figure 9-4. A beam of elec- trons from a heated filament is attracted by a small potential difference toward an ionization chamber. The electrons pass through a hole into the chamber. Electrons hit gas molecules in the chamber and ionize them. The source magnet causes elec- trons to travel in a helical path and increase the probability of collision and ionization. An ion repeller ejects the posi- tive ions out of the slit in the ionization chamber. An ion lens, consisting of two focusing half-plates which can be separately adjusted to the proper potentials, concentrates the ion beam at the center of the slit in the exit plate. Use of such an ion lens increases the intensity of the ion beam and the sensitivity to an input sample of tracer gas. 9.4.3 Low-vacuum Pumping Sxstem A mechanical pump, or some similar device, must be provided for roughing the test item to low enough pressures to transfer it to the leak-detector system. Some mass-spectrometer leak de- tectors incorporate an automatic test station that changes valve positions at preset pressure levels. The test item is evacuated to some preset value; then the test valve opens automatically and the roughing valve closes. After completion of the leak test the test valve closes and the test item is automatically veDted to the atmosphere. 9-11 Collector Plate Suppressor M w_ Plate To J801 .... Ground / Plate Source Magnet' Ionization Chamber °:°: LEGEND /_!_o:-• GAS MOLECULES • Et ECTRONS Ion • IONS Repeller Anolyzlng Magnet Exit Plate FOCUS t Ion Source Filament Figure 9-4. Operation of Modern Mass-spectrometer Analyzer Tube. (Reprinted with per- mission from the Analytical Measure- ment Business Section, General Electric Company, Schenectady, New York.) 9.4.4 Cold Trap The purpose of a cold trap in a vacuum system is to remove gases and condensable vapors of water and oil. The vapor pres- sure of water at 20°C is 17.5 torr, but its vapor pressure at liquid-nitrogen temperature (-196°C) is approximately 10 -Is torr. The lower the temperature of the trap the more effective it is in reducing pumping time and assuring a clean vacuum system. The recommended refrigerant is liquid nitrogen. Liquid air, though equally effective, may present an explosion hazard, because of its liquid-oxygen content. Good vacuum practice requires that the liquid in the cold trap be maintained at a reasonably con- stant level. If the trap is neglected and allowed to go dry, the operating efficiency of the leak detector will be impaired. A high background pressure will develop and will shorten the life of the filament. If liquid nitrogen is not available, a slurry of dry ice and alcohol or an inflammable solvent such as trichlorethylene may be used. The boiling points of these materials are not so low as that of liquid nitrogen, and their trapping effectiveness is less. 9-12 A refrigeration unit manufactured specifically for leak-de- tector cold traps is available. This unit uses the adiabatic ex- pansion of compressed air as the refrigeration principle, and may be operated from any clean compressed-air source. The vacuum manifold connecting the test piece to the leak- detector system usually incorporates several vacuum compression- seal couplings. It is good practice to leave a standard leak in one of these inlets so that a rapid qualification may be performed before and after a leakage test. 9.4.5 Control Valves Two high-vacuum, bellows-sealed control valves are usually incorporated in the vacuum system. These include an inlet throt- tle valve and a diffusion-pump isolation valve (see Figure 9-2). The inlet throttle valve is especially designed with a throttling plate that varies the size of the valve opening as it changes from a fully closed to a fully open position. This valve is used to throttle a gas sample from a large vessel or from a test piece with large leaks so that the pressure in the leak-detector vacuum system does not exceed a safe upper limit. The diffusion pump valve provides a means of isolating the diffusion pump from the vacuum chamber, cold trap, and mass- spectrometer tube for servicing and maintenance. The cold trap and mass-spectrometer tube can be removed for cleaning, the fil- ament can be changed, and other maintenance functions can be per- formed without shutdown of the diffusion pump and forepump. A valve is available which permits two discrete detector sensitivities while also allowing accumulation techniques of leak detection. The sensitivity choke on the valve provides a constant and fixed sensitivity increase, of a factor of about three times, by changing the pumping speed through the spectro- meter tube. Opening the valve two to three turns from its closed position produces a fixed low pumping speed, which results in a higher sensitivity. For faster pumping, this valve may be fully opened and the choke lifted off its seat. The sensitivity and pumping speed can thus be changed without disassembly and with reproducible results. It is not necessary to recalibrate each time the valve position is changed. However, it is important that both calibration and operation be performed at the same valve setting. Figure 9-5 shows an exposed view of this valve. As an alternative to the two-position valve, it is possible to use a permanent orifice to reduce pumping speed. Although such an orifice would increase the system sensitivity, it would also increase the system response time. 9.4.6 Leakage Indicator The leakage indicator is usually a milliammeter which regis- ters the amplified ion current. The detector usually has a multi- 9-13 Figure 9-5. Exposed View of a Diffusion-pump Isolation Valve. (Reprinted with permission of the Analytical Measurement Business Section, Gen- eral Electric Company, Schenectady, New York.) position stepping switch so that the current range displayed on the meter may be changed. For the convenience of the operator, who may be unable to see the output meter while he is probing the test system, a loud- speaker, audio oscillator, and amplifier can be installed on the equipment. An audible note is emitted whose pitch is related to the meter reading and hence to the magnitude of the ion current; that is, the pitch of the note rises when a leak is probed. 9.4.7 Vacuum Gages Mass-spectrometer leak detectors usually employ two types of gages; Pirani, or thermocouple, gages for pressures greater than 10 -3 torr, and ionization gages for pressures less than I0 -_ torr. The Pirani, or thermocouple, gage indicates pressure in the fore- pump line and shows when the diffusion-pump line may be opened. The ionization gage is usually of the cold-cathode or Phil- lips discharge type. This type of gage is more rugged and does not contain a hot filament which could burn out if accidentally exposed to atmosphere. 9.4.8 General Characteristics and Specifications of Commercial Detectors Table 9-1 lists the general characteristics of commercially available mass-spectrometer leak detectors. Specific information 9-14 regarding many of the available models will be found in Part III of this Handbook. A performance specification for helium leak detectors has been issued by the Electronics Research Center of the National Aeronautics and Space Administration (Ref. 9-13). This speci- fication details such items as sensitivity, response time, clean-up time, warm-up time, noise, and drift. Table 9-1 COMMERCIAL MASS-SPECTROMETER LEAK DETECTORS Characteristics Sensitivity Tracer gas Output signal Power requirement Size Weight Price Necessary accessory Avera@e Values 1 × 10 -11 atm-cc/sec: 0.i part per million helium in air Primarily helium; also hydrogen, argon, neon, butane Millivolt meter or microampere meter i000 watts, 105/125 60 hertz AC; 220/250 60 hertz AC Width = 25 inches, Height = 40 inches, Depth = 20 inches 500 pounds $5oo0 Liquid nitrogen 9.5 LEAKAGE TESTING The mass-spectrometer leak detector can be used in any of the following ways: i. Leakage measurement • Steady-state • Tracer accumulation o Leak Location • Tracer probe • Detector probe 9.5.1 Steady-state Leakage Measurement The steady-state method can be used on either evacuated or pressurized systems, as discussed in Section 4.5, "Leakage Mea- surement Testing." The evacuated side should not contain volatile materials or materials sensitive to vacuum, because the test space will be at Z 9-15 a pressure of 10-2 torr or less. The time required for this test is not much greater than the pumpdown time required for the evauation of the test item. The whole procedure can be highly automated. The leakage measurement testing of pressurized items in- volves a time interval of about three hours per test plus a similar time for calibration of the test system. Continuous monitoring of the leak-detector signal is necessary with this method. 9.5.2 Leakage Measurement b X Tracer Accumulation Quantitative measurements using this method are subject to much greater erroz than those of the preceding subsection (9.5.1). Tracer gas is allowed to accumulate on the downstream side of the leak, and subsequently the concentration of the accumulated gas is determined. Section 4.6, "Tracer Accumulation Testing," dis- cusses this method in detail. With the helzum leak detector, a note of caution is advis- able because this method can give false readings as a result of outgassing from the test object (see Section 9.2, "Sensitivity"). When careful attention is given to detail it is possible to mea- sure leakage rates smaller than 10 -11 atm-cc/sec (Refs. 9-14 and 9-15). 9.5.3 Leak Location -- Tracer Probe Detection time with this method includes the time to evacu- ate the test object and the time required to spray all areas with tracer gas. Location of individual leaks using a fine tra- cer gas stream can be very time consuming. Testing of a large object may be initiated by loosely fitting a hood of vinyl plas- tic around the object to retain the helium to determine if any leaks exist. In systematic leak checking, gas is sprayed on the top of the component first, helium gas being lighter than air, and then gradually down over all other suspected areas. This is done so that the helium will not drift to an undetected leak and produce a leak indication at the wrong location. The detection procedure should be carried out in an area free from drafts and breezes. 9.5.4 Leak Location -- Detector Probe Use of the detector probe (see 5.2.2.1) with the mass spec- trometer results in a considerable loss in detection sensitivity (about a thousand times less) over that attainable with a tracer probe. In the vicinity of a small leak, the rapid diffusion of he- lium into the air causes a steep helium concentration gradient to be established in the vicinity of the leak. When the probe 9-16 approaches the leak area it samples the air-helium mixture. (It is important that the probe's orifice be close to its input end.) If the flow rate into the probe were high, it would sweep the helium in. However, the flow is usually very low and has little effect on the concentration gradient. If the probe misses the leak by as small a distance as one-fourth inch, the sensitivity will be reduced by approximately ten to one because of the steep gradient in concentration. To overcome the effect of the gradient, a small rubber suc- tion cup can be placed over the end of the probe. When the cup covers a leak during probing, the helium concentration begins to increase in the space and will soon reach a detectable level. Both the probing speed and the distance from the test ob- ject to the detector probe are critical. Figure 9-6, reprinted from Reference 9-16, is an example of the effect of probing speed and distance on the sensitivity of the technique. The data re- presents one manufacturer's results obtained under ideal labora- tory conditions. Such high sensitivity cannot be obtained under field conditions. At a probing speed of three feet per minute, even under ideal laboratory conditions, the probe must be within one-fourth inch of the leak to be able to detect and locate a 10 -_ atm-cc/sec leak. If a weld whlch is wider than one-fourth inch is being checked for leaks, at least two parallel passes must be made to check the weld completely. For best sensitivities the leak detector should be operated at about 1 x i0 -_ torr detector pressure. Lower pressures re- sult in low speed and longer time constants, while at higher pres- sures the inherent sensitivity of the leak detector begins to de- crease. The use of long vacuum leads between the machine and the probe should be avoided if possible. The additional volume cre- ated by these leads adds to the time constant and, hence, reduces the apparent sensitivity. Sensitivity is not actually reduced, but slow response interferes with prompt detection of leaks as the probe is moved over the suspected area. When pressure-testing large objects, It is preferable to use a short hose and to move the leak detector rather than to use a long hose and a stationary leak detector. Response time increases approximately linearly with probe length in the absence of adsorp- tion and outgassing. That is, doubling the length should double the response time. Actually, doubling the length will probably double the outgassing rate and reduce the sensitivity. Figure 9-7, also from Reference 9-16, is an example of the effect of tubing length on the clean-up and response time of the leak. The most successful flexible hose to the probe is of the metal bellows type, although rubber tubing (preferably neoprene) is often used. The problem of sorption of helium can be ignored if metal lines are used. Rubber vacuum hose readily absorbs the 9-17 ± D T I x 10-7 I_D ETECTOR PROBE ..----SLEEVE : .':.. HELIUM • ,eAK / I,, // /i I/ | o w Ix I0 "e ,v. w _J =E =E z >_ o n- n 0. _F Ix 10-9 0 0.5 1.0 1.5 2.0 2.5 3.0 LINEAR PROBING SPEED (ft/min) Figure 9-6. Effect of Probing Speed and Probe Distance on Sensitivity. (Reprinted with permission from Consolidated Electrodynamics Corpora- tion, Pasadena, California.) 9-18 IO0 80 6O 5O 4O 30 "$ 25 ,,,w- -...- 20 a w m 15 z I0 en _ 8 o 6 -r 5 ° 4 2 W J 3 2.5 2 1.5 1.5 2 2.5 3 4 5 6 7 8 9 I0 15 20 25 30 40 50 60 80 I00 TIME (seconds) Figure 9-7. Response and Cleanup Time Versus Probe Length for a Mass Spectrometer Leak Detector. (Re- printed with permission from Consolidated Electrodynamics Corporation, Pasadena, Cal- ifornia). 9-19 .L helium, removing it from the stream and reducing the sensitivity. Later released, this helium a_ds to the helium background. The complete removal of helium from a vacuum hose is a tedious pro- cess and frequently requires several hours. Clean-up rate can be improved by passing a dry gas through the line at a fraction of a torr of pressure. When using a detector probe consider the following: i. The use of a specially shaped probe is sometimes ad- vantageous. For example, a simple probe made by attaching the flattened end of a piece of copper tubing to a needle valve varies the suction through the probe as described in Section 5.2.2.1. 2. The flow through the probe is sometimes too large to be handled by the pumping system of the leak detector. Then an auxiliary pump must be used, although this will reduce the detector sensitivity. 3. The sensitivity can be increased by placing a boot over the end of the probe. 4. After testing in one location, the probe may use up all the helium issuing from a leak there. The probe should be removed until a detectable concentration of helium has built up again around the leak. The test object should be kept out of drafts to allow helium to build up in a concentration around a leak. The minimum detectable conductance of a leak can be changed by pressurizing the vessel to be tested. If such an increase in pressure implies too great an ex- pense in tracer gas, the gas may be diluted, but with some loss of sensitivity. For example, if a system pressure is increased by a factor of i0, the flow through the leak, providing it is laminar, will in- crease by a factor of i00. Decreasing the tracer-gas concentration by a factor of i0 will decrease the sen- sitivity only by a factor of i0. . So The relative sensitivity of the probe technique may be es- tablished by placing the probe near a calibrated leak which has been pressurized, at a known pressure, with helium. The leakage indicator on the leak detector is read and the distance of the probe from the calibrated leak noted. Indicator readings are obtained for several spacings and a curve obtained of metec re- sponse versus spacing plotted. The curve is then extrapolated to find the meter indication that corresponds to zero spacing. This is the indlcation that would be obtained if the entire out- put of helium from the leak were to be accepted by the detector probe. The relative loss in sensitivity arising from moving the probe away from the leak varies as the ratio of the meter indi- cation at a given distance to that at zero distance. The maximum sensitivity of the detector is reduced in this same ratio. 9-20 9.6 OPERATION AND MAINTENANCE The specific steps involved in using a commercial leak de- tector will differ from model to model and from manufacturer to manufacturer. Details of operation for each model are usually spelled out carefully by the manufacturer. Maintenance problems are generally minimal. The openings for air circulation through the cabinet of the leak detector should not be blocked. Vibra- tion of the unit should be avoided. A maintenance schedule should be set up for changing both the mechanical- and diffusion- pump oils. Gasketed joints that are disassembled periodically -- such as the flanges for connecting test objects, the liquid ni- trogen trap, and the standard leak -- should be inspected on disassembly. Spare parts -- such as filaments, gaskets, and certain electronic parts -- should be kept on hand. The manu- facturer can provide a list of parts that are most likely to be needed. A great number of machine adjustments may be used to vary the sensitivity of the leak detector. Zero adjustment will change the sensitivity to some extent, as will internal pres- sure variation. Perhaps the greatest effect on sensitivity is the cleanliness level of the detector and the system being tested. A philosophy needs to be developed for both personnel and equipment. Leak detection is no better than the operator. The following illustrate some of the established operator rules that have been known to minimize maintenance and increase efficiency. An operator should: i. Refuse to test systems or parts which appear unclean or which visually appear to have contaminants on their surfaces -- i.e., oil, chips, lint, threads, water stains. 2. Use only jigs and fixtures developed for specific parts and standard setups. 3. Acquaint the supervisor or process control engineer with any parts which have been damaged or appear ab- normal in any way prior to its test. 4. Determine that the apparatus has been checked out by the maintenance man before operating the detector at the start of each shift. The maintenance check should be recorded in a log book attached to each station. 5. Report all variations in machine performance to a maintenance man. 6. Maintain all cold traps diligently. The cleanliness of the detector can be greatly enhanced by use of the nitrogen bleed technique described in Section 5.3. This technique should be used whenever the system is left over- night and use is anticipated the next day. Under no circum- stances should the pumps of the leak detector be used for drying 9-21 wet systems or evacuating dirty systems. Overnight use of the nitrogen bleed technique keeps the leak-detector pumping system unavailable to night-shift personnel who might not be knowledge- able in its proper use. No matter what the circumstances of vacuum testing, a reli- able, informed operator is needed. Although most commercial leak detectors are now almost completely automatic, some individual, responsible for the equipment, its operation, and use, should be familiar with the principles of vacuum technology. Helpful in- formation will also be found in References 5-3 and 5-4. It is desirable to check sensitivity at the start and at the end of a work shift. It is also advisable when the detector is operation- al, to rapidly check after each testing task by admitting tracer gas into the detector through a calibrated leak. The leak detector should be leak-tight when in uses It is possible to locate leaks in the detector system by a tracer probe technique, using the mass spectrometer itself to locate its own leaks. When the mass-spectrometer leak detector is checked, a leak may be indicated when helium is brought close to the exhaust of the mechanical pump. This is caused by the high diffusion rate of helium, which permits the gas to flow against the general gas flow. The operator of the equipment should be aware that such counter diffusion is a normal occurrence. False signals due to this counter diffusion may be avoided by preventing large amounts of helium gas from accidentally reaching the area near the mech- ical pump. 9-22 10.1 10.2 10.3 10.4 10.5 10.6 Section lO HEATED-ANODE HALOGEN LEAK DETECTOR INTRODUCTION ................ SENSITIVITY ................. DESCRIPTION ................ GENERAL CHARACTERISTICS .......... LEAKAGE TESTS ............... SAFETY ................... 10-1 i0-i 10-2 10-5 10-8 10-11 k ib t Section lO HEATED-ANODE HALOGEN LEAK DETECTOR lO.l INTRODUCTION In a halogen leak detector, minute quantities of halogen vapor enter a detector cell and are ionized catalytically on a heated platinum anode. Ions are collected on an adjacent cathode electrode at a potential which is negative with respect to the anode. A current proportional to the rate of ion forma- tion flows in an external circuit to produce an indication on a meter. The rate at which ions are formed is proportional to the halogen concentration in the gas which passes into the de- tector cell. A unique feature of the detector cell is that the ionization process can be accomplished in air at atmospheric pressure. The ionization process is specific to halogen vapors. The halogens are chlorine, iodine, bromine, and fluorine. Materials containing these elements are usually called halides. The most common halide materials used in leak detection are those contain- ing chlorine. 10,2 SENSITIVITY Sensitivity of this instrument to R-12 vapor, for example, can be as high as one part per billion of halogen in air, corres- ponding to a leakage rate near 1 × 10 -9 atm-cc/sec. A vacuum- operated halogen detector works at a pressure of 10 -I to i0 -_ torr and is capable of detecting halogen gas in concentrations as low as 0.2 part per million. Sensitivity of the detector varies wlth the different halo- gen compounds. This variation is shown by Table i0-i, which is reprinted from Reference i0-i. The velocity with which a halo- gen-containing sample is passed through the detector cell also affects the production of ions and, therefore, the sensitivity of the cell. The response of the sensing element changes markedly with temperature. Below approximately 850°C, the emission current is too small to be easily utilized. Above approximately 950°C it becomes unstable. Random fluctuations in ion production occur and can completely mask a leak signal. The sensitivity of the detector unit will decrease as a re- sult of prolonged exposure to pressures of less than 10 -3 torr. Exposing the element to air for a while or bleeding a small amount of air into the system should restore sensitivity. If, after the leak detector has been used for some time, there is a lack of sensitivity or there is erratic or off-scale indication, the sensitive element must be removed and cleaned or replaced. 10-1 --i- Table I0-i SENSITIVITY OF HEATED ANODE HALOGEN LEAK DETECTORS TO VARIOUS HALOGEN COMPOUND GASES (Ref. i0-I) Limited experimental data indicates that to give the same leak signal as R-12, the leak rate of another gas will be the R-12 leak rate multiplied by a factor as shown below. Generic Name Dichlorodifluoromethane Trichlorofluoromethane Chlorotrifluoromethane Chlorodifluoromethane Trichlorotrifluoroethane Dichlorotetrafluoroethane Sulfurhexafluoride Methyl chloride Perfluorocyclobutane Perchloroethylene Trichloroethylene Carbon tetrachloride Trade Chemical Designation Formula R-12, F-12 CC12F2 R-II, F-II CCIsF R-13, F-13 CCIF _ R-22, F-22 CHCIF 2 R-II3, F-113 CCI_Fs R-II4, F-II4 C2C12F_ FC-43 FC-75 C C1 F SF6 CH3C1 Freon C-318 C_Fe C2CI_ C2HCIg CCl_ Approximate Multiplying Factor By Volume By Weight 1 1 1 1/4 3/4 35 40 1 3/4 1/6 --- 1 i 1/4 131 --- 30 i00 200 240 1 1/4 3 * It is believed sensitivity to this gas is one percent of R-12 (multiplier 100), but supporting experimental data is not available. ** It is believed sensitivity to this gas is almost equal to sensitivity to R-12, but experimental supporting data is not available. I0.3 DESCRIPTION Figure I0-i is a photograph of a typical heated-anode halo- gen leak detector. This instrument includes: • A two-element sensing structure, as shown in Figure 10-2 (see also Ref. 10-2). Vapor to be detected is passed between two closely spaced cylinders. The inner cylinder, or cathode, is kept red-hot by an internal wire heater. The outer cylinder, or anode, is operated at a negative potential with respect to the cathode. 10-2 Figure i0-i. Heated-anode Halogen Leak Detector. (Re- printed with permission of the Instrument Department, General Electric Company, West Lynn, Massachusetts.) ION-EMITTING AIR OUT S I_![ ] t AIR SAMPLE IN Figure 10-2. Detector Element of Heated-anode Halogen Leak Detector. (Reprinted with permission from W.E. Briggs, A.C. Jones, and J.A. Roberts, "Leak Detection Techniques," 1958 Fifth National Symposium on Vacuum Technology Transactions, Symposium Publi- Cations Division, Pergamon Press, New York (Ref. 10-2).) 10-3 • Means of forcing a gas sample through the cylinders at a constant low velocity. • A basic circuit (Figure 10-3) containing a low-voltage supply for the heater and a supply of a few hundred microamperes at 50 to 500 volts alternating or direct current for use as the interelectrode potential. A-C OR D-C I HEATER. OUTER CYLINDER'_ INNER CYLINDER /\ v C>.. ./',,, __ m t AIRFLOW Figure 10-3. Basic Circuit of Heated-anode Halogen Leak Detector. (Reprinted with per- mission from W.C. White and J.S. Hickey, Electronics, Vol. 21, March 1948, McGraw-Hill Publications, New York.) The ion current can be directly displayed on a microammeter or a galvanometer. By another method the change in voltage across a high resistance is utilized to operate an amplifier which, in turn, operates a suitable meter or relay. An audible tone can be obtained by adding a relaxati:_n-type circuit which incorporates a capacitor and glow-discharge tube with a loudspeaker as an indicating element. The current through the sensing element builds up a charge in the capacitor. When the voltage is sufficiently high, the glow-discharge tube fires. The pulse of current resulting from the discharge of the capa- citor produces a click in the loudspeaker. The repetition rate of the clicks is an indication of the amount of current. With any circuit used, it is desirable to include a protec- tive resistor to prevent injury to the sensing element or indic- 10-4 -° ating device which could result from an overdose of tracer gas or a short circuit between electrodes. Equipment modifications provide adjustable sensitivity, auto- matic signal balancing, and special probe designs. An example of the latter is an air proportioning probe for use in areas where the background signal is unusually high. By the use of such a probe the sensitivity of the test can be increased and the signal stability improved. Use of the probe is described in Section 10.4. Specific information regarding the models which are available can be found in Part III of this Handbook. 10.4 GENERAL CHARACTERISTICS The detector is designed specifically for halogen compounds. Although halogen contamination in the atmosphere will sometimes present a problem, the specificity leaves no doubt that only the tracer gas will be detected. The response of the instrument de- pends upon the halogen concentration. Up to one part per million the response is linear. Between one and i000 ppm it is exponen- tial, and above 1000 ppm the detector saturates. The detector operates directly at ambient conditions, and can be used without complex pumping equipment. It is relatively cheap and portable, and can be used by inexperienced personnel without extensive instruction. The detector can be exposed to mists of the halogens, pro- viding exposure is limited to a relatively short time. If the sensing element is exposed to a halogen mist for too long a time, or to a highly concentrated vapor, it may lose its sensitivity. Prolonged operation at full temperature in a current of pure air and with voltage between electrodes will restore sensitivity if the contamination has not been excessive. The degree of contam- ination varies greatly from one compound to another; for example, carbon tetrachloride contaminates the electrodes more easily than the other halogenated hydrocarbons. With proper maintenance and operation the elements used in industrial leak detectors can be expected to last 500 to i000 hours. The element used in a serviceman's type of leak detector is much smaller and will not last as long. In general, little can be done to extend the life of these units. The element used in a serviceman's leak detector, however, is much lower in cost than is the general laboratory instrument. The halogen detector also responds to solid particles of the iodides, chlorides, bromides, and fluorides. Therefore, it de- tects smoke from burning materials containing such compounds. The tobacco used in cigarettes must contain such a compound since the detector responds readily to cigarette (and to some extent cigar and pipe) smoke. A No Smoking rule should be enforced in the test area. The detector also responds to solder fluxes, cleaning compounds, and aerosol propellants. Such materials must be eliminated from the test area. 10-5 Rubber and plastic tubing must be avoided in any test sys- tem. Halogen gases are easily absorbed by these materials and may be released later to interfere with the test readings. The inherent sensitivity of the halogen detector cannot be reached in practice if there is background contamination. A large leak near a small leak may completely obscure the signal from the small leak. In many factory test areas, a background level of halogen gas will build up because of leaks in the units being tested, leaks in the refrigerant supply tank, dumping of gas, and other sources that may allow halogens to enter the area. The chief precaution in a test setup is to make certain that the testing is carried on in an ambient that is sufficiently free of halogen vapors. In many instances, an exploration of the available floor space will indicate a location that is free of these vapors. If such a location is not available, it may be necessary to partition off a testing area and provide proper ventilation to bring in halogen-free outside air. It should be understood that the presence of halogen vapors in proportions of ten parts per million may be sufficient to contaminate the air enough to cause a loss of sensitivity in the testing equipment. With the automatic balance feature, the control unit will balance out a certain amount of halogen background, provided the concentration is constant or changing slowly. If this background level builds up to a point where normal air currents present in the room cause sudden changes in background concentration, leak signals may result even when the detector has not encountered a leak. There are three methods of combating this condition: i. Eliminate sources of background 2. Provide a controlled environment of fresh air in the testing area 3. Use a proportioning probe detector For the first method, it should be possible to control in- discriminate dumping of refrigerant charges, leaky lines, de- greasers using halogen solvents, paint fumes, etc. Manufacturers of refrigerators and air conditioners have found it desirable to use the second method and construct small room or booth for testing, since the background level of tracer gas is usually very high in their production areas because of the many sources of halogen gas. This room or booth is fed fresh air from the outdoors at a very low velocity to prevent excessive drafts and eddy currents of air within the room. The booth, in effect, isolates the leakage testing area and helps to keep background contamination from interfering. Fresh air is introduced through the roof so as to provide an air change once or twice a minute. A test booth is illustrated in Figure 10-4. w_ 10-6 AIR INTAKE FROM ROOF PEG BOARD CANVAS CURTAINS Figure 10-4. Controlled Atmosphere Test Booth. (Reprinted with permission from W.C. Hutchins, "Production Leak Testing of Appliances," Home Ap- pliance Builder, October 1961, pp. 1-6 (Ref. 10-3).) Some important facts should be kept in mind in construct- ing a booth: I. Fresh air should be supplied to the booth from the out-of-doors. In some cases, this air should go through an activated-charcoal filter bed to remove any halogen gas that may be present. 2. The fresh air from the blower should be distributed as it enters the booth so as to prevent drafts or eddy currents of air within the booth. A false ceiling made of peg board is ideal to provide an even flow of air in the booth. When the booth is kept under this fixed positive air pressure, contaminated air will not come in from the shop or factory. 3. If a conveyor goes through the booth, canvas or rub- ber curtains help to maintain the booth's integrity. 4. An air conditioner in the booth will be helpful in providing comfort for the booth personnel and to clear the air. It will, of course, also help lower the humidity. Care should be taken to baffle the air conditioner so that the cool air is distributed as evenly as possible in the booth. 5. Construction techniques will vary. Some factories fabricate the booth out of wooden studding; sheathing 10-7 can be a type of hardboard or sheet rock. Others use the movable metal partitions commonly found in offices. The chamber of the charcoal filter should be large enough to contain an ample amount of activated charcoal. The larger the chamber, the less often the charcoal will have to be chan_ed. Thought should be given to the ease of changing the charcoal fil- ter. One way to contain the charcoal is to use a drawer, the bottom of which can be a fine-mesh screen to allow air-flow through the charcoal. In many areas where the background level is much lower it may not be necessary to use a special ventilating booth. A poz- table 16-inch or 20-inch fan placed in a window or doorway near the test area may be adequate. The fan will usually clear out the halogen background to the point where leakage testing can be accomplished satisfactorily. Another method of overcoming the problem of high halogen backgrounds involves the use of a proportioning probe. This probe is so constructed that a supply of clean, halogen-free air from an external source can be mixed with the test sample of gas and passed through the detector. The proportion of clean air to test sample is adjusted by means of valves. Clean air can be obtained by filtering shop air through a bed of activated charcoal, or tank nitrogen may be used (see Figure 10-5). I FRESH \\ \\\ \ \\\\\\\\\\\\\\\\\\\\ VOLUMEII]| SM,0,LL BLOWER )IAMETER DUCT Figure 10-5. Fresh-air Ducting for a Propor_zu,_,,_ :zcL_ 10.5 LEAKAGE TESTS It is possible to use the halogen detector to test for liq' uid leakage from sealed devices. The only requirement is that the leaking fluid contain a halogen compound with a high vapor pressure. In some cases it may be possible to add a halogen tra- cer to the liquid and, by application of heat, to increase the vapor pressure of the tracer. 10-8 Packaged refrigeration machines are given a warehouse leakage test by insertion of the probe of the detector through a hole punched near the bottom of the carton. The accumulation of tra- cer gas in the carton can be substantial, varying with the length of time that the unit has been sealed in the carton (Ref. 10-3). The halogen leak detector may be used for leakage measure- ment or leak detection In a vacuum by inserting the detector head directly into equipment having integral pumping systems. The op- timum pressure for vacuum operation is between 10_ 3 and 10 -I torr(Ref. 10-4). (In vacuum operation, the detector is somewhat sen- sitive to pressure variation.) The best sensitivity will _be ob- tained if the valve to the diffusion pump is throttled. If the leakage is not large enough to maintaln the optimum pressure, a small air bleed can be inserted to do so. For checking leakage in the forepump portion of the system, as well as in the high-vacu- um chamber, the detector may be located just ahead of the fore- pump. When vacuum leakage-testing small items on a short time cycle, the detector should be maintained in a ready condition in a small vacuum system of its own. This is desirable because of the large thermal inertia of the detecting diode. The sys- tem should maintain the element at about 5 × 10-3 torr pressure, and provide a small, steady flow of air through it to maintain sensitivity. The units to be tested should be evacuated to a pressure somewhat above that in the detector system, and a samp- ling valve opened between the two before starting the leakage- testing procedure. Great care should be taken to make all vacu- um piping short in length and large in diameter, as the tracer gas moves primarily by diffusion. Sensitivity multiplication can be obtained in vacuum leak- age testing by using pressurized external tracer gas, or allow- ing accumulation in the system, or both. When the tracer probe is used for leak location, probing should be initiated at the bottom of the system. Movement should continue upward in a care- ful pattern. If probing is done above an undetected leak, tracer gas will drift down and provide a spurious signal. Halogenated gases are about three times as dense as air. Tracer gas emerging from a relatively large leak will flow into all nearby nooks and crannies and remain for long periods of time. Its presence in confined spaces may give "ghost" readings up to twenty-four hours after the original leak has been repaired. The nature and persistence of these "ghost" signals are highly dependent upon the geometry of the stagnant pocket and the ven- tilation around it. Pure halogenated gas in an open beaker will be undetectable about fifteen minutes after it is filled. An open-mouth Erlenmeyer flask, on the other hand, will contain de- tectable amounts after sitting on a table top for twenty-four hours or more. If the same flask were placed in a light breeze near an open window the halogenated gas would vanish in a few minutes (Ref. i0-i). 10-9 The low diffusion coefficient of the dense halogenated tra- cer gases must be considered in preparing a test procedure. In order to produce a dependable signal at a leak,the tracer gas mixture with which the system is charged must have uniform compo- sition. Any blind passages in the system must be flushed with well-mixed tracer gas; otherwise leaks in these cul-de-sac8 will simply exude air and escape detection. Those not flushed will remain at low halogen concentration for long periods, because of the low _iffusion rate of tracer gas in air (about 0.3 mole per square foqt hour per unit molar concentration gradient). _he time required for a blind duct one yard long to reach fifty percent of full halogen concentration (Ref. 10-5) is on the order of three hours if diffusion alone is acting. Figure 10-6 shows the time required for various lengths of blind duct to reach ten percent and fifty percent of open-end halogen con- centration. Settling out of heavier halogen gas from an initially well-mixed tracer gas is not significant. 14 12 I0 u% = 8 O e- l 6 4 - CL/c e = O. 5 _,_ I I I I I I I C°l = 0,1 0 I 2 3 4 5 6 7 8 9 L- feet ' Figure 10-6. Diffusion of Halogenated Hydrocarbon R-12 in a Blind Duct. (Reprinted with permis- sion from R.C. Quisenberry, Leak Detection Techniques Improvement Study for Space Ve- hicles, Second Formal Report, Ohio Univer- sity, NASA Contract NAS8-2563, Athens, Ohio, June 1963.) The halogen tracer gases are soluble in oil. Although small leaks are effectively plugged by oils, diffusion of the halogen .... material through the oil permits detection of the leak. The most popular tracer gases for leak detection are the refrigerants R-12 (dichlorodifluoromethane - CCIaF2) and R-22 (monochlorodifluoromethane - CHCIF2). These gases are stored I0-i0 as liquids under pressure; at room temper_tture they exert vapor pressures of 70 pslg and 122 p_g. If the retr_gerant in the cylinder is bled through a valve and introduced into a cha_,ber, some or all of the Izqu_d w_,l VdpO[l::e CO tlll the chamber. Liquid from tn? cylinder w111 cuntzn:,e to vaporize u,,cZl the pressure In the gas c_%am.bor zs equal _o L},_ vapor p_essuz) ci_ed above or untal no more la4uzd _s le:t. During the vapo=zz._tzcn process these refrigerant gases cool conslderably. If :he gases .,re vented into a rather large cham- ber, the refrigerant cyl_nder :nay cool to the polnt where vapor- izatio:: is _ntremely ' low. ZnouL,| thls occur, It mlght be ai_- ",isable to hasten vapor tzatlon try p£aclng t_ cy].lnder In a tank of warm water. It Is frequently des_:a,,le to dilute these tracer gaseG for the follow_ng reasons: • Since R-12 and R-22 llquefy at 70 pSl q and 122 psig re- pectzvely at room temperature, a pcessurzzed system be- ing tested cannot have a re,rlgerant gas pressure great- er than the_e pressure_. If leakaue testl-q _s tO be d_,ne at higher pressures, then _ressur-ze_ a_" must be added on top of the retrlqerant to ohtaln the desired test pressure in the system. Thls d11utior with air reduces the _ensit_v_cy zn p_opot_on to tlte decrease in concentration; but a more than compensatlng Increase in senszt_vzty Is reallzed heca_-_e _t Is v.rop_rt'.onal to the squ_r_ of th= pressuze r_se, asstu.,zng laminar flow governs tt:e leakage. • If _ Is desirable to, measure the _eakeg¢ quantitatively, the halogen concentrat'_cn :e.,c_ing the detector _ust be relat,-vel7 low, less than one pa_t no,- mt[!_,:::_ to _tay _'.thz: • the !'_n_ar rzn_: c_ _hc z.-.._Lru;,_enL. • In teztzng large systems, the cost of the tracer gee may be cons)d_raDie. IZ only l_rge leaks a_'e of _nter- est, the dilution of the tracer gas will reduce the overall cost and, as an added feature., d_'crease the am_snt of background contam_natzen by the leaks. 10.6 _AFETY The detection ezement of the haLegen leak detector operates at temperature: o£ about 9_0_C (l_00'E'; and wlth potentials of 300 volts. The following safety preca_tlonc n_ust _o cbservud: • Never enter an area where there is an explosAve vapor. I£ there _s any question, _tr_t test the area w&th an explosion meter. • Hevvr test zn enclosed spaces, such as bearing housings, ell tanMs, or p,plnj, w_thout _z_t testing wlth an oxplosz_n motor, • Since voLta._s as h_gh as 100 volts azu present, the c,,_.e should _ _upt _ ground [_o_en_al .,;zth a three-prong gt,;unded zeceptacle OZ other suitable gzoundlng lead. IReproduced from _best available copy. I0-II - "_' ii.i 11.2 11.3 11.4 11.4.1 11.4.2 11.4.3 11.4.4 SECTION II PRESSURE C}IANGE METHOD OF LEAKAGE TESTING INTRODUCTION ........................ SENSITIVITY ........................ DESCRIPTION OF TEST EOUIPMENT ......... LEAKAGE TESTING METHODS ................ Vacuum Leakage Test Considerations .. Volume Sharing Method ............... Automatic Leakage Testing Methods ... Leak Localizer ..................... PAGE II-I ii-i ii-i ii-i 11-2 11-5 11-6 11-9 II_1 Section II PRESSURE CHANGE METHOD OF LEAKAGE TESTING II.I INTRODUCTION Leakage testing by the pressure change method zs accomplished by observing the change in pressure between the inside and the outside of the contalnment vessel or structure under test. The method is suitable only for leakage measurement and is used pri- marily in the testing of large systems. The use of tracer gas is non requlred, and instrumentation is relatively slmple. The pressure gages on the system will fre- quently be adequate; in other cases special dlfferentzal gages designed for leakage testing may be necessary. Thls will depend upon the accuracy required. Testing times are long, especially when working near the l_mlt of sensltivlty of this method. 11.2 SENSITIVITY In a pressurized system, sensitzvlty is dependent on the minimum detectable change of the pressure fluctuation. In an evacuated system sensztlvlty is dependent not only on the pres- sure change which may be observed, but also on the degree to which this pressure change is due to outgasslng. Removal of the out- gassing factor causing pressure change will Increase the sensi- tivity of the technique. However, the evacuation mode is a more sensitive technique, because smaller changes in pressure can be detected. This is an accumulation leakage measurement procedure; therefore, sensitivity is largely dependent on the duration of the test. In all cases, care must be taken to ensure that the pressure indicating device is properly calibrated for the pres- sure range over which _t wzll be used. 11.3 DESCRIPTION OF TEST EQUIPMENT A suitable test device must be capable not only of withstand- ing the pressure differential applied during the test but also of indicating very small changes in pressure. The most sensitive equipment available detects pressure changes by the movement of a diaphragm which acts to unblance a capacitive bridge circuit. Table Ii-i summarizes the characteristlcs of the available pres- sure-change leak detectors. Speclfic information on this equip- ment may be found in Part III of thls Handbook. 11.4 LEAKAGE TESTING METHODS Measurement of leakage in either an evacuated or a pressur- ized device usually requires knowledge of the volume of the sys- tem under test. Change in pressure _s noted after some elapsed time, and the system leakage calculated according to Equation 4-10, where V is the system volume. ll-1 Table ll-1 COMMERCIALPRESSURE-CHANGEDETECTORS General Characteristics Sensitivity Pressure range Tracer gas Output signal Power source Size Weight Price Avera@e Values 1 × l0 -5 torr 3 x I0 -_ torr to l0 _ psi None Visual observation 115/230 volts, 50 to 400 hertz Sensor: 4 × 4 × 3 inches Electronic Unit: 8 × 8 x 12 inches 8 to 175 pounds Up to $6000 When the system is complex and the enclosed volume difficult to determine, the system leakage can be determined by the "addi- tional-leakage" method of Hjerten, et al. (Ref. ii-i). In this method the results of a normal leakage test are compared with the measurements obtained with an additional known leakage which is connected to the system. Where the duration of the test is more than a few hours it is possible that temperature variations may become significant. The resulting pressure changes would introduce large variations in the calculated leakage. The American Nuclear Society Stan- dard 7.60, which is reproduced in Appendix B, describes a pro- cedure for incorporating the temperature into the test method; this is known as the "absolute-temperature-pressure" method. The error propagated by the temperature variations can be canceled by introducing a "reference system" in the test vessel. Keshock (Ref. 11-2) found this method had significantly less er- ror than the absolute method. He cautions that the reference method as described in ANS 7.60 is not particularly useful, and shows how reliable results can be obtained. 11.4.1 Vacuum Leakage Test Considerations When leakage measurements are made on an evacuated system the outgassing, or evolution, of absorbed gases may be expected to occur. In some instances the pressure achieved during pump- down may be limited by the outgassing. When an evacuated system is isolated from the vacuum pump, the system pressure will rise. If only outgassing takes place, then the pressure will rise to a steady-state value, as shown in curve a of Figure ii-i. If the pressure rise is due solely to a leak, then the pressure ll-2 n- u_ o9 w n_ CURVE o PRESSURE RISE DUE TO SYSTEM OUTGASSING SYSTEM ISOLATED FROM PUMP TIME Figure ll-1. Effect of Leakage and Outgassing on a Pressure Versus Time Curve 11-3 change will behave in the manner illustrated by curve b. The combination of outgassing and leakage is illustrated by curve c. It is possible for outgassing to mask leakage. Therefore the adsorbed gases must be reduced below the level of the average deviation of the test. To minimize outgassing, the system should be kept clean and dry. Any oil or grease on the inner surfaces of the system should be removed before testing. The system should not be ex- posed to water or water vapor. Liquids having a measurable va- por pressure should not be present in the system, since the sys- tem pressure will rise to that pressure value. Two ways to reduce outgassing in a system are: l) heating the system under vacuum, and 2) use of a dry gas bleed (see Section 5.3). If the system being tested is isolated from the pumps, the pressure rise due to outgassing will cease when an equilibrium is established between the gases in the vacuum and those on the system surfaces as is illustrated in Figure ii-i. It is there- fore necessary to wait until this equilibrium is established be- fore taking leakage measurements. The pressure rise may be con- sidered as due only to leakage when the rise in pressure during successive time increments is equal. Many of the gases evolved during outgassing of a system are condensable. If a liquid-nitrogen trap is placed between the gage and the system wherein the pressure rise is being measured, the pressure rise observed will be due only to leakage (air is not a condensable gas under these conditions). Care must be taken that an equilibrium value of pressure rise is obtained when such a technique is employed. When the liquid-nitrogen trap is first cooled, system pressure will decrease because of the pumping effect on condensable gases by the trap. After these gases have been condensed, the leakage measurement can be started. It is possible to discrlminate between outgassing and leak- age by means of an auxillary vacuum hood, as illustrated by the schematic drawing in Figure 11-2. The technique involves two sets of readings. The first is taken with the system under test evacuated in the normal manner, and measurements made of the pressure rise over a selecte6 in- terval of time. The hood is then lowered over the component, and sealed on a suitable base. The hood is evacuated to appzox_- mately the same pressure as the system. A second measurement of pressure rise is then made. The rise is now due to outgassing only, since there is no pressure difference between the inside and outside of the system. The arithmetical difference between the two rates gives the true leak rate. It will be appreciated from the brief description 11-4 that this method is most suitable for repetitive testing of stan- dard components, where the provision of a suitable hood and an additional pump station is justified by the saving in time. The same pumping system can also be used to evacuate both the hood and the system under test. F_AUXILIARY HOOD HOOD II ISOLATING _u7 ! SYSTEM I UNDER TEST :::_ GAGE % SYSTEM ISOLATING VALVE VACUUM BREAK % VA LV E PUMP ISOLATING .-_ VALVE ! VACUUM PUMPS Figure 11-2. Test Setup for Pressure Change Testing, Using a Vacuum Hood 11.4.2 Volume Sharin 9 Method The volume sharing method of leakage testing is applicable to systems or parts of systems which do not contain their own pressure gages. The arrangement is illustrated in Figure 11-3. A leak-tight container of known volume, V 2 , is connected between the known volume to be tested, V I , and a vacuum pump. Valve A is located between the two volumes and valve B between the container and the pump. A pressure gage, P, is located on the container. The procedure for testing for leakage into V I is as follows: i. Pump both tanks to base pressure PI- 2. Close valve A. Allow leakage to enter V I . 3. After holding time, t_, close valve B and open valve A. 4. Allow pressure to equalize in both chambers at a level P2. (P2 will be greater than PI if leakage has occurred.) -q- 11-5 ° 5. Calculate leakage rate Q where Q = (Vz + v2) (P2 - P1)/tl (ii-i) This method can be made highly sensitive since the holding time can be arbitrarily lengthened. Vacuum components are some- times isolated for days by this means to test for small leaks. B I CONTAINER GAGE V I SYSTEM BEING TESTED _, LEAKAGE Figure 11-3. Volume Sharing Technique of Leakage Measurement II.4.3 Automatic Leakage Testing Methods The pressure rise technique has been used in an automated test setup (Ref. 11-3), where a carrousel-type vacuum lock was developed for expeditiously locking the specimens in and out of the test chamber (Figure 11-4). The carrousel lock consists of an upper stationary steel plate and a lower rotating steel disc. The rotating steel disc contains eight pouches, connected with a small auxiliary pump which keeps the pressure below 0.7 torr. Thus, any possible leaking path to the high-vacuum chamber has only i/i000 of the atmospheric pressure at its inlet. This reduces spurious leak- age. With a test rate of 60 units per hour, all leakages of 2 × 10 -8 torr liters per second and higher can be detected. The manometer, an ionization gage, is included in series with a liquid-nitroqen trap. 11-6 SMALL OIL DIFFUSION PUMPS COLD TRAP MANOMETER BULB '_ I I/ I JAR Fi 4-_ ,-I 00._r- 0 _0_0 I o9 .,o . I ,_o_ _ _ _o=_ o J _ Ill I ,===_ .==. IC) i.i./ __ __ ..... ,-4 :_ :_ '_ C Olr_ _ -,..I , - k_ 0 . ._ _ -IJk61 _Ul_ 0 _ Ol_ --_ 14-1 i o "-';o,.-_,,,1--_-I- o° _1 IN _ \ & "' 0,,I O_ O_ C_ ..... _sd '3_NSS3EId I I l l l l I I I oa u_ O'_ 0 _'0 0 0 0 _ v _,- _ _ - P- 40 _40 Eu_4o _ _ • t_O_. Oh 0 _ 11) .,-t I/_ -,-I _40 _ • I 0 -M r_ ,sd 'd9 13 -4 If large vessels have to be tested, immersion may be impos- sible. Channels to contain the test fluid can often be built around suspected areas. The system or section being tested may be pressurized in numerous ways. Considerable ingenuity may have to be exercised in making up special clamps and fittings for sealing the component and attaching the air (or gas) hose. Rubber sheeting and C-clamps are useful in these respects. When it is not possible to immerse the test object, a small quantity of soap solution may be applied directly to the sus- pected leak area. A bubble-free solution should be applied gently to preclude bubble formation during application. The solution should be flowed rather than sprayed or brushed onto the surface. The sensitivity of this technique is dependent on the time and care taken to observe bubble formation. Two cautions are in order: • When testing flanges, threads, or any joint which has a large exposure area, it is absolutely necessary that the solution bridge the entire joint. Gas will invar- iably slip out through the smallest plnhole which is not covered. • The second caution is in the choice of a suitable solu- tlon. For high sensitivity it is necessary that the film does not break away from the jolnt and that the bubbles formed are not broken by air drying or low sur- face tension. Guthrie and Wakerling (Ref. 13-3) propose an idea that is applicable to very large vacuum chambers. A volunteer equipped with an oxygen mask is requested to enter the chamber, which is pumped out to about three-fourths atmosphere. The man applies a soap solution to the inside surface of the system and looks for the formation of soap bubbles. Needless to say, the most care- ful precautions must be taken during this procedure. The man in- slde the vacuum system should be under observation at all times so that any slgns of exhaustion or other difficulty will imme- diately be apparent. A continuous and uninterrupted source of oxygen must always be available. Also, every precaution must be taken to preven_ any chance for the valve between the vacuum sys- tem and the pumps to be opened wide by mistake. The real value of the method lies in finding large leaks in parts of the surface of a large vacuum system that are not accessible from the outside. The method obviously has qulte limited application. 13.4,2 Liquids for Bubble Tests Water, fluorocarbon liquids, mineral oil, and a silicone oil are the liquids commonly used for immersion testing. A steady stream of extremely fine bubbles appears in an oil bath. If water is used, it must be treated to reduce the surface tension; this reduces the bubble size and the tendency of bubbles to cling to the surface of the component and build up to a relatively large 13-5 size before breaking loose and rising to the surface. This means that in water small leaks would require a long period of time to produce a bubble that would be visible. A component would most probably be passed as acceptably sealed before time was allowed for a conclusive test. A disadvantage common to tests using oil is the fact that the components, after being tested, must be degreased to remove the oil that adheres to the surfaces. A silicone oil bath is particularly expensive to use, because the oil clings to the component after immersion and cannot be completely recovered. In addition to fluorocarbon liquids, methyl, ethyl, or iso- propyl alcohols may also be used as test liquids. The one ad- vantage in the use of these materials that is not found with the other fluids is their cleaning ability. Not only is the degreas- ing process eliminated, but they also clean foreign matter from the body of the component. After the component is removed from the bath, the rapid evaporation rate of these liquids leaves the surfaces clean and dry. Alcohols should not be used in the heated bath procedure be- cause of their toxicity and flammability. Adequate ventilation is required to prevent poisoning or eye damage from the vapors. A soap solution for leak detection by topical application may be prepared from equal parts of corn syrup, liquid detergent, and glycerin (Ref. 7-1). The solution should not be prepared more than twenty-four hours before the test, and bubble formation properties should be checked with a sample leak every half hour during the test. 13-6 14.1 14.2 14.3 14.4 14.5 14.5.1 Section 14 USE OF RADIOACTIVE TRACERSIN LEAKAGETESTS INTRODUCTION ................ SENSITIVITY ................ EQUIPMENTAND MATERIALS .......... RADIFLO METHOD ............... OTHERMETHODSOF LEAKAGE TESTING ...... Pipeline Testing ........... 14-1 14-i 14-1 14-2 14-6 14-6 /I-4 Section 14 USE OF RADIOACTIVE TRACERS IN LEAKAGE TESTS 14,1 INTRODUCTION Radioactive isotopes are used as tracers in the detection and measurement of leakage. Only a very small quantity of radioactive material is needed to load the system or item which is to be tested. The nuclear radlatlons from leakage of the radioactive material are detected by means of special electronic instruments. Uses of such radloactive leakage tests are varied, with the applications ranging from the production- line testing of small sealed components to the testing of pipe- line systems. 14.2 SENSITIVITY The sensitivity of this technique may be as high as l0 - I_ atm-cc/sec under ideal operating conditions. To attain these conditions, the soaking and counting tlme must be selected for high sensitivity, and the units being tested must be of a "clean" construction, with no possibility of adsorption of radioactive material on the outer surfaces. A practical value of 10 -l_ atm- cc/sec is the sensitivity to be expected under routine test con- ditions. 14_3 EQUIPMENT AND MATERIALS For conducting leakage tests in the field, conventional scintillation counters or Geiger tubes are employed. When leak- age tests are performed on a mass-produced item, the test pro- cedure frequently used is that known as the "Radiflo" method. The Radiflo equipment is automated and its operation is ex- tremely simple. However, since the use of radioactive material presents a potential danger, the operators and supervisory per- sonnel must take a course in instrument operatlon and health physics before they can be allowed to operate the equipment. Although the initial cost of the detector is high, the main- tenance and operation costs are low because almost all radioactive gas is recovered. The procedure is economical when the number of components to be tested range in the thousands per day. Radiflo can be calibrated for leakage rate. The manufacturer gives the following data for testing 5/16-inch transistors: • Radioactive materlal costs $250 per i0,000 or 2-1/2 cents per transistor • Activation labor is 15 minutes for i0,000 units • Radiation check takes 0.16 minute per transistor 14-i .i Inglis (Ref. 14-i) describes the 100-percent acceptance inspec- tion of propellant items; inspection rates of 200 to 500 pieces per hour are claimed. Specific details regarding this type of equipment may be found in Part III. Radioactive materials used are usually gamma-emitting iso- topes with the following properties: • They must emit gamma rays of sufficient intensity to be easily detected. They must be available at a low cost with a suffi- ciently high activity to permit the use of an inex- pensive detector. For example, radioactlve krypton-85 is used in the Radiflo method of leakage testing. With a half-life of 10.3 years, this material can be used over and over again if it does not become too diluted with air or lost in the atmosphere. Only 0.7 per- cent of the dlsintegrations give 0.54 megavolt gamma rays. The primary usefulness of krypton-85 for leak detection is dependent on this small proportion of gamma-emitting disintegrations. The other 99 percent of the disintegrations are the less powerful beta rays. The half-life of 10.3 years is equivalent to 3.25 x 108 sec- onds. One cubic centimeter of pure krypton-85 at normal pres- sure and temperature will contain 2.7 × i0 _6 atoms which will pr O - duce disintegrations at the rate of 5.78 _ 10 I° per second. Only 0.7 percent of these disintegrations, or 4 x 108 per second, yield gamma quanta. Krypton-85 recelved from Oak Ridge National Labor- atory contains five percent of the radloactive isotope. In use this gas is further diluted with air or another gas for two rea- sons: i) to give the gas the effective viscosity of air, and 2) to obtain a sufficient volume for filling dead spaces in pres- surized containers. Radioactive krypton-85, because of its chemical inertness, does not participate in any metabol_c processes in the body if inhaled or ingested in any way. If accidentally inhaled for a short time, normal breathing of noncontaminated air will rapidly remove any krypton from the lungs and body tissue into which it might have diffused. With an adequate ventilating system, proper gamma-ray shielding of storage tanks and reasonable care, krypton-85 can be handled with negligible risk to the operators. Many other radioactive materials are available for leakage testing. A few of these are listed in Table 14-1. 14.4 RADIFLO METHOD In this method of leakage testing, the components to be tested are placed in a tank, which is then sealed and evacuated 14 -2 Table 14-1 MATERIALS USEDFOR RADIOACTIVE LEAKAGE TESTING Element Compound Half-life Energy (Me@avolts) Beta Gamma Gas Leaks Br _ CH3Br 36 hours 0.46 1.31 Xe I_ 5.3 days 0.35 0.08 Kr ss i0 years 0.70 0.54 A _ 1.8 hours 1.18 1.3 Rn _ 3.8 days None* None C 14 CO_ 5600 years 0.16 None Liquid Leaks Na _ NaCI, NaHCOa 15 hours 1.39 2.75 As 7s (NH4 h AsO4 27 hours 2.96 1.2 1 I_ NaI 8 days 0.16 0.36 Sb1_2 (CsH6)s Sb 2.8 days 1.97 1.26 *Alpha emitter to about two torr. Diluted krypton-85 is then pumped into the tank under a pressure. The radioactive gas diffuses into exist- ing leaks in the components. After a prescribed "soaking" period (a few minutes to a few hundred hours), the krypton is pumped out of the tank and stored for reuse. A suitable combination of kryp- ton pressure and soaking time may be selected to give the desired sensitivity. After this, an air wash is circulated over the com- ponents to remove any residual krypton from the external surfaces. The components are then removed from the tank. Those with leaks will retain some radioactive atoms, which emit gamma radiation. This radiation is detected by a suitable radiation counter, the measured radiation being a function of the leak rate (Ref. 4-1). Occasionally components with very large leaks (10 -s atm-cc/ sec) tend to slip through the leak test as acceptable. This is due to rapid escape of the radioactive gas through the large opening during the final pump-down phase of the test cycle. This does not occur if the component contains any organic or other adsorptive material. In the absence of such internal adsorptive material, it is sometimes necessary to retain a slight partial pressure of krypton in the pressurizing tank before its removal for counting. Alternatively, the components could be bubble-tested after the Radiflo test; the bubble tests will detect these gross leaks. Since the fluid used in bubble-testing will clog very small leaks, bubble-testing should be performed only after Radiflo has deter- mined that no small leaks exist. 14 -3 -q- Disadvantages of the Radiflo technique are: • Sample sizes limited to approximately one cubic foot • Leaks cannot be localized • Many organic materials will take up krypton-85 under pressure, and will hold it for various lengths of time after the pressure is released Items to be leakage-tested frequently have adsorptive sur- faces, such as organic coatings, or small areas of organic insu- lation or gasketing. The radioactive gas adsorbed by these sur- faces could make the item appear to be a leaker when, in fact, it is not. Radiflo is a classic use of the back-pressure testing de- scribed in subsection 4.8.2. As explained in that section, very large leaks may be overlooked because of rapid leakage out of the system during pump-down. However, if adsorbents are present inside the device, krypton-85 will remain inside the device. Absolute leakage standards are not available because tests are performed on sealed systems. Standards are available to ascertain the activity of the test gas and the accuracy of the test instruments, but test leaks to qualify the procedure do not exist. There is even some question as to validity of the cor- relation between the measured flow of krypton-85 and the amount of air flow it represents. Clark, Jones, and Karoly (Ref. 14-2) found that because of difficulty in predicting the flow mode in- volved, leakage as measured by the Radiflo technique correlates to only one decade with flow measured by the mass-spectrometer leak detector. Figure 14-1 is a schematic diagram of the Radiflo unit. Programmed electronic circuity is used to assure the protection of operating personnel from the radiation hazard. Both beta and gamma rays are detected by means of a thin wall Geiger-Muller counter. Krypton-85 adsorbed on surfaces will give readings of both beta and gamma rays. However, the walls of the device will adsorb any beta rays being emitted inside it. Therefore, it is possible to distinguish by the beta-to-gamma radiation ratio whether the radiation indication is due to adsorption or leakage. I-. goes without saying that if radiation due to adsorption on 6xternal surfaces is large, small amounts of leakage will go un- detected. Precautions must be taken to assure that all s_c_aces are clean. Routine checking of rejected parts by means of a thin-window Geiger-Muller tube consistently reveals surface-contaminated parts. Comparison of such rejected parts with acceptable parts of the same surface composition will determine the significance, if any, of the surface contamination. Those parts with significant con- tamination can often be decontaminated by a brief exposure to heat. Frequently, such a heating cycle is routinely incorporated into the testing procedure of certain parts having organic coatings. 14 -4 / •!_ "r-----_-'_'-_VAN E I SYSTEM ___ CONTROL T TPRESSURE vACUUM j_ j./ psi° mm / Hg _'('_ i ACTIVATIO N I ! TANK _, EXHAUST ADMIT AIR ---'f ,.D GM TUBE r_ DUAL F_ ' RATEMETER I MONITOR _ Ii STORAGE SW. GM TUBE-_]. I (_II I TRANSFER SYSTEM 2 STORAGE TANK ADMIT TRACER GAS PRESSURE psio Figure 14-i. Unit for Radiflo Testing. (Reprinted with permission, W. Inglis, Materials Evaluation, Vol. 24, No. 3, p. 150, 1966, Copyright 1966, Society for Nondestructive Testing, Inc., Evanston, Ill.) 14-5 For mass-production testing, an automatic counting station will perform GO-NOGO testing functions at a rate from 600 to as high as 2000 units per hour, depending upon the size of the part being tested. Activated parts are placed in a shaker unit, auto- matically fed into cups on a continuously moving conveyor, and carried to a detector for analysis. A scaler measures and com- pares the activity against a preset rejection threshhold. The tested parts are then deposited in an appropriate "accept" or "reject" bin. 14.5 OTHER METHODS OF LEAKAGE TESTING Radioisotopes are used in leak location on very large sys- tems where the usual methods would be extremely difficult to apply. The advantages of radioisotope methods are their high sensitivity, compatibility with any gas or liquid being used in the system, and the fact that the tracer does not have to be re- moved from the leakage site to be detected. However, these techniques require experienced personnel to handle radioisotopes, measure radioactivity, and interpret per- tinent data. Moreover, the use of radioisotopes represents a potential health hazard, and disposal produces more handling problems than are encountered with other tracers. Courtois and Gasnier (Ref. 14-3) have reviewed the proce- dures using radioactive liquids, gases, and capsules. 14.5.1 Pipeline Testin 9 Pipeline leakage is frequently detected by means of radio- active liquids or gases. A radioactive tracer is introduced in- to the system with the filling fluid. The fluid escapes through the leak, producing contamination in the vicinity of the leak. The tracer can be detected at the leak after flushing the system. The three stages -- filling, contamination, and detection -- can be accomplished in various ways. The pipe may be filled with a homogeneous tracer or a slug (or puff) of tracer. With a homo- geneous solution, the search can be carried out in a pipe under constant pressure and with no flow. It is necessary, however, to check the homogeneity of the product introduced and to remove a considerable volume of tracer-contaminated fluid. Alternatively, a "puff" of a radioactive tracer is in_ected into the stationary liquid held between two scraper pistons, or go-devils, in the pipe. Only a relatively limited quantity of liquid is contaminated in this kind of tracing. Detection may be at ground level, from the interior of the pipe, or by probing. At ground level, which is, of course, the simplest method, the detection team moves along the pipeline equipped with portable radiation detectors. Heavy activity 14-6 of the radioelement is requlred because radiation must pass through a ground layer of conslderable thickness, often _ncluding a layer of paving, cement, or other coverlngs. Thls method of detection requires the use of very sensltive detectors; for example, sodi- um iodide (thalllum act±vated) crystal scintillation counters. In the case of gas leaks, considerable diffuslon of gas takes place toward the surface. Diffusion is largely determined by the nature of the ground as well as of the tracer gas. This reduces the accuracy of locallzatlon, but permits the use of a radioele- ment of lower activlty by reducing the distance between the tra- cer and the detector. It is posslble to probe for the leak from inside the plpe, as descrlbed by Put_man and Jefferson _Refs. 14-4 and 14-5). This procedure includes passing through the pipe a scraper piston, or go-devil, whlch contalns the electronic detection system and a "memory." As this detecting scraper is moved along inside the pipe by the fluid flow it records any increase of activity in the ground where contamination by leakage has occurred. The great advantage of the pipe probe method is that it re- quires only a low tracer actlvlty at the leak because the radi- ation emitted need only pass through the plpe wall to reach the detector. The actlvitles requlred are usually some 1,000 times less than those necessary for detection from ground level. Some of the practical parameters whlch limit the use of this method are: i. The pipe diameter must be sufficient to permit passage of the detection electronlc device. 2. The bends of the pipe must be such that the scraper piston, the length of which Is generally in the order of one and a half tlmes the diameter of the pipe, may pass through. 3. After the passage of the tracer fluid, the plpe must be rinsed so as to be free from traces of activity. 4. The plpe must, insofar as possible, be free from ele- ments likely to adsorb the tracer. 5. The suspension of the electronic detection equipment and its memory must be able to absorb the consider- able shocks to which the scraper _s subjected. 6. The detecting scraper must be absolutely _mpervious. 7. A number of small radioactive sources (e.g., Co 6°) can be placed at certain distances along the pipeline. The presence of these sources is recorded to make easler the localization of the leak. If detection from the inside of the pipe is impossible, the thickness of the ground layer between the source and the detector is reduced by digging holes and lowering the detection probe. 14 -7 -q° For systematlc examinatlon, the holes must be very close together. This kind of exploration would be possible only on very short pipelines. It is often sufficient to probe only suspicious points (connections, valves, etc.). Various modifications of the methods described here have been used. In one instance, a slug of radioactivity was introduced suddenly and its rate of movement along the pipe followed. At a leak there was a discontinuity in the flow rate of the slug. This spotted the trouble, in another instance both ends of the main were closed, and the isotope was introduced at the center. The operator observed the dlrection the tracer flowed in the pipe, to the right or to the left Then he bisected the offend- ing section and tried again. Still another modification involves the use of a sealed cap- sule that has been tagged radioactiveiy_ Leaks are found by placing a properly weighted radioactive capsule, or float, in the fluid of a sealed pipe and allowing it to be carried by the current° With normal exits closed, the only current is that of fluid escaping through the leak. The float moves with the cur- rent and stops at the leak. If the course of the piping has been marked beforehand, a man with a detector can easily follow the radioactive float. When there are leaks of different sizes, the float often goes to a large leak and stops. It may slow down, however, as it passes a small leak, and an experienced observer can often recognize such a change of speed. If no speed changes are ob- served, the operator can locate and repair the largest leaks, then reexamine the line for smaller ones. Use of sealed capsules for leak location is advantageous since smaller amounts of actlvity can be used and the active ma- terial does not mix with the pipe contents or contaminate sur- roundings. Further discussion of these methods may be found in Gemant (Ref. 14-6) and Black and Kerwick _Ref. 14-7). 14 -8 15.1 15.2 15.3 15.4 Section 15 USE OF THE HALIDE TORCH IN LEAK LOCATION INTRODUCTION ................ SENSITIVITY ................ DESCRIPTION OF EQUIPMENT .......... LEAKAGETESTING METHOD ........... 15-i 15-i 15-i 15-2 _ . Section 15 USE OF THE HALIDE TORCH IN LEAK LOCATION 15.1 INTRODUCTION The halide torch is used to locate leaks in pressurized systems filled with a halogen-containing gas. The burner heats a copper plate with a flame that is a pale blue only if air is pulled into the burner. If small amounts of vapor containing halogen compounds come in contact with the plate, the flame turns green. 15.2 SENSITIVITY The torch permits locating leakages of about eight to ten ounces of refrigerant gas per year, which is approximately one hundred parts per million. This makes the general optical sen- sitivity approximately i0 -_ atm, cc/sec. When an electronic photometer is used to sense color changes, the sensitivity may be improved to about i0 -s atm-cc/sec. 15.3 DESCRIPTION OF EQUIPMENT The halide torch (Type i) consists of a burner connected to a tank of halide-free gas or alcohol. A portion of the combus- tion air is drawn into the flame (chimney fashion) through a tube near the base of the burner. A flexible extension of this tube is used as a probe to locate leaks (see Figure 15-1). BURNER HOLE TO VIEW FLAME .COPPER PLATE GAS CONTROL VALVE HALIDE-FREE GAS (ACETYLENE) AIR'INTAKE TUBE USED TO SEARCH FOR LEAKS Figure 15-1. Halide Torch for Leak Location 15-1 The torch is available either as an attachment to portable gas cylinders or as a complete unit with an integral fuel supply. A more sensitive instrument, with direct-reading dials (Type 2), can be obtained. Both devices are portable, easy to operate, and of relatively small size. Table 15-1 summarizes the characteristics of these items. A more complete description can be found in Part III. Table 15-1 CHARACTERISTICS OF HALIDE TORCH DETECTORS General Characteristics Average Values Type 1 Type 2 Sensitivity Tracer gas Output Power require- ment Size 10 -4 atm-cc/sec Halogen compounds Visual Halide-free fuel 15 inches x 4 inches diameter Weight 1 pound Price $10 i0 parts per mil- lion;10 -_ atm-cc/ sec Halogen compounds Meter 120 volts, 60 hertz AC 15 inches × 16 inches x 9 1/2 inches 35 pounds $675 15.4 LEAKAGE TESTING METHOD To probe for leaks, the torch is lighted and checked for pro- per operation by sucking in a trace of halogen gas from the tracer supply tank. The surface of the system being tested is then searched with the probe tube at the rate of a fraction of an inch per second. Since the tracer gas has four times the density of air, it is advisable to start work on the lower side of a possible leak. A small trace of halogen gas will show up as a green flame, a large quantity as a violet flame. Servicemen usually move the probe about one-fourth inch per second to locate leaks down to eight ounces per year. Although any halide gas could be used in this test, Freon (CC12F2) is the best with respect to sensitivity, vapor pressure, inertness, and safety. Depending on the size of the vessel and the sensitivity de- sired, the air may or may not be evacuated before the tracer gas is introduced. Evacuation takes longer and is not practicable for very small pipes; but if accomplished, it makes possible a pure tracer-gas atmosphere that can later be pumped back into the storage tank. 15-2 In general, the halide torch test is as sensitive and rapid as the soap-bubble test. In addition, the torch method permits location of leaks in places where soap bubbles could not be seen. There is no residue of water and soap to be removed before the tested apparatus can be used. Freon is nonflammable, and once a leak is found it can be soldered without fear of explosion. The torch has no means of accurate calibration. It should be realized that it is difficult, in a contaminated atmosphere, to locate leaks smaller than eight or ten ounces per year even when the unit to be tested is filled with one hundred percent refrigerant gas. A major drawback is the fact that the procedure consumes oxygen and may give off enough toxic gas to make it unsafe in confined areas that are not adequately ventilated. The open flame may be a serious hazard in certain atmospheres. Therefore, the torch should not be used in confined areas. Carbon tetrachloride vapors are toxic; continued exposure to them is dangerous. This material should never be used with- out adequate ventilation. Persons using it should be carefully instructed beforehand to ensure safety in testing. A single large leak may mask adjacent smaller leaks, neces- sitating prior location (and correction) of such larger leaks by separate test. This procedure uses halogenated hydrocarbons and is subject to diffusion and stratification problems. 15-3 16.1 16.2 16.3 16.4 Section 16 SONIC DETECTION OF LEAKAGE INTRODUCTION ................ SENSITIVITY ................ DESCRIPTION OF EQUIPMENT .......... LEAKAGE TESTING METHOD ........... 16-1 16-1 16-1 16-3 16-x. Section l 6 SONIC DETECTION OF LEAKAGE 16.1 INTRODUCTION Leakage in either vacuum or pressurized systems may be de- tected by means of the sonic energy generated in the fluid vor- tices which accompany leakage flow. The only requirement is that the sonic signal be of sufficient intensity to be distin- guished from the background noise. Special tracer fluids are not required. Frequency of the leakage noise ranges from the audible to the ultrasonic. Detection is accomplished by any of several simple methods: • Listening to the audible signal • Electronic amplification of the audible signal • Conversion of the ultrasonic signal to an electrical signal of lower frequency The ultrasonic component of the leakage noise is broadly peaked at a frequency in the range of 30 to 50 kilohertz. Using the third method above, such sounds can be easily detected, even when the audible component is masked by a noisy background (Ref. 10-5). Sometimes normal flow of fluids through a pipe will give an input to the instrument, making it useless except under static conditions. At other times the ultrasonic energy is reflected from hard surfaces, posing a problem in establishing the exact location of a source if the operator cannot get close to it. This requires some experience on the part of the operator to quickly recognize whether he is intercepting a direct wave or a reflection. The ability to recognize the direct and reflec- ted waves can be readily acquired and is not a serious problem. 16.2 SENSITIVITY This method has a sensitivity of approximately l0 -3 atm-cc/ sec -- a relatively large value of leakage -- under conditions of turbulent flow. Laminar flow will not produce a usable signal. 16.3 DESCRIPTION OF EQUIPMENT To aid in the detection of audible signals an industrial stethoscope can be used. When these signals are too weak to be heard, an electronic stethoscope with an amplifier may make them audible. Ultrasonic sound-detector probes are of two types: the di- rectional probe, and the contact probe. The directional probe, 16-1 _i -¸ or transducer, has a horn with which the operator scans an area and locates a leak, in much the same way that a radio direction finder is used to obtain radio bearings. One unit has a direc- tional pattern that is 22 degrees wide at -3 decibel points. The short wavelengths of the ultrasonic frequencies make it possible to design highly directional horns that are small in size and convenient to use. Use of a parabolic dish permits a directivity pattern of a fraction of a degree. The contact probe is used in the location of internal leaks in hydraulic systems and requires direct contact with the compo- nents of the system. The ultrasonic energy produced by the mov- ing fluid is conducted through the valves, tubing, or vessel walls. Thus it is possible to detect leakage and changes in the flow conditions that are usually difficult to locate without dis- connecting lines and partially disassembling the system. The detector is portable and can be used as a leakage locator with either the directional or contact probe. For production-line operation the detector units can be equipped with alarm or relay circuits (Ref. 16-1). Figure 16-i is a functional diagram of a typical ultrasonic leak detector circuit. TRANSDUCER 35000 - 45000 Hz AMPLIFIER MODULATOR T OSCILLATOR 40000 HZ AMPLIFIER LOUD SPEAKER 0- 5000 Hz Figure 16-1. Block Diagram of an Ultrasonic Leak Detector. (Courtesy of Hewlett-Packard Company, Delcon Division.) The electrical output produced by the ultrasonic transducer is amplified and then translated into the audible range in the modulator by the conventional mixing process commonly used in superheterodyne radio receivers. These converted ultrasonic sig- nals exhibit audible sound characteristics that are very similar to their audible counterparts because of the same physical pheno- mena (e.g., a leak has the hissing sound that is characteristic of air escaping from a pressure vessel; friction has a scratching sound that is characteristic of two surfaces rubbing together). Table 16-1 summarizes the characteristics of these instru- ments. Additional details may be found in Part III. 16-2 Table 16-1 CHARACTERISTICSOF SONIC LEAK DETECTORS General Characteristics Output Power require- ment Ultrasonic Audible signal and meter Avera@e Values Sonic Audible signal and meter Battery Battery Stethoscope Audible signal None Size 5 inches × 5 5 inches × 3 inches × l0 lnches× 3 inches inches Weight 8 pounds 5 pounds 1 pound Price $300 $i00 $20 16.4 LEAKAGE TESTING METHOD McElwee and Scott (Ref. 16-2) describe the use of a stetho- scope and a simple electrical amplifier to detect leaks by the sound they generate in the audible range. This method involved detection from the inside of pipes. The injection of a sonic wave into a system was proposed by Quisenberry (Ref. 10-5). Sonic energy emerges with the leaking fluid and is detected by frequency shift and correlation methods. With the aid of push rods and a protective tip for the trans- ducer, it is possible to probe ducts for leakage by observing the signal level as the probe is pushed along the duct. For example, the leakage from underground transmission cables can easily be located and the spot to excavate pinpointed (Ref. 16-3). Calibration of sonic leak detectors is done by giving a brisk squeeze to a small plastic "squeeze bottle." The sound may be detected over a distance of 50 feet. 16-3 17 .i 17.2 17.3 17.4 Section 17 LEAKAGE DETECTION BY ABSORPTION OF ELECTROMAGNETIC ENERGY 17-1 INTRODUCTION ................ 17-3SENSITIVITY ................ 17-3DESCRIPTION OF EQUIPMENT .......... 17-3LEAKAGE TESTING METHOD ........... J9.2. background components. Almost all hydrocarbons can be used in a background of air and give results in the low ppm range of detec- tion. Other gases which may be used are: carbon monoxide, sul- fur dioxide, and the halogenated hydrocarbons. 17.2 SENSITIVITY The infrared detector is in the same general class of appli- cability and sensitivity as the heated-anode halogen detector. These instruments are capable of a full-scale reading of i00 parts per million nitrous oxide in air. This implies a detect- able limit of several parts per million. With an internal pump- ing speed of a few cubic centimeters per second, these instru- ments can detect leaks in the range of 10 -6 atm-cc/sec. However, the response time of the infrared detectors is twice that of the equivalent halogen system and they are at least one decade less sensitive. Their prices are at least twice those of a halogen detector. 17.3 DESCRIPTION OF EQUIPMENT The available equipment is compact and rugged, suitable for field tests. Optional features include audio or visual alarm units which may be set for any point in the operating range of the instrument. The leakage test system may be automated for assembly-line operation. An instrument as provided usually consists of a detector probe, filter, analyzer, flowmeter, metering valve, and pump. The valve adjusts the flow to the rate required for adequate sensitivity and response time. A neon light is provided at the end of the probe to indicate leakage conditions when the opera- tor is in a noisy area and out of visual range of the indicator. The sampling system operates at slightly subatmospheric pressure; the pump can provide flow rates up to two liters per minute; aux- iliary pumps can be used to increase pumping speed. Table 17-i summarizes the characteristics of light absorption leakage detectors. Descriptions of individual instruments may be found in Part III. 17.4 LEAKAGE TESTING METHOD The absorption detector may be used for leak location or leakage measurement in a manner very similar to that discussed in Section i0, "Heated-anode Halogen Detector." Neither the ultraviolet nor the infrared detectors will be damaged by high concentrations of tracer gas. Nitrous oxide, the usual tracer gas, is not soluble to any large extent in rubber or plastic; hence, systems using these materials may be leak-checked with no difficulty. Because the molecular weight of this gas is only slightly higher than that of air, nitrous oxide does not stratify as much as do the heavier halogenated hydrocarbons. 17 -3 Table 17-1 CHARACTERISTICSOF LIGHT ABSORPTIONLEAKAGEDETECTORS General Characteristics Sensitivity Tracer gas Output Power requirement Size Infrared Average Values 1 x 10 -6 atm-cc/sec i0 parts per million Nitrous oxide, carbon dioxide Mllliammeter 115 volts 60 hertz or 190/260 volts 50 hertz 12 inches × 12 inches x 20 inches Weight 60 pounds Price $2000 Ultraviolet 5 parts per million Chlorinated hydro- carbons; aromatic hydrocarbons Milliammeter 115 volts 60 hertz Amplifier: 8 1/2 inches x II inches x 5 inches Detector: 6 inches x 6 inches x 19 inches 30 pounds $400 When used for leak location, the system has a response time of approximately three seconds. This, of course, can be changed by altering pumping speed or probe length. The response of the instrument is linear over the full scale, and calibration is ac- complished by introducing tracer gas of a known concentration from a compressed-gas cylinder into the sample chamber of the detector. In this way, the instrument response is obtained in parts per million of tracer gas. The leakage rate is obtained by multiplylng this response by the flow rate of gas through the sample chamber. The detector may be either evacuated or at atmospheric pres- sure. If evacuated, the system pressure should not be allowed to vary by more than fifty times the pressure of the tracer gas, because of the outgassing products usually found in an evacuated system (water, carbon dioxide, and hydrocarbons) which also ab- sorb infrared radiation. Kaufman (Ref. 17-5) has shown that the infrared detector may be used in locating leaks in buried water lines. Water lines were injected with nitrous oxide to a ratio of 0.37 volume of N20 to one volume of water. Leakage out of the lines was located by a detector probe as a result of the diffusion of gas to the surface of the ground. 17-4 passes through the reference cell as well as through the sample cell. The two radiation beams are admitted alternately into the detector by a chopper. The radiation detector is a pneumatic device consisting of two chambers separated by a very thin membrane. These two cham- bers are filled with an infrared active gas, usually the same gas for which sensitivity is required. Hence, the name "selective detector." The membrane is metallized and mounted close to a fixed plate to form a small electric capacitor. Chopping of the radiation causes the gas in the detector to be alternately heated and cooled. The resulting pressure changes flex the membrane to cause a variation in the electrical capacitance. The capacitance variation modulates a sensitive radio-frequency oscillator whose signal is demodulated and rectified to drive an indicating meter. Gases suitable for use in the absorption cell have absorption wavelengths in the range of two and ten microns (Ref. 17-1). Such gases have polyatomic molecules of dissimilar atoms. Other re- quirements of the tracer gas are that it must be: • Noncorrosive to the system material • No fire or explosion hazard • Nontoxic • Reasonably priced and readily available • Producing good discrimination in normal atmospheric contaminants Nitrous oxide (N20) is most often used as the tracer gas be- cause it meets these requirements. Its major absorption band at 4.5 microns affords excellent discrimination ratios against at- mospheric contaminants normally found in manufacturing plants. It is completely nontoxic. With oxygen, it is a simple as- phyxiant in the same class as nitrogen, helium, and hydrocarbons(Ref. 17-2). Nitrous oxide is an anesthetic, but a very weak one, since a concentration of more than 80 percent is necessary in order to produce deep anesthesia (Ref. 17-3). There is no evidence in the literature of any toxic effects due to ingestion or inhalation of nitrous oxide. The compound is noncorrosive and nonreactive with most materials (Ref. 17-4). Nitrous oxide (N20) should not be confused with nitrggen oxide (NO), n_+tric oxide ((NO) 2), nitrogen dioxide (NO_ ..... _- gen tetroxide (N20_), or nitrous fumes (a mixture of NO and NO_) _ With the exception of nitrous oxide (N20), all the oxides of ni- trogen listed above are corrosive and poisonous. Unless the equip- ment is designed for their use, no attempt should be made to use any of these other nitrogen oxides for infrared leak detection. - Other gases besides nitrous oxide can be used as leak tra- cers. They must of course, be infrared-active, and their sensi- tivity will depend mostly on the discrimination ratios of the 17-2 Section 17 LEAKAGE DETECTION BY ABSORPTION OF ELECTROMAGNETIC ENERGY 17.1 INTRODUCTION Leakage may be detected through the molecular absorption of radiant energy by the tracer gas. An absorption spectrum will not only identify the specific molecule involved but can also tell how much of that molecule is present in a given mixture. Energy wavelengths in the ultraviolet and infrared regions are most commonly used in commercial instruments. The detection system consists of a radiation source, gas sample, reference sample, and radiation detector. Radiation passing through the sample is compared with that which passes through the reference gas. The difference in attenuation between the two absorptions is a measure of the concentration of the gas. Each instrument is specific for only one species of gas molecule and, by design, the possible interference by other gases is mini- mized. Ultraviolet-type instruments are usually used for leakage monitoring. Infrared instruments are used for leak location and leakage measurements. The instruments are designed to be used at atmospheric pressure, but they can be modified for use under other conditions of pressure. Figure 17-1 is a schematic diagram of a typical infrared de- tector. Two hot-wire sources provide the radiant energy which BEAM GATE INFRARED WINDOW WINDOWS souRcE. W. .................................. _ I_ STANDAROCOMPARISON CELL _'_ _'_'_ FROM PROBE MIN UTE TEMPERATURE / COMPENSATING HOLE i DIAPHRAGM _///CONDENSER PLATE FIXED CONDENSER V PLATE AC OUTPUT SIGNAL TO AMPLIFIER B INDICATING METER DETECTOR SAMPLE OUTLET TO VACUUM PUMP Figure 17-1. Infrared Leak Detector. (Reprinted with permission, from Neeley, A.H., Nitrous Oxide for Leak Detection, A: Chemical, Physical and Pharmacological Proper- ties, with Results of Corrosion Tests (Ohio Chemi- cal Technical Information Series: IA) ; Division of Air Reduction Company, Inc., Madison, Wiscon- sin, May 1957.) 17-1 18.1 18.2 18.3 18.4 18.4.1 18.4.2 18.4.2.1 18.4.2.2 18.4.2.3 Section 18 LEAK LOCATION BY MEANS OF CHEMICAL INDICATORS INTRODUCTION ............... SENSITIVITY ............... MATERIALS AVAILABLE ............ LEAKAGE TESTING METHODS .......... Penetrant Tests ............ Chemical Tests ............. Ammonia Gas ............. Carbon Diozid8 Gas ......... MisoelZan_oua Chemical 2esCs .... 18-i 18-I 18-I 18 -2 18-2 18-3 18-3 18-4 18 -5 Section 18 LEAK LOCATION BY MEANS OF CHEMICAL INDICATORS 18.1 INTRODUCTION With the use of chemical indicators, leaks are located by the appearance of a liquid or the color change of a liquid. There are two different types of tests which may be employed: • Chemical tests -- color indication is due to a reaction between the leaking tracer and a developer • Penetrant tests -- color is inherent in the penetrant and is evident at the leak site because of migration to that point Penetrant tests in addition to locating leaks, reveal cracks, sur- face imperfections, and poor welds. The procedures are qualitative; thus the size of a leak can- not usually be determined. Each type of test (i.e., penetrant or chemical) must be considered individually since each has its own advantages and limitations. For example, the major limitation of the chemical tests is the possibility that reactive chemicals might damage system parts. The penetrant tests can locate both leaks and surface imperfec- tions; however, since penetrants are liquids, clogging of leaks can occur (see Section 6.6). This fact limits the utility of penetrants; they should not be used on systems which must subse- quently be tested for very small _ 10 -6 atm-cc/sec atm) leakage rates. 18.2 SENSITIVITY Chemical indicator tests are more sensitive at long exposure times. Unfortunately, the tests are not quantitative, because the indication of a leak is in the intensity of the color and area covered by the product of the reaction. However, the estimated sensitivity of the chemical reaction indicators is in the range of 10 -3 atm-cc/sec. The sensitivity of penetrants is thought to be several de- cades greater. Sensitivity of a penetrant is determined by know- ledge of the time required for sufficient penetrant to flow through and be observed. When the physical properties of the penetrant are known, it is possible to calculate the sensitivity (Ref. 6-3). 18.3 MATERIALS AVAILABLE Chemicals used for indicator tests are available from labor- atory supply houses. Reagent grade chemicals should be used. 18 -1 Penetrant materials are specially compounded dyes, oils, and solvents. These formulations are proprietary, but most of them depend upon a color-contrasting dye which is drawn into the defect. Sources of penetrants may be found in the listings of Part III. 18.4 LEAKAGE TESTING METHODS These methods are easily performed, without the need for highly trained technicians or elaborate test equipment. 18.4.] Penetrant Tests The penetrant test consists in applying a liquid penetrant to the surface of a part where it can enter into any defects open to the surface. After the penetration period expires, ex- cess material on the surface is removed and a developer is placed on the surface. The developer is a light-colored, powdered ma- terial (possibly in suspension), which adsorbs the penetrant that had previously seeped into surface openings. Development pro- duces contrasting spots, much larger than the surface openings with which they are associated. Penetrants are usually of two types: dye which fluoresces under ultraviolet light, or colored dye which is in high contrast to the metal or developer. The penetrant may be applied on the same surface as the developer, showing both leaks and surface im- perfections, or the penetrant may be placed on one side of a sur- face and the developer on the other side. In this manner only leaks through the part will be seen. Most commercial penetrants have properties of high wetting power, low surface tension, low viscosity, and high indicating ability. Complete details for conducting tests may be found in the Nondestructiv_ Testin E Handbook (Ref. 18-I). Other fluids which will indicate the presence of a leak can be used, especially if they are inherent to the system. For example, many oils are fluorescent under ultraviolet light and their presence can be used as an indication of leaks. Large systems can be tested under stress by filling the sys- tems with a testing fluid under pressure and examining for leaks. A patent by Polito (Ref. 18-2) describes a water solution for such tests; it consists of 0.5 percent (by weight) monoethanoiam- ine, 0.05 percent polyethylene glycol tert-dodecylthioether, and 50 parts per million fluorescein. The amine is used in this case as an antioxidant and a corrosion inhibitor. The thioether is used as a surfactant to reduce the surface tension of the solu- tion and to better wet the walls of the leak. The indicator is fluorescein, which glows brightly in ultraviolet light. After pressurizatlon with the test liquid, the suspected leak areas on the outside of the system are examined with a portable ul_ravio- let light. 18-2 18.4,2 Chemical Tests Chemical test methods depend on a chemical reaction to pro- duce a smoke or change in color at the leak site. A number of typical examples are described below. 18.4.2.1 Ammonia Gas. Ammonia gas makes an excellent tracer because it is chemlcally baslc, Is not highly toxic, and is only mildly corrosive. Its corrosive nature is strongly exhibited only on brass parts. Delafosse, No_ and Troadec (Ref. 18-3) describe a variety of possible tests using the gas. The ammonia tracer can be introduced as an anhydrous gas, or a cloth satur- ated with ammonia solution can be placed within the pressurized space. The sensitivity of the tests will be dependent upon the concentration of the gas. Where leaks are present, the leakage of ammonia will be re- vealed by a white chemical fog which develops when the atmos- phere is probed with a swab wetted with 0.1 N hydrochloric acid. Sulfur dioxide, such as from a sulfur candle7 can also be used to reveal the presence of ammonia. Smoke has also been used to detect leaks (Ref_ 18-4). A variety of indicator solutions may be used to give a color change with ammonia. These all depend on a change of pH of the indicating solutlons. Therefore, the pH of the solutions should be carefully ad]usted so that they are at the threshold of color change prior to use. A cloth dampened with a phenolphthalein solution and placed over the test area shows the location of leaks by a pink discol- oration. The indlcator consists of 1.0 percent phenolphthalein in a solution of equal amounts of water and ethyl alcohol. A better indicator is: fzve parts two-percent phenolphthalein in alcohol, two parts distilled water, ten parts glycerin, and suf- ficient titanium oxlde powder to thicken the solution to the consistency of a thln palnt. The titanium oxide powder serves the additional purpose of providing a white background against which the color change is contrasted. For a yellow-to-purple color change (Ref. 18-5) 40 milli- grams of bromocresol purple is dlssolved in four milliliters of 0.02 N sodium hydroxide. This is diluted to 100 milliliters. In a separate container, ten grams of starch is added to 500 milliliters of boiling water and stirred to form a slurry. The dye solution is added to the starch slurry. To this mixture is added five milliliters of Tween 40 wetting agent, and the pH is adjusted to 5.0 with dilute hydrochloric acid. To test, a small portion of the indicating agent is put on a piece of paper and the paper is moved rapidly through the air, horizontally, about 12 inches away from the open top of a bottle of standard ammonia reagent. Immediate appearance of purplish color on the paper shows the agent is ready for trial application. Otherwlse, slight additional pH ad3ustment may be necessary. 18-3 It is posslble to use alizarin between a pH of 5.5 and 6.8 or methyl red between a pH of 4.4 and 6.0 as an indicator (Ref. 18-3)_ These show a color change better _f a trace of methelene blue is added to the solution. The addition of calcium chloride to the indicator solution to complex the ammonia increases color retention as well as increasing the sensitivity of the test. 18.4,2,2 Carbon Dioxide Gas. Carbon dioxide can be used as a tracer gas. It is not as sensitive as ammonia but is noncorro- sive. The system should be filled with the gas and the outside sprayed with an agar-agar solution of an indicator (Ref. 18-6). Agar-agar solutions can be "loaded" with sodium carbonate and phenolphthalein, yielding a bright cherry red solution which turns white upon contact with carbon dioxide. This solution can be sprayed onto the surface to form a stable red film. Car- bon dioxide causes a white spot to be produced in the agar-agar film at poants of leakage. Studies indicate that the volume of agar-agar film which is discolored is directly proportional to the amount of carbon dioxide that enters the film. Therefore, the area of discoloration is directly proportional to the amount of carbon dioxide which has escaped. The spray solution consists of (parts by weight): agar-agar, 1.0; distilled water, 40.0; anhydrous sodium carbonate, 0.I0; and phenolphthaiein, 0.15. It is important to obtain the proper vis- cosity of agar-agar solution, which should be between eight and ten millipoises at the spraying temperature. When the spray solution is prepared, the dry powders (agar- agar, sodium carbonate, and phenolphthalein) should be blended thoroughly in proper proportions. To the dried powders boiling distilled water should be added, with stirring to disperse the solid constituents. The resulting mixture should be heated with constant stirring, to between 96 and 98°C, on either a hot plate or a steam bath. When the solid is completely dissolved and a clear solution is obtained, it should be allowed to cool to be- tween 65 and 70°C_ At this temperature it may be stored in a closed container and sealed to exclude air and small quantlties of carbon dloxide. To perform the test, the hot agar-agar solution from the storage container tat 65 to 70°C) is poured into the preheated sprayer bottle. The compressed air supply should be preheated in a heat exchanger to the spraying temperature° The spray noz- zle should be held approximately two feet from the test piece. A single coating should be applied, in one pass. Multiple coat- ings should be avoided. Spraying should always be done in a hori- zontal direction, never vertically. After testing, _he agar-agar film can be removed completely with a jet of high-velocity air from an air nozzle. Thls leaves the surface cf the device clean and dry. 18 -4 18.4.2.3 Miscellaneous Chemical Tests. Hydrogen sulfide has been used as a tracer gas to locate leaks (Ref. 18-7) with an indicator of a five-percent solution of stannous chloride. The leak location is shown by a brown stain of stannous sulfide. Be- cause of the poisonous nature of hydrogen sulfide, this is not a very popular method. A variety of other chemical reactions may be used for leak location. For example, precipitates may be formed by hydrogen sulfide with silver or lead salts (Ref. 18-5). Leaks in gas pipelines have been located by the reaction of silver salt solu- tions with acetylene gas (Ref. 18-8). Water has been used as a penetrant (Ref. 18-9), with anhydrous copper sulfate as a devel- oper. Anhydrous copper sulfate turns blue in the presence of water. Leak-indicating paints have been reported by Griffith (Ref. 18-10). An immediate color change occurs upon contact with liq- uid hydrazine or its derivatives. Exposure to oxidizers contain- ing nitric acid or halogens (bromine pentafluoride and chlorine trifluoride) immediately bleaches the paint. However, exposure of the paint to direct sunlight destroys the indicating ability within two weeks. 18 -5 19.1 19.2 19.3 19.4 19.5 Section 19 LEAK LOCATION BY HIGH-POTENTIAL DISCHARGE INTRODUCTION ................ SENSITIVITY ................ DESCRIPTION OF EQUIPMENT .......... LEAK TESTING - SPARK DISCHARGE ....... LEAK TESTING - CORONADISCHAPJGE ...... 19-1 19-i 19-1 19-2 19-2 Section 19 LEAK LOCATION BY HIGH-POTENTIAL DISCHARGE 19.1 INTRODUCTION Leaks in evacuated systems can be located with the aid of a high-potential discharge. There are two different ways by which this method may be applied (the choice will depend upon the particular system to be tested): i. The exterior of the system is probed with an electrode. Leaks are detected by the appearance of a spark be- tween the electrode and the system. 2. The color of a corona discharge within the system is observed as the exterior is probed with a tracer ma- terial. The first method is limited to glass systems or to the glass parts of metal systems; while the second method does not have these limitations, it does require the presence of a window for view- ing the nature of the discharge. 19.2 SENSITIVITY These methods are qualitative and are useful only from a few torr to about 10 -2 torr. They will probably detect leakages of about i0 -_ atm-cc/sec. Pirani and Yarwood (Ref. 5-3) claim to have detected a leakage of 10 -12 atm-cc/sec; however, an elap- sed time of six months was required while the pressure in the test device increased from 1.0 to 1.01 torr. ]9.3 DESCRIPTION OF EQUIPMENT A hand-held high-potential probe is available from labora- tory supply houses as a "spark-coil detector," or Tesla coil. An auxiliary glow-discharge tube (Geissler tube) can be attached or built into the system with electrodes sealed into the ends, to which a source of high voltage (DC or AC) can be connected. Both of these devices operate at potentials of several kilo- volts. The output should be provided with a circuit to limit the current to a few microamperes. The glow-discharge tube may be converted to an audible de- tector by letting the tube be the variable factor in a relaxation oscillator circuit. Figure 19-1 is a schematic diagram of such a circuit, suggested by Lloyd (Ref. 19-1). He observed the am- plitude of the oscillations to peak at 4 × 10 -1 torr (2.5 kilo- hertz). On either side of this pressure the oscillations fell off to zero at pressures of 5 x 10 -2 torr and i0 torr. 19-1 +900 V -I IF ] 0.001 _F DISCHARGE TUBE /_ LOUDSPEAKER cm I°I2 3 °r Figure 19-1. Discharge Tube Audible Leak Locator. (Reprinted with permission from J.T. Lloyd, Journal of Scientific Instru- ments, Vol. 27, 1950, p. 76; The In- st-_te of Physics and The Physical Society, London.) 19.4 LEAK TESTING - SPARK DISCHARGE With the system evacuated to a pressure between l0 and l0 -2 torr, the exterior is probed with the spark coil. The probe tip should be held about 0.5 to 1.0 centimeter from the surface which is to be tested and the probe moved slowly over the suspected leak. Continual application of the probe to one spot may punc- ture the glass wall of the system, score the barrel of a Teflon stopcock, or rupture gaskets. The probe cannot be brought closer than several centimeters from metal parts, as the spark will ground through the metal. The presence of a leak is shown by the appearance of a spark from the electrode through the leak which will then ap- pear as a white spot. The reliability of this method depends upon operator skill in probing the complete system. 19.5 LEAK TESTING - CORONA DISCHARGE This test method is quite similar to that of the spark-dis- charge test. The pressure in the test system must be in the same range as that for the spark discharge, and a suitable glass view- ing window or tube must be available for observing the color of the discharge. 19-2 If the system has a glass section, then a spark coil can be used to excite the discharge. Guthrie (Ref. 5-4) recommends that a spark gap of about 0.5 to 1.0 centimeter be connected in paral- lel with the high-voltage electrode and grounded to eliminate the possibility of puncturing the glass. A corona-discharge tube can be attached to the system, pref- erably near the forepump, where the pressure will be sufficiently high for a glow to occur. A leak is located by applying a tracer material to the suspected leak and observing the color change in the corona glow. The nature of this discharge will depend on the pressure and on the gases in the system. The color is characteristic of the gases present. For air, the color tends toward red or purple. The exact color (as for other gases; depends to some extent on the glass used in the system. Pyrex or soda glass will show a yellow-green fluorescence, while lead glass shows a blue fluor- escence. The tracer material can be a gas or a liquid. Some ma- terials commonly used are: Illuminating gas, ether, and carbon dioxide. With the first two materials the discharge takes on a grayish-blue appearance. This is similar to the characteristic color of carbon dioxide but, possibly because of fluorescence of the glass, the color is often reported as bluish-green. Volatile liquid such as benzene, acetone, or methanol are frequently used. In fact, any material whose discharge color contrasts with the background could be used as tracer material. However, gasoline, benezene, pyrldine and solutions containing nitrogen compounds should not be used because they adhere to glass. Table 19-1 shows the glow-dlscharge colors which are associated wlth a number of dlfferent tracer materials. The problem of two leaks of more or less equal size occurs rarely but must be considered with complicated apparatus. It is fortunately solved by the fact that in a mixture of more or less equal parts of carbon dioxide and alr the color of the positive column tends toward that of carbon dloxide. So if there is car- bon dloxide on either of the leaks, that leak is located and can be stopped, and the other can be found later. Although the sensitivity and reliabillty of leak location by hlgh-potential discharge are dependent upon operator skill, recognltlon of a leak is relatively easy. The operator must be knowledgeable in the probing of all possible leakage areas and able to recognize the indication of a leak. Probing of the sys- tem may proceed at a rate of approximately one foot per minute. Because of the high molecular weights of some of the tracers, considerable delay may occur between the time the tracer enters the vacuum system and the time it passes into the discharge area. (The entire system may be checked for leakage by hooding with tracer gas as described in Section 5.2.) 19-3 Gas Air Nitrogen Oxygen Hydrogen Helium Argon Neon Krypton Xenon Carbon monoxide Carbon dioxide Methane Ammonia Chlorine Bromine Iodine Lithium Sodium Potassium Mercury Table 19-1 DISCHARGECOLORSIN GASESAND VAPORS AT LOWPRESSURES* Negative Glow Blue Blue Yellowish white Bluish pink (bright blue) Pale green Bluish Red-orange Green Bluish white Greenish white Positive Column (Reddish) Yellow (red gold) Lemon Pink (rose) Violet-red Deep red (violet) Red-orange (blood red) (White ) Blue (White) Reddish violet Yellow-green Greenish Yellowish green Orange-yellow Bright red Yellowish green (whitish) Green Green (goldish white) Light green Reddish Peach-blossom colored Yellow Green Greenish blue (greenish) *Reprinted with permission from Vacuum Technology, by A. Guthrie, John Wiley and Sons, Inc., New York, 1963, p. 456. Indicates no distinctive color given. 19-4 This testing method may be applied to sealed systems which contain a suitable indicating gas; for example, neon. The color of the induced glow discharge is compared with a standard whose pressure is known. Pirani and Yarwood (Ref. 5-3) suggest such a test for quality control tests where extensive experience in production is lacking. For the smallest leaks, a discharge tube and a stopcock should be connected to the line between the forepump and the diffusion pump. When the stopcock is closed, gas coming through the diffusion pump accumulates in the discharge tube. If the discharge tube is clean, it is possible to distinguish between tracer gas and air in the accumulated gas. Traces of gas on the walls of the discharge tube will interfere seriously with the test if they are freed. So, if it takes longer than a few min- utes to make a test, the discharge should not be started until it is time to test it. With this precaution, however, one may make conclusive tests and locate a leak definitely, even when it takes hours to accumulate enough gas. 19-5 Section 20 IONIZATION-GAGE LEAKAGETESTING 20.1 20.2 20.3 20.4 20.5 INTRODUCTION ................ GAGERESPONSEIN LEAK SENSING ....... IMPROVING SENSITIVITY ........... DISCHARGEGAGES AND ION PUMPS IN LEAK SENSING ................. APPLICABILITY OF METHOD .......... 20-1 20-2 20-6 20-10 20-12 Section 20 IONIZATION-GAGE LEAKAGE TESTING 20.1 INTRODUCTION An ionization gage may be used as a sensitive indicator of gas or vapor leakage either into or out of an evacuated system. In this gage a stream of electrons is provided to ionize gaseous components in the vicinity of the gage electrodes. As the ions approach a negatively charged collecting electrode, they cause a current to flow in an external metering clrcuit. This current is dependent on the product of the electron current, the density of the gas in the gage, and a sensitivity factor which is characteristic mainly of the type of gas involved. The ion current of a gage may be calibrated in terms of pressure if the type of gas, the temperature, the electron current, and the gage sensitivity factor are known. The sensitivity factor depends on the probability of ionization, which is in turn dependent on ap- plied voltage and the total number of electrons per molecule. A change in ion current will occur when there is a change in gas composition such as may be brought about by leakage of a gas tracer into a chamber in which a gage is located. Leakage identification and leak location with an ion gage depend upon a change in response to a change in gas composition. Testing by ionization gage is not normally made specific to any particular tracer gas, and changes in gage response can arise as a result of changes in parameters other than gas composition -- such as changes in the pumping speed and outgassing rates. Electrons required to generate ions in an ionization gage may be supplied from a thermionic emitter, or from a high-vol- tage gas discharge which is sustained at low gas pressures by a static magnetic field. The emitter in a hot-cathode ioniza- tion gage is sensitive to loss of emission by oxidation, deposi- tion, or alloying of a nonemitting layer on the hot surface of the emitter. Loss of emission can be irreversible unless the operating pressure is kept below approximately 5 × 10 -4 torr. The ion-discharge (Pe_nning) type of gage may be employed to monitor pressures at levels higher by three orders of magni- tude without causing permanent harm to the gage. The ion-dis- charge type of gage may also be constructed to monitor changes in gas density at extremely low pressures. Cold-cathode gages having the geometry of an inverted magnetron have been built to measure pressures between 10 -3 and 10 -12 torr (Ref. 2-3, pp. 334-336). They are, of course, adaptable for monitoring minute changes in gas pressure or gas composition in that pressure range. It is more common to find a hot-cathode triode ioniza- tion gage as part of a vacuum system. This type of gage is --i- 20-i most likely to be available for use in detecting system leakage in the range of i0 -_ to 10-e torr. 20.2 GAGE RESPONSE IN LEAK SENSING A procedure for using an ionization gage in leak sensing and location is described below. An expression is derived for the change in response which may be expected when a tracer gas is used. Figure 20-1 shows how an evacuated chamber which is being continuously pumped may be tested with an ionization gage. The surfaces of the chamber are exposed to tracer gas from a tracer probe (or they can be flooded with tracer gas by enclosing the chamber with a hood). If a leak is present, both air and tracer gas enter the chamber and pass to the vicinity of the gage. The change in gage response may be derived as follows: TRACER GAS PROBE •,_<-LEAK 0_ ... ,w., _GAGE SYSTEM BEING TESTED VOLUME - V ONDUCTANCE -C r. SION SPEED - S ! I Figure 20-1. idealized System for Vacuum Gage Response Testing 20-2 Assume that the base pressure in the chamber is constant at a value P2 with an outflow of gas to the pumps Q. C is the molec- ular flow conductance of the tubing leading to the pumps from the chamber, and is assumed to be the effective pumping speed at the site of the gage. Thus: Q = P2 C (20-1) If leakage is governed by laminar flow it will be related to pressure, leak conductance for laminar flow, and viscosity. If PI is the total pressure of incoming leakage, Since PI > > P2, C L 2 2 QL = -_ (PI - P2 ) (20-2) C L PI 2 QL = H (20-3) Suppose the relative concentration of tracer gas is X. The relative concentration of a±r is then I-X. The leakage will be removed from the chamber at a rate Q such that: Q = Ca P2a + Ct P2t (20-4) At the same time leakage into the chamber will consist of two terms like that of Equation 20-4. The exiting rate of a given gas component will be equal to the rate of entrance of that com- ponent when equilibrium of the system is reached. Thus: C L PI 2 (X) = Ct P2t (20-5) n t C L PI 2 (l-X) = C P (20-6) Ha a 2a The total pressure in the chamber is obtained from the above two equations: = 2 x (l-X) 7 P2 = P2t + P2a CLP* HtC----_ + _a Caj (20-7) When no tracer gas is present the equilibrium equation is: CLPI 2 I (20-8) Ha = Ca P2a X=0 J The change in total pressure which occurs when tracer gas appears at the leak entrance is obtained by subtracting Equation 20-8 from Equation 20-7. Thus : 2 I X + l-X 1 1 (20-9)Ap 2 = CLP, tC t naC a _aCa ___ 20-3 If the leak is assumed to be flooded %.-ith tracer, X = l,and 5P = CL p 2 [ 1 1 3 : [ _tCt _---_- . (20-10)a aj If the sensitivity of the ion gage to air is K a and to the tracer gas Kt, the change in gage reading, AG, on applying the tracer is: I_G = CLP _ _ a (20-ii) rltCt naC a J It can be seen that the maximum change in gage reading will be obtained when there is: , 2. 3. 4. Complete coverage of the leak by the tracer gas High sensitivity of the gage for the tracer gas Low viscosity of the tracer gas A small value of Ct, the effective pumping speed for tracer gas The tracer gas should have a high molecular weight, since the conductance of the tubing leading to the pump, Ct, is inversely proportional to the square root of the molecular weight of the gas involved. The above derivation of gage response assumes that flow through the leak is laminar. In small leaks ( < 10 -6 atm-cc/sec) the flow will be molecular. If the leakage into the system is molecular, and the pumping speed is determined by the tubulation leading to the pump, the change in gage response can be expressed as: 5G = P (X) [K t CLt CLal (20-12) 1 L C---_ - Ka CaJ where CLt and CLa are the molecular-flow conductances of the leak for tracer gas and air respectively. Quite evidently the leak conductances are not generally known in advance. However, the equation does show the desirable condi- tions for obtaining a maximum response to tracer gas: I. Tracer gas should flood the lea< _zea; X--)I. 2. Pumping conductance for tracer aas, Ct, should be low. 3. Gage sensitivity for tracer gas should be higher than that for air. 4, Pressurizing the outside of a container will increase the change in gage response. Response will increase linearly with pressure if the flow is molecular. 5. Gage response will be independent of the viscosity of the tracer gas. 20-4 Since there are a variety of factors involved in choosing a proper combination of gas and gage, it is often easier to determine the sensitivity factor experimentally. Blears and Leck define this factor as: pressure caused by tracer @as on the leak = pressure on system with air on leak The experimental values of this factor are shown in Table 20-1 for both a hot-cathode gage and a thermal-conductivity (Pirani) gage. by : where AP 2a Qmin C a The minimum detectable leak can be determined AP C _miO-n = 2a a (20-13) = smallest measurable air pressure variation = smallest measurable leakage = pumping speed for air at the gage Table 20-1 LEAKAGE TESTING SUBSTITUTION FACTORS (Ref. 4-6)* Hot-cathode Tracer Gas Ionization Ga@e Pirani Ga@e Butane 10 1 Diethyl ether 5 0.7 Carbon dioxide 1 0.3 Carbon tetrachloride 1 0.05 Benzine 0.3 0.1 Hydrogen 0.4 0.4 Coal gas 0.25 0.25 *Reprinted with permission It is apparent from the above discussion that the minimum measurable leakage will be within a decade of the minimum mea- surable pressure change multiplied by the pumping speed at the pressure measurement site. In the design of this type of leak- age measurement, the response time of the system must also be taken into account. The pumping speed used is the pumping speed at the site of the gage. Thus the location of the gage affects the sensitivity. If the gage is connected by way of a restric- tion, it will be difficult to detect small leaks anywhere except near the gage itself. 20-5 In the testing of an evacuated system it is important that pressure fluctuations (such as those which arise from the back- ing and the diffusion pumps) be reduced to deviations not exceed- ing 0.2 percent. This can be accomplished by reducing the cross section of the pumping port or by constricting the gage tubulation. In the latter case the gage response then becomes slower and a longer time is required to achieve high sensitivity. It is desirable that the tracer gas have as different an ioni- zation efficiency from the background gas (air) as possible. In general, gage sensitivity increases with the number of electrons in the molecule (Ref. 2-3, p. 321). It is possible for the change in gage response to decrease in the presence of tracer gas rather than increase (Ref. 19-1). Examination of ion gage sensitivities suggests that the best materials for this procedure are either those of low molecular weight (hydrogen, helium, neon) or those of high molecular weight (acetone, ether or alcohol). In using liquids, care must be taken that they do not plug the leak. Response may be delayed by adsorption on the leak surface. As long as the leaks being located are the ones that limit the system pressure, this method may be applicable to very low pressures and/or very low leak rates. It has been shown to be a more sensitive method than the use of the mass-spectrometer leak detector (Ref. 20-1). The sensitivity of the ionization-gage method of leak sens- ing is greatly dependent on the stability and sensitivity of the electrometer used to measure the ion current as well as upon gage, tracer-gas, and pumping parameters. For routine testing with a conventional triode gage and current monitor, the detection of leakage rates between i0 -_ and 10 -6 atm-cc/sec can be expected. Modified gages permit extension of the sensitivity to i0 -I° atm- cc/sec (Ref. 20-2). 20.3. IMPROVING SENSITIVITY In order to improve the sensitivity of this method, the background ionization current may be nulled by means of a sensi- tive difference amplifier or a galvanometer with backing-off voltage control, so that very small changes in ionization cur- rent may be detected. An example of a circuit for such testing is shown in Figure 20-2. The indicating instrument has been re- placed with a potentiometer and the null balance instrument is a galvanometer or a sensitive microammeter, either of which is pro- vided with a suitable shunting circuit. In a stable vacuum a constant current flows through the gage tube and the potentio- meter, creating a steady voltage drop across the potentiometer. The battery provides a reference voltage and the potentiometer can be adjusted to give a null indication on the galvanometer. The shunting switch is left closed until this adjustment is made. 20-6 0cPOWERSUPPLY POTENTIOMETER IONIZATION GAGE TO VACUUM SYSTEM - C>-----NULLINDICATOR REFERENCE VOLTAGE Figure 20-2. Null Balance Circuit for Leak Location. (Reprinted with permission from W.E. Briggs, A.C. Jones, and J.A. Roberts, "Leak Detection Techniques", 1958 Fifth National S_nnposium on Vacuum Technology Transactions, Symposium Publications Division, Pergamon Press, New York (Ref. 10-2).) Care must be taken that the tracer gas does not permanently react and change the gage sensitivity. For example, Varicak (Ref. 20-3) found that after carbon dioxide had been applied for some time, the sensitivity of a Penning gage changed. The dis- charge current decreased about 30 to 40 percent, probably because of a film of carbonates on the electrodes. The sensitivity of an ionization gage to tracer gas can also be increased if the gas is brought selectively to the gage, by the use of a selective membrane or a cryogenic trap in front of the gage. For example, if an ionization gage is separated from the test system by means of a palladium membrane, and if the mem- brane is heated to about 700°C, the presence of hydrogen can be easily detected by the gage because of the rapid and selective permeation of hydrogen through hot palladium. When the palladium barrier gage is used and maximum sensi- tivity is desired (_p N 2 x 10 -8 torr) it is necessary to place a liquid nitrogen trap between the gage and the rest of the sys- tem; this excludes hydrocarbons and water vapor from the gage. . 20-7 Such vapors dissociate at the hot palladium surface to give hy- drogen, which produces a spurious response. In addition, the cracked hydrocarbons build up a carbon layer on the palladium which reduces its permeability. It is also desirable to use a mercury rather than an oil diffusion pump in the vacuum system since the hydrogen which re- sults from the decomposition of diffusion-pump oil gives rise to an unstable background ion current in the gage. In a system con- taining multiple leaks, oxygen in the air entering the undetected leaks combines at the hot palladium surface with the hydrogen en- tering through a leak which is being probed. If there is an ex- cess of oxygen all hydrogen will react with the oxygen before it can pass through the barrier, and will therefore be undetected. Under these circumstances, Ochert and Steckelmacher (Ref. 6-7) have suggested that a controlled leak of hydrogen should be ad- mitted to the system to take up the oxygen. To obtain maximum leak-detection sensitivity in the presence of oil vapor it has sometimes been found necessary to maintain a hydrogen partial pressure in the system of about 3 × 10-7 torr by the addition of a glowing tungsten filament at about 800°C (Ref. 20-4). If air is admitted to the ion gage, the palladium becomes oxidized even if it is cold. Whenever this occurs, two to three hours of run-in time are required to obtain reproducible results on duplicate runs. Therefore, even if the gage is not in use the forepumps should be operated continuously to prevent air con- tact with the palladium. If the gage is left exposed to the at- mosphere, several warm-up runs should be made, allowing hydrogen to pass through the calibrated leaks and pumping down between successive runs. As another example, it is possible to use an absorbent bed which will pass the tracer gas and block air. Silica gel, out- gassed at 300°C and then cooled to liquid nitrogen temperatures, is commonly used for this purpose. Under these circumstances, silica gel readily passes hydrogen and the noble gases (helium, neon, argon) but not air. A system using a silica gel bed with a cold cathode gage and hydrogen has been described by van Leeuwen and Oskam (Ref. 20-5). Further refinements of this gage separated it from the system by a liquid nitrogen cold trap filled with silica gel (Ref. 20-6). Van Leeuwen and Oskam claimed this system to be about a hun- dred times more sensitive than the palladium-hydrogen system. However, several hours were required to measure leaks of the or- der of 10 -I; atm-cc/sec, and careful degassing of the leak detec- tor and the tube to be tested was necessary. One advantage claimed for silica gel is a long usage time before it has to be degassed. The increased sensitivity of silica gel is claimed to be due to less gas evolution from the gel than from heated pal- ladium; this results in lower pressures. This detector, although very sensitive, is limited by long pump-down times. 20-8 A dual magnetron leak detector is described by Beck and King (Ref. 20-7). Two magnetron ionization gages are connected in series, with a cryogenic trap between them. The outputs of these two gages are balanced on a bridge. Tracer gas changes the cur- rent of the first gage, but is condensed in the trap and therefore does not affect the second gage. With two gages, background pres- sure variations do not affect the detector. The sensitivity of this detector is reported to be 10 -_° atm-cc/sec. The inverted magnetron can be converted to an extremely sensitlve helium leak detector IRef. 9-9). It operates with- out a hot filament, is inexpensive, small, rugged, and bakeable, and the electronic circuitry is simple. Leakages of 10 -_ atm- cc/sec are readily detected, while with selective pumplng the minimum detectable leak is claimed to be i0 --J atm-cc/sec. Negative-ion forming tracer gas {such as refrigerant F-12) can be detected in a modified ionizatlon gage described by Perkins and Robinson (Ref. 20-8). Because refrigerant gases are uncommon in vacuum systems it is possible to use them to probe for leaks. At a system pressure of 10 -4 torr a negatlve-ion partial pressure of i0 -I_ torr can be detected. One very sensitive means of locating leaks in vacuum sys- tems is to observe the temperature-limited emlssion of a tungsten filament in a vacuum. Lawton (Ref. 20-9) found that when a stream of oxygen is blown over the outside of a leak, the resulting in- crease in oxygen pressure in the vacuum system causes the emls- sion of the filament to drop. Although the principle has been known for a long time, and various circuits developed for its use (Ref. 20-10), this technlque has not been extensively used. Leger (Ref. 20-I1) developed an instrument using this tech- nique. Barton (Ref. 20-12) describes experiments in which the grid of a triode ionization gage was connected externally to the collector to form a diode. This was used to detect oxygen ad- mitted to the apparatus under controlled conditions. He reports that an air leak which gave rise to a partial pressure of 10- torr was readily detected when probed with oxygen. The detection circuit used was a modified ionization-gage control unit. The filament was heated by a regulated power sup- ply but was not emission-regulated. The emission current was read on a 0 to i0 microammeter in series with a 4.5-volt battery and a resistor. In this way, it was possible to read a change of a microampere at an emission of more than ten microamperes. Bloomer and Brooks (Ref. 20-13) examined the requirements for stable operation of this type of detector, using thoria- coated tungsten filaments. They found it best to reduce the thoraa to thorium at the beginning of the test by heating for a few seconds to a temperature of 2400°K. The greatest sensi- tivity is at an operation temperature 3ust below 1900°K, when the tungsten surface is partly covered with thorium. This can --o- 20-9 be obtained only when leaks of 10 -9 torr-laters per second or less are remaining in a well-baked system pumped at a speed of 0.I liter per second. The filament can become desensitized when it is carburized. Because of the danger that this could happen in the presence of hydrocarbon vapors, and because of the influence of residual water vapor upon the emission of electrons from the thoriated tungsten, the detector is not very suitable for use in an unbaked apparatus. If a filament accidentally becomes carburized it must be replaced; no thermal treatment cycle will bring it back to a sensitive state. But in a well-baked system thoriated filaments can, if necessary, always be restored to a desired state of sensi- tivity by a short period of running at a temperature of about 2400°K. 20.4 DISCHARGE GAGES AND ION PUMPS IN LEAK SENSING Cold-cathode, gas-discharge ion pumps are convenient instru- ments for leak location. An ion pump acts not only as a pump but also as an effective pressure gage, since the pump current is pro- portional to the number of molecules being pumped. Pump current is also dependent on the ionization efficiency. Pumping speed is dependent on the chemical reactivity of the gas molecules being pumped rather than on their molecular weight. Therefore, the response of an ion pump to a tracer gas will be different from that of a triode ionization gage. Figure 20-3 shows the response of ion-pump current to leak- age as a function of time for five typical trace gases (Ref. 20-2). The short-term response is generally quite different from the long-term time response. To make full use of the procedure the tracer gas must be applied to suspected leak areas for a time period which is about five times the ratio of the pumping speed to system volume. The best gases for use in leak location by ion pump are ar- gon, oxygen, and carbon dioxide. Estimates of the minimum de- tectable leakage that can be located with an ion pump are about 10 -11 torr-liters per second. This is a conservative estimate of the sensitivity. The current changes being measured are several orders of magnitude greater than the corresponding mass- spectrometer ion currents (Refs. 20-2, 20-4). A novel leak detector has been described by J.R. Young (Ref. 20-15). Using the system shown in Figure 20-4, the pro- cedure is to evacuate an ion pump and keep it operating at low pressure with the valve VI closed. The system to be leakage- tested is first evacuated by a mechanical pump to a pressure of i-I0 x 10 P3 torr. Valve Vl is then opened and V2 closed. An equilibrium pressure is reached in a few minutes. When the leak is probed with argon, the ion pump current increases rapidly, presumably because of the low speed of the pump for argon. Prob- ing with hydrogen and oxygen causes a reduction in pressure, 20-10 0.6 0.5 04 03 0.2 z 0.I O o_ uJ n- 0.0 Z ILl n" D -0. I Q. D -0.2Q- Z O -0.3 -0.4 -0.5 / /, / \ I ! i I i I J i i / -_/ \ /\ / 'k f I F V \ \ I AI f f i f J /- ,/ _I He / / / I _,./i H2w,THAOOEO_ /_" PUMPING _..,,, _ _ ,.,,,_,W_ -_ ''' He WITH ADDED_ [//_ PUMPING / J 0z ) C02 -0.6 0 Figure I 2 20-3. 3 4 5 6 7 8 9 I0 II RELATIVE TIME Response of Ion Pump Current to Various Gases. (Reprinted with permission from 1962 Trans- actions, Ninth National Vacuum S_nnposium of the American Vacuum Society, J.W. Ackley and others pp. 380-383, Copyright 1962, American Vacuum Society.) 20-i1 ION PUMP ... _ER PROBE •.'_i_ LEAK SYSTEM BEING TESTED TH ERMOCOUPLEGAGE II I Figure 20-4. Ion Pump Leak Detector. (Reprinted with permission from J.R.Young, Re- view of Scientific Instruments, Vol. 32, 1961, p. 85; Copyright 1961, Amer- ican Institute of Physics.) since these gases are pumped more rapidly than air. Helium is also used as the search gas, but the sensitivity is lower than for argon. Leaks as small as 10 -I° torr-liters per second can be lo- cated by this technique. Leaks between 10 -3 and 10 -s torr-liters per second can be located by partially opening Vl and having V2 opened sufficiently to avoid a pressure increase in the system during the testing procedure. Leaks of i0 -s to 10 -8 torr-liters per second can be determined a few minutes after opening V, and closing V2. Leaks smaller than 10 -e torr-liters per second re- quire a longer time, depending on the volume and outgassing pro- perties of the item under test. 20.5 APPLICABILITY OF METHOD In general, when testing evacuated systems by means of ioni- zation gages little additional equipment is necessary. Leak lo- cation can be performed with gages already on the system and with a variety of tracer gases. The method is inexpensive and requires no highly trained personnel. The method is dependent upon maintaining a constant pressure in the system. If the system pressure varies for reasons unre- lated to testing, leak location by this procedure is not practical. 20-12 The method cannot be used in a contaminated atmosphere, be- cause the gages will respond to the other gases present in the air. Therefore, they are not used in areas where welding (inert gases), cleaning (solvent fumes), brazing (combustion products), or painting (paint solvents) operations are performed. 20-13 21.1 21.2 21.3 21.4 21.5 21.5.1 21.5.2 Section 21 LEAK DETECTION WITH THERMALCONDUCTIVITY GAGES INTRODUCTION ................ APPLICATION TO LEAK DETECTION ....... SENSITIVITY ................ OPERATINGAT ATMOSPHERICPRESSURE ..... LEAKAGETEST METHODS ............ Evacuated Systems ........... Pressurized Systems .......... 21-1 21-2 21-2 21-2 21-4 21-4 21-6 Secti on 21 LEAK DETECTIONWITH THERMALCONDUCTIVITYGAGES 21.I INTRODUCTION Gages which sense a change in the thermal conductivity of a gas at low pressure can be employed to indicate leakage into or out of a chamber. Such gages are commonly attached to vacuum systems to indicate pressure in the range of a few torr to per- haps 5 x I0 -_ torr. These gages do not detect pressure directly and must be calibrated in terms of pressure. When a small wire, or similar element, is heated electrically, the temperature at- tained by the wire depends upon the rate at which heat is removed by the surrounding gas. At high gas pressure the mean free path of the gas molecules is much shorter than the distance between the heated wire and the nearest cold wall; hence, the thermal conductivity of the gas is independent of pressure. However, as this mean free path becomes comparatively long, as at low pres- sures, the heat that is conducted away by the gas is linearly proportonal to the gas pressure. In fact, the rate of heat removal per unit area of heated surface is proportional to the product of the pressure, the molecular heat conductivity of the gas, and the difference in absolute temperatures of the hot and cold surfaces (Ref. 2-3, p. 281). Heat loss by radiation is kept very small by operating the heated wire at a relatively low temperature, in the range of i00 to possibly 200°C. When a constant current is fed through the wire, the temper- ature of the wire will increase proportionally as the gas pres- sure decreases. The temperature change in the wire will cause a change in its resistance which can be sensed by connecting the wire as one arm of an electrical bridge circuit, as is done in a Pirani-type gage. Greater sensitivity to changes in gas pressure can be obtained by using higher impedance circuits and semicon- ductor thermistor elements to detect small changes in temperature. Stability of the bridge circuit against changes in ambient tem- perature can be improved by using a matched pair of thermistors, one element being located in the vacuum chamber and the other in a sealed chamber at the same ambient temperature as the chamber in which the sampling thermistor is located. In a thermistor form of thermal conductivity gage the bridge output current is linearly proportional to pressure over three decades of pressure from 2 × 10 -_ torr upward. The temperature of the element heated with a constant current in a low-pressure environment can be monitored directly with a thermocouple rather than indirectly by measuring a change in the resistance of the element. Thermocouple gages of the thermal con- ductivity type are preferred for monitoring foreline pressure on 21-1 present-day vacuum systems, since only an approximate indication of pressure signifies that a diffusion or ion pump can be turned on without harm to the pump oil. The relatively low operating temperature of the sensing ele- ments makes these detectors quite safe to use under most indus- trial conditions. The functional life and long-term stability of the sensing elements are good. The only ill effect which has been noted after long periods of operation under industrial con- ditions has been the accumulation of a dust deposit in the intake line which is easily removed. 21.2 APPLICATION TO LEAK DETECTION The response of a low-pressure thermal conductivity gage depends in part upon the composition of the gas in the chamber in which the gage is located. When there is leakage of a tracer gas into the chamber the gas composition and its thermal conduc- tivity change. As a result, the gage responds to the presence of the tracer gas. For example, a change in response of perhaps 25 percent will take place when a noble gas is substituted for air in the chamber. In a thermocouple gage the response varies with junction temper- ature and increases with the molecular weight of the gas. In gages involving a resistance bridge the response may be made to increase or decrease, according to the location of the sensing element in the circuit. In any event, leakage detection depends upon there being a difference in the molecular conductivity of the ambient gas and the tracer gas. 21.3 SENSITIVITY The maximum sensitivity of thermal conductivity @ages for the sensing of leakage is in the range of 10 -_ to I0 -° atm-cc/sec. For field-testing the sensitivity may be only 10 -3 atm-cc/sec, while the ultimate sensitivity is obtained only by using special temperature compensation and control procedures. 21.4 OPERATING AT ATMOSPHERIC PRESSURE Gages in which heat is removed from a sensing element by convection can be used for leak location at atmospheric pressure. Changes in gas composition due to the presence of a tracer gas cause a change in resistance or temperature of the element. This type of gage is relatively insensitive to pressure. A typical example of a detector probe employs a hot-wire resistance bridge having a resistance element in each of two arms of a bridge network. One element is exposed to air con- taining tracer gas, while the other is exposed only to air and serves as a reference to compensate for changes in ambient con- ditions (Ref. 21-1). 21-2 As shown in Figure 21-1, the sensing elements are mounted in a metal block inside a hand-held probe unit. Gas samples are drawn up through a narrow bore tube by the action of a small fan which can be run at two speeds: a fast speed for maximum re- sponse, and a slower speed to provide increased detection sen- sitivity at some sacrifice in response time. MOTOR FAN FILAMENT THERMAL CONDUCTIVITY REFERENCE BRIDGE TUBE Figure 21-1. Thermal Conductivity Leak Detector. (Reprinted with permission from W. Steckelmacher and D.M. Tinsley, Vacuum, Vol. 12, No. 3, 1962, pp. 153-159; Copyright 1962, Pergamon Press, Inc., New York.) To obtain a good response, the sensing elements must be small enough to fit into chambers of small volume. Since this detector is intended to discover changes in gas concentration rather than rates of flow, the gas should be made to flow past the entrance of the element chambers rather than through them. The sensing elements are coils of thin tungsten wire mounted on glass-metal seals in a compact assembly. In more recent designs, thermistors have replaced the tungsten wires (Refs 21-2 and 21-3). The electronic circuitry can be transistorized, and thereby made compact enough so the unit can be hand-held. The components consist mainly of a stabilized power supply for the thermal con- ductivity bridge, an amplifier to increase the amount of bridge unbalance, and a meter or signaling device. The electrical power source can be either batteries or line current. An atten- uator makes it possible to vary the sensitivity of the instru- ment. 21-3 21.5 LEAKAGE TEST METHODS 21.5.1 Evacuated Systems When the system pressure is in the range of the thermocouple gage the suspected leak area is simply probed with a suitable tracer. Best results will be obtained if the pumping speed is relatively low. A suitable location for the gage is the line be- tween the diffusion pump and the forepump. In principle, any tracer gas having a thermal conductivity different from that of air can be used. The sensitivity depends upon relative differences in thermal conductivities of the gases. It is apparent in Table 21-i that both hydrogen and helium show large relative differences, and are therefore the most sensitive tracer gases for this method. For special applications, it is sometimes desirable to employ one of the other tracer gases. The table, based on data from Reference 21-4, gives some indication of the results to be expected. It is clear that those gases with a thermal conductivity greater than air (such as hydrogen, helium, neon, methane) or those with thermal conductivities less than air (such as halogenated hydrocarbons, argon, carbon dioxide) would be suitable. The resistance bridge used in this detector does not actu- ally measure thermal conductivity. Because of its structure, the readings obtained are dependent not only on thermal conduc- tivity but on density, accommodation coefficient, and viscosity. Therefore, the values of thermal conductivity merely give an in- dication of the trend to be expected in behavior. While the use of liquids to probe for leaks is not recom- mended, Minter (Ref. 21-5) reported a 20:1 improvement in signal strength with water, compared to that obtained with hydrogen as a tracer material. When probing with hydrogen an increase of tracer-gas partial pressure can be obtained by reducing the dif- fusion-pump heater voltage (Ref. 21-6). This decrease of hydrogen- gas pumping speed is obtained without materially reducing the pumping speed for other gases. Modifications of the simple leak location technique are similar to those described in Section 20 for ionization gages. For example, Kent (Ref. 21-7) describes a Pirani leak detector using hydrogen gas; the gage is isolated from the system by a cooled charcoal trap. With this device it is possible to locate leaks as small as i0 -s atm-cc/sec. Ishii (Ref. 21-8) developed a differential leak detector using butane gas. It has two Pirani gages in a Wheatstone bridge circuit. One of the gages is in series with a charcoal trap. This arrangement has stability because any random pressure changes will be detected by both gages, while the butane tracer gas will be absorbed by the charcoal. The charcoal does not have to be heated during detection. The sensitivity of this system is reported to be 10 -6 atm-cc/sec. 21-4 Table 21-1 THERMAL CONDUCTIVITIES OF TRACER GASES* Chemical Molecular Oa___s Formula Weight Air (Mixture) 29.9 Acetylene C2H2 26 Ammonia NH3 17 Argon A 39.9 Benzene C6H6 78 Butane C_HI0 58 Carbon dioxide C02 44 Carbon disulfide CS2 76 Carbon monoxide CO 28 Ethane C2H_ 30 Ethylene C2H_ 28 Halogenated CCIsF 137.4 hydrocarbon F-f1 Halogenated CC12F2 120.9 hydrocarbon F-12 Halogenated CHClzF 102.9 hydrocarbon F-21 Halogenated CHCIF2 86.5 hydrocarbon F-22 Halogenated CCI2F-CCIF 2 187.4 hydrocarbon F-If3 Halogenated CCIF2-CCIF2 170.9 hydrocarbon F-II4 Helium He 4 Hydrogen H2 2 Hydrogen sulfide H2S 34 Krypton Kr 83.8 Methane CH_ 16 Neon Ne 20.2 Nitric oxide NO 30 Nitrogen N2 28 Nitrous oxide N_O 44 Oxygen 02 32 Propane C_H0 44 Sulfur dioxide SOz 64 Water vapor H20 18 Xenon Xe 131.3 * Data from Reference 21-4. **Thermal conductivity values for a temperature of 20"C in units of BTU/(hr)(sq ft) ("F/ft). 21-5 Thermal Conductivity** 0.01478 0.01128 0.01333 0.01016 0.00538 0.00822 0.00873 0.00410 0.01360 0.01102 0.01025 0.00470 0.00542 0.00554 0.00660 0.00438 0.00629 0.08740 0.10770 0.00770 0.00540 0.01872 0.02660 0.01180 0.01462 0.00925 0.01490 0.00925 0.00514 0.01087 0.03000 Measurement of the total leakage can be obtained by the methods suggested in Sections ii and 12. 21.5.2 Pressurized Sxstems The minlmum leak discernible by a detector probe, in terms of quantity of tracer gas per unit time, depends upon the rate of flow of the gas through the leak detector and the minimum concentration to which the detector will respond. With reduc- tion of the rate of flow, smaller leaks can be detected. How- ever, there is a practical limit, since it is important in leak location that the detector should respond quickly when the probe traverses the position of the leak. Reducing the rate of flow lengthens the response time, and beyond a certain point the in- dications from the leak detector become meaningless. For tests with the thermal conductivity detector the atmos- phere must be free from tracer gas. If a system with a very large leak is being tested, the local atmosphere may become con- taminated with tracer gas. While this will be inherently bal- anced out by the reference circuit, ultimate sensitivity is bound to decline. This shortcoming has been overcome by the use of a reference gas in a four-element thermistor bridge circuit (Ref. 21-9). The reference, or ambient, gas is passed over two of the bridge elements and the sample is passed over the other two elements. Leakages of 3 x i0 -_ atm-cc/sec of refrigerant F-12 were easily detected in confined conditions. 21-6 Section 22 LEAK DETECTIONBY GAS-TO-PARTICLE CONVERSION 22.1 22.2 22.2.1 22.3 22.3.1 22.3.2 INTRODUCTION TYPICAL PARTICLE COUNTER Particle Sensitivity GAS-TO-PARTICLE VERSION Gas or Vapor Sensitivity Stability and Response Time oo. OoeooeooeOe°° eoee.oo'°" oeoeoooOO ooeoeoO" 0o .eeoo-o ee.ooo 22-1 22-1 22-2 22-2 22-3 22-3 Section 22 LEAK DETECTION BY GAS-TO-PARTICLE CONVERSION 22.1 INTRODUCTION A relatively novel approach to the detection of gas leakage makes use of instruments developed primarily for the detection of submicron particles in the atmosphere. These instruments are known as condensation nuclei, or CN, counters. In such instru- ments water vapor is caused to condense on small particles in an incoming stream of carrier gas to form droplets which are much larger than any of the particles. The droplets scatter visible light and are easily detected (Ref. 22-1). In order to detect a gas, it is necessary to convert gas molecules to solid particles. This is done by reacting the gas, chemically or otherwise, with another substance. 22.2 TYPICAL PARTICLE COUNTER Figure 22-1 is a schematic diagram of a typical CN counter, showing the arrangement of the basic components. In the diagram submicron particles in a sample of air are drawn into a humidi- fier and then into an expansion chamber. The left valve closes and the right opens, to allow a rapid evacuation of the chamber to a pressure near 10 torr. The relative humidity rises rapidly from 100 percent to as high as 400 percent during this expansion. Water condenses on the tracer nuclei and droplets grow to a size DARK FIELD -_ AIR+ OPTICS r_<_,./EXPANSION CHAMBER PARTICLES _ I I [- _,I II I _ | _] I l/[!i_\_ PRESSURE L--_ / ,k L_/ I I V[_:I_--"_T>_/_ REGULATOR _--'--" VAC HUMIDIFIER I I I MA I / STRIP RECORDER VALVE AND DRIVE 5 CPS "J/_ /ki'J/rHIGH VOLTAGE1 H POWER I I I[ SUPPLY J VOLTMETER @ READ OUT Figure 22-1. Condensation Nuclei Counter 22-1 -q° - of about five microns in a time of about twenty-five milliseconds. All droplets attain the same size, regardless of the initial sizes of the entering nuclei. A beam of light shining into the chamber and a dark-field optical system are employed to view the vapor cloud. Only light which is scattered by the water droplets is registered on a de- tecting photo tube. The intensity of the scattered light is a measure of the number of droplets present in the chamber, and therefore of the number of nuclei particles which entered the chamber. After a measure of the scattered light has been taken, the chamber is emptied and flushed with a new gas sample, and the cycle repeated at a rate of about five hertz. 22.2.1 Particle Sensitivit X This type instrument will easily detect particles as small as 10 -3 microns or 10 -_ centimeters in diameter, and will count as few as i0 to as many as l0 T particles per cubic centimeter. The sensitivity is as high as one part in i0 I_ by mass. The re- sponse is linear up to 105 particles per cubic centimeter. Sample flow rates of i00 cubic centimeters per second are normally in- volved, at atmospheric pressure. 22.3 GAS-TO-PARTICLE VERSION Figure 22-2 shows how the particle detector can be employed to detect gases. The tracer gas sample and carrier gas are first SAMPLE CARRIER GAS AMBIENT GAS "_1 I IPARTICLES I PARTICLEFIL ER I CARRIERsAMPLEGAsGAS _ CARRIER(;AS J c*e I SUBMICROSCOPICAIR _r'_ J BORNEPARTICLE AS PAI_fICLE I A FUNCTI NOF CONVERTOR I__SAMPLE GAS _w.__..j/CONCENTRATION NUCLEI DETECTOR _ ELECTRICALANALO0OF SAMPLE GAS I LOW I CONCENTRATION PRESSURE PUMP Figure 22-2. Gas-to-particle Conversion Concept fed through a filter to reduce the particle background to a neg- ligibly low level, and then are fed to a converter. There a re- action with the tracer gas occurs, resulting in the formation of condensation nuclei particles; a fixed number of tracer gas mole- 22-2 cules are involved in the creation of each particle. The par- ticles then are passed to the expansion chamber to be counted as before. 22.3.1 Gas or Vapor Sensitivit X Table 22-1 is a list of gases and vapors which have been de- tected by means of a gas-to-par_acle conversion process. Some nine different conversion processes are involved in this listing. In a photochemical converter, for example, the incoming gas is simply irradiated by a small ultraviolet lamp. Chemical conver- sion for unsymmetrical-dimethylhydrazine (UDMH) involves an acid- base reaction with dilute nitric acid vapor. Propellants and oxidizers such as UDMH and inhibited red fuming nitric acid (IRFNA) can be detected directly with high sensitivities of at least 0.I and 0.5 ppm respectively (Ref. 22-2). The sensitivities for sulfur dioxide and ammonia gases are in the parts-per-billion range, exceeding the sensitivity of the helium mass spectrometer by several orders of magnitude when operating in a detector-probe or "sniffer" mode. Many of the gases whlch readily form nucleation sites are chemically reactive. Their use as tracers should be evaluated in terms of the hazards that might arise. Helium and argon cannot be converted to particles, and so cannot be used as tracer gases. The sensitivity to halogenated hydrocarbons is not high when pyrolysis is used for conversion. 22.3.2 Stabilit X and Response Time When calibrated for a specific gas the CN counter will oper- ate stably within plus or minus five percent for days at a time. The response time of the counter is about one and one-half seconds and is the same for all particle concentrations. This is unlike many instruments, whose response time increases with sensitivity. More information is needed about factors affecting quantita- tive measurement of a gas leakage rate with this type of instru- ment. There is little doubt, however, that the CN counter can be readily adapted to sensing, locating, and monitoring system leakage, and that very sensitive and easily used leakage testing techniques can be developed around this type of instrument. In addition to detecting gas leakage, the condensation nu- clei counter can be used to locate leaks in HEPA (high-efficiency particulate air) filter installations (Ref. 22-3). 22-3 Table 22-1 SOMEGASESDETECTEDBY GAS-TO-PARTICLE CONVERSION Substance Aluminum iodide Ammonia Benzene Carbon dioxide Carbon monoxide Chlorine Ethyl alcohol Freon 12-21 Fuming nitric acid Hydrochloric acid Hydrocarbons Methyl mercaptan Monoethylamine Mercury Metallic carbonyl Nitrogen dioxide Naptha Octane Sulfur dioxide Sulfur hexafluoride Sulfuric acid Solvesso No. 100 Toluene Unsymmetrical- dimethylhydrazine Type Conversion Hydrolysis Acid base Photochemical Electrochemical Chemical Chemical Reversed photochemical Pyrolysis Hydrolysis Hydrolysis Photochemical Oxidation Chemical Photochemical Hydrolysis Hydrolysis Reverse photochemical Photochemical Photochemical Pyrolysis Hydrolysis Reverse photochemlcal Reverse photochemical Chemical Concentrations Utilized PPM 0.01 0.005 2 5 1 1 5 2 0.5 0.5 0.i 0.01 0.5 0.001 0.001 0.5 5 2 0.001 1 1 1 1 0.I 22-4 Section 23 MISCELLANEOUSLEAKAGETESTING METHODS 23 .i 23.2 23.3 23.4 23.5 23.6 23.7 23.8 23.9 INTRODUCTION ................ COMBUSTIBLEGAS DETECTORS ......... ANALYTICAL MASS SPECTROMETER ........ GAS CHROMATOGRAPH ............. GAS CAPACITANCELEAKAGETEST ........ PROPELLANTLEAK DETECTOR .......... HYDROGENLEAK DETECTORS .......... OIL LEAK DETECTOR ............. BIOLOGICAL TECHNIQUESADAPTEDFOR LEAKAGE TESTING .................. 23-1 23-1 23-2 23-2 23-2 23-3 23-3 23-3 23-3 Section 23 MISCELLANEOUSLEAKAGETESTING METHODS 23.1 INTRODUCTION This section is a collection of leakage testing procedures which are unusual, or have application only under specific con- ditions. Although the selection has been arbitrary it is hoped that it will give some idea of the variety of leakage procedures which may be employed. Almost any detector which will show a change of gas concen- tration or composition may be used for leakage measurement. The sensitivity and practicality will depend on the ingenuity with which the detector is employed. For example, a dental mirror can be used to detect refrigerant leakage. A spot of condensed moisture clouds the mirror where the leaking refrigerant, cooled by expansion through the leak, strikes the surface of the mlrror. The list of similar possibilities is amost limitless. 23.2 COMBUSTIBLE GAS DETECTORS Combustible gas detectors are manufactured by several com- panies (Table 23-1). Details of this type of test equipment may be found in Part III under the heading "Catalytic Combustion." These detectors are designed for leak location by the detector probe technique on systems filled with combustible gases. Table 23-1 CHARACTERISTICS OF COMBUSTIBLE GAS DETECTORS General Characteristics Avera@e Values Sensitivity Tracer gas Output Power requirement Size Weight Price 1 cu.ft/hr., l0 ppm hydro- gen, 1% lower explosive limit Combustible mixtures Meter, tone, and light 115 volts, 60 hertz, battery From 4 x 8 x i0 inches to 15 × 17 x l0 inches 2 to 60 pounds $75 to $60o Each detector is a hand-held unit, usually with its own pump and power supply. As in the thermal conductivity detector, the tra- cer gas is passed over a thermocouple or other temperature sensor. In the combustible gas detector, however, the heat sensing ele- ment is in contact with a combustion catalyst. When a combus- 23-1 -q- tible tracer gas comes in contact with the catalyst, the heat of combustion raises the catalyst temperature and produces a response of the heat-sensing element. 23°3 ANALYTICAL MASS SPECTROMETER A mass spectrometer is sometlmes a part of the analytical equipment present on a vacuum system. This instrument is more versatile than the mass-spectrometer leak detector described in Section 9. It can quantitatively measure the concentration of any gas. Such an instrument can be used to diagnose problems with a vacuum system, and occasionally locate the source of a leak. The use of the analytical mass spectrometer is essentially the same as that outlined for the residual gas analyzer discussed in subsection 9.1.1. 23°4 GAS CHROMATOGRAPH A gas chromatograph separates a mixture of gases and mea- sures their individual concentrations. The separation is by means of the differences in their residence times in a column of sorbent material. This instrument has been used to measure the permeability of polymers (Ref. 23-1). The same basic equip- ment design can be used for leakage measurement. The system is pressurized with tracer gas and placed in a chamber which is at atmospheric pressure. An inert carrier gas, passed through the chamber, sweeps across the system. The concentration of tracer gas in the carrier is measured. Three advantages of the chromatograph in leak detection are: • The chromatograph measures leakage at atmospheric pressure. • The leakage measurement can be calibrated by measur- ments traceable to the Bureau of Standards. • Leakage of the contents of a container may be one of a variety of vapors or gases which can be detected directly with a gas chromatograph. Thus no tracer would be needed to detect a leak in the container. 23.5 GAS CAPACITANCE LEAKAGE TEST Integrated circuit modules which have already been mu_nted on printed circuit boards can be tested for leakage by measur- ing the change in capacitance of the module as gas composition changes _Ref. 23-2). A back-pressurizing technique which utilizes a gas whose dielectric constant is one to two percent different from that of the original filling gas makes it possible to detect leakages of less than 10-' atm-cc/sec. Several hours are required to make such a test. Care must be taken in interpreting the data, to separate the mechanlcal changes from the gas-concentration changes. 23-2 23.6 PROPELLANT LEAK DETECTOR It is possible to detect the leakage of propellants by sens- ing the temperature drop caused by evaporation of the leaking propellant. Juran (Ref. 23-3) found that the cooling effect was between 0.01 and 0.3 watt for each cubic centimeter per hour of leakage, and that changes in temperatures could easily be de- tected. For example, at a leakage of 5 x 10 -2 atm-cc/sec the temperature change recorded was 2°F. 23.7 HYDROGEN LEAK DETECTORS An activated oxide film has been shown to be sensitive to small amounts of hydrogen or other reducing gases (Ref. 23-4). Changes in resistivity of these films are rapid in ambient air; the response time amounts to only a few seconds and recovery is nearly as rapid. Sensitivity is reported to be about 10 -I to 10 -2 atm-cc/sec. Another hydrogen detector is a "stick-on" sensor that turns color in the presence of hydrogen (Ref. 23-5). Less than 1 atm- cc/sec will cause the reaction. The detector consists of powdered palladium oxide and a reaction-quenching material, all enclosed in a porous packet on the outside of which is a heat-sensitive paint. In use these detectors are mounted on flanges and other connections where hydrogen leakage may occur. 23.8 OIL LEAK DETECTOR Leakage of fuel oil, hydraulic fluids, and organic solvents from flanges or other joints can be detected by the use of a wrap-on tape which turns red in the presence of oil leakage. The tape does not burn and is nontoxic. It can be applied by hand to any surface configuration (Ref. 23-6). 23.9 BIOLOGICAL TECHNIQUES ADAPTED FOR LEAKAGE TESTING It has often been suggested that one simple method of leak location is to fill a system with honey, release ants, and watch where they enter the system. Although this dubious technique is related in jest, attempts have been seriously made to develop a leak location technique using a sex hormone of a butterfly (Ref. 23-7). This hormone was injected into pipelines, and the loca- tion of the leaks was clearly established by the congregation of a large number of butterflies. Presumably, it was felt that the sensitivity of the technique could be increased by using a drive greater than hunger. Biological techniques are not always used in such a sophis- ticated fashion. Gas companies routinely place an odor-produc- ing compound in natural gas. This odor-producing compound serves as a leakage monitor, indicating the existence of a leak. To a certain extent, a leak can be localized by the use of such olfactory techniques. 23-3 The sensitivity of the nose as a leakage testing instrument should not be underrated. It has been estimated that a concen- tration of propyl or butyl mercaptan as low as one part per bil- lion in the atmosphere can be detected. This fact is regarded with envy by manufacturers of mass-spectrometer leak detectors, whose standard instruments can detect helium at a concentration of only one part per ten million. Fortunately for these manu- facturers, olfactory response is neither quantitative nor very directional. However, specially trained dogs have been used to detect leakage from buried pipes. Vegetation response can be used for leak location. The growth of many plants is affected by the presence of natural gas. Gas companies frequently locate leaks in pipelines by traveling the route of the line and observing adjacent plant growth (Ref. 11-5). Leaks in the line will produce stunted plant growth in the vicinity of the leak. This will be exhibited by a presea- sonal color change or a slowdown on the growth rate. Such changes can be readily detected by trained personnel. 23-4 Section 24 Section 25 Section 26 Part III CHARACTERISTICS AND SOURCES OF COMMERCIALLY AVAILABLE LEAK DETECTORS Section 27 Section 28 Section 29 Section 30 q_, Section 24 COMMERCIAL LEAK DETECTORS Section 24 COMMERCIAL LEAK DETECTORS Part III of thls Handbook presents the characteristics of the various types of commercial leak-detecting equipment and their sources. To th±s end, a survey and review was performed of all known leak detectors, their characteristics and specifi- cations. The descrzptlve information is presented in condensed form, and is intended to serve as a general guide and aid in the selection of leak-detecting equipment suited for specific applications. To obtain factual and current information, letters of inquiry were sent to more than three hundred manufacturers in the United States, Belgium, England, France, Germany, Holland, Italy, Japan, Sweden, and Swltzerland. In the interests of uniformity and of obtaining more speciflc performance data and physical descrip- tions, each of these flrms was asked to complete and return "in- formation fill-ln" forms for its units. One hundred and twenty- eight vendors submitted useful information. Twenty-nine differ- ent principles are used in the leak-detecting equlpment being offered. Vendor replies were received in various degrees of complete- ness. Information extracted from these replies has been arranged in tabular form for each leak-detecting equipment. A scrupulous effort has been made to avoid any interpretation or extrapolation of the vendor-submitted information. Monitoring types of equip- ment have not been generally included. However, the classifica- tion of leak-detecting and leak-monitoring types of equipment is not always clear-cut- The commercial field of leak-detecting equipment is highly competitive and is _n a continuing state of change. Despite this, much of the submitted information should continue to be useful as a general guide to leak-detecting equipment, its characteristics, specifications, and sources, for several years to come. 24.1 ARRANGEMENT OF TABLES The data have been arranged in five different tables to facilitate the retrieval of information regarding specific types of leakage-testing equipment and their sources. The order of listing is alphabetlcal in each of the tables. 24-1 Section 25 MANUFACTURERS OF LEAK DETECTING EQUIPMEHT - MAILING ADDRESSES MANUFACTURERS OF LEAK DETECTING EQUIPMENT - MAILING ADDRESSES . 1 . , . , , . , i0. ii. Accessory Controls & Equipment Corp. 815 Bloomfield Avenue Windsor, Connecticut Aerojet-General Corporation Aerometrics Division Box 216 San Ramon, California 94583 Aero Vac Corporation Box 448 Troy, New York 12181 Alamo Specialty Company Dist; Alamo Mill Supply Co. 702 Culebra Avenue San Antonio, Texas American Design, Inc. 37116 Second Street South Box 31169 Birmingham, Alabama American Gas & Chemicals, Inc. Leak Tech Division 511 East 72nd Street New York, New York 10021 Andar Corporation 185 East Evelyn Avenue Mountain View, California 94041 Associated Electrical Industries Distributed & Maintained by Picker Nuclear 1275 Mamaroneck Avenue White Plains, New York 10605 Automation Industries, Inc. Sperry Products Division i000 Shelter Rock Road Danbury, Connecticut 06810 Bacharach Instrument Company Division of American Bosch Arma Corporation 200 North Braddock Avenue Pittsburgh_ Pennsylvania 15208 Beckman Instruments, Inc. Scientific & Process Instruments Division 2500 Harbor Boulevard Fullerton, California 92634 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 25-1 Bendix Corporation Scientific Instruments Division 3625 Hauck Road Cincinnati, Ohio 45241 Bernzomatic Corporation 740 Driving Park Avenue Rochester, New York 14613 Burnett Electronics Lab., Inc. P.O. Box 23015 San Diego, California 92123 Canal Industrial Corporation 5635 Fisher Lane Rockville, Maryland 20852 Cargille Scientific, Inc. R.P. Cargille Laboratories, Inc. 33 Village Park Road Cedar Grove, New Jersey 07009 Century Geophysical Corporation Century Electronics & Instr., Div. P.O. Box C Admiral Station 6540 E. Apache Street Tulsa, Oklahoma 74115 Consolidated Electrodynamics Corp. Subsidiary of Bell & Howell 1400 South Shamrock Avenue Monrovia, California Datametrics, Inc. 87 Beaver Street Waltham, Massachusetts 02154 Davis Emergency Equipment Co, Inc. Instrument Division 45 Halleck Street Newark, New Jersey 07104 Dawe Instruments Ltd. Western Avenue Acton, London W. 3 England The Decker Corporation 45 Monument Road Bela Cynwyd, Pennsylvania 19004 Devco Engineering, Inc. 37 Pier Lane West Fairfield, New Jersey 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. Dragerwerk Lubeck (West Germany) Agents: Scott Aviation Corp. 225 Erie Street Lancaster, New York 14086 Eastern Laboratories, Inc. 1229-31 Washington Avenue Vineland, New Jersey 08360 Edwards High Vacuum, Inc. 3279 Grand Island Blvd. Grand Island, New York 14072 Electronic Associates, Inc. 4151Middlefield Road Palo Alto, California 94303 Erdco Engineering Corporation 136 Official Road Addison, Illinois 60101 Euphonics Industries, Inc. 1634 West 33rd Place Hialeah, Florida 33012 Distributor: The Elwood Corp. 2180 Elmwood Ave. Buffalo, N.Y. 14216 Excelsior Varnish, Inc. 1219-43 West 74th Street Cleveland, Ohio 44102 Fisher Research Laboratory, Inc. 1975 University Avenue Palo Alto, California 94302 Flamort Chemical Company 746 Natoma Street San Francisco, California Flow Technology, Inc. 401 South Hayden Road Tempe, Arizona 85281 Fluid Data, Inc. 651-661Calebs Path Hauppauge, New York 11787 The Fredericks Company Anne Street Bethayres, Pennsylvania Galaxie Products Box 3412 South E1 Monte, Calif. 91733 37. 38. 39. 40. 41. 42. 43. 25-2 Gas Analysis Systems, Inc. P.O. Box 146 Basking Ridge, New Jersey 07920 Gas Purifying Materials, Inc. Instrument & Equipment Division 3-15 26th Avenue Long Island City, N.Y. 11102 General Air Products Corporation 5345 North Kedzie Avenue Chicago, Illinois George W. Gates & Co., Inc. P.O. Box 216 Hempstead Turnpike & Lucille Ave. Franklin Square Long Island, New York Ii010 General Electric Company Instrument Department 40 Federal Street West Lynn, Massachusetts General Electric Company Materials Engineering Laboratory Research & Development Center P.O. Box 43 Schenectady, New York 12301 General Electric Company Vacuum Products, Business Section I River Road Schenectady, New York 12301 44. General Monitors, Inc. 3019 Enterprise Street Costa Mesa, California 92626 45. Goldak Company, Inc. 1544 W. Glenoaks Blvd. Glendale_ California 91201 46. Gow-Mac Instrument Company I00 Kings Road Madison, New Jersey 07940 47. Granville-Phillips Company 5675 East Arapahoe Avenue Boulder, Colorado 80302 48. Hastings-Raydist, Inc. Hampton, Virginia 23361 49. 50. 51. Hays Corporation 742 East Eight Street Michigan City, Indiana Heckerman Corporation 814 West Hyde Park Blvd. Inglewood, California 90302 Hewlett-Packard Company Delcon Division 333 Logue Avenue Mountain View, California 94040 61. 62. 63. Kobbe-McCawley Corporation 530 Columbus Avenue P.O. Box 1437 Melbourne, Florida 32901 Lenk Manufacturing Company P.O. Box 324 Franklin, Kentucky 42134 Lion Research Corporation 60 Bridge Street Newton, Massachusetts 02195 52. Highside Chemicals, Inc. I0 Colfax Avenue Clifton, New Jersey 07013 64. Loenco, Inc. 2092 N. Lincoln Avenue Altadena, California 91001 53. Hilger & Watts, Ltd. Hilger - I.R.D. Ltd. 98 St. Pancras Way Camden Road London, N.W. i England Agent: Calibrated Instruments, Inc. 17 West 60th Street New York, New York 10023 65. 66. Lumidor Products Corporation P.O. Box 357 2500 W. 6th Avenue Hialeah, Florida Magnaflux Corporation 7300 W. Lawrence Avenue Chicago, lllinois 60656 54. 55. 56. 57. 58. 59. 60. Hoke, Inc. I Tenakill Park Cresskill, New Jersey Honeywell, Inc. Apparatus Controls Division 2701 Fourth Avenue Minneapolis, Minnesota 55408 Houston Atlas, Inc. Box 19035 Houston, Texas 77024 Johnson-Williams, Inc. 2300 Leghorn Avenue Mountain View, California 94040 Japan Vacuum Engineering Co., Ltd. i, l-Chome, Kyobashi Chuo-Ku Tokyo, Japan Justrite Manufacturing Company 2061 N. Southport Avenue Chicago, Iii. 60614 Kelite Chemicals Corp. 1250 North Main St. Los Angeles, California 90012 25-3 67. 68. 69. 70. 71. 72. 73. Marcol, S.A. Brussels, Belgium Agent: M. Paquet & Co., Inc. 17 Battery Place New York, New York Mast Development Company 2212 E. 12th Street Davenport, lowa 52803 The Matheson Company, Inc. P.O. Box 85 E. Rutherford, New Jersey 07073 Met-L-Check Company 11919 S. Western Avenue Los Angeles, California 90047 Mine Safety Appliances Company 201 North Braddock Avenue Pittsburgh, Pennsylvania 15208 Minear Scientific Instruments P.O. Box 6187 San Diego, California 92106 Minnesota Mining & Manufacturing Co. Chemical Division 2501 Hudson Road St. Paul, Minnesota 55101 74. 75. 76. 77. 78. 79. 80. 81. 82. 83. 84. 85. 86. MKSInstruments, Inc. P.O. Box 215 Lexington 3 Massachusetts 02173 MoakMachine & Foundry Co. Port Huron, Michigan 48060 ModernEngineering Company,Inc. P.O. Box 8159 St. Louis, Missouri 63103 National ResearchCorp. Equipment Division Subsidiary of Norton Company 160 Charlemont Street Newton, Massachusetts 02161 NewarkControls Company 15 WardStreet Bloomfield, NewJersey 07003 Nuclear Products Company N.U.P.R.O. Company 15635Saranac Road Cleveland, Ohio 44110 Perkin-Elmer Corporation Ultek Division P.O. Box 10920 Palo Alto, California 94303 Phoenix Precision Instrument Co, Inc. 3803-05 North 5th Street Philadelphia, Pennsylvania 19140 Joseph G. Pollard Co., Inc. NewHydePark L.I., NewYork 11040 QuantumDynamics, Inc. 19458Ventura Blvd. Tarzanaj California 91356 Riken Keiki Fine Instrument Co._ Ltd. 2-7-6 AzusawaItabashiku Tokyo, Japan Ruska Instrument Corporation P.O. Box 36010 6121Hillcroft Avenue Houston, Texas 77036 Salen & Wicander, AB Box Sundbyberg3. Sweeden 25-4 87. 88. 89. 90. 91. 92. 93. 94. 95. 96. 97. 98. Schneider Manufacturing Co. Reading, Massachusetts Distributor: The Grisby Company 1204 "_' Street Washington, D.C. Shannon Luminous Materials Co. Tracer-Tech Division 7356 Santa Monica Blvd. Los Angeles_ California 90046 Sherwin, Inc. Belmont Chemicals Division 5007 East Washington Blvd. Los Angeles, California 90022 J. and S. Sieger Ltd. Poole - Dorset England Sierra Engineering Materials Research Division 6220 San Fernando Road Glendale, California 91201 Sloan Instruments Corporation 535 East Montecito Street Box 4608 Santa Barbara, California Spectronics Corporation Black Light Eastern Division 24 Kinkel Street Westbury, L.I., New York 11590 Sprague Devices, Inc. Huron Street Michigan, Indiana 46360 Starr-Kapp Engineering Co. 15115 Diversey Street Dearborn 3 Michigan 48126 Superior Signal Company, Inc. W. Greystone Road Spotsworth, New Jersey 08884 Technicon Inc. Saw Mill River Road Ardsley (Chaucey), New York 10502 Technology/Versatronics, Inc. Division Technology Corporation 506 South High Street Yellow Springs_ Ohio 45387 99. I00. Techsonics Inc. Santa Fe Road Taos, NewMexico 87571 Tel Air Products Corporation 7010N.W., 37th Court Box 814 Miami, Florida 112. 113. Union Carbide Corporation Linde Division P.O. Box 6000 Florence, South Carolina 29501 Union Industrial Equipment Corp. 150 CoveStreet Fall River, Massachusetts 02720 I01. 102. 103. Teledyne_ Inc. Analytical Instrument Div. 370 South Fair OaksAvenue Pasadena, California 91101 Tenvac, Incorporated Pembroke,Massachusetts 02359 TescomCorporation Smith Welding EquipmentDiv. 2633 S.E. 4th Street Minneapolis, Minn. 55414 114. 115. 116. United States Gulf Corporation 609 SawMill River Road Ardsley, NewYork 10502 U.S. Safety Service Company Division M 1535 Walnut Street Kansas City, Mo. 64108 Uson Corporation 2120 South Postoak Houston, Texas 77027 104. Testing Systems, Inc. 2826 Mr. Carmel Avenue Glenside, Pennsylvania 19038 117. Universal Controls Corp. P.O. Box 20276 Dallas, Texas 75220 105. 106. Texas Instruments, Inc. Apparatus Division IPG P.O. Box 66027 3609 Buffalo Speedway Houston, Texas 77006 Thermal Industries of Florida, Inc. 3655 N.W. 74th Street Miami, Florida 33147 118. 119. Varian Associates Vacuum Division 611Hansen Way Palo Alto, California Varian Mess Analysen Technik GmBH Heraeus-Engelhard, Inc. Seco Road Monroevillej Pa. 15146 107. Thermal Instrument Company Box 72 Cheltenham, Pennsylvania 19012 120. Veeco Instruments Inc. Terminal Drive Plainview, New York 11803 108. 109. Tinker and Rasor Detectron Division P.O. Box 243 San Gabrielj California Trans-Sonics, Inc. P.O. Box 326 Lexington_ Massachusetts 02173 121. 122. Volumetrics 1025 Arbor Vitae Inglewood, California 90301 Vacuum Instrument Corporation 6 Stepar Place Huntington Station Long Island, New York 11746 ii0. Iii. Turco Products, Inc. Div. of Purex Corp., Ltd. 24600 South Main Street Wilmington_ California 20th Century Electronics Ltd. King Henrys Drive New Addington Croydon Suffrey England 123. 124. 25-5 Wallace and Tiernan, Inc. 25 Main Street Belleville, New Jersey 07109 Watsco_ Inc. 1800 West 4th Avenue Hialeah 3 Florida 33010 125. 126. 127. 128. The Welch Scientific Company 7300North Linder Avenue Skokie, Illinois 60076 Whittaker Corporation Pace-WianckoDivision 12838Saticoy Street North Hollywood, California 91605 Winton Products Co., Inc. Box 3332 Charlotte, North Carolina 28203 Yellow Springs Instrument Co., Box 279 Yellow Springs, Ohio 45387 Inc • 25-6 Section 26 CODE SYMBOLS FOR TYPES OF LEAK DETECTING EQUIPMENT ° CODE SYMBOLS FOR TYPES OF LEAK DETECTING EQUIPMENT Detector Principle I. Bubble (Liquid Applicant) 2. Catalytic Combustion 3. Chemical Indicator - Dye 4. Chemical Indicator - Dye - Pressurized 5. Chemical Indicator - Reagent 6. Electrochemical Cell 7. Flame Ionization 8. Flow 9. Gas Density I0. Halide Torch - Flame Color II. Immersion 12. Infrared Absorption 13. Interferometer 14. Ion Gauge 15. Mass Spectrometer 16. Particle Detector 17. Pressurized CO 2 18. Pressure Change - Gas 19. Pressure Change - Liquid 20. Pressure - Water 21. Sonic - Sonic Range 22. Sonic - Ultrasonic Range 23. Spark Coil (High Frequency) 24. Thermal Conductivity 25. Tracer - Halogen 26. Tracer - Radioactive 27. Tracer - Smoke 28. Ultraviolet Absorption 29. Volumetric Displacement Code B C D DP R EC FI FL GD FC IM IR IN IG M PD CP GP LP WP S US SC TC TRH TRR TRS UV V 26-1 Section 27 MANUFACTURERS OF LEAK DETECTING EQUIPMENT - PRINCIPLES USED _-_, LEAK DETECTING EQUIPMENT M-_NUFACTURERS - PRINCIPLE USED io 2. 3. 4. 5. 6. 7. Andar Corporation 8. Manufacturer Accessory Controls & Equipment Corp. Aero Vac Corporation Aerojet-General Corp. (Aerometrics Division) Alamo Specialty Co.)Alamo Mill Supply Co. (Exclusive Agent: American Design, Inc. American Gas & Chemicals, Inc. Associated Electrical Industries (Distributed & Maintained by Picker Nuclear) 9. Automation Industries, Inc. (Sperry Products Division) I0. Bacharach Instrument Division of American Bosch Arma Corporation II. Beckman Instruments, Inc. (Process Instruments Division) 12. The Bendix Corporation (Scientific Instruments Division) 13. Bernz-0-Matic Corporation 14. Burnett Electronics Lab, Inc. 15. Canal Industrial Corporation 16. Cargille Scientific, Inc. 17. Century Geophysical Corp. (Century Electronics and Instruments Division) 18o Consolidated Electrodynamics Corp. (Subsidiary of Bell and Howell) 19. Datametricsj Incorporated 20. Davis Emergency Equipment Co., Inc. (Instrument Division) 21. Dawe Instruments 22. The Decker Corporation 23. Devco Engineering, Inc. 27-1 Detector Principle GP M V B WP B&R M& IG M D R&C&TC& TRH & EC IR & TC & b_7 M FC US IG B FI GP &M GP & LP TC & Fi & FC & C US GP TRH & TC Manufacturer 24. Dragerwerk-Lubeck (West Germany) Scott Aviation, Lancaster, Pa. (US distributor) 25. Eastern Laboratories, Inc. 26. Edwards High Vacuum, Inc. 27. Electronic Associates, Inc. 28. Erdco Engineering Corporation 29. Euphonics Industries, Inc. (The Elwood Corporation is the sole distributor) 30. Excelsior Varnish, Inc. 31. Fisher Research Laboratory, Inc. 32. Flamort Chemical Company 33. Flow Technology, Inc. 34. Fluid Data, Inc. 35. The Fredericks Company 36. Galaxie Products 37. Gas Analysis Systems, Inc. 38. Gas Purifying Materials Company, Inc. 39. George W. Gates & Co., Inc. 40. General Air Products Corporation 41. General Electric Company (Instrument Department) 42.G General Electric Co., Materials Engineering Laboratory Research and Development Center 43. General Electric Company - Vacuum Products Business Section 44. General Monitors, Inc. 45. Goldak Company, Inc. 46. Gow-Mac Instrument Company 47. Granville-Phillips Company 48. Hastings-Raydist, Inc. 49. The Hays Corporation 27 -2 Detector Principle R B M & TC & IG M C US B S &US B FL US IG B TC TC&C D CP TRH PD M& IG EC&C S &US TC GP &IG&M FL EC 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74. Manufacturer The Heckerman Corporation Hewlett-Packard Company (Delcon Division) Highside Chemicals_ Inc. Hilger & Watts, Ltd. (Hilger-l.R.D. Ltd.j Division) Calibration Instruments 3 Inc. Hoke_ Inc. Honeywell_ Inc. (Apparatus Controls Division) Houston-Atlas, Inc. Japan Vacuum Engineering Co., Ltd. Johnson Williams Products - Bacharach Instrument Co. 3 Div. American Bosch Arma Corporation Justrite Manufacturing Company Kelite Chemicals Corporation Kobbe-McCawley Corporation Lenk Manufacturing Company Lion Research Corporation Loenco, Inc. Lumidor Products_ Corp. Magnaflux Corporation Marcol_ S. A. (M. Paquet & Companyj Inc. distributor) Mast Development Company Matheson Company_ Inc. Met-L-Chek Companyj Inc. Mine Safety Appliances Company Minear Scientific Instruments Minnesota Mining & Manufacturing Co. - Chemical Division MKS, Instruments, Inc. 27-3 Detector Principle B US DP & B IR B UV C M C FC B R FC FL TC US D S EC C&TC&R D C & TC & IR & IG S IM GP _I. Manufacturer 75. Moak Machine & Foundry Company 76. Modern Engineering Company 3 Inc. 77. National Research Corp. (Equipment Division) Subsidiary of Norton Company 78. Newark Controls Company 79. Nuclear Products Company (NUPRO Co.) 80. Perkin-Elmer Corporation - Ultek Division 81. Phoenix Precision Instrument Company 3 Inc. 82. Joseph G. Pollard Company, Inc. 83. Quantum Dynamics_ Inc. 84. Riken Keiki Fine Instrument Company 3 Inc. 85. Ruska Instrument Corporation 86. Salen & Wicander, AB 87. Schneider Manufacturing Company 88. Shannon Luminous Materials Company (Tracer-Tech Division) 89. Sherwin, Incorporated 90. J. & S. Sieger, Ltd. (Poole-Dorset - England) Agent: Smith-Jeese, Inc. 91. Sierra Engineering Company (Materials Research Division) 92. Sloan Instruments Corporation 93. Spectronics Corporation (Black Light Eastern Division) 94. Sprague Devices, Inc. 95. Starr-Kap Engineering Co. 96. Superior Signal Company, Inc. 97. Technicon Corporation 98. Technology/Versatronicsj Inc. 99. Techsonics, Inc. 27-4 Detector Principle WP & IM & GP FC M GD B M&IG PD S FL IN&C GP C S D D C TRR M D B GP & LP TRS R FL & EC US Manufacturer I00. I01. 102. 103. 104. 105. 106. I07. Tel Air Products Corporation Teledynej Inc. (Analytical Systems Co._ Teledyne Analytical Instruments Division) Tenvac_ Inc. Tescom Corporation - Smith Welding Equipment Division Testing Systemsj Inc. Texas Instruments_ Inc. Thermal Industries of Fleridaj Inc. Thermal Instrument Company 108. Tinker & Rasor (Detectron Division) 109. Trans-Sonics 3 Inc. II0. Turco Products 3 Inc. (Division of Purex Corp. 3 Ltd.) IlL 20th Century Electronics 3 Ltd. 112. Union Carbide Corporation (Linde Division) II_ Union Industrial Equipment Corp. II_ United States Gulf Corporation II_ United States Safety Service Company I16_ Universal Controls Corp. 117. Uson Corporation ll& 119. 120. 121. 122. 123. 124. 125. Vacuum Instrument Corporation Varian Associates (Vacuum Division) Varian Mess Analysen Technik (Hereaus-Engelhard Vacuum, Inc. distributor) Veeco Instrumentsj Inc. Volumetrics Wallace & Tiernan_ Inc. Watsco_ Inc. The Welch Scientific Company 27 -5 Detector Principle US C & IR & TC & FI & EC &UV M FI D GP TRH FL S GP D M FI IN&R&C B R FL TC M M M M V GP B SC 126. 127. 128. Manufacturer Whittaker Corporation (Pace-Wiancko Division) Winton Products Company, Inc. Yellow Springs Instrument Company, Inc. Detector Princ ip Ie GP EC 27-6 Section 28 TYPES OF LEAK DETECTING EQUIPMENT MANUFACTURERS AND TRADE NAMES TYPES OF LEAK DETECTING EQUIPMENT - MANUFACTURERS AND TRADE NAME Bubble - _ Applicant) Manufacturer Alamo Mill Supply Company (Exclusive Agent: Alamo Specialty Co.) American Gas & Chemicals, Inc. Cargille Scientific_ Inc. Eastern Laboratories_ Inc. Excelsior Varnishj Inc. Flamort Chemical Company Galaxie Products Heckerman Corporation Highside Chemicals 3 Inc. Hoke, Incorporated Kelite Chemicals Corporation Nuclear Products Company (NUPRO Co.) Sprague Devices 3 Inc. United States Gulf Corp. Watsco, Inc. Winton Products Co., Inc. Trade Name Alspec FM Inert & Leak-Tec Sho-Gas Bubble-Coat Leak Finding Compound Detect-A-Leak 1-Spy Leak Detector Heck-Check Leak Finder Foam Chek-Seal Bubble-Fluid Snoop & Real Cool Snoop Air Push Derek Search Sherlock Catalytic Combustion Bacharach Instrument Division of American Bosch Arma Corp. Davis Emergency Equipment Co. 3 Inc. (Instrument Div.) Erdco Engineering Corporation Gas Purifying Materials Co. 3 Inc. (Instrument & Equipment Div.) Bacharach Gastron Vapotester Gastester Tox-Ex Vaporgraph Odorgraph 28-1 -a Catalytic Combustion Manufacturer General Monitors, Inc. Houston Atlas, Inc. Johnson-Williams Products - Bacharach Instr. Co. Division American Bosch Arma Corp. The Matheson Company Mine Safety Appliance Co. Riken Keiki Fine Instrument Co., Ltd. Salen & Wicander, AB J. S. Sieger, Ltd. (Poole-Dorset-England) Agent: Smith-Jeese, Inc. Teledyne, Inc. (Analytical Instrument Division) Union Industrial Equipment Corp. Chemical Indicators - Dye Automation Industries, Inc. (Sperry Products Division) George W. Gates & Co., Inc. Magnaflux Corp. Met-L-Chek Co., Inc. Shannon Luminous Material Co. Sherwin, Inc. Spectronics Corp. (Black Light Eastern Division) Testing Systems, Inc. Turco Products_ Inc. Division: Purex Corp., Ltd. (Tracer-Tech Div.) Chemical Indicator-Dye-Pressurized Highside Chemicals, Inc. Trade Name Duotector Gascope Explosimeter Salwico Zyglo Met-L-Chek Flaw Findr Tracer-Tech Dubl-Chek Fluoro Finder Fluor Chek & Dy Chek Trace 28-2 Chemical Indicator (Reagent) Manufacturer American Gas & Chemicals_ Inc. Bacharach Instrument Division of American Bosch Arma Corp. Dragerwerk-Lubeck (West Germany) Scott Aviation_ Lancaster (US Distributor) Kobbe-McCawley Corporation The Matheson Company 3 Inc. Techniconj Inc. Union Industrial Equipment Corp. United States Safety Service Company Electrochemical Cell Bacharach Instrument Division of American Bosch Arma Corp. General Monitorsj Inc. The Hays Corporation Mast Development Co. Technology/Versatronics_ InCo Teledyne 3 Inc. (Analytical Instrument Division) Yellow Springs Instrument Co. 3 Inc. Flame Ionization Century Geophysical Corp. (Century Electronics & Instr. Div.) Davis Emergency Equipment Co._ Inc. (Instrument Division) Teledyne_ Inc. (Analytical Instrument Division) Trade Name Bug-It & Jet/Tec Auto-Analyzer Kitagawa Detector Saf-Co-Meter 28-3 Flo___._w Manufacturer Flow Technology, Inc. Has tings-Raydis t, Inc. Lion Research Corporation Quantum Dynamics, Inc. Technology/Versatronics, Inc. Thermal Instrument Company Universal Controls Corporation Newark Controls Company Gas Density Halide Torch-Flame Color Bernz-O-Matic Corp. Davis Emergency Equipment Company, Inc. (Instrument Division) Justrite Manufacturing Company Lenk Manufacturing Company Modern Engineering Company, Inc. Tescom Corporation (Smith Welding Equipment Division) Union Carbide Corporation (Linde Division) Immersion Moak Machine & Foundry Company Minnesota Minning & Manufacturing Company (Chemical Division) Trade Name Linurmass Dragnet Jiffy 28-4 Infrared Absorption Manufacturer Beckman Instrumentsj Inc. (Process Instruments Division) Hilger & Watts_ Ltd. (Hilger-l.R.D. Ltd._ Div.) Calibrated Instruments, Inc. Mine Safety Appliances Company Teledyne_ Inc. (Analytical Instrument Division) Interferometer Riken Keiki Fine Instrument Co., Ltd. Union Industrial Equipment Corp. Ion Gau_e Andar Corporation Canal Industrial Corporation Edwards High Vacuum, Inc. Fredericks Company General Electric Company (Vacuum Product Business Section) Granville-Phillips Company Mine Safety Appliances Company Perkin-Elmer Corporation Ultek Division Mass Spectrometer Aero Vac Corporation Andar Corporation Associated Electrical Industries Distributed and Maintained by Picker-Nuclear 28-5 Trade Name Lira Televac Billion-Aire Minimass Mass Spectrometer Manufacturer The Bendix Corporation Scientific Instruments Division Consolidated E!ectrodynamics Corp. Subsidiary of Bell & Howell Edwards High Vacuum, Inc. Electronic Associates, Inc. General Electric Company (Vacuum Products Business Section) Granville-Phillips Company Japan Vacuum Engineering Co., Ltd. National Research Corporation, Subsidiary of Norton Company (EquipmentDivision) Perkin-Elmer Corporation Ultek Division Sloan Instruments Corporation Tenvac, Incorporated 20th gentury Electronics 3 Ltd. Vacuum Instrument Corporation Varian Associates Vacuum Division Varian Mess Analysen Technik GmbH (Heraeus-Engelhard Vacuum_ Inc. distributor) Veeco Instruments, Inc. Particle Detector General Electric Company, Materials Engineering Laboratory, Research and Development Center Phoenix Precision Instruments Co., Inc. Pressurized CO 2 General Air Products Corporation 28-6 Trade Name Spectrascan Manumatic Centronic Test-King Pressure Chan_e (Gas) Manufacturer Accessory Controls & Equipment Corp. Consolidated Electrodynamics Corp. (Subsidiary of Bell & Howell) Datametrics, Inc. Decker Corporation Granville-Phillips Company Moak Machine and Foundry Company MKS Instrumentsj Incorporated Ruska Instrument Corporation Starr-Kap Engineering Company Texas Instruments, Inc. Trans-Sonics, Inc. Wallace & Tiernan, Inc. Whittaker Corporation Pace-Wiancko Division Trade Name Barocel Baratron Air-Chek Datametricsj Inc. Starr-Kap Engineering Company Pressure Chan_e (Liquid) Barocel Leak Chek American Design, Inc. MoakMachlne & Foundry Company Pressure - Water Fisher Research Laboratory Goldak Company_ Inc. Sonic - Sonic Range Audlo-Scope & Master Electronic Witch__ Dual-tronic 28-7 Sonic - Sonic Range Manufacturer Marcol, S. A. (M. Paquet & Co., Inc. - distributors) Minear Scientific Instruments Joseph G. Pollard Company, Inc. Schneider Manufacturing Company Tinker & Rasor (Detectron Division) Sonic - Ultrasonic Range Burnett Electronics Lab, Inc. Dawe Instruments Euphonics Industries, Inc. (The Elwood Corporation is the sole distributor) Fisher Research Laboratory Fluid Data, Inc. Goldak Company_ Inc. Hewlett Packard Company Delcon Division Lumidor Products Corporation Techsonics, Inc. Tel Air Products Corp. Spark Coil The Welch Scientific Company Thermal Conductivi_ Bacharach Instrument Divison of American Bosch Arma Corp. Trade Name Airsonic Leakscope Globe Geophone Leakdata Hunter Detec-tor Son-Tector Tel-A-Leak 28-8 Thermal Conductivity Manufacturer Beckman Instruments 3 Inc. Devco Engineering_ Inc. Edwards High Vacuum_ Inc. Gas Analysis Systems_ Inc. Gas Purifying Materials Co._ Inc. Gow-Mac Instrument Company Loenco_ Incorporated The Matheson Company_ Inc. Teledyne_ Inc. (Analytical Instruments Division) Uson Corporation Tracer - Halosen Bacharach Instrument Division of American Bosch Arma Corp. Devco Engineering_ Inc. General Electric Company (Instrument Department) Thermal Industries of Florida_ Inc. Tracer - Radioactive Sierra Engineering Company Materials - Research Division Tracer - Smoke Superior Signal Companyj Inc. Beckman Instruments_ Inc. Ultraviolet Absorption 28-9 Trade Name Therma Bridge Analograph Loenco Leakator Radioflo Ultraviolet Absorption Manufacturer Honeywell, Inc. (Apparatus Control Division) Teledyne, Inc. (Analytical Instruments Division) Trade Name _olumetrie Displacement Aerojet-General Corporation (Aerometrics Division) Volumetrics 28-10 Section 29 GENERAL SUMMARY OF CHARACTERISTICS FOR LEAK DETECTORS L ° GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS OPERATING PRINCIPLE : MANUFACTURERS : OUTPUT SIGNAL IMPEDANCE : RANGES : SENSITIVlTY: REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: LIFE EXPECTANCY: PORTABILITY: SIZE : WEIGHT: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Bubble (Liquid Applicant) 16 firms Visual - Liquid will bubble. Does not apply Maximum claimed 1 x 10 -5 cc/sec. Good Almost instantly to, l minute. Min. -65°F Max. 212°F Does not apply Shelf life one year generally Hand carry 4 oz. to 55 gallon drums Usually 4 oz. bottles. Also available up to 500 Ibs. Max. 26 years .70¢/4 oz. to $5/gal. Stock approx. I week Usually is non-inflammable 3 non-toxic3 leaves no residue; and can be obtained to meet military specifications. Can be formulated to be compatible with particular fluids or gases. Solutions are available which are stable up to approximately 750°F. ° 29-1 -?-._ GENERAL SUMMARY OPERATING PRINCIPLE : MANUFAC_JRE RS : SPECIFICITY: EXCiTA._ON : OUTPUT SIGNAl. IM2EDANCE: RANGES: SENSITIVITY: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: PORTABILITY: SIZE: WEIGHT: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS: LEAK DETECTOR CHARACTERISTICS Catalytic Combustion 14 firms One unit is specific for hydrogen. 31 units for combustible gases and vapors. 9 units l15v 60 Hz 23 units battery operated, some rechargeable. Various combinations of visual sign audible signal, panel meter and output for recorder. 0 - 1.0% concentration to 0 to 100% LEL combustible gases. 1.0 cu. ft./hr., I ppm, 1% full range (0-i.0 L.E.L.) +1% to 5% of full scale One to 30 seconds Normal environment does not affect performance of most units. One unit sensitivie. To i0 G's vibration. No Replace or recharge batteries periodically. Sensor - one year. Instrument - 5 to 20 years. 8 units hand carry 4" x 8" x I0" to 15" x 17" x I0" 1 3/4 Ibs. to 60 Ibs. 1 year to 20 years $75 to $1200 Stock (I week) to 3-6 months Units are available with accessories for special applications. 29-2 OPERATINGPRINCIPLE: MANUFACTURERS: EXCITATION: OUTPUTSIGNAL IMPEDANCE: SENSITIVITY: REPEATABILITY: RESPONSETIME: ENVIRONMENTEFFECTS: MAINTENANCE: LIFE EXPECTANCY: PORTABILITY: SIZE: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS: GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS Chemical Indicators - Dye Visible Dye Penetrant Fluorescent Penetrant 9 firms Variety of ultraviolet lamps for use with fluorescnet penetrants. Requirements are from 90 v dc to llSv ac. Visible or dye fluorescent. Photocell readout systems available. Smallest f%aw detectable is 75 millimicrons and leaks down to I x i0"" std. cc/sec. Good Dwell time for penetrant 2-15 minutes for developer an additional 5-15 minutes. Greater sensitivity is obtained when dyes are used with ultraviolet lamp. Temperature range 60°F to 212°F. None Shelf life - i year to indefinite Penetrants are usually in kit form - hand carry Penetrant kits are usually packaged 3 or 4-12 ounce spray cans. Up to 16 years Penetrants kits are $22.50 to $150. Usually from stock - I week. Liquid and fluorescent penetrants detect cracks_ flaws and porosity in ceramicsj plastic and metals. Process requires application of penetrant_ then em_Isifier_ and then a developer solution. Some preparation qualify under MIL-I-25135C 3 MIL-I-6866B; and NAVSHIPS 250-1500-1 specifications. 29-3 OPERATINGPRINCIPLE: MANUFACTURERS: SPECIFICITY: RANGES: SENSITIVITY: OUTPUTSIGNAL IMPEDANCE: RESPONSETIME: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: EEMARKS : GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS Chemical Indicator - Dye - Pressurized I firm None 0-5000 psi Varies with time and pressure applied Colored fluid penetrates surface. Varies inversely with size of leak Indefinite 2" x 2" x 5" container 4 ounces, plastic bottle Yes 20 years $1.15 for 4 ounces to $18.40 for one gallon Stock An intensely colored oil is circulated through the system. Leaks are detected by colored spots appearing on the outside of the system at the location of the leak. 29-4 GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS OPERATING PRINCIPLE : MANUFACTURERS : SPECIFICITY : EXCITATION : OUTPUT SIGNAL IMPEDANCE : RANGES : SENSITIVITY : RESPONSE TIME : ENVIRONMENT EFFECTS : MAINTENANCE : LIFE EXPECTANCY: PORTABILITY: WEIGHT : TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Chemical Indicators - Reagents 8 firms Gases 120v ac One type of detection tube requires visual inspection. Other units provide an electrical output. I ppm to 30% by volume 0.I ppm is maximum 2 minutes to 5 hours - varies inversely with concentration. Compensation for temperature and humidity is usually built into the equipment. As needed Single test per unit to indefinite Hand carry I to 70 ibs. Up to 25 years $I00 to $5000 with pump and case. Tubes $6.50 per I0 i week to 3-6 months Some products consist of a detector tube that is used for a single test, others are colorimetric sensors and still others are photoelectric devices that detect color change. 29-5 _ ° GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS OPERATING PRINCIPLE : MANUFACTURERS : SPECIFICITY: EXCITATION : OUTPUT SIGNAL IMPEDANCE: RANGES: SENSITIVITY: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: PORTABILITY: SIZE: WEIGHT: TIME ON MARKET: PRICE: DELIVERY TIME: Electrochemical Cell 7 firms Strong oxidents (ozone, chlorine, etc.) Oxygen N204, UDMH and hydrazines, depending on model. Three units are galvanic cells, others require 120v 60 Hz or battery power. Panel instrument and dc voltage 0-5% to 0-50%. Oxygen or 0-5 ppm to 0-I00 pphm by volume (oxidants) 0.05% 02; I pphm by volume of ozone, chlorine and iodine; 1/2 ppm for oxidizers. 1% to 5% full scale 5 to 50 seconds 30°F to 125°F No Recharge cells periodically (20 days to 3 months)- replace cell annually. 8 to 12 months Yes 3" x 4 1/2" x 5 3/4" to 16" x 18" x I0" 2.5 to 67 ibs. 1 1/2 to 4 years $245 to $3000 2 weeks to 4 months 29-6 GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS OPERATING PRINCIPLE : MAkU/FACTURE RS : SPECIFICITY : RANGES : EXCITATION : OUTPUT SIGNAL IMPEDANCE : SENSITIVITY : REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAlL SAFE: MAINTENANCE: PORTABILITY: SLZE: WEIGHT: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS: Flame Ionization (Hydro-carbon gases are ionized in a hydrogen flame, carbon ion current is measured with an electrometer circuit.) 3 firms Hydrocarbon gases and vapors in air. Multi-ranges 3 to 8 l15v 60 Hz Indicating panel instrument - 5 and 25 my dc. Varies with composition. Typical maximum sensitivity = 2 ppm methane in air; 25 ppm propane in air 1% to 2% of full range 2 to 4 seconds Sample in air, requires 18% oxygen No Maintain hydrogen supply Both portable and stationary models. Portable unit 15" x 16" x 9 3/4" Portable unit 30 Ibs. I to 3 years $1445 to $ii,000 2 weeks to 6 months Useful for measuring hydrocarbons in trace concentrations. 29-7 OPERATINGPRINCIPLE: MANUFACTURER: SPECIFICITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: RANGES: SENSITIVITY: REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : PORTABILITY: SIZE : WEIGHT: TIME ON MARKET: PRICE : REMARKS : GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS Flow 7 firms Units are available for either gases or liquids 28v dc - Hand pump Audible - visual (Frosting at leak) - Meter - Digital. 0.001 std. cc/sec, to 3 x 105 std cc/min. Air - 0.001 to 0.I gpm liquid 1 x 10-2 cc/sec. (air) and 30 std. cc/min. Oxygen Best is 0.1% of full scale 0.I second to I0 seconds Accuracy is affected by environmental temperature Usually yes. Some larger units are not. I0" diam. x 30" to 4" x 4" x 5" (sensor) 28 oz. to 300 Ibs. Up to 15 years $99 to $1295 Many modifications are available to meet application requirements, 29-8 GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS OPERATING PRINCIPLE: MANUFACTURER: EXCITATION: OUTPUT SIGNAL IMPEDANCE: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: PORTABILITY: SIZE: WEIGHT: TIME ON MARKET: PRICE: DELIVERY TIME: Gas Density (A gas density switch - temperature com- pensation achieved by a trapped volume in a reference bellows). 1 firm Provides electrical contacts only Switch action .001 second Designs available for use at environmental temperatures of -85 ° to + 400°F Yes None 3 to 5 years Yes I" diam. x 2" 2 ounces 6 years $60 to $200 4 to 8 weeks 29-9 OPERATING PRINCIPLE: MANUFACTURERS: SPECIFICITY: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS : MAINTENANCE : PORTABILITY: TIME ON MARKET: SIZE : WEIGHT: PRICE : REMARKS : GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS Halide Torch - Flame Color (Flame color change in presence of halides) 7 firms Non-combustible refrigerant gases or vapors - Halides_ halogenated hydrocarbons. Largest is 15 to 1,000,000 ppm in air Maximum is 15 ppm Photocell type units require l15v_ 60 Hz. Torch type require no power. Change in color of flame - Panel meter for photocell type units. 2 seconds Useful over temperature range from -65 ° to +150°F Change gas cylinders as needed Hand carry Longest is 23 years Max. 15" x 16" x 9 3/4" to 1 1/4" diam. x 6" long 1/4 to 35 Ibs. $8 to $16 for visual type; $715 for photocell type One Unit uses an electric arc instead of flame, another unit burns alcohol and other units burn compressed gas. 29-10 GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS OPERATING PRINCIPLE : MANUFACTURERS : SPECIFICITY: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : PORTABILITY: REMARKS : Imme rs ion 2 firms None Leaks as small as i x 10-7 std. cc/sec. None required Gas bubbles Usually not portable Leak detection systems are often designed for specific components in production lines. Immersion fluids can be water or higher boiling-polnt liquids. Components being tested can be pressurized with a gas or heated to increase pressure of sealed-in gas. 29-11 GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS OPERATING PRINCIPLE: F_ANUFACTURERS : SPECIFICITY: RANGES : SENSITIVITY: EXCITATION: OUTPUT S IGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS: Infrared Absorption 5 firms Generally specific to nitrous oxide gases. Selectivity can be obtained by various filters of the infrared beam. Set to customers requirements. Typical full ranges: 100ppm N20 _ 50 ppm CO Locates leaks to I0_2 lusec (1.28 x 10-5 std. cc/sec.) l15v 60 Hz or 50 Hz. Others available. Panel meter (milliameter or millivoltmeter) +1% full scale m 5 to 30 seconds (full response). Temperature range: 30 to 120°F No effect from normal humidity Not usually but can be made so. 6 month interval. Check span and zero daily. I0 years 12" x 12"x 19" to 37" x 38" x 35" 50 to 200 ibs. Some units are portable I0 to 15 years $2400 to $5400 60 to 120 days Used as leak detector with nitrous oxide tracer gas. Can detect cyanogen_ hydrazine 3 hydrogen:cynide_ nitric oxidej H2S J CO_ CO 2 and hydrocarbons. Variations and modifications are available to conform with customers requirements. 29-12 GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS OPERATING PRINCIPLE MANUFACTURERS : SPECIFICITY: RANGES : SENS ITIVI TY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Interferometer 2 firms For gases. Unwanted background gases can be filtered OUt. As low as 0 to 270 hydrogen, methane, propane, etc. As low as 0.02% by volume. l15v 3 60 Hz or battery Panel meter and audible and visual alarm. +5% full scale 3 seconds Designed for use at ambient temperature of -30 to +45°C No Nominal I0 years 2 1/2" x 3 i/2" x 7 1/2" to 8 5/8" x 7 1/8" x ii 7/8" 3 1/2 to 15 Ibs. Yes I0 years $15oo 3 to 4 weeks The displacement of interference light fringes produced by the optical path difference between the sample gas and an air reference, is measured by a photo-electric circuit. 29-13 GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS OPERATING PRINCIPLE: MANUFACTURERS : SPECIFICITY: RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WEIGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Ion Gauge 6 firms offer gauges and 2 firms offer accessories. For gases. Can be made to respond to a specific gas. I0 to I0"II torr in decade steps; 0-3 ppm to 0-50 ppm of Hydrazine and UDMH. 0.5 ppm Hydrazine_ 0.15 ppm UDMH. l15v 60 Hz; batteries (some rechargeable) Panel meter 3 voltage output; signal lamp Best is +1% full scale 15 seconds Designed for normal ambient temperatures and humidity. Most do not but one unit is fail safe. Replace batteries or recharge periodically, 5 years to indefinite 4 1/2" x 3" x 2" to 19" x 7" x 9" 1 1/2 to 45 Ibs. Most units are portable 3 to 8 years $350 to $1495 Stock to 60 days. Probe gas is detected within an evacuated test system. 29-14 OPERATINGPRINCIPLE: MANUFACTURER: SPECIFICITY: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSETIME: ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS Mass Spectrometer 19 firms All gases, mass I - 600. Varies between units. Multirange taps up to ii per unit. Abundance - 0.02 PPM Partial Pressure - 10 "15 tort (N2) Helium 5 x 10 -13 std. cc/sec. I0 amps per torr for N2 I05/125v 3 220/240v Panel meter; audible signal; I microamp to I ma; I0 mv to 10v dc Short term: _1% to _5%; Long term: _5% to _I0% 0.I to 1.0 sec. Suited for normal factory environments - Analyzer tubes useable to 200°C and bakeable to 400°C 20 units - yes; 6 units - no; I unit - can be Units va / from once every 2, to once every 12 months Vary from 5 to 15 years Minimum - W = II inches - H = 7 inches - Depth = I0 inches Maximum - W = 7 feet - H = 5 feet - Depth = 3 feet From 12 Ibs. (less magnet) to 1450 ibs. Movable From 1 to I0 years From $1975 to $27,000 From stock to 4 months Many accessories are available. for one gas. Some units are specifically_ i 29-15 OPERATINGPRINCIPLE: MANUFACTURERS: SPECIFICITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: RANGES: SENSITIVITY: RESPONSETIME: DOESIT FAIL SAFE: MAINTENANCE: PORTABILITY: SIZE: WEIGHT: TIMEONMARKET: PRICE: DELIVERY TIME: REMARKS: GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS Particle Detector Gases and vapors converted to particles and counted in chamber or forward scattering of light is detected. 2 firms Usually not specific but it is possible to detect specific gases with use of special chemical converters. llSv 60 Hz Panel instrument I00 to .001_ grams/liter of 0.3 micron particles. Examples: Halocarbon refrigerant - 2 PPM; sulphur dioxide -.001 PPM unsymmetrical dymethyhydrazine - 0.i PPM I to 5 seconds No Detector chamber must be clean - valve requires lubrication every 2000 hours. Movable on roller table Approximately 22" x I0" x 20" 90 to 127 Ibs. 6 to 13 years $2213 to $4800 4 to i0 weeks Useful for detection of clean room seals and noxious gas leaks. Can detect phosgenej unsymmetrical dimethyl hydrazine_ chlorine and nitrogen dioxide. 29-16 GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS OPERATING PRINCIPLE : MANUFACTURER: MODEL NO. & TRADENAME: OUTPUT SIGNAL IMPEDANCE : DOES IT FAIL SAFE: MAINTENANCE: DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : EIGHT: PORTABILITY: TIME ON MARKET: PRICE DELIVERY TIME : REMARKS : Pressurized (CO 2) - Frosting of atmospheric moisture One firm Test-King Pressure gage, audible signal and visual observation of frosting of moisture in the area of a leak. Yes Tank requires periodic recharge with CO 2 Yes Tank requires periodic recharge with CO2 20 to 30 years 25" x 6 3/4" 40 ibs. Can be hand carried 15 years $9O 2 weeks Test system is connected to the regulator of a pressurized CO 2 tank. Tank may be removed for recharging or for use elsewhere _hile leaving system being teste_ under pressure. Detects leaks by frosting of atmospheric moisture, provides an audlble leak signal and a system pressure gage. Meets all Interstate Commerce Commission regulations. 29-17 OPERATINGPRINCIPLE: MANUFACTURERS: SPECIFICITY: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSETIME: ENVIRONMENTEFFECTS: DOESIT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: REMARKS: GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS Pressure Change - Gas 13 firms None 0-0,0001 tort to 0 -I0_000 psi differential 0 - I torr to 0 - I00 psi absolute 0.0000i torrj maximum Some units require only fluid pressure sourcesp others require I05-125v_ 50 to 400 Hz and 220-240v_ 50-60 Hz. Varies with unit: Dial gage_ panel meter (analog and digital)_ voltages to 10v dc and lOv ac FM. Maximum is 0.002% FS 3 milliseconds to 2 minutes Most units are temperature sensitive No Some manufacturers offer maintenance contracts. Normally; zero check and periodic calibration. Up to 20 years From 6" x II" x 7" to 25" x 22 'bx 19" - some are in two parts. From 8 Ibs. to 175 Ibs. Most are portable Units vary from I to 20 years From $670 to $6000 From stock item to 12 weeks Most designs have a pressure sensing cell and a remote electronic unit. 29-18 GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS OPERATING PRINCIPLE : MANUFACTURE R: SPECIFICITY: RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAlL SAFE: SIZE: WEIGHT: PORTABILITY: PRICE: REMARKS : Pressure Change - Liquid 2 firms None Basic ranges from 0-I torr to O-I00 psi differential with a 9 position pressure range selector switch which scales sensitivity from XI to X0.0001. -5 I x I0 tort, maximum llSv_ 5 to 400 Hz Digital panel indicator and analog output _5 or _10v dc 3 milliseconds at 760 torr Pressure transducer: 0 - 150°F Electronic system: 0 - ll0°F No Electronic System: 8 3/8" x 14" x 9 1/2" Pressure Transducer: 3 1/4" x 3" x 3 3/4" 25 ibs. Yes Electronic System: $I050 to $2050 Pressure Transducer: $890 to $1200 Complete System: $2750 For some units the system liquid must be electrically non-conductlng. Pressure transducers and leak testing systems require vacuum back-filling with appropriate system liquids. --i- 29-19 GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS OPERATING PRINCIPLE: MANUFACTURERS : SPECIFICITY: EXC ITAT ION: SIZE : TIF_ ON MARKET: REMARKS : Pressure - Water 2 firms None Requires pressurized hydraulic systems. Tape is 2" wide (Tape) - Less than one year Water leaks are observed visually in one model and by electrical continuity of a water soluble tape in another. Use of rust inhibitors in water are advocated. 29-20 GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS OPERATING PRINCIPLE: MANUFACTURERS: SPECIFICITY: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAlL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE : WEIGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Sonic - Sonic Range 7 firms None Up to 17 kHz. Some have multiple ranges. Unit can detect air escaping through a hole 0.0005" in diameter at a system pressure of 80 torr. Self contained battery. Some units Visual and audible signals Up to the speed of sound Normal atmospheric humidity and temperature will not affect performance. No Battery replacement 5 to 25 years From 3" diam. x 5" long to 15" x i0" x II" From 5 oz. to 20 Ibs. Yes From i to 50 years From $6.50 to $395 Maximum is 2 weeks Some units are simple stethoscope types while others are much more sophisticated and provide means for amplification and tuning to frequency of interest. 29-21 OPERATINGPRINCIPLE: MANUFACTURERS: SPECIFICITY: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: RESPONSETIME: ENVIEONMENTEFFECTS: DOESIT FAIL SAFE: MAINTENANCE: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: REMARKS: GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS Sonic - Ultrasonic Range (36 to 44 kHg). i0 firms None Can detect leaks down to 0.001" diameter_ pressurized at 2 psi at a distance of one foot. Self contained battery indicating meter and audio signal (headphones) Speed of sound Designed for use in normal ambient atmosphere. No Replace internal batteries after 150 to I000 hours of use. From 1 1/2" diameter x 9" long to 12" x 8" x 5" From 12 oz. to Ii ibs. Yes From 1 to 30 years From $130 to $850 Maximum time is 3 weeks All audible sounds are filtered out and the ultrasonic sound made by a fluid leak through an irregular orifice is detected and converted into audible sound. 29-22 GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS OPERATING PRINCIPLE : MANUFAC TUBER: SPECIFICITY : EXC ITATI ON : OUTPUT SIGNAL IMPEDANCE : SIZE: PORTABILITY : PRICE : REMARKS : Spark Coil (Telsa Type) 1 firm For detecting leaks in glass vacuum systems. 115 v ac or dc A glow appears in a vacuum system when the coil probe approaches a system leak. 2" diam. x 12" long Hand held probe $16.75 Not recommended for thin wall systems. --i- 29-23 OPERATINGPRINCIPLE: MANUFACTURERS• SPECIFICITY: RANGES: SENS IT IV!TY: EXCITATION OUTPUT SIGNAL .IMPEDANCE : REPEATAB IL ITY: RESPONSE TI'ME: ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: S IZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET: PRICE: DELIVERY TIME : REMARKS : GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS Thermal Conductivity i0 Firms Selectivity to specific gases can be achieved with suitable filters. 1/2 to I0 oz/yr, of RI2 gas - 10 ppm H2S and others to 100% of gas of interest. Maximum is 1 x 10 -5 std cc/sec helium and I ppm. llSv; 60 Hz or internal batteries (some rechargeable) Panel instrument, signal lamp_ tone, dc signal Vary from 1/2% to 25% Full Scale Vary from 1/2 sec. to several minutes Designed for use in normal ambient environment. Some units de Replace batteries periodically. Span check monthly for high sensitivity units. Vary from 5 to 20 years. From 3" x 4" x 9" to 15" x 7" x i0" From A to Ii0 ibs. Most units are portable From i to 15 years From $165 to $53000 From I week to 4 months Usually for use in measuring concentrations in by- gaseous mixtures. 29-24 OPERATINGPRINCIPLE: MANUFACTURERS: SPECIFICITY: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: RESPONSETIME: ENVIRONMENTEFFECTS: DOESIT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS : GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS Tracer- Halogen 4 firms Halogen gases From 1 to I0 ranges Maximum is I x 10-9 std. cc/sec. (6 x 10 -6 oz./year) R-12 115 or 230v_ 60 Hz or internal batteries Lamp, panel meter or audible signal Approximately I second Suited for use in a temperature environment from 0 to 55°C (avoid areas with high concentrations of halogen gases and corrosive vapors and salt spray.) Most do not. Replace batteries periodically. Replace sensing element when required. Depends on exposure time of element to desensitizing agents. From 6" x 3" x 2" to 20" x 14" x II" From 1 1/2 to 20 Ibs. Yes From I to 15 years From $90 to $1115 From I to 6 weeks Leak standards are available which permit quantitative calibrations. Detectors must not be used in the presence of flammable vapors. 29-25 OPERATING PRINCIPLE : MANUFACTURER: SPECIFICITY: MODEL NO. & TRADENAME : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : DOES IT FAIL SAFE: SIZE : WE IGHT: PORTABILITY: TIME ON MARKET: PRICE : GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS Tracer - Radioactive i firm Krypton 85 (Krypton-85 and Nitrogen mixture) Radioflo Model 44-462 I x I0 -II std. cc/sec. l15v; 25 amps 3 60 Hz (50 Hz available) Scintillation Crystal Counting Station Yes 56 1/4" x 54 7/8" x 44" Complete system: 3640 Ibs. (5 gallon Activation Tank) No 12 years Price on request 29-26 GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS OPERATING PRINCIPLE : MANUFACTURER: MODEL NO. & TRADENAME : EXCITATION : OUTPUT SISAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Tracer - Smoke 1 firm Superior Smoke Candles and Superior Smoke Bombs None required. Flame manually applied to fuse. Visual observation and odor of escaping smoke through leak. Approximately 5 minutes Should be stored below 65° humidity and 85°F Yes 18 months Four sizes from 1/2" x 1 3/8" OD to 14" x 1 3/8" OD with burning time of 30 seconds, 60 seconds, three minutes or five minutes. 1 1/2 oz. to I lb. each Yes 14 years $4.50 to $25.80 per dozen 2 weeks After the smoke device is started a blower injects the non-toxlc smoke into the system to be leak tested. Smoke will be observed escaping from leaks. This method can be used on large systems such as sewer lines. On smaller systems a blower may not be necessary and merely insertion of the smoke device is sufficient. Smoke volume normally should be sufficient to fill an area 5 or 6 times that of the test system. Various types of smoke devices available. Smoke will not stain clothing nor corrode metal. 29-27 OPERATINGPRINCIPLE: MANUFACTURERS: SPECIFICITY: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT : PORTAB ILITY: TIME ON MARKET: PRICE : DELIVERY TIME • GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS Ultraviolet Absorption 3 Firms Not usually designed for specific gases but this can be achieved by selecting specific light sources and filter elements. From ppm to 100% concentration ± 1% Full Scale llSv, 50 or 60 Hz. Voltage or current signal; panel instrument ± 1% to ± 15% i to 30 seconds Designed for use over environmental temperature range of 40-110°F. No Annual check of electronic tubes and standard cell in one unit. 5 years Amplifier 8" x Ii" x 5" to 9" x 8" x 18" Analyzer 6" x 6" x 19" to 29" x 8" x i0" 30 ibs for portable unit One unit is portable 2 years for portable unit $600 for the portable unit 4 weeks for portable unit 29-28 OPERATINGPRINCIPLE: MANUFACTURER: SPECIFICITY: SENSITIVITY: OUTPUTSIGNAL IMPEDANCE: ENVIRONMENTEFFECTS: DOESIT FAlL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: GENERAL SUMMARY LEAK DETECTOR CHARACTERISTICS Volumetric Displacement 2 firms None 1 x 10 -5 std. cc/sec, is maximum Liquid level in a calibrated sight glass in one unit and a digital indicator in the other. Units are sensitive to environmental temperature. No None required 250j000 cycles Approximately 6" x I0" x 3" 4.8 and 12 Ibs. Yes 2 years for digital unit $395 for digital unit Digital unit is in stock 29-29 Section 30 LEAK DETECTORS - THEIR CHARACTERISTICS MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RANGES : EXCITATION: OUTPUT SIGNAL IMPEDANCE : ENVIRONMENT EFFECTS : MAINTENANCE : LIFE EXPECTANCY: PORTAB IL ITY: TLME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Accessory Controls & Equipment Corporation Pressure Change-Gas (detects pressure difference between test system and a trapped supply) ACE-234 -20 to +20 inches of water differential pressure 0-300 psi - compressed gas Reading on pressure gage (mechanical) Temperature sensitive - large air currents should be prevented from passing over system or leakage detector. As required Depends on care and useage Can be hand carried I0 years $670 6 - 8 weeks Temperature of test system and detector must not vary during test. 30-1 °MANUFACTURER: OPERATING PRINCIPLE : SPE ClFIC ITY: MODEL NO. & TRADENAME: SENSITIVITY: EXCITAT ION: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE: WE IGHT: PORTABIL ITY TIME ON MARKET: PRICE : DELIVERY TIME : Aero Vac Corporation Mass Spectrometer All gases, mass 2 to 200 Model 370, Process Control Analyzer 10 "12 torr (I0 ppm) 105 to 125 volts ac, 15 amps X Axis 0-10v dc; Y Axis 0-100my dc Less than i second Yes Approximately once every three months Ten years 24" x 24" x 60" (WDH) 450 ibs. On casters 18 months $12,400 One month 30-2 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: RESPONSETIME: DOESIT FAlL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: Aero Vac Corporation Mass Spectrometer All gases, mass2 to 300 Model No. 685 Mass 2 to 300 10"13 tort (i.0 ppm) I05-125v ac X Axis O-10v de; Y Axis O-!00mv dc Less than 1 second Yes Approximately once every 3 months I0 years WDH48" x 24" x 60" 600 lb. On casters 2 years $163000 4 months 30-3 _-l_ MANUFACTD-RE R: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGE S : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB IL ITY: TIME ON MARKET: PRI_ : DELIVERY TIME : Aero Vac Corporation Mass Spectrometer All gases_ mass I to 500 Model No. 686 Mass i to 500 10 -13 tort (0.02 ppm) i05-125v ac X Axis 0-10v dc; Y Axis 0-100my dc Less than i second Yes Approximately once every 3 months I0 years WDH 60" x 24" x 60" I000 lb. On casters 2 years $27,000 4 months 30-4 MANUFACTURE: OPERATLNGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: RESPONSE TIME : DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE: WE IGHT: PORTAB ILITY : TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Aero Vac Corporation Mass Spectrometer All gases, mass 2 to 70 M270 Mass 2 to 70 I0 -I0 tort (20 ppm) I05-125v ac 15 amps X Axis O-lOv dc; Y Axis O-lOmv dc Less than 1 second Yes Approximately once every 3 months I0 years WDH 24" x 24" x 60" 450 ibs. On casters 4 years $8900 Stock Versatile. Simple conversion from leak testing af pressurized or evacuated systems to high vacuum gas analysis and vice versa. 30-5 MANUFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADE_ : RANGES : SENS IT IV ITY: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : SIZE : PRICE : REMARKS : Aero Vac Corporation Mass Spectrometer Model AVAI Residual Gas Analyzer Mass numbers 2 to 70 standard; option of extending to i and to 200. Sensitivity range for Nitrogen: I0"I0 torr Meter indication of pressure_ mass scanj and emission. Recorder output: i0 MVF. S.; pressure: i0 VF.S. mass. 30 secs. and 2 min. per range Cabinet 21" x 23" x 13" Rack Panel 19" x 8 3/4" $2940 Spectrometer tube is bakeable to 400°C. Maximum operating pressure: 10 -3 torr. Total pressure measurement range: 10-3 to I0-I0 torr. 30-6 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADE NAME : RANGE S : SENS ITIV ITY: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : SIZE : PRICE : REMARKS : Aero Vac Corporation Mass Spectrometer Model AVAI-100 Residual Gas Analyzer Mass range from 2 to 200 -12 Sensitivity range for Nitrogen: i0 tort Meter indication of pressure, mass scan, and emission. Recorder outputs: i0 my FS pressure; I0 VFS mass. 8 min. per range Cabinet: 21" x 23" x 16 1/2" Rack Panel: 19" x 12 1/2" $4900 Spectrometer tube is bakeable to 400°C -i- 30-7 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: SENSITIVITY: OUTPUTSIGNAL IMPEDANCE: ENVIRONMENTEFFECTS: DOESIT FAIL SAFE: SIZE: WEIGHT: PORTABILITY: REMARKS: Aerojet-General Corporation- Aerometrics Division Volumetric Displacement None Displacement Leak Meter 0.008 std cc/min. Displacement of a liquid in a calibrated sight glass. + 40 to + ll0°F No 4" x 6" x 8" 12 ibs. Yes The detector design incorporates a back pressure balancing principle which practically eliminates back pressure to the leakage source. It can be used to measure leakage rates in air or any inert gas system. In use the detector is connected to a sealed cavity formed around the area of a pressurized system being leak tested (seals 3 assemblies etc.). 30-8 biANL"FACTURER: OPERATING PRINCIPLE: MODEL NO. & TRADENAME : OUTPUT SIGNAL IMPEDANCE : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS : Alamo Mill Supply Company Exclusive Agent: Alamo Specialty Company Bubble (Liquid Applicant) KA-OX-10, ALSPEC (Federal Stock List No. 6810-286-6019_ MIL-25567A) Visual - White bubble formation in leaking area Type I: +33°F to +180 ° , Type II: -65 ° to +32 ° Yes Indefinite 4 ounce polyethylene squeeze bottle. 5 gallon polyethylene container. 4 oz. and 40 Ibs. Yes 5 years $2.50 per 4 oz. polyethylene bottl_$35.00 per gallon standard pack 25-4 oz. bottles per case. Stock This product is an inert compound developed for fast, safe positive detecting of leaks in pressurized gas systems. Above formula is for use with oxygen system and most other gases. Other formulas are available for specific systems such as chlorine 3 air conditioning, telephone cables and LP gases. --l- 30-9 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : SIZE : TIME ON MARKET: REMARKS : American Design, Inc. Pressurized - Water -(Conducting Tape) Tape is water soluble Leak Detection Tape Tape is 2" wide 3 months Tape is multilayered. A strip of aluminum foll is electrically insulated from the test system by a strip of water - soluble paper. A wider strip of adhesive tape permits adhereing the assembly to the surface being leak tested. An electrical continuity circuit is required for detecting a loss of the water soluble paper. The tape has been developed by the Boeing Company on a NASA program. 30-i0 _LANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : SENSITIVITY: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS : SIZE : PORTABILITY: PRICE : REMARKS : American Gas & Chemicals_ Inc. Bubble (liquid applicant) "Leak-Tec" i x 10-5 STD. cc/sec or 0.013 cubic feet/year Bubble Almost instantly Formulae available to -65°F. 4 ounce plastic container Can be hand carried Approximately $1.50 each non-explosive non-flammable non-injurious non-corrosive Typical formulas available - See "REMARKS" For detection of gas and air leaks in pressurized systems. Special formula available for vacuum testing. Leave no residue. (+35 to) . MIL-L-25567A(ASG) (-65 °) #OX-65-C for oxygen (.65UF) Type II #16-OX for oxygen (regular) - MIL-L-25567A(ASG) (STD) Type I #577-V for vacuum testing #177 for refrigeration_ air conditioning (not for ammonia) eleven other chemical formula available. 30-11 r-_-L. MANUFACTURE R: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : SENSITIVITY: OUTPUT SIGNAL IMPEDANCE : ENVIRONMENT EFFECTS : REMARKS : American Gas & Chemicals, inc. Bubble (Leak Detection Liquid) FM Inert Will detect leakage rates down to 10 -5 standard cc/sec. Visual (Bubble) Thermal stability: approximately 750°F For testing handling and storage equipment for missile fuels and oxidizers when the equipment is pressurized with air or other gas before filling with fuel. Liquid and residue are inert to the following reagents: Con_nercial concentrated nitric acid White fuming nitric acid (cold and hot) 907ohydrogen peroxide Commercial concentrated sulfuric acid (cold or hot) Commercial hydrazine and UDMH Liquid oxygen 30-12 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : SENS IT IVITY: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : REMARKS : American Gas & Chemicals_ Inc. Chemical Indicator (Reagent) Water BUG-IT W-15 Visible detection to i/i0_000 of 1 cc. Black light inspection increases sensitivity to 2/1005000 of icc. Visual - Water is indicated by the appearance of a red pattern on the white surface. See remarks. Immediate BUG.IT is supplied in sheet form. It should be wrapped around the area of suspected leakage, securing it with the pressure sensitive adheshive. The color change is irm_ediate and irreversible. With experience_ the red pattern size can be interpreted quantitatively. --i- 30-13 -.-L. MANUFACTURER : OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : SENSITIVITY: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : REMARKS : American Gas & Chemicalsj Inc. Chemical Indicator (Reagent) Freon BUG'IT FR-20 Visible detection to 4/103000 of icc. Visual - Freon is indicated by the appearance of a blue pattern on the surface. See remarks. Immediate BUG-IT is supplied in sheet form. It should be wrapped around the area of suspected leakage, securing it with the pressure sensitive adhesive. The color change is immediate and irreversible. With experience, the pattern size can be interpreted quantitatively. 30-14 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : SENSITIVITY: OUTPUT SIGNAL IMPEDANCE: RESPONSE TIME: REMARKS: American Gas & Chemicals3 Inc. Chemical Indicator (Reagent) Hydrazine and other nitrogen containing compounds such as hydroxylamine also to components of tobacco smoke. BUG-IT H-25 Indicates presence of 5 PPM of hydrazine in the atmosphere by color change in five minutes. An actual leak of hydrazine vapor of 1.6 x 10 -4 cc/sec is indicated after several minutes. Smaller leaks down to I x 10 -6 cc/sec require proportionately longer testing time. Visual - see note above. 5 minutes BUG. IT H-25 paper is supplied in 4" x 5 1/2" sheets with "band-aid type adhesive ends which can be cut to required size. Develops an irreversible orange pattern on contact with hydrazine vapors. (Color changes to yellow at high vapor concentrations and on contact with liquid hydrazine). It is deactivated by ammonia and amine vapors. --i- 30-15 Mkk"JFACT_/RE: OPERATINGPR_CIPLE: SPECIF__CITY: MODELNO. & TRADENAME: SENSITiVITY: OI'TPUT SIGNAL IMPEDANCE : ENVIKONMENT EFFECTS : REMARKS : American Gas & Chemicals, Inc. Chemical indicator (Reagent) Fuel_ oil; hydraulic fluids and organic solvents. BUG'IT Fi05 Develops an irreversible blue pattern on contact with even a fraction of a drop (approx. 0.001 cc) of engine fuel; oil, hydraulic fluids or any of a number of different solvents. This response occurs most rapidly with light hydrocarbons; but becomes more intensive with heavy oils. Visual - blue coloring; see note above Operational temperature: -65°F to 250°F BUG'IT is supplied in 4" x 5 1/2" sheets with a pressure sensitive backing and can be cut to desired size. Can be left in place indefinitely. 30-16 MAN-_'FAC_JFER: OPERATINGPRLNClPLE: SPECIFICITY: MOREL NO. & TRADENAME • SENS ITiV !TY: OUTPUT SIGNAL IMPEDANCE : ENVIRONMENT EFFECTS : SIZE : PORTAB IL iTY: TiME ON MARKET: PRICE : DELIVERY TIME : REMARKS : American Gas & Chemlcals_ Inc. Chemical Indicator (Reagent) Engine fuels_ hydraulic fluids_ oils and organic solvents JET/TEC 3 type A perforated 0.05 cc Visual - develops an irreversible red pattern at the leak source. Temperature: -65°F to 380°F 2 1/2 inch x 4 feet strips (20 per package). Some special sizes available. Easily by hand 3 years $38.50 (20 strips 2 1/2 in. x 4 1/2 ft.) Stock JET/TEC is a wrap-on foll backed asbestos leak detection tape that locates leaks instantly. Supplied in strips 2 1/2" x 4 1/2". Non-toxlc; non-corroslve and non-stalning. The package priced above contains the required heat resistance tape for fastening the strips. 30-17 --l- MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME: SENSITIVITY: EXCITATION: REPEATAB ILITY: RESPONSE TIME-: ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB IL ITY: TIME ON MARKET : PRICE: DELIVERY TIME : REMARKS : Andar Corporation Mass Spectrometer Helium Series LD-300 2.6 x i0-II std. cc/sec, of helium 115/230 v.3 3 amp_ 50/60 Hz. ± 1Z Instantaneous Practically no influence Yes 6 mo6ths intervals. (No o11, 6o llquld nitrogen, getter ion pumped) 15 years Cabinet 24" x 24" x 38" 300 ibs. Mounted on casters i month $4600 and up 45 days Is also able to detect gross leaks. Optional equipment and accessories available. 30-18 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RANGES : SENS ITIVITY: OUTPUT SIGNAL IMPEDANCE : RE PEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE: WE IGHT: PO RTAB ILITY: TIME ON MARKET: PRICE : DELIVERY TIME: REMARKS : Andar Corporation Ion Gauge - Amplifier LD-100 2 (high_ low) I x 10.9 std. cc/sec. Reading on microammeter ±0.1% Instantaneous Not affected except by extreme temperature and humidity. No Replace batteries every 6 months Basic unit - 5 years exclusive of battery change. 1 3/4" x 3" x 4" 14 oz. Can be hand carried 6 months 9250 From stock Used for locating leaks in vacuum systems. Unit is designed for use with ion gauge or ion pump control unit. Detector amplifiers and displays differential input voltage. 30-19 MANUFACTURER : OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENS ITIV ITY: EXCITAT ION: OUTPUT SIGNAL IMPEDANCE : RE PE ATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: MAINTENANCE : SIZE : WE IGHT: PORTABILITY: TIME ON MARKET : PRICE : DELIVERY TIME: REMARKS : Associated Electrical Industries Distributed and maintained by Picker Nuclear Mass Spectrometer (Residual Gas Analyzer) Preferably helium, but can be used with all gases in mass range 2-200. MSI0 i000:I in seven ranges. High test range gives sensitivity quoted below. Range extension accessories available. 5 x 10-13 std. cc per sec. I00 to 260 volts, 50/60 Hz - 150 watts 3" meter indication, i0 mV recorder at I00 ohm source. ±2 1/2% 0.6 secs. Faster response with pro-rata sensitivity reduction. Unaffected by 6% line voltage fluctuations. Unaffected by humidity. Analyzer tube useable to 150°C and bakeable at 400°C. Yes Annual service recommended. 17"W x 18"D x i0 I/2"H Basic Instrument - 112 ibs. Yes. Needs vacuum connection to test chamber or system. 6 years $5290 f.o.b. New York 30 days Above specification refers to basic instrument. A wide range of vacuum and inlet systems and special purpose accessories are available. 30-20 MANUFACTURE R: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE : SIZE: WE IGHT: P ORTAB IL ITY : TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS: Associated Electrical Industries Distributed and maintained by Picker Nuclear Mass Spectrometer (Partial Pressure Gauge) Preferably helium. Can be used with all gases in mass range 2-240. Minimass i00000:i in 9 ranges and decade multiplier. i0 -II std. cc/sec for nitrogen 115-120 and 220-240v 3 50/60 Hz, ac 120 v amp 3" meter indication - 10mV recorder output ±3% I second Unaffected by humidity. Analyzer tube useable to 200°C bakeable to 400°C Yes Annual service recommended 7 13/16"H x 19 3/4"W x 16 II/16"D 74 Ibs. Yes. Needs vacuum connection to test chamber or system. 1 year $2650 f.o.b. New York 30 days Instrument available in glass and metal analyzer configurations. --i- 30-21 MAN-jFAC _cIRER : OPERATLNG PRINCIPLE : MODEL NO. & TRADENAME : RESPONSE TIME: ENVIRONMENT EFFECTS : SIZE : PORTAB:LITY: PRICE : DELIVERY TIME: REMARKS: Automation industrles_ Incorporated Sperry Products Division Chemical Indicators - Dye Sperry Penetrants - DP-400 Penetrant, DW-525 Developer 2 minutes to i0 minutes depending on material tested and nature of defect. Material should be at least 68°F and clean for best results. Must be thoroughly dry before application of penetrant. Single 16 oz. spray can to 55 gallon drum Can be hand carried DP-400 Penetrant, single spray can - $5.00 or $11.00/gallon DW-525 Developer_ single spray can - $5.00 or $7.90/galio_ From stock Requires spray, brush, or dip of red dye. Dye is then wiped off, developer is applied, and imperfections show up as red marks. Depth of defects indicated by richness of color and speed of bleed out. Is non-toxlc. One gallon covers 3000 sq. ft. 30-22 MANUFACTURER: Bacharach Instrument Division of American Bosch Arma Corporation OPERATING PRINCIPLE: Catalytic Combustion SPECIFICITY: Combustible gases and vapors MODEL NO. & TRADENAME : Bacharach Gastron: Model 282 (Code 23-7059) for combustibles_ and Model 310 (Code 23-7060) for H2 and combustibles. RANGES : Model 282: 50 ppm to 25% natural gas Model 310: 50 ppm to 5% hydrogen SENS IT IV ITY: Model 282: Better than 50 ppm Model 310: Approximately I0 ppm EXCITATION: 5v, 4.0 amp.-hr, rechargeable nickel cadmium battery OUTPUT SIGNAL IMPEDANCE : Audio earphone and meter. DC meter is 0-50 micro-amps. REPEATABILITY: + 25% RESPONSE TIME: ENVIRONMENT EFFECTS: 2 seconds or less Can be operated satisfactorily between -30°F and +130°F. Storage limits between -60°F to 150°F. DOES IT FAIL SAFE: Calibration kit provided to check overall operation. MAINTENANCE : Recharge battery after I0 hours continuous operation. Replace detector cell after 40 hours normal use. LIFE EXPECTANCY: S IZE : I0 years normal use Main housing: 3 i/2" x 3" x 6 1/2". probe and pistol grip. Does not include WE IGHT: 2 ibs. 6 oz. (instrument only) 4 Ibs. I0 oz. (complete with battery) PORTAB IL ITY: Designed to be carried by hand TIME ON MARKET: 5 years PRICE: DELIVERY TIME : Model 282: Model 310: 21 days $695.00 list, complete with accessories. $745.00 list, complete with accessories. REMARKS: Designed to detect leakage from buried natural gas distribution lines without need to sink "bar holes". Also useful for hydrogen leak testing applications where extreme sensitivity required. 30-23 --i_ MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : OUTPUT SIGNAL IMPEDANCE : ENVIRONMENT EFFECTS : MAINTENANCE : LIFE EXPECTANCY: PORTABILITY: PRICE : DELIVERY TIME : Bacharach Instrument Division of American Bosch Arma Corporation Chemical Indicator-Reagent Oxygen #10-5054; #10-5011: #10-5046 Fyrite Gas Analyzers 0-7.6%; 0-21%; 0-60% Visual - liquid in a column Ambient temperature from -30 ° to 150°F. Gases up to 850°F may be tested. Change fluid after approximately I00 samplings See maintenance Yes $61.00 2 weeks 30-24 .MANUFACTURER: OPERATING PRINCIPLE: MODEL NO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAlL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Bacharach Instrument Division of American Bosch Arma Corporation Thermal Conductivity Model SA65A Gas Leak Detector (Code 23-7027) Range selector incorporates XI, X2, X4, XIO_ X20 and XI00 positions. 6.8 x 10 -5 std. cc/sec. Helium. 6.3 volt rechargeable sealed lead acid battery rated at 2.6 ampere-hours. Audible (earphone) and visual (meter). Meter is 0-50 microamp. ± 25% i to 2 seconds Satisfactory performance in ambient range of 0 to 140°F. Not affected by humidity. Non-nutrient materials used. MIL-I-26600 RFI tested. Yesj operator's check list provided Battery recharge required after 8-9 hours continuous operation. Estimate I0 yearsj depending on duty cycle. 3 1/4" x 9 1/4" x 9 3/4" 8 1/2 Ibs. including battery and charger Can be hand carried 2 years $750 llst 21 days after receipt of order The SA65A Leak Detector has been tested and approved Intrinsically Safe by Factory Mutual for use in Class I, Division i_ Group A, B_ C 3 and D hazardous atmospheres. FM Report available on request. 30-25 MAN_JFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RANGES : SENS IT IV ITY: EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE : REPEATAB ILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB ILITY: TIME ON MARKET: PRICE : DELIVERY TIME : Bacharach Instrument Division of American Bosch Arma Corporation Thermal Conductivity Model SA63 Gas Leak Detector (Code 23-7001) In terms of R-12 gas: 1/2, I, 2, 5 and I0 oz./yr. 4.4 x 10-5 std. cc/sec., Hydrogen Six size D dry cells Signal light and tone ± 25% 3 seconds Satisfactory performance in ambient range of 32 ° to ll0°F. Not affected by humidity. Yes, operator's check list provided Batteries require replacement after 40 hours continuous service. Use alkaline maganese type. 5-10 years, depending on duty cycle 3 1/4" x 7 3/4" x 9 3/4" 7 1/2 lbs. with batteries Can be hand carried 4 years $250 list 21 days after receipt of order 30-26 MAN-UFACTL'RE: OPERATLNGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: SENSITIVITY: EXC!TATION: OUTPUTSIGNAL IMPEDANCE: RESPONSETIME: ENVIRONMENTEFFECTS: DOESIT FAlL SAFE: MAINTENANCE: SIZE: WEIGHT: PORTABIL ITY: PRICE: DELIVERYTIME: Bacharach Instrument Division of American Bosch ArmaCorporation Tracer - Halogen (TRH) RII_ RI2_ R22 and similar refrigerants "Leakator" (Bach Code#23-7023) 1/2 ounce per year of RI2 2 size D batteries Visual - light goes out when leak is detected I second Operates: O-120°F; not affected by high humidity Stored: 0-140°F Yes Replace batteries periodically (30 hours life) 4 1/2" x 2" x 7 1/2" 1 1/2 Ibs. Yes $97.50 Stock --i- 30-27 ---t_ MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME: RANGES: EXCITATION: OUTPUT SIGNAL IMPEDANCE: ENVIRONMENT EFFECTS: MAINTENANCE: SIZE: WEIGHT: PORTABILITY: PRICE: REMARKS: Bacharach Instrument Division of American Bosch Arma Corporation Electrochemical Cell Oxygen Model K Oxygen Indicator 0-5% and 0-25% oxygen (#23-7049) None required. Unit is a self generating electrolytic cell. Visual - indicating panel instrument Under normal operating conditions, the instrument is not affected by position, temperature and altitude. Reactivate cell at six month intervals 3" x 4 3/8" x 5 3/4" 2.5 Ibs. Yes $295 Gas sample is drawn into the instrument with an aspirator bulb. Sample passes through a teflon membrane permeable to oxygen and into an electrolytic cell. Also available in range 0-25% oxygen (#23-7047) $195j and 0-25% and 0-100% oxygen (#23-7048) $225. 30-28 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: RESPONSE TIME: SIZE: PORTABILITY: REMARKS : Beckman Instruments, Inc. (Process Instruments Division) Infrared Nitrous oxide (N20) #15A i00 ppm N20 full scale 1.0 cu. in./hr. (6 x 10 .5 std. cc/sec.) with 10% N20 in system being checked. For systems containing 100% N20 , leaks of 0. i cu. in./hr. (6 x 10 -6 std. cc/sec.) may be detected. l15v, 600w either 50 or 60 Hz models Visual on indicating instrument and changing frequency (audio) at earphones. 3 seconds from time probe draws in sample to initial meter response. 38 1/2" x 37" x 35" Mounted on four 12 inch pneumatic tires. Fitted with probe and 50 ft. cables. If system to be leak checked normally carries a gas that has good infrared absorption, the leak detector may be sensitized to that gas, and it is not necessary to evacuate the system. In this case, the leak detector can be used during actual working conditions. 30-29 MAI_JFACT_JRER: OPERATING PRINCIPLE : SPE CIPIC ITY: MODEL NO. & TRADENAME: RANGE S: SENSITIVITY: EXCITATION: OL_PUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME: REMARKS : Beckman Instruments, Inc. (Process Instruments Division) Infrared Absorption Sensitized at time of manufacture for nitrous oxide (N20) , unless another gas is specified. W 138220 Mobile Infrared N20 Leak Detector i00 ppm N20 full scale 1.0 cu. in./hr. (4.5 x 10 -3 std. cc/sec.) with 10% N^0 in system being checked or 0. I cu. in./hr. (_.5 x 10-4 std. cc/sec, with systems containing I00_ N20. ll5v_ 600w either 50 or 60 P_ models Visual or indicating instrument and charging frequency (audio) at earphones. ±0.5% full scale Three seconds from time probe draws in sample to initial meter response. ll5v, ±lbv, 60 ±0.5 Hz, -20 to 120°F No Check zero and span daily; no specific servicing interval. Indefinite with normal maintenance 38 1/2" x 37" x 35" 200 Ibs. Mounted on four 12 inch pneumatic tires; fitted with probe and 50 ft. cables I0 years $5400 90-120 days The model 315A NDIR analyzer, used as the detector, features all solid state electronics. If system to be leak checked normally carries a gas that has good infrared absorption, the leak detector may be sensitized to that gas and it is not necessary to evacuate the system. In this case, the leak detector can be used during actual working conditions. 30-30 MANUFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADENAME RANGES: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSETIME: SIZE: WEIGHT: PORTABIL ITY: PRICE: REMARKS: BeckmanInstruments_ Incorperated Thermal conductivity Model TBA-2100"Therma Bridge" Analyzer 0-i00 divisions on a 4" long scale llSv_ 60 Hz, 35w Panel Instrument ±1%of full scale 30 secondsor less at 1SCFH for 90%of change 8" x 13 1/2" x 12 i/2" 17 ibs. Yes $350 Some available accessories - A O-iOmv dc output for continuous recording of all analyses. Alarm contact (meter operated) to provide warning of high or low concentrations of the gas of interest. 30-31 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGE S : SENSITIVITY: EXCITAT ION: OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : SIZE : REMARKS : Beckman Instruments, Incorporated Ultraviolet Absorption Detects gases which absorb energy in the 400 m_ region. Model 255 (Ultraviolet Filter Photometer) From ppm to 100% concentration, dependent on application. Accuracy ±1% full scale llbv, ±lbv, 60 Hz, or llbv, ±15v, 50 Hz Choice of: Current - 0 to 5ma, 500 ohms maximum Voltage - adjustable to any potentiometric recorder (spans of I through 100my) ±1% of reading Electronic - 0.5 sec. for 90% of full scale Sample flushing - dependent on volume of cell Ambient temperature range: 30°F to 120°F Analyzer: 29" x 8" x 9 5/8"; Amplifier: 8 3/4" x 8 3/16" x 18 9/16" Transformer: 9" x 12" x 4 1/4" Maximum zero drift: 1% of span in 8 hours Maximum span drift: ±1% of full scale in 24 hours 30-32 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : SENSITIVITY: EXCITATION : OUTPUT SIGNAL IMPEDANCE : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: SIZE : WEIGHT: PORTABILITY: PRICE: REMARKS: The Bendix Corporation (Scientific Instruments Divison) Mass Spectrometer Mass range I to 500 AMU Model MA-I i PPM; 10 "13 torr for N2; I00 amps/torr; 10 "12 gram l15v - 60 Hz - 15 amp circuit Simultaneous 4 mode scope and recorder readout The ion source may be operated from normal ambient to 300°C. The analyzer_ including the magnetic electron multiplier is bakeable to 300°C. Yes Table top cabinet - 19" x 18" x 26" Analyzer console - 27" x 27" x 35" Table top cabinet - I00 Ibs. Analyzer console - 150 ibs. Analyzer console is on casters. As residual gas analyzer - approximately $8000 The analyzer tube with or without its pumping system can be remote_ up to I00 feet from the control console. - 30-33 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : EXCITATION: OUTPUT SIGNAL IMPEDANCE : RE PEATAB IL ITY: ENVIRONMENT Effects : DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE !GHT: PORTAB IL iTY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Bernz-O-Matic Corporation Halide Torch - Flame Color Non combustible refrigerant gas or vapor (R-II,R-12, R-22,R-II3,R-II4 and carrine). Tx-12M Leak Detector Unit Propane flame Color change in flame Operator ability to detect flame color change. Performs from -20°F to + 130°F No Replacement of disposable propane cylinder every 10-15 hours of use. Indefinite (except for changing cylinder) Shipping size i0" x 6" x 3" 4 Ibs. Designed as completely portable, self-contained unit i0 years $15.70 retail with cylinder From stock Color of propane flame in contact with reactor plate turns from pale blue to yellow in presence of a halide gas. 30-34 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENS IT IVITY: EXC ITAT ION : OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT : PORTABILITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Burnett Electronics Lab_ Inc. Sonic-Ultrasonic Range Air Burnett Model 609 Ultrasonic Listener Variable uncalibrated gain control A 0.001" diameter hole can be detected in a system pressurized to 2 psi_ at a distance of one foot. Batteries 1.5 volt. Audio signal and indicating meter Speed of sound Replace batteries 400 to 500 hours of use 5 years Approximately 8" x i0" x 3" ii ibs. Yes 2 Years $295.00 Shelf item Has speaker mounted in amplifier or can be used with special headset to screen out background noise. Probe is directional and hand held. 30-35 -_- MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENS IT IVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TiME ON MARKET: PRICE: DELIVERY TIME: REMARKS: Canal Industrial Corporation !on Gauge Freon, Helium Model 100B Photometric Leak Detector and Vacuum Gauge. Uncalibrated (responds i std. cc/sec, to 3 x 10 -8 std. cc/sec.) 3 x 10 -8 std. cc.sec, at 10-5 mm Hg; i x 10-7 std. cc/sec, at 10P • l10-120v ac, 50-60 Hz. Visual reading on indicating instrument Sensitive to vacuum level, otherwise within 10%. Less than 15 seconds after gas enters chamber. Voltage range: ii0-125v, 50-60,%-, - no effects under normal temperature and humidity. Yes Photocell window requires cleaning. Frequency depends on vacuum. Indefinite 8 1/2" x 7" x 14" 15 Ibs. Can be hand carried 3 years $1240 Stock item. Photodetector senses color or brightness of ionized tracer gas. 30-36 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : SENS IT IVITY: LIFE EXPECTANCY: SIZE : WE IGHT : PORTAB IL ITY: PRICE : DELIVERY TIME : REMARKS : Cargille Scientific_ Inc. Bubhle-(Liquid Applicant) Sho-Gas 0.25 std cc/hr Determined by use Varies (quart plastic bottle to 5 gallon can) Depends on container purchased. Can be hand carried From $2.60 to $25.00 depending on amount purchased. ($2.60/quart-5 gallon container at $5.00/gallon) Stock Conforms to MIL-L-25567A (ASG) except 4.5.6 skin toxicity is not known. --io 30-37 MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : RANGE S : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY: S IZE : WEIGHT: PORTABILITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Century Geophysical Corporation Century Electronics & Instruments Division Flame Ionization Methane Detector cell manufactured by Perkin-Elmer (213B), modified by Century. XI, X3, XIO, X30, XIO0, X300, XIO00, X3000 I ppm 1-300 v battery, 4-6 v lantern batteries, 1-115 v 60 cycle inverter powered from 12 v truck battery. 200 ohms: Indicating instrument and audible signal. i % of full/scale 4 sec. from sample intake to indication on pen recorder. Range cell temperature is thermostatically controlled. Inverter frequency must be ± 0 cps ± 3 cps. No Calibrate. Check zero and span daily. Check compressor and blowers weekly. With proper maintenance - indefinite. Console size 35" wide X 24" deep X 30-1/4" high Approx. 125 Ibs. - console only Mounted in 3/4 ton "personnel carrier" type truck. i year $ii,000.00 6 months Air tank, hydrogen tank and calibration gas tank mounted externally to the console. This firm features leak detection service. 30-38 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : LIFE EXPECTANCY: SIZE : WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: Consolidated Electrodynamics Corporation (Subsidiary of Bell and Howell) Mass Spectrometer - Quadrupole Yes_ all gases, mass/to 300 Type 21-440 1 to 300 AMTJ3 continuous I0 amps per tort for N2 -14 Minimum detectable partial pressure is 5 X I0 torr N 2 l15v, 60 Hz_ 15 amperes lOv dc into oscilloscope or high impedance recorder (50K ohms) 3% of reading_ short range; 10% long range 30 milliseconds to 30 minutes per scan as desired. Tube bakeable 400°C operable to 200°C. Electronics for 70 R.H. and ll0°F operation (ambient) 10-15 years Tube 24" long 4" diameter Electronics 21" W. X 12" H. X 18" D. 125 Lbs. total Yes May 1968 $5300 - with oscilloscope is $6200. 4 weeks --_o 30-39 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS : SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS: Consolidated Electrodynamics Corporation (Subsidiary of Bell and Howell) Pressure change (gas) (force balance system) Force Balance Pressure Transducer, Type 4-333-0001 Servo Amplifier, Type 1-156-0001 1.5 to _ 500 psi% other units to 0-i0,000 psid 0.001% full scale 105 to 125v, 60 to 400 Hz, 35 watts maximum. + i0 volts full scale 0.05% full scale 0.I second for 99% full scale pressure step. Operating ambient temperature range: Transducer; 40°F to 165°F, Servo Amplifier; 32°F to 120°F - 0.025% full scale shift per degree F change. Humidity; meets MIL-E-5272B, Procedure i. Type 4-333-0001: 4" X 3" X 2 1/2" Type 156:4 1/2" W X 9 3/16" D X 5 1/8" H Type 4-333-0001:2.6 Lbs. Type 156:6.5 Lbs. Yes Since 1960 Pressure Transducer: $995 Servo Amplifier: $1950 30 days Must supply your own analog output voltage indicator. 30-40 MANUFACTURE R: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RANGES : SENS ITIVI TY: EXCITATION : OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: ENVIRONMENT EFFECTS: MAINTENANCE: LIFE EXPECTANCY: SIZE: WE IGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME: REMARKS : Consolidated Electrodynamics Corporation (Subsidiary of Bell & Howell) Pressure change (gas) (dlaphragm/variable capacitor) Type 23-105 - Micromanometer -3 I to 150 X I0 torr Absolute -3 0.I X I0 tort l15v 3 60 Hzj 30 watts Capacitance bridge balanced by driving diaphragm back to null by electrostatic force and reading voltage on the duodial control. + 0.5 X 10 -3 torr Ambient temperature range: 20 to 40°C Contract maintenance service is available 20 years Gage: 6" X 6" X 3 1/2" - Bridge/Amplifier: 4" X 2" X 4 1/2" Control unit: 19 1/2" X 8 1/2" X 7 1/2" 40 Lbs. total Yes 20 years $2600 4 weeks System volume on sampling side is 50 cc. 30-41 MANUFACTURER: OPERATING PRINCIPLE : SPECIFIC!TY: MODEL NO. & TRADENAME : RANGES : SENS ITIV ITY: EXC ITAT lON: OUTPUT SIGNAL IMPEDANCE : RE PEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS : MAINTENANCE : LIVE EXPECTANCY: SIZE : WE IGHT: PORTABILITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Consolidated Electrodynamics Corporation (Subsidiary of Bell & Howell) Mass Spectrometer (less vacuum system) - Cycloidal Residual Gas Analyzer Yes: mass range 2 to 200 Type 21-614 m/e 2 to ii and m/e 12 to 200 Partial pressure of N2 of 5 x 10-12 torr l15v_ 60 Hz_ 3 amps Panel Meter and 0-I0 mv dc output signal for high impedance recorder (50K ohms) 1% of reading 7 min. per octave to i0 sec. per octave as desired. Electronics: up to 70% R.H. and llO°F (ambient) Tube bakeable to 250oc Contract maintenance service available. I0 to 15 years Control unit: 21" x 18" x 21 3/4" Analyzer: 17" x 17" x 12 1/2" Control unit: Movable 6 years $7700 4 weeks Cycloid tube and envelope are bakeable to 250°C. 150 ibs. - Analyzer Assembly: 90 ibs. 30-42 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRAD_AME! RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Consolidated Electrodynamics Corp. (Subsidiary of Bell & Howell) Mass Spectrometer (Helium Leak Detector) Helium; standard modifications available for Argon, Neon Hydrogen. Type 24-120B 9 ranges (Xl to Xl0000 range multiplier switch," i0 positions) 5 X i0 "II arm cc/s - He 105 to 125v, 60 Hz, 800 watts (50 Hz available) Linear output, 0-I00 meter scale divisions + 5?. Less than 1 sec. required to produce 50% full scale deflection on XI scale. Tamp: +40°F to ll0°F (ambient) Humidity: up to 95% Yes 6 months - clean manifold and change oil At least i0 years. 30" wide X 20" deep X 22" high 200 Lbs. (shipping weight 275 Lbs.) 4 carrying handles on unit. May be mounted on an accessory mobile workstand for mobility. 24-120 series - 9 years. $3,700 Stock item l. 2. 1 Remote Control Unit is included with basic instrument. Several standard accessory Seml-automatlc Test Port Stations are available for use with basic instrument. -:- Other accessories available are: Spray Probe Audio Alarm Standard Leaks Bell Jars & Plate Sniffer Probes 2 & 3 Valve Inlet Manifold Port Adapters Mechanical pumps Auxiliary Cold Trap 30-43 MANUFACTURER : OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGE : SENS IT IV ITY: EXC ITAT ION" OUTPUT SIGNAL IMPEDANCE : REPEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS : MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT : PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Consolidated Electrodynamics Corporation (Subsidiary of Bell & Howell) Mass Spectrometer - (less vacuum system) Gas Analyzer Yes - mass range 2 to i00 AMU Type 21-615 Residual Mass range 2 to i00 N 2 partial pressure to 2 x 10 "12 torr/division 105 125v, 60 Hz, 2 amperes Panel Meter and output to high impedance recorder (50,000 ohms). 3% short term; 5% long term. Scan rate is 60 seconds per octave. Electronics up to 70% R.H. and ll0°F (ambient) Analyzer - bakeable to 400°C. Contract maintenance service available I0 to 15 years Control unit: 12" x 22" x 16" Analyzer: 15" x II" x ii" Control unit: 50 Ibs. - Analyzer: 40 Ibs. Easily moved 2 1/2 years $3500 2 weeks Cycloid tube and envelope are bakeable to 450°C. 30-44 M_%NUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY : E XC ITAT ION: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS : SIZE : WE IGHT : PORTAB IL ITY: PRICE : REMARKS : Datametrics inc. Pressure Change (Gas or Liquid) Electrically nonconducting gases and liquids Type 1014 Electronic Manometer - "BAROCEL" Basic ranges are from 0-I torr to 0-i00 psi differential, each with a 9 position pressure range selector switch which scales sensitivity from x I to x 0.0001. -5 i x i0 torr_ maximum 115 volts; 50 to 400 Hz; 60 watts ±5 volts at full scale on 7 ranges (±i0 volts on special models) To 3 milliseconds at 760 torr Sensor type 511 0 to 150°F Electronic manometer type 1014 - 0 - llO°F Type 1014:8 3/8" x 14" x 9 1/2" (Electronic Manometer) Type 511:3 1/4" x 3" x 3 3/4" (Pressure Sensor) Shipping weight is approximately 25 Ibs. Yes - Hand Carry Type 1014 - $1050 (Electronic Manometer) Type 511 - $890 (Pressure Cell for use with the 1014) Provided with 9 position range selector switch from x .0001 to x 1 of full range. The type 521 pressure sensor with all hermetic seals can also be used with the 1014. The type 531 pressure sensor with bake out temperatures o up to 300 C can also be used with the 1014. Pressure transducers for liquid systems require vacuum back-filllng with the appropriate system liquid after connecting the pressure transducer into the system. Pressure differences measured between the pressurized test system and a static reservoir indicate the existance of leaks. --_o 30-45 --i_ MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY : MODEL NO. & TRADENAME : RANGES : SENS IT IVITY : EXC ITAT ION: OUTPUT S IGNAL IMPEDANCE : ENVIRONMENT EFFECTS : SIZE : WEIGHT: PORTABILITY: PRICE: REMARKS : Datametrics Inc • Pressure Change (Gas or Liquid) Electrically nonconducting gases and liquids Type 1018 - Electronic system for type #511 "BAROCEL" pressure sensor 0-i0_ 0-i00_ 0-i000 torr and 0-I_ 0-I0 psi - Full range - varies with model. 0.01% full scale 115 volts; 50 to 75 Hz Digital Panel Indicator - Also analog output: 0 to ±lOv dc Source impedance 50Q Type 511 - pressure transducer - 0 to 150°F Type 1018 - Electronics system - 40 to ll0°F Type 1018:8 3/8" x 14" x 9 1/2" - Electronic System Type 511: 3 1/4" x 3" x 3 3/4" - Pressure Sensor Shipping weight approximately 25 Ibs. Yes - Hand Carry Type 1018 - $2050 Type 511 - $890; Type 521 - $1200 Can be used with pressure sensor types 511 or 521. Panel is provided with a 4 position range switch xl_ xO.l_ x 0.01, x 0.001. Pressure trandsucers for liquid systems require vacuum back-filling with system liquid after connecting the pressure transducer into the system. Pressure differences measured between the pressurized test system and a static reservoir_ indicate the existance of leaks. 30-46 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO.& TRADENAME: RANGES: EXCITATION: OUTPUTSIGNAL IMPEDANCE: ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : WE IGHT: PORTABILITY - PRICE : DELIVERY TIME : REMARKS : Davis Emergency Equipment Co., Inc. (Instrument Division) Catalytic Combustion Combustible gases and vapors. D-6 Vapotester #11-660 2 scale instrument 0-100% LEL of Hexane in air_ 0-10% LEL Battery operated (8 size D cells) Reading on panel indicating instrument Must not be used on pure oxygen No Replacement of batteries and/or filaments when necessary Slightly over 4 ibs. Portable unit $15_ i - 2 weeks Unit calibrated on Hexane. Many different calibration curves are available for interpreting readings of various combustibles in terms of PPM. Accessories available include: various type probe assemblies_ sample dryerj liquid trapj cotton filters 2 fixed and variable dilution valves 3 calibration kit 3 etc. Spare filaments placed in case compartment. 30-47 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES: EXCITAT ION: OUTPUT SIGNAL IMPEDANCE: ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE: WE IGHT: PORTAB IL ITY: PRICE : DELIVERY TIME : REMARKS: Davis Emergency Equipment Co., Inc. (Instrument Division) Catalytic Combustion Combustible gases or vapors D-2 Vapotester #11-410 One - 0-100% of LEL of Hexane in air Zero adjuster simultaneously sets operating voltage. Battery operated (8 size d cells) Reading on panel indicating instrument Must not be used on pure oxygen No Replacement of batteries and/or filament when necessary. Slightly over 4 Ibs. Portable unit $i00 1 - 2 weeks Unit is calibrated on Hexane. Is single filament, single control unit designed for general use. One control knob permits adjustment of meter pointer to zero and simultaneously sets fixed operating voltage across the bridge. Spare filament mounted on filament block. Accessories available include: various type probe assemblies; sample dryer, liquid trap, cotton filters, fixed and variable dilution valves, calibration kit, etc. Model #11-470 can be calibrated for customer's specific gas: 30-48 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: EXCITATION: OUTPUTSI_'RqAL LMPEDANCE: ENVIRONMENTEFFECTS: DOES IT FAIL SAFE: MAINTENANCE : WE IGHT: PORTAB IL ITY: PRICE : DELIVERY TIME : REMARKS : Davis Emergency Equipment Co._ Inc. (instrument Division) Catalytic Combustion Combustible gas or vapors D-I Vapotester #11-325 One_ 0-100% LEL of Hexane in air Separate zero and operating voltage adjustments. Battery operated (8 size D cells) Reading on panel indicating instrument Must not be used on pure oxygen No Replacement of batteries and/or filaments when necessary. Slightly over 4 ibs. Portable unit $105 i to 2 weeks Model #11-326 is calibrated on natural gas. Model #11-327 is calibrated on customer's specified gas. Model #11-325 is calibrated on Hexane. One active and one reference filament are connected in bridge circuit. Zero stability maintained even as the battery voltage decreases. Bridge voltage can be periodically checked and adjusted during long tests_ without disturbing instrument zero. Spare filaments in carrying case. Accessories available include: various type probe assemblies_ sample dryer 3 liquid trap_ cotton filters_ fixed and variable dilution valves_ calibration kit_ etc. 30-49 MANUFACTURER: OPERAT_GPRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME: RANGES: EXCITATION: OUTPUT SIGNAL IMPEDANCE : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : WE IGHT: PORTAB IL ITY: PRICE : DELIVERY TIME : REMARKS : Davis Emergency Equipment Co., Inc. (Instrument Division) Catalytic Combustion and Thermal Conductivity (dual cell instrument) Combustible gases and vapors D-5 Gastester #ii-575 Catalytic - 0 to LEL natural gas Thermal conductivity - 0-100% gas concentration - natural gas Battery operated (8 size D cells) Reading on panel indicating instrument Must not be used on pure oxygen - combustible mixtures. No Replacement of batteries and/or filaments when necessary. Slightly over 4 ibs. Portable unit $157 2-4 weeks Unit is calibrated on natural gas. Scales calibrated on other true gases can be supplied on request. O-LEL scale uses catalytic filaments. 0-100% gas scale operates on thermal conductivity principle. Flashback arrester is built into filament block. Approved by Factory Mutual Laboratories. Unit used for detection and measurement of a true gas in air. Accessories available include: various type probe assemblies_ sample dryer_ liquid trap_ cotton filters_ fixed and variable dilution valves. Calibration kit_ special calibrations on true gases. Spare filaments in case. 30-50 MANUFACTURER: OPERATIONPRINCIPLE: SPECIFICITY: MODELNO. & _"q%ADENAME: RANGES: SENSiTIV iTY: EXC ITAT ION: OUTPUT SIGNAE IMPEDANCE : RE PEATAB ILITY : RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : SIZE : WE IGHT: PORTABILITY: PRICE : DELIVERY TIME : REMARKS : Davis Emergency Equipment Co. 3 Inc. (Inst_ament Division) Flame Ionization Hydrocarbons in air #11-654 Six range factors: 13 103 25_ I00, 250_ i000 Typical full scale maximum sensitivities are: 5 ppm Benzene in air; 20 ppm methane in air; 25 ppm propane in air_ 35 ppm Halocarbon Refrigerant 12 ll5v_ 50/60 Hz Reading on panel indicating instrument 25my dc for external recorder. 2% of full scale Varies directly with sample flow rate. 2-3 secondsj exclusive of external sample transport. Sample requirement: sample in air or with a minimum of 18%. 02 (for exceptions_ contact factory) No Lecture fuel bottle must be replaced when necessary 15" x 16" x 9 3/4" 30 Ibs. Portable unit $1445 --- $1700 with audible alarm 2 - 4 weeks Output signal is function of specific hydrocarbon being detected and rate of combustion of the hydrogen fuel mixture. Hydrogen flame ionizes hydrocarbon molecules_ Sample flow is obtained by internal diaphragm type pump. Sample is drawn directly through the analyzing cell. Has rotameter with needle valve to set sample flow rate through cell. Positive sample pressures of up to 3000 psig can be_- measured by means of optional pressure regulator accessories. Audible alarm is optional. Contains integral flame arrestors for added safety. 30-51 MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : RANGES: SENSITIVITY: EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: SIZE : WEIGHT: PORTAB IL ITY: PRICE : DELIVERY TIME : REMARKS : Davis Emergency Equipment Co., Inc. (Instrument Division) Halide Torch - Flame Color (Electric Arc Halide detector) (Blue lines of copper spectrum in electric arc produced in presence of a halide vapor phototube detects intensity). Halogenated hydrocarbons #11-9000 One 0-50 microamps, converted to 500 ppm using calibration chart. I0 ppm ll0v, 60 Hz Reading on panel indicating instrument 10% full scale accuracy 15" X 16" X 9 3/4" 35 Ibs. Portable unit $715 2 = 6 weeks Halide vapor comes in to contact with the hot tip of a copper electrode and reacts to form a copper halide, which vaporizes at the temperature of the electrode and is carried into an electric arc between two electrodes. The intensity of the blue lines of the copper spectrum produced in the electric arc is continuously measured with a photo- electric photometer using a blue sensitive phototube fitted with a blue glass color filter. The intensity of the blue spectrumls in proportion to concentration of halide vapor present. This is converted to reading on indicating instru- ment. Sample is pumped through a flow indicator, into an arc chamber where analysis is accomplished. It is then dis- charged through a vent at the top of the chamber. 30-52 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB lL ITY: TIME ON MARKET: PRICE : DELIVERY TIME: REMARKS: Dawe Instruments_ Ltd. Sonic - Ultrasonic Range 1873A Ultrasonic Leak Detector Indication only Leaks down to 0.002" dia. at 2 psi can be detected Battery 7.5v Meter indication and headphones Limited by meter response to approximately 0.2 sec. 0°F _ 140°F No Check batteries - internal meter and replace as necessary (150 hours use) i0 years 2" dia. - 13 1/2" long 2 ibs. (I kg) approximately Very portable unit is shaped like a large round flashlight 1 1/2 years 120 (Approximately $265) 3 weeks Unit is supplied complete in carrying case with contact probe - for checking leaky valvesj etc.3 and extension lead. The flat carrying case can be strapped to the chest and the microphone used on the extension lead. This is particularly convenient when large and complex systems are being checked. 30-53 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENS IT IV ITY: EXC ITAT ION: ovrPUT SIGNAL IMPEDANCE : REPEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : The Decker Corporation Pressure change - gas None LT-101 and LT-102 Full range 0. i inches of water differential3 others available Leaks down to i x 10 -4 std. cc/sec, can be detected with I0 sec. test time. llSv, 60 Hz Panel Meter. Relay and 5v dc high impedance 2% Full Scale i sec. to i0 sec. At excitation of 105 to 125v and 60°F to 80°F_ performs within stated repeatability. No Check zero and span daily if required. No specific servicing interval. I0 years 25" x 22" wide x 19" deep 40 to 80 pounds depending on manifolding Can be set on wheeled cart 2 years $3,600 to $6_000 6 to 12 weeks Variations available to conform to customer's requirements. LT-IOI and 102 are fully automated production Leak Detectors 3 with electrically sequenced operation. Adjustable high and low limits give out-of tolerance relay signals and red light reject signal. Optional accessories: recorder 3 counter_ alarm buzzer_ calibration samples_ etc. 30-54 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RANGES : SENS IT IV ITY: EXC ITAT ION: RE PEATAB ILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: PORTAB iL ITY: REMARKS : Devco Engineering, Incorporated Thermal Conductivity #MHA 40 Single or multiple available Under proper design conditions and operating temperature, sensitivity of I ppm or lower can be achieved. llSv, 60 Hm ±2% of full scale for most applications Detection within approximately I0 seconds. Deflection of 90% of final reading within approximately 30 seconds. Presence of more than 2 _ases can affect accuracy. No Is not portable - installed at site. Units are usually designed for required sensitivity to detect percentage concentration of bi-gaseous mixtures. Highest sensitivity is obtained when the 2 constituent gases vary greatly in thermal conductivity. Various dc readout instrumentation available. Units are basically monitoring units for either gases or vapors. 30-55 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : RANGES : EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE : RE PEATABIL ITY: RESPONSE TIME : DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY: WE IGHT : PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : Devco Engineering, Inc. Thermal Conductivity Selectivity to specific gases can be achieved with suitable filters. MHA-90 Typical 20 PPM H2S , others available. llSv ac, 60 Hz Meter, recorder 0.5% full scale 90% in 5 sec. Yes Check span every 60 days Contingent on maintenance. Depends on design No 15 years $1200 to $5000 60 days 30-56 MA_FACTURE: OPERATINGPRINCIPLE: SPECIFICITY: MODELNOo & TRADENAME: RANGES: SENSITIViTY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: RESPONSETIME: ENVIRONMENTEFFECTS: DOESIT FAlL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABIL ITY: PRICE: DELIVERYTIME: REMARKS: Devco Engineering, Incorporated Tracer - Halogen Halogen gas #FB23-A One 0.02 oz./yr. Arcton (dichlorodifluoromethane) 115 or 230v, 60 Hz Flashing lamp Almost instantaneous Test area should be free of halogen contamination. Exposure to high concentrations of halogen gases tends to desensitize sensing element. No Whenevernecessary - no specific servicing interval Determined by exposure of sensing element to de- sensitizing agents. 8" x 3 1/2" x 5" 6 3/4 Ibs. Canbe hand carried $345 From stock Unit must be regarded as "naked flame" and must not be used in presence of inflammable vapors. 30-57 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENS IT IVITY: EXCITAT ION: OUTPUT S IGNAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT : PORTABILITY: PRICE : DELIVERY TIME : REMARKS : Devco Engineering, Incorporated Tracer - Halogen Halogen gas #FB24 Two (X5 range switch) 0.02 oz./yr. Arcton (dlchlorodlfluoromethane) II0/120v3 60 Hz or 200/250v, 60 Hz Output meter 0-I0 flashing lamp and speaker Almost instantaneous Test area should be free of halogen contamination. Exposure to high concentrations of halogen gases tends to desensitize sensing element. No Whenever necessary - no specific servicing interval Determined by exposure of sensing element to de- sensitizing agents. 9 1/2" x 8 1/2" x 7 i/2" 20 ibs. Can be hand carried $975 4 - 6 weeks Unit must be regarded as "naked flame" and must not be used in presence of inflammable vapors. Sensing head is connected to the main instrument by cable, hence providing greater ease in probing for leaks. 30-58 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGE S : SENSITIVITY: RESPONSE TIME: ENVIRONMENT Effects: MAINTENANCE : LIFE EXPECTANCY: S ZZE : WE IGHT : PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME : REMARKS : Dragerwerk-Lubeck (West Germany) Scott Aviation, Lancaster (U.S. distributor) Chemical Indicator - Reagent Reagent type detector tube chosen for specific gas of interest. Available for detecting about I00 different vapors and gases. Scott/Draeger Model 21/31 multi-gas detector Depends upon gas of interest. For most common gases several different tubes available_ each with different range. Depends upon gas of interest. Some tubes sensitive to as little as 0.i ppm_ others range to 250 t000 ppm. Depends upon number of strokes of hand-pump required for specific tube being used. Performance not effected by temperature or humidity changes. Replacement of rubber parts in pump recommended annually. Infinitej if rubber parts periodically replaced Can be held in one hand Pump alone - 1 lb. Pump with carrying case - 4 lb. 4 oz. Furnished with carrying case 6-3/4" long. 5" wide 5-3/4" deep. More than i0 years Pump with carrying case $95.00. Tubes vary depending on type_ average $6.50/pkg. of i0 tubes. Tubes most commonly used available immediately from stock. Types less frequently usedj i to 2 weeks. Unit uses a 1-hand operated bellows type pump to draw gas through a reagent type detector tub% in which the reagent changes color if the gas of interest is present in the specimen. Tubes are marked with a direct reading scalej the quantitative reading being determined by the length of the stain. 30-59 --i_ MANUFACTURER: OPERATING PRINCIPLE: MODEL NO. & TRADENAME : EXCITATION: OUTPUT SIGNAL IMPEDANCE : DOES IT FAIL SAFE: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS : Eastern Laboratories_ Inc. Bubble (Liquid Applicant) "Bubble-Coat" Non e Visual - Bubble (foam) formation at leak No 8 ounces; 1 gallon; 55 gallon Up to 500 Ibs. Yes 8 years 8 oz. size - 70¢ to $I depending on the formulation Immediate Some solutions useful to -65°F. Non-toxic_ non-corrosive 3 odorless, non-irritating_ non-flammable and meets MIL-L 25567A spec. 30-60 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENS ITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : S IZE : PORTABILITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Edwards High Vacuum_ Inc. lon Gauge (with palladium window) Hydrogen Model LT4A with PL2 detector head Five 1 x 10-7 torr liter/sec. 100-125 v 50/60 Hz or 200-250v 50/60 Hz. Visual indication as indicating instrument and also audible leak indicator. Detector head- 9 5/16" long x 2 1/4" dia. Control unit 19" wide x I0 1/2" high x approximately 16" deep. No 5 years $1145 (for Model LT4A control unit with PL2 detector head) 6-8 weeks. Highly evacuated hot cathode ionization gauge detector, in detector head is isolated from the pumping system by means of a palladium metal barrier which also acts as the detector anode. During operating the palladium anode is heated to red heat by electron bomardment, at which temperature it becomes permeable exclusively to hydrogen. Hydrogen 3 applied to a lea_ passes through the hot palladium anode into the detector head where it is ionized_ changing the ion current. This change is amplified by the control unit (LT4A) and indicated on an indicating instrument. Indication is compared to indication caused by calibration of unit using calibrated reference leak. Control unit has overload relay which switches off detector head power if ion current becomes excessive. Hand held leak indicating instrument available as an accessory. 30-61 --i_ MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENS IT IVITY: EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE : SIZE: WE IGHT: PORTAB ILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Edwards High Vacuum, Inc. Thermal Conductivity Vane Model LT6B with remote hand Four 1 x 10 -5 tort liter/sec. 100-130v or 200-260v 60 Hz Visual on panel indicating instrument and audible leak indicator. Main unit - 13 3/4" wide x 7 3/8" high x 8 1/2" deep. Remote hand unit-body length 9 1/2" x approximately 2" diam. with 4 3/4" tube type probe. Main unit - 16 1/2 ibs. Remote hand unit 3 1/2 ibs. Is portable 5 years $650.00 (for main unit with remote hand unit) 6-8 weeks. Wide range of search gases can be used, but best results are obtained with gases whose thermal conductivities differ most from air, such as hydrogen or helium. The leak test unit connected to the system under test, detects leaks covering all pressure states, from vacuum to positive pressures. System being tested is partially or totally enclosed by a bag filled with a search gas or the outside can be sprayed with the search gas, Use of the remote hand unit, which is connected to the main unit, enables testing of pressurized vessels or pipelines. The hand unit has a built-in fan which draws leaking gas through its probe and into a chamber containing a heated filament. Cooling effect of leaking gas is compared as a change of resistance with the cooling effect of the surrounding atmosphere on another filament. Resistance difference indicates a leak by instrument indication and change in loudspeaker tone. 30-62 MAN_JFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIV!TY: EXC iTAT ION : OVrPL'r SIGNAL LMFEDANCE : E._iRONMENT EFFECTS : DOES IT FAlL SAFE: MAINTENANCE: SIZE : WE !GHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Edwards High Vacuum Inc. Mass Spectrometer - (180 ° Sector Field) Gas selection switches makes it suitable for Helium3_ Heliumd, Hydrogen and Argon. Model 8A i0 Ranges, 10-2 tort liter/second-maximum 10 -12 torr liter/second, varies with ranges 115 or 220 v, 60 Hz Both audible and visual (speaker and panel instrument) Designed for: 50°F to 95°F No Check mechanical and diffusion pump oll electrical checks spelled out in working instructions. 29" wide, 22-3/4 deep, 38" high 320 ibs. Main unit mounted on 4 casters, readout indicator unit is hand carry type. 2 years $4,800.00 stock Filament is protected both electrically and mechanically with large LN 2 trap. Fully demountable portable unit gives operator local control. 30-63 -.-l_ MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION : OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS: Electronic Associates, Inc. Mass Spectrometer - Quadrupole (RGA) All gases I -150 amu QUAD 150 I - 150 1 x 10"15 torr for N 2 115 v, 60 Hz, 6 amp 1 _a to i00 ma/l meg ohm 5_ I00 milliseconds Detector from 15°K to 250°C Console from 0°F to 125°F No No specific program required I0 years Head: 6 diam. by 10" long; Electronics: 19" x 8 3/4" 150 Ibs. Yes 18 months $7_950 4 weeks Special systems available to meet customer requirements_ including integrated vacuum systems_ process control 3 etc. Quadrupole assembly is bakeable at 400°C. 30-64 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSETIME: ENVIRONMENTEFFECTS• DOESIT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: REMARKS: Electronic Associates 3 Inc. MassSpectrometer - Quadrupole (RGA) All gases 1-500 amu QUAD250 I- 50; I0 - 150; 50 - 500 1015I x tort for N2 llSv, 60 Hz, 6 amp I _a to iO0 ma/l megohm 5Z I00 milliseconds Detector from 15°K to 250°C Console from O°F to 125°F No No specific program required i0 years Head: 6" diam. x I0" long; Electronics: 22 1/2" x 25 1/2_' x S0" 500 Ibs. Yes 3 years $13,635 4 weeks Special systems available to meet customer requirements, including integrated vacuumsystems, process control, etc. Quadrupole tube is bakeable to 400°C. 30-65 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES : SENS IT IVITY: EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE : REPEATAB IL!TY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE: WE IGHT: PORTAB ILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Erdco Engineering Corporation Catalytic Combustion Combustible Gases 05HCS - TOX-EX 0-100% LEL, 0-10% LEL 5% full scale Battery operated 3 2D Cells, 2 #228 cells for audible alarm. Visual reading plus audible alarm 5Z Less than 3 seconds with 25' hose. Temperature Compensated No 9 Months 5 years 9" x 2 3/4" x 3 1/2" 40 ounces Hand carried portable 1 1/2 years $183.50 complete with handle Stock item. Detects combustible gas leaks - electrically differentiates methane from petroleum vapors. Accessories include sampling hose, calibrator. Can be purchased with Ni-Cad rechargeable batteries. Gas sample can be admitted by diffusion or by aspirator bulb. 30-66 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABIL ITY: RESPONSETIME: DOESIT FAlL SAFE: MAL_TENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABiL ITY: TIMEONMARKET: PRICE: DELIVERYTIME: REMARKS: Erdco Engineering Corporation Catalytic Combustion Combustible Gases 03HCS- TOX-EX 0-100%LEL 5%LEL Battery operated - 2 D Cells Visual reading on indicating instrument 5% Less than 3 seconds with 25' hose No 9 Months 5 years 8" x 1 3/4" x 3" 28 ounces Hand carried portable 2 years $75.00 Stock item Detects combustible gas leaks - electrically differentiates methane from petroleum vapors. Accessories include sampling hosej dilution valve for reading concentrations above LEL. Can be purchased with Ni-Cad rechargeable batteries. Gas sample can be admitted by diffusion or by aspirator bulb. 30-67 ---l_ MANUFACTURE R: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENS IT IVlTY: EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME ." DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Erdco Engineering Corporation Catalytic Combustion Combustible Gases 06HCS - TOX-EX 0 - 100% LEL 5% Battery operated - 8D Cells Visual reading on indicating instrument 5% Less than 3 seconds with 25' hose. No 9 months 5 years 6 - 3/4 " x 5 - 7/8" x 3 - 1/4" 4 ibs. Neck strap portable 3 months $i10.00 Stock item Detects combustible gas leaks - electrically differentiates methane from petroleum vapors. Accessories includeseml-rigia nylon tube probe and a calibrator. Model 06HCS is fully illuminated for unlighted areas. Gas sample can be admitted either by diffusion or by aspirator bulb. 30-68 M_NLTACT'JRER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : SENSITIVITY : EXCITATION : OUTPUT SIGNAL IMPEDANCE : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS: Euphonies Industries, Inc. Sonic - Ultrasonic Range El-100 Leak Detector (The Elwood Corporation is the sole distributor) A function of pressure, orifice_ and detection distance. 9 volt battery (standard transistor radio type) Audio, 2000 Ohms (earphones) Uneffected by the normal variations of humidity and temperature. No None with the exception of battery change. I0 years 9" long and 1 1/2" diameter. 1 3/4 pounds in the carrying case, 9 ozs. without case. Hand held instrument One year $115.00 From stock Ultrasonic sound is converted to sonic range and detector by earphones. Leaks can be detected at a distance. 30-69 MANUFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADENAME: OUTPUTSIGNAL IMPEDANCE: SIZE : WEIGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME: REMARKS : Excelsior Varnish, Inc. Bubble (Liquid Applicant) Excelsior Leak Finding Compound Bubble Packaged in 55 gal. drums, 30 gal. 1/2 drums, 5 gal. pails 8 1/3 pounds per gallon concentrated Applicator can be hand carried 26 years Depends on quantity purchased Orders shipped in 24 hours Is diluted with equal amount of water. Covers 1,000 to 1,500 square feet to the gallon after reduction. Will not clog small holes. Will not freeze or deteriorate in the package. Will not harden or cake in hot weather. Apply over welded metal surface then use 3 to 5 pounds of air pressure to the opposite side for long lasting bubbles that show up leaks. Quickly rinses off with clear water. 30-70 MANUFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADENAME: RANGES: SENSITIV!TY: EXCiTATION: OUTPUTSIGNAL LMPEDANCE: REPEATABILITY: ENVIRONMENTEFFECTS: DOESIT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTAB!L ITY: TIMEONMARKET: PRICE: DELIVERYTIME: REMARKS: Fisher ResearchLaboratory, Inc. Sonic - Sonic Range WM,"Master Electronic Witch" 4 ranges 32db full scale to I00 db full scale. Battery operated (9v de) Visual and audio (2000_ earphones) Good Input voltage should be within ±10%, temperature range - -20°C to + 60°C No Mainly dependson battery life, approximately 2000 hrs. of operation. i0 years 15 1/2" x 9 1/2" x ii 1/2" 20 Ibs. Canbe hand carried 4 years (transistorized model) $395 F.O.B. Palo Alto Stock item Vibrations in frequency range of 40 to I0,000 cycles are detected and amplified. This unit is a leak detector and pipe finder combination. Chiefly used for locating pipe leaks principally in oil and water systems. 30-71 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RANGE S : SENS ITIV ITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Fisher Research Laboratory Sonic - Sonic and Ultrasonic range LT-10 30 Hz to i0 kHz. Tunable filter zero - in desired frequency Low position 32 db, mid position 55db, hi position 85 d5 9 volts dc internal battery Audio signalj panel meter Speed of sound Temperature -20°C to +60°C. Input voltage ±15%. No Battery replacement, approximately 300 hrs. of operation Under normal instrument care 5 yrs ii" x 7.12" x 3.25" Operating weight - complete 4.5 Ibs. Sturdy leatherette carrying case with compartment for accessories. Transistorized model 6 yrs. Tube model over 30 yrs. $199.50 In stock High gain audio amplifier with sonic transducer as pick-up probe. Detecting vibration of escaping liquid through an irregular orifice. Designed primarily for locating fluid leaks in water and oil systems. Exclusive tunable filter circuit to pinpoint exact leak frequency, eliminating other noise sources. Also broad position for preliminary detection. Very good portability and compactness. 30-72 MANUFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: RESPONSETIME: ENVIRONMENTEFFECTS: DOESIT FAIL SAFE: MAINTENANCE• LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE : DELIVERY TIME : REMARKS : Fisher Research Laboratory Sonic - Sonic and Ultrasonic range LT-15 30 Hz to i0 kHz-nine frequency filters Four sensitivity ranges - Xi-32db X2-52db X3-81db X4-110db. 9 volts dc internal battery Audio signal. Panel meter. Speed of sound through the ambient Temperature 20°C to +60°C. Input voltage ±15%. No Battery replacement after approximately i000 hrs. of operation. Under normal instrument care, 5 years 12" x 8" x 5" Operating weight 7 ibs. Sturdy leatherette carrying case with compartment for accessories. Transistorized model 7 yrs. Tube models over 30 yrs. $395 with carrying case and complete accessories In stock High gain audio amplifier with sonic transducer as pick-up probe. Standard accessories: stainless steel-varlable length extension rods, ground sound plate, various type attachments for the crystal pick-up, transducer, headphones, extension _: cables. Designed primarily for locating leaks in fluids. Nine position narrow band filter, four sensitivity ranges and FINE tuning sensitivity control. 30-73 -_-L_ MANUFACTURER: OPERATING PRINC IPLE : MODEL NO. & TRADENAME : RANGES : SE NS IT IV ITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Fisher Research Laboratory Sonic - Ultrasonic range GT-4 36kHz to 44kHz Will detect a leak through hole of a .006" of I psi at distance of 5 ft. 9 v dc internal battery Audio signal_ optional panel meter Speed of sound Normal operation temperature -20°C to +60°C. Input voltage ±15%. No Battery replacement 150 - 200 hrs. Under normal operating conditions 5 yrs. 6" x 2.5" x 1.25" 12.5 oz. Pocket size. Can be attached on a belt. 4 years $149.50 In stock Detects vibrations of gas pressure or vacuum leaks in ultrasonic frequencies and converts the same to audio range. Sensing probe has conical dire6tivity of 22 °. Can be used to detect leaks in pressure or vacuum systems (especially checking pressurized telephone or power lines). Unit does not respond to ambient noise. Pressure leaks can be detected from a distance in excess of 50 ft. Contact probe optional. 30-74 MANUFACTUPFR: OPERATINGPRINCIPLE: MODELNO. & TRADENAME: RANGES" SENSITIV ITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: RESPONSETIME: ENVIRONMENTEFFECTS: DOESIT FAlL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: REMARKS: Fisher ResearchLaboratory Sonic - Ultrasonic range GT-5 36 kHz to 44 kHz Will detect a leak through hole of .006" of i psi at distance of 5.5 ft. 9 volts internal battery dc. Audio signal (speaker or headphones)_panel meter Speedof sound Normal operation temperature -20° to + 60°C. voltage ±15%. Input No Battery replacement after 750-800 hours of service. Under normal operating conditions 5 years 9" x 5.5" x 4.75" 5 ibs. including probe and battery. Can be hand carried. 4 years $395 In stock Detects gas pressure or vacuum leaks in ultrasonic frequencies and converts the same to the audio range. Sensing probe has conical directivity of 22 °. Can be used to detect leaks in pressure and vacuum systems (especially checking pressurized telephone and power lines). Unit does not respond to ambient noise. Pressure leaks can be detected from a distance in excess __ of 50 ft. Contact probe optional. 30-75 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADE"NAME : RANGES : SENSITIVITY: EXCITATION : OUTPUT SIGNAL IMPEDANCE: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS: Fisher Research Laboratory S_nic - Sonic range AS "AUDIO-SCOPE" Audio ranges of 30 Hz to I0 kHz 80 db_ controlled by the sensitivity knob 9 v dc Audio signal - headphones Speed of sound Normal operation temperature -20°C to +60°C. Input voltage +15%. No Battery replacement after approximately 700 hrs. of operation. Under normal instrument care 3 5 years Length 5" diameter 3" ii oz. Pocket size 5 years $67.50 including headphones and 6" contact rod In stock Transistorized amplifier_ self-contained vibration and leak detector. Detects vibration of escaping fluids. Ground sound plate-optio.al. Carrying case-optional. 30-76 MANUFACTURER: OPERATING PRINCIPLE: MODEL NO. & TRADENAME: OUTPUT SIGNAL IMPEDANCE: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS: Flamort Chemical Company Bubble (Liquid Applicant) Detect-A-Leak Visual (bubbles) 8 oz. can with brush attached to cap. Carton of 12 - 8 ozs. cans. 9 3/4 Lbs. Yes 12 years $12.60 per carton of 12 - 8 oz. cans; I gal. $4.80. From stock Can be used safely on rubber, plastic or any type of metal. It is non-corrosive and non-inflammable. 30-77 _-t_ MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: ENVIRONMENT EFFECT: REMARKS : Flow Technology, Inc. Flow Sensor Any gas or liquid FTL series Liquid: 0.001 to 0.I gpm Gas: 4 to 4000 cc/min. 24 v dc (isolated) Voltage pulses (50 my) i to 500 Hz proportional to flow rate. 0.1% of full scale. Normal: -20°F to +165°F Available: -430°F to +550°F Unit is a turbine type flowmeter. 30-78 MANUFACTURER: OPERATINGPRINCIPLE: MODELNO.& TRADENAME: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: RESPONSETIME: ENVIRONMENTEFFECTS: DOESIT FAIL SAFE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: REMARKS: Fluid Data Inc. Sonic-Ultrasonic range Model UD-100"Leakdata" Dependson distance between location of leak and testing point. 4.5 v dc battery I0 mwin 600 ohmheadphone Speedof sound Over normal temperature and humidity - slight range variation. No Batteries have 500 hours life. Electronics 4" X 8" X 2" - Probe (hand held) 1 1/2" diam. X 6" long. 3 Lbs. Yes Year About $200.00 2 - 3 weeks Solid state electronics. 30-79 --t_ MANUFACTURER: OPERATING PRINCIPLE : MODEL No. & TRADENAME : RANGES : EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE : ENVIRONMENT EFFECT9: WE IGHT: The Fredericks Company Ion Gauge (hot filament) MODEL 3A-5 "Televac" 10-3 to 2 x 10 -9 torr in 5 ranges l15v_ 60 Hz Indicating panel instrument and a "null balance" type recorder. Output from 0 to Iv (normally factory set at 10my full scalel; Power supply is regulated to compensate for llne voltage variations from 95 to 130v. Approximately 45 Ibs. 30-80 MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : RANGES : OUTPUT SIGNAL L-MPEDANCE: SIZE: PORTABILITY: Galaxle Products Bubble (Liquid Applicant) None I-SPY LEAK DETECTOR Minus 10°F to +212°F Visual - bubble formation at the leak 4 oz. and 8 oz. polyethylene squeeze bottles. plastic container Yes i gallon 30-81 MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENS ITIVITY: EXC ITAT ION : OUTPUT SIGNAL IMPEDANCE : RE PEATA BIL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: S IZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Gas Analysis Systems, Inc. Thermal Conductivity High signal response to all co,=nonly used non-corrosive pressurizing or contaminating gases and vapors. LC-5 Continuous attenuation (manual control of gain) i x 10 -5 std. - cc/sec, helium in air ** llbv 60Hz or Type 'C' flashlight batteries Visual 0-i00 relative signal Approximately ± 10% Approximately I second Ambient temperature_ flow rate and background gas composition changes can be nulled out instantaneously. Yes No specific servicing intervalj (except battery replacement).v 5 years 3 1/2" x 4" x 9" - with 4' sample pick-up hose and probe @ 4 ibs. Can be hand carried or suspended by neck strap 2 years - (this instrument series introduced 6 years ago). $165.00 Shelf stocked This instrument was designed for quickly checking leaks in pressurized piping or tanks and possible contaminated areas for toxic or non-toxic concentrations. Vacuum systems can be checked by temporarily pressurizing at i psig. ** Interchangeable bases are available. 30-82 MANUFACTURER: GasPurifying Materials Co., Inc. (Instrument & Equipment Division) OPERATINGPRINCIPLE: Catalytic Combustion Thermal Conductivity Dual Cell Instrument SPECIFICITY: MODELNO. & TRADENAME: Combustible gases and vapors. Conductivity. #GPM"Vaporgraph" Inert gases by Thermal RANGES: Catalytic 0-0.1% Natural Gas Combustion 0-1.0% Natural Gas 0-5.0% Natural Gas Thermal Conductivity 0-100%Natural Gas EXCITATION: Nickel Cadmiumbatteries with built-in charger (ll0v ac) OUTPUTSIGNAL IMPEDANCE: dc mv output proportional to concentration - recorder available. REPEATABILITY: -+ 1Z RESPONSE TIME: I second ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: Compensated for temperature and humidity variations. No MA INTE NANCE : Operation check using known standard when necessary. LIFE EXPECTANCY: Indefinite SIZE: 3" x 6" x 8" WE IGHT: 7 pounds with battery PORTABILITY: Portable unit TIME ON MARKET: 2 years PRICE : $360 DELIVERY TIME: 3 - 6 months REMARKS : Automatic sampling by steady flow diaphragm pump. Standard Ranges: 0 to 1.0%; 0 to i00% natural gas. Additional Ranges Available: 0 to 0.1%; 0 to 57_ natural ga_l Special Ranges available to suit application. Options include: Outlets for recorder and alarm and dc power supply. * 5% natural gas is LEL. 30-83 -_-t_ MANLTA CT_JRER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY : EXCITATION : Ob"I_UT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WEIGHT : PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Gas Purifying Materials Co., Inc. Thermal Conductivity and Catalytic Combustion Gas and vapor detection is positive by separation by gas chromatography - Air carrier for atmospherics ANALOGRAPH For combustible vapors and gases can read from 1 ppm to 100%. Four filament bridge permits I PPM and upper PPB detection. I00 - llSv, 60 Hz or battery Millivolts or microamps - low impedance _1% of output 1/2 second to several minutes - totals immediate Temperature compensated by balanced bridge circuit. Can be installed if requested - hi-lo limits alarm Indefinite - monthly check suggested Indefinite 6" x 6" x 8" I0 pounds without batteries 14 Ibs. with batteries Portable unit One year $1200 4 months Each unit is constructed to suit the specific requirements of the purchaser for example modifications can be made to sense sulfur dioxide, hydrocarbons, gases, etc. Concen- tration sampling can be installed. Diaphragm pump draws in sample if necessary. Recorder outlet and power failure alarm optional. 30-84 MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : SIZE : WE IGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Gas Purifying Materials Co., Inc. Equipment Division) (Instrument & Catalytic Combustion Thermal Conductivity Reagent (colorimetric) Triple Cell Instrument Catalytic - combustible gases and vapors Thermal Conductivity - inert gases Reagent reactive and low concentrations toxic components ( Mercaptans Propylene, Co.) #GPM "Odorgraph" Catalytic Combustion 0-0.1% Natural Gas 0-1.0% Natural Gas 0-5%* Natural Gas Thermal Conductivity 0 to 100% Natural Gas Colorimetric Reagent Tube 0 - i00 ppm 0.1% full range Nickel Cadmium batteries with built-in charger (llOv ac). dc my output for catalytic and thermal conductivity cells. ± 1% Electrical - i second Colorimetric - i minute Compensated for temperature and humidity variation. No As needed. 3" x 6" x 8" 7 pounds with battery Portable unit 6 years $360 3 - 6 months Automatic sampling by steady flow diaphragm pump. Standard Ranges: 0-1.0%; 0-100%; 0-i00 ppm Natural Gas. Additional Ranges available: 0-0.1% and 0-5%* Natural Gas. Special Ranges available to suit application. Options include: dc power supply, recorder outlet and alarm outlet. * 5% natural gas is LEL. 30-85 _-L- MANUFACTURER: OPERATING PRINCIPLE: MODEL NO. & EXCITATION: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS: MAINTENANCE : LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME : REMARKS : George W. Gates & Company, Incorporated Chemical Indicator - Fluorescent Dye GPC Water Soluble Fluorescing Agent -SGA Oil Soluble TFS4-Bg0 Raymaster Battery operated 2-45 volt B batteries for "black light" lamp Bright glow of fluorescence under rays of exploring lamp. Glow can be seen at once. Darkened area for best results - no changes Depends on care and usage. Determined by usage Battery unit 4 1/4" x 5 1/2" x 8" Lamp unit 3 1/4" x 6 1/2" x 1 3/4" Battery unit Ii Ibs. Lamp unit I lb. Can be hand carried 15 years $37.00 for "Raymaster" unit - $5.50/Ib. water soluble fluorescing agent - $13.00/Ib. oil soluble fluorescing agent. 3 to 4 days Non-corrosivej non-toxlc-dffferent fluorescing agents available for customers requirements. Agent is a dry powder and is diluted in liquid in system to be leak tested. GPC agent is for water dilution. 5GA agent is for oil dilution. Detection equipment is for liquid leaks 3 not gas or vapor. 30-86 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADE NAME : OUTPUT SIGNAL IMPEDANCE : DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY : SIZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : General Air Products Corporation Pressurized (CO2) - frosting of atmospheric moisture Test-King Pressure gage, audible signal and visual observation of frosting of moisture in the area of a leak. Yes Tank requires periodic recharge with CO 2 20 to 30 years 25" x 6 3/4" 40 ibs. Can be hand carried 15 years $90.00 2 weeks Test system is connected to regulator of pressurized CO 2 tank. Tank may be removed for recharging or for use elsewhere while leaving system being tested under pressure. Detects leaks by frosting of atmospheric moisture. Provides an audible leak signal and a system pressure gage. Meets all Interstate Commerce Commission regulations. 30-87 MANI/FACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME: RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME : General Electric Company, Instrument Department Tracer - Halogen Halogen Gas Type H-II Serviceman's Leak Detector One 0.5 oz./yr. R-12 1,25 v3 7 ampere-hour rechargeable battery Change in flashing rate of neon probe lamp. Good - built-in reference leak prov[des check on accuracy. Approximately i second DOES IT FAIL SAFE : MAINTENANCE : ENVIRONMENT EFFECTS: (2) 32°F to 136°F (0°C to 58°C) operating range 32°F to 104°F (0°C + 40UC) charging range must avoid corrosive fumes and salt spray No As required - normally only new sensing element need be replaced. LIFE EXPECTANCY: Determined by usage SIZE: Detector 8 1/2" x 4 5/8" x 3 1/2" Charger 4" x 4" x 2 3/4" Detector - 3 Ibs. - Charger - 2 ibs. Can be hand carried i year (1) - $130.00 Available from stock - sold through air conditioning and refrigeration distributors (wholesalers), REMARKS: (I) Unit furnished as one package, including detector and charger. (2) Unit must not be used in presence of flammable vapors. WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: 30-88 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE : WE IGHT: P ORTAB IL ITY: TIME ON MARKET: PRICE : REMARKS : General Electric Companyj Instrument Department Tracer - Halogen Halogen gas. Type H-10 Two High sensitivity range - 0.5 oz./yr. R-12 Low sensitivity range - 1.0 oz./yr. R-12 iI0-127v_ 60 Hzj 15w Change in flashing rate of neon probe lamp. Good Approx. I second 32°F to l13°F (0 to 45°C) operating temperature range. Must avoid corrosive fumes and salt spray. No As required - normally only new sensing element need be replaced. Determined by usage. 4 1/2" W x 2 5/8" H x 8 9/16" L 3 ibs. Can be hand carried. Approximately 1 1/2 years $90.00 Above information is for Type H-10 leak detector. Units must not be used in presence of flammable vapors. 30-89 -j__ MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCE: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: REMARKS : General Electric Companyj Instrument Department Tracer - Halogen Halogen gas Type H-2 I0 ranges covering span from I0 x 10 -5 std. cc/sec, to 3 x 10-9 std. cc/sec full scale. Maximum 1 x 10 -9 std. cc/sec. (6 x 10 -6 oz./yr.) R-12 120v or 240v, 60 Hz, 100w Amplified signal read-on control unit indicating instrument and indicating instrument on detector unit. Also audible signal. Good if environmental conditions are kept constant. Temperature range: 32°F to 131°F (0 to 55°C) - Air velocity not to exceed 10 mph. No signs of corrosion after 16 hours, 90_ relative humidity at 40°C. Exposure to high concentrations of halogen gases tends to desensitie sensing element. No Whenever necessary - no specific servicing interval. Determined by use and exposure to desensitizing agents 20" W x 14" H x II" D (These are control unit dimensions used with various detectors.) Control unit 15 ibs., detector units 1 to 2.51bs. Can be hand carried Latest model - approximately 3 years older models - approximately 15 years. Control unit $770. Detector unit - $345. Calibrated leaks, capsules and leak standards are available for quantitatively calibrating units. Must not be used in presence of flammable vapors. 30-90 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: General Electric Company, Instrument Department Tracer - Halogen Halogen gas Model H-5P I0 ranges covering span from I0 x 10-5 std. cc/sec, to 3 x I0_9 std. cc/sec, full scale. Maximum i x 10 -9 std. cc/sec. 120v or 240v, 60 Hzj lO0w Amplified signal read on control unit indicating instrument. Also audible signal. Good i second. Temperature range: 32°F to 131°F (0 to 55°C). Air velocity not to exceed I0 mph. No signs of corrosion after 16 hoursj 90% relative humidity at 40°C. Exposure to high concentrations of halogen gases tends to de- sensitize sensing element. No Whenever necessary - no specific servicing interval. Determined by use and exposure to desensitizing agents. 20" W x 14" H x II" D (These are control unit dimensions used with the various detectors.) Control unit 15 ibs. Detector units I to 2.5 ibs. Can be hand carried. Latest model - approximately 3 years. Older models - approximately 15 years. Control unit - $770. Detector unit - $345. REMARKS : Calibrated leaks 3 capsules and leak standards are available for quantitatively calibrating units. Must not be used in presence of flammable vapors. 30-91 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO.& TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: RESPONSETIME: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: TIMEONMARKET: PRICE: DELIVERYTIME: REMARKS: General Electric Company,Materials Engineering Laboratory, Researchand DevelopmentCenter Particle Detector. Gasesand vapors converted to particles type CNC(condensation nuclei counter). Selectivity is possible with the use of specific chemical converters. "Condensation Nuclei Counter" Cat. No. I12L428. Eight Varies with gas or vapor. Examples: Halocarbon refrigerants 12-21 = 2 PPM; Sulphur Dioxide - 0.001PPM; Unsyn_netrical dimethylhydrazine = 0.i PPM. l15v, 60 Hz, 220 watts. (llSv, 220v, 50 Hz units available) Panel instrument: Provision for Recorder (1500 ohms) Outputs: 0-I madc, 0-i0 mv dc, positive above ground. 2 seconds as particle detector, order of 2 to 5 seconds as gas detector. Lubricate sleeve valve every 2000 hours, clean detector chamber and optics as needed. Clean prehumidifier - period determined by nature of gas to particulate conversion. i0 years Cabinet 22" W x I0" H x 20" deep 127 ibs. 6 years $4800 less conversion units 8 - I0 weeks I. Typical gases detected: nitrogen dioxide - ammonia - chlorine unsymmetrical dimethylhydrazine - phosgene 2. Automatic range changer available with or without recording devices. 3. Similar detectors have been engineered for shipboard and aircraft use. 4. Gas converters are not required for materials such as carbonyls - which produce airborn conversion particles directly. 30-92 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE : WEIGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : General Electric Company - Vacuum Products Business Section Mass Spectrometer Helium 22LC010 & 22LC020 (Includes automatic roughing station) 4-position decade switch to provide ranges of xlj xl03 xl00, xl000. 2x10 "II std cc/sec (22LC010 - 120vj 7 ampsj single phase 60 Hz (50 Hz units are (22LC020 - 120v I 15.4 amps_ single " " available) Panel meter Less than 1 second Units will operate within stated specifications over temperature range 40°F to 120°F, up to 100% RH and within range of 105 and 125 volts. Yes Check sensitivity perlodlcally--occaslonally pump belt replacementj pump oil changej and cleaning--no specific service interval. I0 years 34" H x 25" W x 28" D with 4.8 sq. ft. work surface. 22LC010 is approx. 190 Ibs. 22LC020 is approx. 345 ibs. Mounted on 4-fully swiveling casters. 3 years $3,850 to $5,225 i week Accessories such as standard calibrated leak inlet port adaptorsj sniffing probej helium jet audible alarm and base plate and bell jar attachment are available. Also models are available with mounted I0 cfm 7 15 cfm mechanical roughing pumps in place of the scfm pump normally supplied in the 22LC020. 30-93 MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION : OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: General Electric Company - Vacuum Products Business Section Mass Spectrometer Any gas or vapor having molecular weight in range 1-600. 22MS-I00 8 ranges of Keithley picoammeter Depends on application and probe gas. 115 v, 15 amps, 60 Hz (bakeout ovens 230 v, 115 amps, 60 Hz) Meter display on electrometer, fast response recorder, oscilloscope optional. tbz Depends on sensitivity range - as fast as I millisecond. Line voltage between 105 and 125 v. Can be with options. Quarterly I0 years Control console: 84 x 22 x 24 Analyzer console: 72 x 22 x 28 1450 ibs • Both units mounted on 4 fully swiveling casters. Since March, 1967 $24,500 + accessories Stock to 60 days 30-94 MANUFACTURER: General Electric Company- VacuumProducts Business Section OPERATINGPRINCIPLE: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: RESPONSETIME: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: MassSpectrometer Monopole#600 1 to 600 AMUin a single massrange Minimumdetectable partial pressure: I x 10"14 tort (N) or lower, e I05-125V, 50/60 Hz, 2 amps. Panel meter calibration in mass number. Optional readout: Electrometer with recorder and/or oscilloscope. Slow scan time: I0 to 40 minutes for 1 to 600 AMU. Fast scan time: 50 milliseconds to 250 seconds for i to 600 AMU. 22" H x 19 3/4" W x 19" D Console: 115 Ibs. Monopole Tube 6 Ibs- Yes Marchj 1967 Control Unit - $8000; Analyzer tube - $4000. Stock to 60 days. 30-95 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : General Electric Company - Vacuum Products Business Section Ion gauge, trigger gauge 3 ion pump. Accessory (audible leak detector). Connected to recorder output of ion pump or pressure gauge control.* Variety of gases except air. Model No. 22LCI00 Dependent upon system being tested. 4 millivolt input change produces I00 cycle freq. change. Two batteries 5.4 volts each Audible tone Good Approximately one second Probe gas must be able to effect response of detector previously installed in system. No Battery life I00 hrs. 5 years 4 1/2" x 3" x 2" 1 1/2 ibs. Hand carried 2 years $35o I week For use on vacuum systems only. To be used with vacuum system pressure gage detectors or ion pump controls. *Probe gas penetrates into vacuum system through a leak and causes a variation in the detector tone. 30-96 MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WEIGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : General Monitors, Inc. Electrochemical Cell N2OA, Hydrazines , and UDMH depending on model. Model 150 Toxic Gas Unit 0 to 5 ppm, 0 to 200 ppm Fuel - 1/4 ppm Oxidizer - 1/2 ppm llSv 3 60 Hz 2v into IK ohm load for analog signal. Panel meter provided. 5% full scale or the above sensitivity value whichever is larger. I0 sec. to 90_ reading 35°F to 120°F Yes 20 days - recharge cells. 6 month warranty Sensor - NEMA 12 housing Remote readout - rack mountable 7" panel height 30 ibs. Semi-portable 1965 $3000 class 60 days Miniaturization design in process. Other toxic gases can be handled. Electrolytic supply requires changing after approximately 3 weeks of service. Changing operation requires 5 mlnutes_t 30-97 ---l_ MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY- MODEL NO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WEIGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : General Monitors, Inc. Catalytic Combustion Most flammable gases Model 175 Combustible Gas Detector Adjustable for full scales of 20% to 125% LEL I% of LEL l15v T 20%, 50/60 Hz, 5w Iv into ik ohm load - also panel type indicating meter. 1% of full scale I sec. and up depending on density of gas. Remote probes - 200°F max&# 100% humidity Control units 32°F to 120-F. No 60 to 90 days One year warranty 3 1/2" x 9 1/2" x I0" panel# rack or wall mount. 3 lb./channel No 1968 $425 30 days Low temperature diffusion head probes. Single alarm system, buzzer alarm, contacts and lamp. Similar to Model #170. 30-98 MAI_JFACTIIRER: OPERATINGPRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION : OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : General Monitors, Inc. Catalytic Combustion Most flammable gases Model 172 Explosion Proof Gas Detector Adjustable for full scales of 20% to 125% LEL 1% of LEL l17v T 20% 50/60 Hzj 12v dc, 5w Iv into ik ohm load - also panel indicating meter. 1% of full scale i sec. and up depending on density of gas. Remote probes - 200°F max&, 100% humidity. Control units 32°F to 120-F. Yes 60 to 90 days One year warranty Approx. 9"x 9"x 8"wall mount or panel mount. 20 ibs. No 1967 $850 to $900 60 days Low temperature diffusion head probes. Dual alarm system. Similar to #170j but is in explosion-proof case. 30-99 _-L_ MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : General Monitors, Inc. Catalytic Combustion Most flammable gases Model 170 Combustible Gas Detector Adjustable for full scales of 20% to 125% LEL 1% of LEL llTv _ 20_ 50/60 Hz or 12v dc, 5w Iv into Ik ohm load for remote analog signal - also panel meter. I% of full scale 1 sec. and up depending on density of gas. Remote probes - 200°F max&, 100_ humidity. Control units 32°F to 120-F. Yes 60 to 90 days One year warranty 4 3/8 x 2 1/8 x 8"/channel (rack mountable) 3 ibs. Semi-portable 1966 $550 30 days Low temperature diffusion head probes. Rugged, shock resistance control units and probes. Dual alarm system. Panel mounted readout meter, controls, alarm lamps, alarm buzzer and switches. 30-100 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSETIME: ENVIRONMENTEFFECTS: DOESIT FAIL SAVE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME REMARKS : General Monitors, Inc. Catalytic Combustion Most flammable gases II00G-IIOOE-IIOOM 0 to 100% LEL 2% of full scale 2 rechargeable D cells - built-in charger. Built-in compact panel meter audible alarm. 1% of full scale i sec. and up depending on density of gas 0°F to 120°F No -- audible alarm on low batteries 60 days. Recharge batteries after 8 hours operation. I year warranty except batteries IIOOG - 7.25 x 7.9 x 2.25 II00E - 7.5 x 6.25 x 4 2 ibs. Yes 1968 See remarks 30 days or stock Low temperature diffusion head probes. Remote probes I audible alarm (buzzer)j visual alarms (lamps) are available. Available variations of the #II00 series are: #1100E - $287 - recharge on llbv 3 60 Hz. #1100G - $375 - Same as #1100E_ but has pistol grip design flashing alarm light and pulsating buzzer. #1100M - $600 - Same as #1100G_ but is ruggedized. -30-i01 MA_JFAC_dRER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSETIME: ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : General Monitors, Inc. Catalytic Combustion Type I sensor; most flammable gases Type II sensor 3 hydrogen selective H200 FS Adjustable for full scales of 20% to 125% LEL 1% of LEL 117 _ 10%, 60 Hz 2v dc to I K ohm. 10%, 40 watts/channel Panel type indicating meter and alarms. 1% of full scale 1 sec. and up depending on density of gas. Remote probes - 200°F max., I00_ humidity. Control units - lab environment. Yes - several variations offered. 60 to 90 days. One year warranty Rack mounting, 5 channels. Modules 12 1/2" height. 5 channels - 60 ibs. No 1961 $600/channel 30 days Low temperature (200°F) diffusion head probes. Many options offered - relay panels 3 meter panels_ special probes. Up to 50 channel systems are available. 30-102 MANUFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADENAME: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: ENVIRONMENTEFFECTS: MAINTENANCE: SIZE: WEIGHT: PRICE: REMARKS: Goldak Company, Incorporated Sonic - Sonic Range #LC/4 "Dual-tronic" Pipe - any size or type of metal. Water, air, and low viscosity leaks at 25 psi or more pressure. Battery operated (4 "C" batteries in each transmitter and receiver). Visual and audible Depth range - over 18 feet Tracing distance 250 feet or more under average conditions. Determined by battery life. Transmitter and receiver are the same size 9" x 12" x 3" Total operating weight = 9 1/2 Ibs. $329 Chief use is for locating pipes and the liquid, air_ or fuel leaks therein. w 30-103 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : SENSITIVITY: EXCITAT ION: OUTPUT SIGNAL LMPEDANCE : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WEIGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : The Goldak Company, Inc. Sonic - Ultrasonic Range Water - low viscosity fuel, air under 25 psi or more. Model 727 "Hunter" Leaks to 1/32" 9 volt radio type battery at 500 micro amperes drain. Panel Meter - 2000 ohms - headphones Complete stability +10°F to l15°F No Battery change only - approximately once a year. No limit 6" high 3" wide 3 ibs. Hand carried Two years $129.50 Immediate upon arrival A crystal microphone is used as the detecting element. Leaks can be detected in pipelines buried under earth, hardtop, cement slabs, etc. 30-104 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Gow-Mac Instrument Company Thermal Conductivity No - all gases/vapors other than air 21-200 Gas Leak Detector Battery Operated High, Medium Low 10-3 cc-atm/sec. Helium Battery operated with rechargeable pump batteries Panel Meter/available with audible signal as accessory 21-210 2% full scale 2 seconds for 4 feet of sampling hose 50-100°F No Circuit batteries - approximately 300 hours Pump batteries - 2-3 hours continuous duty Indefinite 5 1/2" x I0 1/2" x 3" 8 ibs. Yes, shoulder strap provided 3 months Model 21-200 $4303 21-210 $510 (with audible signal) Stock to 2 weeks Frequency of audible signal varies with gas concentration. Special units fabricated to customer specificiations. 30-105 ---L- MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION : OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTABILITY: TIME ON MAR/£ET: PRICE : DELIVERY TIME : REMARKS : Gow-Mac Instrument Company Thermal Conductivity All gases/vapors other than air. 21-100 Gas Leak Detector (formerly Gas Hound) High_ Medium, Low 1 x 10-3 cc-atm/sec. Helium II0 volts_ 60 Hz_ less than 1 watt Panel Meter/available with audible signal as accessory 21-110 2% full scale 2 seconds for 4 feet of sampling tubing 95-120 volts_ 50 ° to 100°F No Batteries used for readout require replacement after 3 hours operation. Indefinite 5 1/2" x I0 1/2" x 3" 8 Ibs. Yes_ shoulder strap provided 1 1/2 years Model 21-100-$280, Model 21-110 -$360 (with audible signal) Stock to 2 weeks Audible signal frequency varies with gas concentration. Special units can be fabricated to customer specifications.. 30-106 MANUFACTURER: Granville-Philllps Company OPERATING PRINCIPLE: Mass Spectrometer All gases I to 750 AMU "Spectrascan" #750 SPECIFICITY: MODEL NO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME : SIZE: WEIGHT: PORTABILITY: PRICE: DELIVERY TIME: 1-50 AMU; i0-250 AMU; 100-750 AMU (Tri-range unit) Minimum detectable total pressure --- I x 10 "15 torr Minimum detectable partial pressure - 5 x 10 "15 torr Resolution is i000 at mass 500 I15-230v 3 50-60 Hz_ 700w Direct output from electron multiplier for use with oscilloscope or recorder with an input impedance of 105 ohms or higher. Peak height reproducibility better than _1% at N2 for constant molecular concentration in ionizer volume at I x 10-7 torr. Continuously variable scanning rate from .025 sec. to 30 min. per mass range. 29 1/2" D x 20 3/4" W x 56 1/2" H 395 Ibs. On casters $13,635 - $15,135 Stock 30-107 ..... 2 ...... MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: .ENVIRONMENT EFFECTS: SIZE: WEIGHT: PORTABILITY: PRICE: DELI_RY TIME: REMARKS: Granville-Phillips Company Pressure Change - Gas (non-conducting) Series #212 _apacitance Manometer) Choice of 4 sensing heads: 0-I, 0-I0, 0-I00, 0-I000 tort, differential. Controller has full scale ranges of IX_ 0.3X I 0.1X 3 0.03X_ and 0.01X. Minimum detectable pressure differential: 0-I _orr model: 5 x I0"_ tort 0-i0 tort model: 5 x I0"_ tort 0-I00 tort model: 5 x I0-_ tort 0-I000 tort model: 5 x I0 "A tort l10-120v, 50-60 Hz, or 220-240v, 50-60 Hz, 40w Nulllng method or direct readout on panel meter. Accuracy: T2% of full scale (after calibration) Designed to operate at normal room temperature. Balance unit cont_olled at 50°C. Sensor temperature sensitivity = i0" torr/°C on I0 tort unit. Sensor and balance unit: 3 3/4" diameter x 3 1/2" long. Controller: cabinet style - 8 1/4" x 19 1/2" x I0" rack - 7" x 19" x 9" Controller: cabinet 26 ibs.3 rack 17 ibs. Yes Controller: $585 Sensing and balance units: $664 to $761. Stock item Sensing head can be baked at 450°C 30-108 MANUFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: ENVIRONMENTEFFECTS: MAINTENANCE: SIZE: WEIGHT: PORTABILITY: PRICE: DELIVERYTIME: REMARKS : Granville-Phillips Company Ion Gauge Controller: Series 3263 Model 102 Ionization Gaugej Series 274 (hot cathode-Bayard Alpert type) i0 to I0 "II tort in decade steps Adjustable 105 to 125v_ 50/60 Hz_ 2 amps -3 Panel Meter - Pirani gage mode for pressures above I0 torr and in ion gage mode for lower pressures. Analog output connector: lOv (I ma maximum) I% F.S. Electrometer zero drift, after 30 minute warmup, .03% F.S/hr. or 5 x i0 "Lo amps/hr, whichever is larger. Repair facilities maintained at factory. Controller: 19" x 7" x 9" - rack mounting Ionization gage tube 2 1/4" diameter_ 6 3/4" long Controller - Indicator: 20 ibs. Easily movable Complete gage: manual range switching $850 Automatic range switching $940 Available from stock Solid state circuit boards are quickly replaceable from the factory. 30-109 ---l_ MANUFACTURER: OPERATING PRINCIPLE: MODEL NO. & TRADENAME : RANGES : SENS ITIV ITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TI]_ : ENVIRONMENT EFFECTS : PORTAB IL ITY: PRICE : REMARKS : Hastings-Raydist 3 Inc. Flow Hastings Mass .Flowmeter - LF series 15 ranges 0-0.5 to 0-203000 std. cc/min. Down to 0.01 std. cc/mln, with the lowest range model (LF-Db) ll5v, 50 to 400 Hz LF-D5 must be used with a one millivolt high impedance my potentlometer. Other models have an indicating meter and can be used with a 0-2 mv recorder. Within 1% i0 seconds No gas pressure correction is required from 0. i psia to 250 psia or gas temperatures up to 200°F. Yes - by hand $365 - $725 dependent on requirements Linear scale models and integral amplifiers for 0 - 5v dc output, are available. Add $200 for linear scale and $450 for amplifier. High sensitivity flow sensor can function as leak detector by measuring flow rate from an encapsulated component of a pressurized system. 30-110 MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : LIFE EXPECTANCY: SIZE: PORTABILITY: PRICE : REMARKS : The Hays Corporation Electrochemical Cell (membrane type galvanic cell) Oxygen Model 623.01 Electro-02-Chem Portable Membrane Oxygen Analyzer. 0 to 5%, 0 to 10% 3 0-25% 02 2 1/2" long scale on the panel instrument. None required. Unit is a simple galvanic cell and generates its own power. Panel instrument calibrated in percent oxygen. 25 my dc; requires potentiometric receiver. 1% full scale deflection Dead time 1 second; time constant 6 seconds. Sample gas condition: Temperature +30°F to 120°F. Pressure -2 psig to +5 psig. Flow 0 to i0 CFH. The operating life of the cell is approximately 5 months or 30,000% hours (whichever comes first). 7" L x 5" W x 4 1/4" D Yes $345 Not affected by non-corrosive redox inactive gases such as H23 N2, CO_ A, He and H20. Not affected by CO 2 or most organic gases such as methane, ethane s propane, butane, ethylene_ propylene_ etc. Corrosive and redox active gases such as SO2, C12, and H2S in large concentrations can interfere. After a cell completes its life cycle_ it may be discarded for a new replacement cell or recharged in the field. 30-111 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : SENS ITIVITY: OUTPUT SIGNAL IMPEDANCE : SIZE : WE IGHT : PORTAB IL ITY : TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : The Heckerman Corporation Bubble (Liquid Applicant) Type I for detecting oxygen gas at room temperature (35°F to 160°F). Type II for detecting oxygen gas at -65 ° temperatures (-65°F to +35°F). Type III for detecting all other gases at ambient temperatures. Heck-Check Type I, II and III. 0.25 std. cc per hour Visual 4 ounce bottles_ gallon jugs and 55 gallon drums. (See Size) 4 ounce bottles for tool kit 3 years $22.00 - $35.00 per dozen (4 oz. bottles) Stock This is a bubble type liquid leak detector for use on gas pressurized systems. A mass of white foam forms at the leak source. Type I and Type II meet spec. MIL-L-25567B (ASG) Non Flammable; Non-Toxic; Harmless to skin & clothing. m 30-112 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES : SENS IT IVITY: EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB IL ITY: TIME ON MARKET: PRICE: DELIVERY TIME : REMARKS • Hewlett-Packard Company (Delcon Division) Sonic (Ultrasonic Range) None. Senses all gases Ultrasonic Translator Detector. 4916A, 4918A. 36 to 44 KHz 0. i std. cc/sec. 1.0 psi-minimum pressure Self-contained battery supply Models 4917A, 4905A, Audio signal or audio signal and panel meter Speed of sound Operating temperature -20 to +55°C. Operation unaffected by wind up to 40 mph. Yes Replace batteries 360 to 700 hours of service 5-10 years Min. 4" x 7" x i 3/4" 5 to ii ibs. Yes 5 years $525.00 - $850.00 Factory Stock Models 4917A and 4918A are listed by Underwriters' Laboratories, Inc._ for use in hazardous locations Class I, Group D. Hand manipulated probe is 1 3/8 in diameter and 6 1/4 long. It does not respond to audible noise. 30-113 _-l_ MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RANGE S : SENSITIVITY: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : LIFE EXPECTANCY: SIZE : WEIGHT: PORTAB IL ITY: TIME ON MARKET: PRICE: DELIVERY TIME : REMARKS: Highside Chemicals, Inc. Chemical Indicator - Dye - Pressurized "Trace" 0-5000 psi -40°F to 350°F Depends on time. (Small leaks take longer) Red color Depends on size of leak. Indefinite 2" x 2" x 5" 4 ounces Yes Twenty years $1.15 - 4 ozs. plastic bottle to $18.40 for 1 gallon can. From stock Clifton, New Jersey An intensely colored refrigerant oil added to the system refrigerants is circulated through the system. Leaks are identified by bright red spots on outside of system at point of leak. "Trace" is usually visible through ice or frost. Coloring is harmless to refrigerating system. Can locate leaks that start and stop due to temperature or pressure changes. 30-114 MANUFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADENAME: OUTPUTSIGNAL IMPEDANCE: RESPONSETIME: ENVIRONMENTEFFECTS: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: REMARKS: Highside Chemicals_ Inc. Bubble - (Liquid or foamapplied) Leak Finder Foam Bubble Dependson size of leak Usable in the ranges -50°F to 212°F pressures 0 to 5000 psi. Humidity does not effect use. Indefinite 2" x 2" x 9" 7 ounces Yes One and one-half years $1.25 per 6 ounce plastic bottle From stock Clifton, New Jersey Foam from plastic bottle applied to suspected leak. Leak causes bubble to form. Adheres to surface more readily if surface is dry. Non-flammable - will not burn or support combustion. Non-corrosive, water soluble - may be wiped off with a damp rag. Not suitable for use on vacuum lines. Usable on all piping and machinery where refrigerantsj gas or air leaks may occurr 30-115 MANUFACTURER: OPERATING PRINCIPLE: • SPECIFICITY: MODEL NO. & TRADEN_: RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGKr : PORTAB IL ITY: TIME ON MARKET: REMARKS : Hilger & Watts, Ltd. (Hilger-l.R.D. Ltd., Division) Calibrated Instruments, Inc. Infrared (Infrared absorption - non-dispersive type) As desired, detector tube used determines specificity of unit. Type SC/LC Up to 6 ranges if specified by customer (meter calibrated in volume concentration). Will locate leaks to 10-2 lusec (1.28 x 10 -5 std cc/sec). 95-115 v, 60Hz or 190-260 50Hz i00 va. Panel meter and 50 to 550 microamps into external circuit not exceeding 200 ohms. ±1% of full scale reading. Approximately 15 seconds (depends on flow-rate and range). No effect under normal ambient temperature and humidity ranges. No 6 months interval Approximately I0 years 20 1/4" high x 18" wide x i0 1/2" deep Approximately 50 ibs. Transportable 15 years Customer must supply information on ranges desired, analyzer tubes needed, and detector tubes needed. Modifications available to conform with customer's requirements. Most heteroatomic gases measured - except CO 2 and H20. Typical are carbon monoxide, nitrous oxide, sulphur hexafluoride, sulphur dioxide, etc. 30-116 MANUFACTURER: OPERATINGPRINCIPLE: MODEL NO. & TRADENAME : OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS : SIZE : PORTABILITY: PRICE : REMARKS : Hoke, Incorporated Bubble (Liquid Applicant) 69001 "Chek- Seal" Visual (bubbles or foam) Large leaks will form large bubbles instantly. Small leaks form white foam within 60 seconds. Temperature range: 15°F to 180°F 8 oz. bottles Yes $1.75/8 oz. bottle; $9.45/6 - 8 oz. bottles Chek-Seal is a clear, non-flammable liquid which requires no mixing, and is safe and easy to use. It dries clean leaving no residue or toxic odors. 30-117 MANUFACTURE R: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : EXCITATION: OUTPUT SIGNAL IMPEDANCE : RANGES : SENSITIVITY: REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Honeywell, Inc. (Apparatus Controls Division) Ultraviolet Absorption O Any v_por which absorbs ultraviolet light from 1850 A to 2250 A. Example: perchloroethylene, nitrogen dioxide, hydrocarbon refrigerant 12, hydrazine. Y457 A llSv, 60 Hz Visual indication on panel instrument. Current output for recorder - ±50 microamperes. Single - 0 to i00 ppm or 0 - 5000 ppm determined by vapor of interest. _ppm depending on vapor. ±15% at control point during repeated standardizing cycles. Approximately 5 seconds 12Ov (+I0_ -15%) Ambient temperature: 50 to l15°F at amplifier and detector. Allowable separation: i00 feet maximum between amplifier and detector. Yes Normal servicing - yearly check of electronic tubes built-in standard cell used for automatic self-standardization of unit. 5 years Amplifier - 8 1/2" x II" x 5" Detector 6" x 6" x 19" Approximately 30 Ibs. Can be hand carried 2 years $591.30 4 weeks Vapor Detector consists of RTI92A Amplifier and C7025 detector unit. Detector assembly has a fixed beam of ultraviolet radiation from an argon lamp to a self-quenching ultraviolet sensing tube. Fan draws in air sample to be measured. Stream absorbs UV energy in direct proportion to amount of raper present, thus affecting the count or firing rate of the i_ sensing tube. Detector output is a square wave of constant amplitude and duration for each count of the tube. Amplifier provides means of measuring vapor content against set control reference point. Panel indicating: instrument indicates variations from set control reference point. 30-118 _NUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE : WEIGHT: P ORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TLME : REMARKS : Houston Atlas_ Inc. Catalytic Combustion Any flan_nable gas or vapor is detected in the range below the lower explosive limit (LEL) Model 510 "Duotector" 0-4% Methane or 0 to 100% LEL of any fla_nable gas. 0.4% of gas in air llOv 50/60 Hz 100my from I000 ohms 1% full scale 5 sec. to 90% of final value -20 to +40 degrees C - Coefficient is 0.1% per per degree C. Only as an option Replace detecting element once each 4 months of continuous operation. Check zero once per week. 20 years 5 x 7 x 8 inches 14 ibs. Hand carry. Battery internal with charger for 8 hours use. 5 years $425.00 for single channel unit 30 to 60 days Available in multichannel cabinets for simultaneous monitoring of several remote locations to 1,500 feet with sensing heads. Custom arrangements and systems available. 30-119 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME: RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE : WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: Japan Vacuum Engineering Co., Ltd. Mass Spectrometer Helium gas tracing Model DIMS 1PPMHe Leak down to 1 x I0 "II tort liter/sec can be detected. lO0v 3 50/60 Hz_ 1400w Panel meter (300 ma/torr for He) 3% full scale 50_ change in one second with a standard leak only. 0.25%/°C No Check sensitivity 3 no specific servicing internal. Pumping system 7 years_ ULVATUBE shorter 750 mmW x 760 mmD x 1090 mmH 300 kg Mounted on wheels One year $6_000 (FOB price) 4 weeks 30-120 MANUFACTURER: Japan VacuumEngineering Co.j Ltd. OPERATINGPRINCIPLE: MassSpectrometer SPECIFICITY: MODELNO.& TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSETIME: ENVIRONMENTEFFECTS: DOESIT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: REMARKS: Helium gas tracing Model DLMS-P 1PPM He Subject to the pumping system 100v, 50/60 Hz, flOw Panel meter (300 ma/torr for He) 3% full scale 50% change in one second with a standard leak only. The pumping speed at the test port I liter/sec. 0.25%/°C No Check sensitivity 3 no specific servicing internal Pumping system 7 years_ ULVATUBE shorter 490 mmW x 323 mmD x 250 mmH 15 kg By hand One year $4_000 (FOB price) 4 weeks Model DLMS-P is a portable type of which pumping system should be optionally provided. 30-121 °--t. MANUFACTURER : OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENS ITIVITY: EXCITAT ION: OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Johnson-Williams Products - Bacharach Instrument Company, Division of American Bosch Arma Corporation Catalytic Combustion Combustible gases or vapors 4m 0-I.0 LEL 1% of full scale Battery operated. Internal "D" dry cells (8) Visual reading of millimeter 3v 2% of full scale 3 seconds Useful over normal ambient ranges 0-120°F. No Depends on battery life (dry cells). 5 years 6" x 3" x 5" 4 Ibs. Can be hand carried, fully portable. ii years $100 Stock Can be used for detection of leakage of fuel gases from piping and vessels under pressure, toxicity of working areas, and detection of hydrocarbons, etc. Various accessories available. Hand operated aspirator bulb for sample. Many additional accessories and modified Model G designs are available for specialized applications. 30-122 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: EXCITATION: OUTPUTSIGNAL IMPEDANCE: MAINTENANCE: PORTABILITY: PRICE: REMARKS: Johnson-Williams Products - Bacharach Instrument Company Division, American BoschArmaCorporation Catalytic combustion Usual combustible gases and vapors Model G-P Normally calibrated 0 to 1.0%of LEL Rechargeable batteries Panel indicating instrument 5 hours operation from fully charged battery. Yes Approximately $200 Integral sample pump 30-123 MANUFACTURER : OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADE NAME : RANGES : SENSITIVITY: EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Johnson-Williams Products - Bacharach Instrument Company, Division of American Bosch Arma Corporation Catalytic Combustion Combustible gases or vapors #SS-P 0-i.0 LEL & 0-i000 ppm 1% of full scale Battery operated. Ni-Cd rechargeable batteries (2) charger built into unit. Visual reading of millimeter 2% of full scale 3 seconds Useful over normal ambient ranges 0-120°F. Humidity compensator required. Is supplied with unit. No Typically, every i00 hours. 5 years 8" x 3" x 6" 7 Ibs. Can be hand carried, fully portable. 3 years $350 Stock Can be used for detection of leakage of fuel gases from piping and vessels under pressure, toxicity of working areas, and detection of hydrocarbons, etc. Various accessories available. Has internal sample pump. Basic scale calibrated for benzene. Conversion factors given for other gases or vapors. 30-124 MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : RANGES : EXCITATION: OUTPUT SIGNAL IMPEDANCE : MAINTENANCE : PORTABILITY: PRICE : REMARKS : Johnson-Williams Products - Bacharach Instrument Company Division of American Bosch Arma Corporation Catalytic combustion Principally used for the detection and measurement of natural gas concentrations. Model H-P Dual range (0 to 1.0_ LEL - 0 to i00% natural gas) Rechargeable batteries Panel indicating instrument 5 hours operation from fully charged battery Yes Approximately $250 Integral pump. Actuates alarm lights and relays indicating lights for safe operation and filament burnout. --l- 30-125 ---i_ MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME: MAINTENANCE: WEIGHT: PORTABILITY: PRICE: REMARKS: Justrite Manufacturing Company Halide Torch - Flame Color (Alcohol flame in contact with heated copper turns green in presence of refrigerant gas R-12). (usually halide) non-combustlble refrigerant gas or vapor. #12360 Refill with anhydrous alcohol when necessary. 1 1/2 Ibs. Can be hand carried. $16.00 Burns for 45 to 60 minutes on full charge. 30-126 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS : LIFE EXPECTANCY: SIZE : WE IGHT : PORTAB IL ITY: PRICE : REMARKS : Kelite Chemicals Corporation Bubble - (Liquid Applicant) Bubble Fluid - I0 Bubble Immediately if container is pressurized. Suited for normal ambient temperatures. Depends on use Various 8.39 ibs./gal. Mixture can be hand carried. $2.35/gallon in 55 gallon drums. $2.65/gallon in 15 gallon kegs. One part Bubble fluid mixed with 20 to 30 parts water. Mixture applied with brush. Fluid is non-toxlc and non-flamable. 30-127 MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME: RANGES: SENS TTIVlTY: REPEATABILITY: RESPONSE TIME: ENVIROhMENT EFFECTS : MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: UMARES : Kobbe-McCawley Corporation Chemical Indicator-Reagent Reaction: Burning S vs. NH 3. Nearness or contact white cloud forms. Used for the detection of Armenia RefriEerant8 as above. Anmnonla Leak Detector of Sulphur Taper Detects by nearness of sulphur taper to leakins aE_onla. Extremely small NH3 leaks are detected. Eisht inch taper may be reused. Immediate May be used near dry or damp contacts. Humidity not deterent. None - expendable Indefinite 8" L x 1/8" D (standard) may be Cut to lesser lengths, .01 gram Yes About 25 years SEE BELOW Immediate Item made of high grade sulphurj melted and impresnated into cordese. PRICES: Boxes 200 aa-extra long - slow burning: 1 box - $4.00 2-11 bx8 - $3.75. ee. 12 bxs - $39.00/24 for $76.00 30-128 MANUFACTURER : OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : OUTPUT S IGNAL IMPEDANCE : MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT : PORTAB IL ITY: PRICE : Lenk Manufacturing Company Halide Torch - Flame Color (Color of flame turns green in presence of a non- combustible refrigerant gas leak). Non-combustible refrigerant gases. #425 Visual color change in flame. Replace compressed gas cylinder Depends on length of time used 14 3/4" high - 3" diameter 1 3/4 ibs. Can be hand carried $9.00 30-129 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : RANGE S : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : REPEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: LIFE EXPECTANCY: SIZE : WE IGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : Lion Research Corporation Flow - (Pressure drop across a calibrated length of pipe measured with a sensitive transducer.) Any non-corrosive gas or non-conductlng liquid. FM 400 Flowmeter 3, i, .3, .I, .03, ,01, .003, .001 cc/min, stp Maximum for lowest range is .00003 liters per minute Excitation volts: II0, 60 Hz, Power: 5w I0 ohms .1% Typically 0. i seconds Temperature range -45 to +165°F Humidity 0 to 100% Yes 2 years continuous 5 High 7 Deep 7 1/2 wide in inches (the driver) 4 1/2 High 3 1/2 Deep 6 wide in inches (the sensor) 4 1/2 Ibs. (the exciter) 3 1/2 ibs. (the sensor) Portable except that it requires ii0 volts On market for 3 months $1295 From stock - 2 weeks 30-130 MANUFACTURER: OPERATING PRINCIPLE : SPECIFIC ITY: MODEL NO. & TRADENAME : RANGE S : SENS ITIV ITY: EXC !TAT ION: OUTPUT S IGNAL IMPEDANCE : REPEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WEIGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Loenco, Incorporated Thermal Conductivity Highest sensitivity to helium or hydrogen Loenco Down to i00 ppm full scale Depends upon sensing and background gases Batteries or ac line supply Approximately 200 ohms 0.5% of scale Approximately 5 sec. for 90% response Depends upon required specifications. 90-130 volt line makes no detectable response. Yes, goes off scale Zero adjust when used. Span check approximately once per month. No specific service interval. i0 years except for pump and detector elements. Depends upon application requirements. Size, exclusive of recorder, as small as 5" x 5" x I0". As low as 5 ibs. Some units portable Basic detection system since 1956 Ranges from $500 to $2000, depending upon performance and service requirements. 4 - 8 weeks 3 depending upon requirements Loenco builds custom leak detection systems based on thermal conductivity using either thermistor or hot wire sensing elements. In some cases detection sensitivity (at 28times short term noise) can be as low as one part in i0 in sampled gas. Flame ionization and electron capture detection systems are also manufactured. 30-131 -_-t_ MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RANGES : SENS IT IVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET : PRICE : DELIVERY TIME: Lumidor Products Corporation Sonic - Ultrasonic range LP-600 Detec-tor 35-45 kc .001" opening at 6 psi 9v transistor type radio battery Audible and visual Unconditionally guaranteed for one year. Thereafter unit will be repaired at the factory for a maximum cost of $22.50. i0 years 4" x 7" x 2" 6 ibs. Yes - furnished with carrying case and carrying sling. 5 years $200 7 to i0 days 30-132 MAN_JFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECT : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB ILITY: TIME ON MARKET: PRICE : DELIVERY TIME: REMARKS : MKS !nstruments_ Incorporated Pressure Change - Gas (non-corrosive) MKS Baratron Series 90 0 to ±I to 0 to 30 torr, differential (each sensor has 8 ranges) i x 10-5 torr maximum 105 - 120v at 50 to 400 Hz Analog output 0 to ±I00 mv dc and 0 to 500 mv ac. Also panel meter and 5 place manual digital dials. 0.05% of reading I0 milliseconds for a 63% response to a pressure step Temperature manually compensated to 200°C with i0 turn potentiometer. Uncompensated temperature error is .02 to .05% of reading per °C. No Calibrate at 6 month intervals 5 years minimum Sensor: 2 1/2" diameter_ 2 1/2" long Electronic Unit 2" x 4" x 3" Indicator Unit 6 3/4" x 19" x 5 1/4" Total = 42 Ibs. Easily movable Two years Sensor system - $1470 to $1560 depending on range Indicator unit - $1280 30 days Designed for high temperature service. Mechanical element of pressure sensor is separated from the intermediate elec--_ tronlc module. Pressure sensor can be baked at temperatures of 350 to 400°C. 30-133 -_-i_ MANUFACTURER: OPERATING PRINCIPLE: MODEL NO. & TRADE_ : RANGE S : SENS ITIV ITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : MKS Instruments Incorporated Pressure Change - Gas (non-conducting) MSK Baratron Series 77H Full scale ranges: + or - differential pressure, 0 to I to 0 - i000 torr with 8 sensitivity settings for each range 0.001% of full scale 105 - 120v at 60 to 400 Hz Panel meter and 4 place digital dials. Also analog output 0 - ±I00 mv dc and 0 to 500 my ac Meter readout i to 3% of full scale, depending on range. On 4 place digital dials - 0.02% of full scale + 0.15% of reading. i0 milliseconds for a 63% response to a step pressure change of 30 tort at 760 torr Temperature controlled at 120°F No Calibrate at 6 month intervals 6 years minimum Sensor 4" x 4" x 3 3/4" Indicator Unit 9" x 14" x 12" Sensor plus cable: 7 ibs. - Indicator: 40 ibs. Easily movable 6 years $1195 to $1385 depending on ranges selected 30 days High speed repetative production test leak detecting systems with line pressures up to 500 psi and various degrees of automation and digital readout are available. Special units are available for liquids. 30-134 MANUFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABIL ITY: RESPONSE TIME: ENVIRONMENT EFFECTS: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : MKS Instruments3 Incorporated Pressure Change (Gas) Model i00 (Auto-Digital MKS Baratron) * 0 - I000 torr differential pressure, with eight full scale sensitivity settings As low as 5 parts in 106 of nominal rating ll5v, 60 to 400 Hz ±pressures are indicated automatically to 5 decimal places on a nixie display, a 6th place is provided for over-range. Condition of balance is indicated on a panel meter. Parallel Binary** ±0.02% of reading + i digit. Interpolator permits higher repeatability over first 1% of range. Approximately 250 milliseconds required to achieve balance. Uses sensors of Model 77H and 90 units. See temperature effects listed for them. Calibrate at 6 month intervals 5 years minimum 12" x 18" x 12" 25 ibs.. No 2 years $5,000 and up Units are special building block types for systems approach. A variation of this equipment having 18 bit binary coded output with no lighted front panel display is available as Model 105. *Instrument is designed to operate with and requires an MSK _t Baratron variable capacitance pressure sensor. See information on Models 77H and 90. **Coded Decimal electrical output is available on rear connector. 30-135 -_%_ F_UFACTURE R: Magnaflux Corporation OPERATING PRINCIPLE: Chemical Indicators - Dye (Fluorescent) MODEL NO. & Zyglo TRADENAME: EXCITATION: l15v, 100w (for black light) OUTPUT SIGNAL IMPEDANCE : Flourescent glow under black light RESPONSE TIME : Penetrating time varies with materials being tested and type of defects. ENVIRONMENT EFFECTS: Material must be cleaned before application of penetrant. PORTAB IL ITY: Portable kit PRICE : $125.00 for test kit. 12 oz. spray can penetrant - $3.50 12 oz. spray can wet developer - $2.50 12 oz. spray can cleaner - $2.00 12 oz. can dry developer - $1.65 In cases of 12 REMARKS : Above information is for ZA-43 portable test kit. This kit includes: 2 pressure cans of penetrant, 2 pressure cans of developer, I pint can of dry developer, 4 pressure cans of cleaner, Black-Light unit, cleaning cloths, wire brush, and steel carrying case. Penetrants, wet developers, and cleaners are available in pressurized cans or in bulk quantities. Can be applied by dipping_ flushing_ spraying, or brushing. Dye penetrant is applied to surface. Developer reveals defect. Fluorescent under black light. Three types of penetrants and two types of dry developer available. Zyglo is approved to Mil-Spec MIL-I-25135. 30-136 J MANUFACTURE R: OPERATING PRINCIPLE : MODEL NO. & TRADENAME • RANGE S : EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : DOES IT FAIL SAFE: LIFE EXPECTANCY: SIZE : WEIGHT : PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Marcol, S. A. (M. Paquet & Co., Inc., distributors) Sonic - Sonic Range (non-powered stethoscope) Airsonlc 0 - 17000 Hz. Unit is non-powered Audible - earpieces Good Various depending on conditions No For all practical purposes limitless 12" x 2 1/2" x 2 1/2" 4 ibs. Equipped with a carrying case In U.S. I0 years $139 net delivered_ destination 7 days Tunable to acoustic frequency of interest using tuning knob with reference dial. Unit is equipped with six demountable attachments. Can detect gas leaks which are under pressure. Can locate liquid leaks under pressure. Can locate vacuum leaks. 30-137 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFiCITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION: Ob"fPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Mast Development Company Electrochemical Cell Strong oxidants, including ozone; chlorine, iodine, and nitrogen dioxide. Detector Model 724-21; with recorder - Model 725-21 0 to i00 PPHM by volume, 0-i0 PPHM by volume for strong oxidants 1PPHM by volume or less of ozone, chlorine and iodine. 12Or, 60 Hz, battery operated model available. 0-20.0 microamperes represents 0 to I000 PPB by volume ±2% for same instrument 75% of full reading in 30 seconds Negligible No Needs chemical solution every 3 days. Several years - I year full guarantee Detector unit 11.5" high x 7.5" x 6.5" Strip chart recorder 9" x 6.25" x i0" Detector unit - 10.5 ibs. Strip chart recorder - 14.51bs- Can be hand carried 3 years Detector unit - $950 Strip chart recorder - $545 30 days after receipt of order; rental program available. KI solution is oxidized by oxidant which depolarizes cathode, allowing electric current to flow. Current flow can be measured on strip chart recorder. Pumps its own air sample. Continuous signal. Nitrogen oxide recorder and meter available. Accessories available. 30-138 MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: RESPONSE TIME: DOES IT FAlL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE : WE IGHT : PORTABILITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : The Matheson Company, Inc. Thermal Conductivity None - responds to thermal conductivity of gas of interest. Model 8013 F ive 9 x 10 -5 std. cc/sec. (R-12); 3.6 x I0 -5 std. cc/sec. (Hydrogen); 5.4 x 10 -5 std. cc/sec. (Helium) Self-contained - 6 size D batteries Audible and visual signals. Approximately 2 seconds No Replace batteries every 40 hours of use, other - once a year. Minimum of 5 years 3 1/8" x 7 3/4" x 9 3/4" Approximately 4 pounds Can be hand carried 4 years $195 Stock item. 3 - 5 days. Can be used to detect any type of leak in any constant background. Is more sensitive to gases with larger thermal conductivity difference than background. Wheatstone bridge with 4 tilament_ Detector responds to changes in gas composition. Stable composition returns output to zero. _l 30-139 MANUFACTURE R: OPERATING PRINCIPLE: SPECIFIC!TY: MODEL NO. & TRADENAME : RANGES : SENS ITIVlTY. EXCiTATION_ OIYlPUT SIGNAL IMPEDANCE RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAlL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WE IGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : The Matheson Company, Inc. Chemical Indicators - Reagent (color change in sensor detected by photoelectric system) Carbon Monoxide 8010 and 8011 0-i000 ppm CO full scale 50 ppm CO (2% full scale) Model 8010_ 120v, 60 Hz 3 3w Model 8011, Battery operated/ac Visual on indicating instrument and audible alarm. Typical response time is 45 seconds for i000 ppm (full scale). Voltage range: i05-125v ac Not sensitive to ambient changes of temperature and humidity. No Replacement of indicating tab required after tripping alarm, otherwise maintenance is minimal. 5 years 8 5/16" x 4 I/4" x 3 3/16" 3 1/2 ibs. Both models 8010 and 8011 can be hand carried 4 years Model 8010 - $124050. Model 8011 -$190o00 Stock item. 3 to 5 days. Color change of tab in sensor is detected by photoelectric system. When CO concentration reaches a toxic level, a relay is tripped and a built-in alarm is sounded. In ventilating control, the alarm may be supplemented by setting into action a ventilating system. Model 8011 - when operated on ac, automatically converts to battery operation in event of line failure. 30-140 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVlTY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : RE PEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WEIGHT : PORTAB ILITY : TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : The Matheson Company Catalytic Combustion Combustible gases (methane, ethane, propane, gasoline, etco) 8420 and 8421 0-I00% lower explosive limit 2% full scale (for methane) 4 standard "D" flashlight cells Panel meter reading and alarm 2% full scale 7 seconds with five feet of hose 50 to 120°F No 8 hours of continuous service 5 years 6 3/4" x 5 1/2" x 2 1/2" 5 1/2 ibs. with batteries Carrying case with shoulder strap i year 8420 - $180.00 8421 - $270.00 Stock item 3 to 5 days Operation based on balanced Wheatstone Bridge principle. Combustibles in sample are burned on platinum filament, changing the resistance and unbalancing bridge. 30-141 MANUFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADENA_: SENSITIV ITY: OUTPUTSIGNAL IMPEDANCE: RESPONSETIME: ENVIRONMENTEFFECTS: LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Met-L-Chek Company, Inc. Chemical Indicator - Visible Dye or Fluorescent Dye (liquid penetrant) "Met-L-Chek Flaw Findr" Will detect cracks as small as a few ten thousandths of an inch. Red dye on; white background, or bright fluorescent indications under black light. Penetrant dwell time - 5 minutes or longer. Approximately 5 minutes developer. Recommended use range, 60°F to 90°F or slightly more. Indefinite shelf lifeo 12 ounce spray can, pints, quarts, gallons, 5-gal, 55-gal drum. Kit 5 ibs, complete, 55-gal drum 430 ibs. other sizes in proportion. Kit form 3 spray cans 15 years 3 can kit - $14.00 - 12 oz. spray can $4.25. Prices lower on larger quantities and sizes° Stock - i week (policy to ship all orders same day received). Qualifies under pertinent portions of MiL-I-25135C and NAVSHIPS 250-1500-1. 30-142 MA_\_UFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSIT_FiTY: EXCITATION: OUTPUTSIGNAL LMPEDANCE: REPEATABILITY: RESPONSETIME: ENVIRONMENTEFFECTS: DOESIT FAIL SAFE: MAINTENANCE: LiFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: REMARKS: Mine Safety Appliances Company Infrared Absorption Gas selectivity is obtained by specific detector cells and infrared beamfiltering. "LIRA" Model 200 Customerto specify 0-i0 ppmN20 (Nitrous Oxide) as tracer gas. llOv_ 60Hz_200w_(50 Hz designs also available) Visual reading on indicating meter. 0-I00 mv dc output for potentiometer recorder. .+1%of full scale. Zero drift is less than 1%of full scale in 24 hours. 90%of final reading in 5 seconds. Temperature range of 30 to 120°F. Constant voltage transformer supplied with equipment. No. Canbe madefail safe at extra cost. Zero and span check once a month. I0 years 19" x 12" x 12 3/4" 75ibs. Is portable I0 years $2400to $3230 60 - 90 days Variations and modificatiorsare available to conform with customer's requirements. Can detect most heteroatomic gases typically; nitrous oxide3 sulphur hexafluoride2 s_iphur dioxide_ etc. Unit can be sensitized to pressurized gas normally present within a system. Optional accessories: recorder_ alarm circuit_ calibration. samples_complete console mounted system with probe_ etc. 30-143 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL No. & TRADENAME : RANGE S : SENSITIVITY: EXCITATION: OL_ITUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WEIGHT: PORTAB ILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Mine Safety Appliances Company Catalytic Combustion Combustible gases and vapors Model No. 20 0-100%LEL 5% of full scale 8 standard flashlite batteries Panel meter 10% of full scale 30 seconds No effect at livable ambients No Periodic battery replacement 20 years 5" x 4" x 6" 6 ibs. Yes 12 years $152 From stock - require one week for calibration for specific gas. Models available with calibration for use in sensing pentane 3 acetone_ natural gas and petroleum vapors in air. 30-144 MANUFACTURER : OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME: RANGES : SENSITIVITY: Mine Safety Appliances Company lon Gauge Steady state ion current (generated by alpha emitter in ion- chamber) drops when particulate matter is introduced into the chamber. Incoming gas or vapor of interest is converted into particles by a reagent. Can be made specific to a particular family of gases with the proper selection of reagent. Portable "Billion-Aire" Varies with gas of interest. Examples: Nitrogen Dioxide (or N204): 0-i0 ppm to 0-250 ppm Hydrazine: 0-3 ppm to 0-50 ppm UDMH: 0-3 ppm to 0-50 ppm Varies with compound to be detected_ examples: Nitrogen Dioxide (or N204): 0.5 ppm Hydrazine: 0.15 ppm UDMH: EXCITATION: OUTPUT SIGNAL IMPEDANCE : REPEATAB IL ITY: RESPONSE TIME : DOES IT FAIL SAFE: MAINTENANCE : SIZE : WE IGHT: PORTAB IL ITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Either ll0v ac or from self-contained nickel-cadmium rechargeable batteries. Charger is self-contained. Meter reading_ audible signal 3 flashing red light 0-i0 mv or 0-i00 mv dc for recorder _2% of full scale. Zero drift: less than 1% in 8 hours 90% of final reading within I0 seconds recovery time the same. No If used continuously for period of 16 hours_ batteries should be recharged. 8" x 14" x 8" 18 ibs. Portable model - can be hand carried 8 years $1495 60 days Customer should furnish specific information on his requirements_ environmental conditions, etc. Field calibration kit available for many gases. Billion-Air Trace Gas Analyzer also available for continuous measurement of various compounds. This is not a portable unit. 30-145 ---L_ MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGE S : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : REPEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIl SAVE: MAINTENANCE : LIFE EXPECTANCY : SIZE : WEIGHT : PORTAB IL ITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Mine Safety Appliances Company Catalytic Combustion Combustible gases and vapors Model No. 2A "Explosimeter" 0-100% LEL 2% LEL 6 flashlight batteries Panel meter 10% of full scale 30 seconds No effect at livable ambients No Replace batteries after I0 hours of continuous operation. 20 years 3 3/8" x 5 3/8" x 5 1/2" 4 Ibs. Yes i0 years $i00 From stock Models available with calibration for use to measure oxygen, hydrogen, acetylene or gasoline vapors in air. 30-146 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAlL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ONMARKET: PRICE: DELIVERY TIME: REMARKS: Mine Safety Appliances Company Dual System. One is Catalytic Combustion. Second is Thermal Conductivity. System #i - combustible gases and vapors System #2 - none Model No. 53 - "Gascope" System #i - 0 to 100% L.E.L. natural gas System #2 - 0 to 100% by volume natural gas 5% of full scale 8 flashlight batteries Panel meter 10% of full scale 30 seconds No effect at livable ambients No Periodic battery replacement 20 years 6" x 4" x 5 3/4" 6 Ibs. 5 oz. Yes 15 years $157 From stock Either system is available as a separate instrument. 30-147 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADE NAME : RANGES : SENS ITIVITY: LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Minear Scientific Instruments Sonic - Sonic Range "Leakscope" I00 Complete audio spectrum At a pressure of 80 torr - air detected escaping thru hole 0.0005" in diameter. Depends on care taken with use. About the size of stethoscope 8 oz. Can be hand carried Approximately 5 years $22.95. Adapters: $6.95 each. 2 weeks after receipt of order. Specially designed probe amplifies any air turbulence - does not contact surface. Adapters are available to contact flat or difficult to reach locations. Three different shape adapters, "T", "_' and "J". 30-148 MANUFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADENAME: SENSITIVITY: OUTPUTSIGNAL LV_EDANCE: REMARKS: Minnesota Mining and Manufacturing Company- Chemical Division Immersion Inert Perfluorinated Liquids Type Numbers: FC323FC78, FC77, FC753FC43 Leaks as small as 10-7 std. cc/sec. Gasbubbles These fluids are available with boiling points from 88 to 345°F and Pour Points from -58 to -150°F. They are non-reactive, good dielectrics, non-toxic, colorless, tasteless_ essentially odorless, non-flammable and drain clean. Surface tension is about one-fifth that of water. Exampleof application: Diodes are immersedin a fluorocarbon liquid maintained at 140°C. Air trapped within the componentexpands3 forcing air bubbles through seal imperfections. By using a lighted magnifier, bubbles can be detected to the sensitivity stated above. 30-149 MANUFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADENAME: EXCITATION: OUTPUTSIGNAL IMPEDANCE : RESPONSE TIME : MAINTENANCE : SIZE : WE IGHT: PORTABILITY: PRICE : DELIVERY TIME : REMARKS : Moak Machine and Foundry Company Inwnersion M34 Air (60 psi) Air bubbles in water Depends upon size of part being tested Normal maintenance as for any mechanical equipment Depends upon size of part being tested Varies again upon part being tested Usually not portable Varies with each part being tested Depends upon how much design is needed Leak detection systems are designed and fabricated for specific components in production lines; for example, auto engine blocks. The above equipment provides pneumatically or hydraullcally driven cylinders which seal off openings in a part to be tested. Tests are conducted by applying 60 psi of air to the sealed inner cavity of the test piece and immersing it into a water tank. Leaks will be indicated by bubbles. This leak testing equipment includes the necessary sealing pistons, controls_ manifolds and indicators. 30-150 MANUFACTURER : OPERATING PRINCIPLE : MODEL NO. & TRADE NAME : E XC ITAT ION: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : MAINTENANCE : SIZE : WE IGHT: PORTAB IL ITY: PRICE : DELIVERY TIME : REMARKS : Moak Machine and Foundry Company Pressure Change - Gas Model M24 Air (60 psi) Gas pressure decrease Depends upon size of part being tested Normal maintenance as for any mechanical equipment Depends upon size of part being tested Varies again upon part being tested Usually not portable Varies with each part being tested Depends upon how much design is needed Leak detection systems are designed and fabricated for specific components in production lines; for example_ auto engine blocks. Pneumatic pressure is applied to the sealed cavity and air pressure is monitored to determine the presence of leaks. This leak testing equipment includes the necessary sealing pistons_ controls_ manifolds and indicators. It is necessary to use some type of rust inhibitor in the water so that the part being tested will not rust. This inhibitor must be clear in color. 30-151 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : EXCITATION: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : MAINTENANCE : SI:_.: WEIGHT: PORTABILITY: PRICE : DELIVERY TIME : REMARKS: Moak Machine and Foundry Company Pressure - Wa£er M8 Hydraulic system (60 psi) Water leakage Depends upon size of part being tested Normal maintenance as for any mechanical equipment Depends upon size of part being tested Varies again upon part being tested Usually not portable Varies with each part being tested Depends upon how much design is needed Leak detection systems are designed and fabricated for specific components in production lines; for example_ auto engine blocks. The above equipment provides pneumatically or hydraulically driven cylinders which seal off openings in a part to be leak tested. Tests are conducted by applying high pressure water to the sealed inner cavity. Leaks are indicated by water penetration of part being tested. This leak testing equipment includes the necessary sealing pistons 3 controls 3 manifolds and indicators. It is necessary to use some type of rust inhibitor in the water so that the part being tested will not rust. This inhibitor must be clear in color. 30-152 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : OUTPUT SIGNAL IMPEDANCE : SIZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Modern Engineering Company, Inc. Halide Torch - Flame Color Halides Stock 3081; "Jiffy" Color change in flame 2 1/2" diameter x 6" long i0 oz. Yes I0 years $9.25 Stock This is a conventional air-acetylene operated leak detector for use on halide and refrigerant gas leaks. --io 30-153 MANUFACTURER: OPERATING PRINCIPLE: SPECIF-C-TY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION: OUTPb_ SIGNAL IMPEDANCE REPEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECT: DOES IT FAIL SAFE: .MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB ILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : National Research Corporation (Equipment Division) subsidiary of Norton Company Mass Spectrometer Helium; adjustable for hydrogen N'RC 925-20 Portable Direct-Coupled ii ranges: I0 x 10-5 to i0 x I0 "I0 std. co/see, full scale i0"II5 x std. co/see, helium (slightly under 2 x i0"II std. cc/sec air equivalent) l15v_ 60 Hz input power = lO00w 0-20 microamperes/2500 ohms taut band panel meter +2% full scale for given input signal 63% of change in I second 90-130v (constant voltage transformer built in) 55 - ll0°F Yes h_ Cleaning of (auxiliary 3 if used) cold trap every week cleaning of discharge gauge liner every 2 to 4 weeks Indefinitely long, allowing for replacement of parts subject to wear or failure Three pieces_ less than 2 cubic feet total volume 50 ibs. Table or shelf mounted near vacuum system to be tested. Spectrometer tube mounts on system to be tested. 3 years $2_ 560 2 - 3 weeks Audible alarm included but can be _mitted. ion source is single piece with two filaments built in. lon source is low cost and disposable. Standard accessories include: portable vacuum system - isolated valve -- cold trap standard leak - helium Jet probe Unique dlrect-coupled spectrometer tube attaches to high vacuum chambers like an ionization gauge 3 for fast response and recovery. 30-154 ° MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADE AME : RANGE S : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : RE PEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS: National Research Corporation (Equipment Division) subsidiary of Norton Company Mass Spectrometer Helium; adjustable for hydrogen NRC 925 "Manumatic" (R) ii ranges: i0 x 10-5 to I0 x i0"I0 std. cc/sec. full scale i0-Ii 10 "12I x std. cc/sec, helium (slightly under 4 x std. cc/sec, air equivalent) llbv, 60 Hz Input power = 2200w 0-20 microamperes/2500 ohms taut band panel meter -+2% full scale for given input signal 63% of change in I second 90-130v (constant voltage transformer built in) 55 - llO°F Yes Cleaning of cold trap recommended weekly, cleaning of discharge gauge liner every 2 to 4 weeks Indefinitely long_ allowing for replacement of parts subject to wear or failure 40" W x 25" D x 35 1/2" to work surface 48" overall height 600 Ibs, Mounted on 4" rubber casters 3 years $6, 190 2 weeks Audible alarm included_ but can be omitted. is single piece with two filaments built in. is low cost and disposable. bell Jar base plate helium Jet probe 30-155 Ion source Ion source Standard accessories include: port adapter kit standard leak MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGE S: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE: WE IGHT : P ORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS: National Research Corporation (Equipment Division) subsidiary of Norton Company Mass Spectrometer Helium; adjustable for hydrogen NRC 925 VFT (Very Fast Test) Production Leak Detector ii ranges: 10 x 10 -5 to 10 x i0-I0 std. cc/sec, full scale Basic 1 x I0 "II std. cc/sec helium (slightly under 4 x 10-12 std. cc/sec, air equivalent) Operating: 1 x 10 -9 std. cc/sec, helium llbv, 60 Hz Input power = 2300w Red "reject" lamp 0-20 microamperes/2500 ohms taut band panel meter ±2% full scale for given input signal 63% of change in 1 second 90-130v (constant voltage transformer built in) 55 - ll0°F Yes Cleaning of cold trap recommended weekly, cleaning of discharge gauge liner every 2 to 4 weeks Indefinitely long, allowing for replacement of parts subject to wear or failure 52" W x 25" D x 35 1/2" to work surface - 48" overall height 650 Ibs. Mounted on 4" rubber casters; floor mounted auxiliary pump 2 years $93000 approximately - depends on work fixtures 3 weeks Side mounted standard test port for conventional operation as desired. Ion source is single piece with two filmments built in. Ion source is low_cost and disposable. Standard accessories for side test port: bell jar base plate helium jet probe port adapter kit standard leak Test enclosures: (flat packs, T05, etc.); test headers. 30-156 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME: RANGES: SENSITIVITY: OUTPUT SIGNAL IMPEDANCE: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTABILITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Newark Controls Company Gas Density (A gas density switch - density remains constant while pressure changes with temperature.) Designed specifically for gases, vapors, and vapor- liquid atmospheres. Gas Density Switches - Nos. RM76, SN88, SN98_ SN129 Vary with type switch used Varies with type switch used Opens and closes switch Less than .001 second Switch and gas being sensed must be at same temperature. Temperature range varies with type of switch used (-85OF to +200OF being typical value). Units to +40OF. Yes Throw away and replace 3 to 5 years Approximately i" diameter x 2" long 2 oz. or less Can be hand carried 6 years $60 to $200 4 to 8 weeks When the molecular density of a gas sealed in a chamber being monitored drops below a critical value this unit causes a switch to operate. It responds to gas density change in sealed containers over a specified temperature range. Temperature compensation is achieved by a trapped volume in a reference bellows. 30-157 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : OUTPUT SIGNAL IMPEDANCE : ENVIRONMENT EFFECTS : LIFE EXPECTANCY: PORTAB ILITY: REMARKS : Nuclear Products Company (NUPRO Co.) Bubble (Liquid Applicant) "Snoop" and "Real Cool Snoop" Bubble Operating temperature range "SNOOP" + 27°F to 200°F "REAL COOL SNOOP" - 65°F to 200°F (-65°F to +35°F with oxygen) Depends on usage Dispenser can be hand carried Tradename "SNOOP". Non-toxic, no residue, dries clean, detects leaks on vertical surfaces. Meets MIL-L-25567A (ASG) Type 1. Trade name "REAL COOL SNOOP", has wider operating temperature range. Low degree of toxicity. Dries clean. Is non-flammaBle in liquid state. Meets MIL-L-25667A (ASG) Type II specs. Applicants detect leaks in pressurized systems. 30-158 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: RESPONSETIME: SIZE: WEIGHT: PRICE : Perkin-Elmer Corporation - Ultek Division Mass Spectrometer - Quadrupole I - 150 AMU Quad #150 One 5 x 10"14 tort for N 2. 105 - 125v, 50 - 60 Hz. Indicating instrument on front panel. Output at Electron Multiplier: 20 amps/torr. 130 milliseconds scal mass range Electronics: 8 3/4" x 19" rack mount (cabinet available) Sensing elements in shipping container - 35 ibs. Electronics: shipping weight - 175 ibs. $7950 30-159 °_ MANUFACTURER : OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGE S : SE NS IT IV ITY: EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE: RESPONSE TIME : S IZE : WE IGHT: PRICE : Perkin-Elmer Corporation - Ultek Division Mass Spectrometer - Quadropole I 500 AMU Quad #250 Three ranges (i-50; 10-150; 50-500 AMU) 10-15 tort for N 2 l17v, 60 Hz, 6 amps Designed for use with oscilloscope, strip chart or x-y recorder, i00 amps/torr for N 2. 500 microseconds 22 1/2" x 59 3/4" x 25 1/2" Shipping weight: 470 Ibs. $13,700 (readout equipment extra). 30-160 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO.& TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSETIME: ENVIRONMENTEFFECTS: DOESIT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: REMARKS: Perkin-Elmer Corporation - Ultek Division ion Gauge,Accessory - Is a current amplifier - tracer gas admitted through leak alters magnitude of ion gauge current. This current is amplified and monitored. None. AnY2convenientbottled gas such as helium, argon,oxygen, CO, etc. can be used as probe gas. #60-412 One I% of the pumped gas pressure. l15v, 60 Hz, 10we _isual indication on panel meter 0-220 mv dc for full scale meter reading. Good As fast as 1/2 second. 105 to 125 volts, 50 ° to 100°F performs within stated specifications. Yes In consistent everyday use, replace mercury battery each 3 months. Occasional vacuum tube replacement. 5 years 13 1/4" x 7 3/8" x 4" 8 1/2 Ibs. Can be hand carried 5 years $380 Stock item Requires equipment for measuring pressure such as ion gauge or ion pump systems. The leak detector amplifies the effects of small pressure or gauge sensitivity changes. Oxygen and argon found to give largest and most rapid response for ion pumped systems steady state pressure is cancelled so that any subsequent change in the reading is readily detectable. 30-161 MANUFACTIBIER : OPERATING PRINCIPLE : SPE CIFICITY: MODEL NO. & TRADENAME : RANGE S: SENSITIVITY: EXCITAT ION: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME: ENVlRONME_ EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE: WEIGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Phoenix Precision Instrument Co., Inc. Particle Detector - (Detects airborne particulates by measurement of forward scattered light.) None. Response proportional to total concentration of airborne particulates. Model JM-2000 Sinclair-Phoenix Aerosol Photometer i00 to 0.001 micrograms/liter of 0.3 micron diameter particles. Dependent on sample concentration due to logarithmic response. ll5v 3 60 Hz_ 2 amps - not including vacuum pump Panel instrument. Output for recorder (bmv dc). 50 ohms output impedance. i second Sensitivity adversely affected by excessively high humidity and temperature. No 3 months Indefinite 21" x Ii" x 15" 90 ibs. Moveable from station to station on rolling lab cart. 13 years $2213 4 weeks Described in tentative Test Method by ASTM Committee F-7, sub X; also Sandia Corp. Technical memorandum SC-TM-64-637. Aids in compliance with Fed. Std.#209. Unit is useful in detecting leaks in clean-room filter seals° Also available: Model JM-3000-AL Aerosol Photometer 3 having linear response with approximately 2 orders of magnitude greater sensitivity .... 30-162 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: EXCITATION: OUTPUTSIGNAL IMPEDANCE: WEIGHT: PORTABiL ITY: PRICE: DELIVERYTIME: REMARKS: Joseph G. Pollard Company, Inc. Sonic - Sonic Range None P30 Sonoscope None required Audio - earpiece 5 ounces Ye s $6.50 7 days ARO Unit is an adaptation of a telephone earphone. It contains a tuning rod which protrudes on one end and vibrates on contact with a leaking pipe or system. The other end of the rod terminates at a metal diaphragm which generates sound from the rod vibration. .-_o ° 30-163 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : EXCITATION: OUTPUT SIGNAL IMPEDANCE : MAINTENANCE : SIZE : WEIGHT : PORTABILITY: TIME ON MARKET: PRICE : REMARKS : Joseph G. Pollard Company_ Inc. Sonic - Sonic Range None LT-10 30 to I0,000 Hz. 9 volts - Internal Battery Earphones Replace battery after 300 hours of use 7" x ii" x 3 1/4" 4 1/2 Ibs. Yes I year $199.50 Sound generated by liquid leaking from pressurized system is detecte_ amplified and tuned to leak frequency. 30-164 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RANGE S : SENSITrqlTY: EXCITATION: OUTPUT SIGNAL LMPEDANCE : REPEATABILITY: ENVIRONMENT EFFECTS : LIFE EXPECTANCY: SIZE: WE IGHT : PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Quantum Dynamics, Incorporated Flow Models LST-4 and LBT-2 0. I to I0,000 std. cc/min. 0.02 std. cc/mln* maximum llSv, 60 Hz or 24v dc Digital - can use counter 0.1% of full scale Designed for 50 to 120°F ambient i0 years Single channel: 6" x 6" x 12" Multl-range unit: 24" x 24" x 84" 5 to 300 Ibs. Small units are portable 2 years Single channel unit: $800 Large system, to $9500 90 days Large systems can be used for long term tests (days-weeks), for very low leak rates. Various adaptations are available. Instruments and systems can be custom designed for specific applications. 30-165 MANUFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADENAME: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : ENVIRONMENT EFFECTS : SIZE : WE IGHT: PORTAB IL ITY: REMARKS : Riken Keiki Fine Instrument Company, Ltd. Interferometer Riken Gas Indicator - Type 18 Scale for Methane - 0-I0; 0.5% per division Vernier scale for methane - 0-I: 0.02% per division Single flashlight battery Panel meter Designed for use in -30°C to +45°C ambient. 7 1/2" x 3 1/2" x 2 I/2" 3 1/2 Ibs. Is hand carried Refractive index of the test gas is compared to that of air. Unit is useful for measuring the concentration of any gas in air. Unwanted gases must _irst be filtered out by absorbers. 30-166 MAN-JFACTURER: OPERATLNGPRINCIPLE: SPECIFICIT%": MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTI_ITSIGNAL IMPEDANCE: REPEATABILITY: RESPONSETIME: ENVIRONMENTEFFECTS: DOESIT FAlL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERY TIME : Rfken Keiki Fine Instrument Company, Ltd. Catalytic CG_mbustion All combustible gases can be detected Riken Gas Auto-Alarm-Type GPI20 All combustible gas: LEL 0 - 100% (0-1.8 vol % for C4HI0) 1% of LEL can be detected 100v 50/6O Hz Panel meter and acoustic and lamp alarm (Ima into 60 ohms) ±5% full scale 90% in i0 sec. Design for use at 80 to 120vj 0° to 40°C, and performs within stated repeatability. No Check span every three months Sensor one year, Instrument proper 5 years. Power units: 4" x 8" x 8 1/4" Indicator (for one measuring point) 4" x 8" x 8 1/4" Detector heads (for one measuring point): 4 1/2" x 5 1/2" x 7" ii ibs. (in the case of one measuring point) Stationary type 5 years FOB Japan (US $360) - (in case of i measuring point) Within one mo=th 30-167 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS: Riken Keiki Fine Instrument Companyj Ltd. Catalytic Combustion All combustible gases can be detected Riken Combustible Gas Detector/Alarm-Type GP205 All combustible gas: LEL 0-100% (0 - 1.8 vol % for C4HI0) 1% of LEL can be detected 4 standard flashlight cells. Panel meter and acoustic and lamp alarm (ima into 60 ohms) ±5% full scale 90% in 5 sec. At 2.2 to 3v3 0° to 40°C; performs within stated repeatability. Check span every three months_ battery replacement every 200 measurements. Sensor one year, instrument proper 5 years. 5 1/2" x 6 3/4" x 3 1/2 " 5 1/2 Ibs. Portable (supported by neck strap during use) 3 years F.O.B. Japan (US $75) Prompt There is also a model GP-204 which does not have an alarm and uses fewer batteries. 30-168 MANUFACTURER: OPERATING PRINCIPLE: MODEL NO. & TRADENAME: RANGES: SENS IT IV ITY: EXC ITAT ION: OUTPUT SIGNAL EMPEDANCE : RESPONSE TIME: ENVIRONMENT EFFECTS : SIZE: WEIGHT: PORTABILITY: PRICE: REMARKS : Ruska Instrument Corporation Gas Pressure Change -Gas (_used Quartz Bourdon Tube) Series 38 0-2 psi through 0-i000 psi. Other ranges available on request. Resolution (i0,000 counts) - 0.01% full scale llOv 3 60 Hz (llva to llOva depending on model) Digital counter (built-ln) Slew rate: manual - 40 seconds full scale motorized and servo - 20 seconds full scale Operational temperature: 32° - 100°F 0°Storage temperature: - 120°F Standard and motorized 14 1/2" x 8 1/2" x i0 1/2" Standard - 22 Ibs.; motorized - 23 Ibs.; servo - 30 Ibs. Yes Units with ranges of 200 psi or less: Model 3823 - $1245 Model 3825 - $1690 Model 3833 - $1315 Model 3820 - standard Model 3823 - motorized Model 3825 - servo-matic Model 3830 - standard power pack ) Model 3833 - motorized power pack ) rechargeable battery 30-169 rMANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: ENVIRONMENT EFFECTS: MAINTENANCE : SIZE: WEIGHT: PORTABILITY: PRICE: DELIVERY TIME: REMARKS: Salen & Wicander, AB Catalytic Combustion (Combustion with photocell monitoring of filament) Combustible gases and vapors. KVC - 5/pli15 0-100% LEL of the gas concentration 10% LEL Battery with built-in llSv_ 60 Hz. Trickle charger. Audible and visual Temperature: 0 to 125°F Pressure: atmospheric Recharge batteries every 6 hours (4 hours if pump is worked continuously). 6" x 8" x i0" 17 pounds Can be hand carried $580 Stock item Audible and visual alarms adjustable from i0 to 100% LEL. Used to indicate % of LEL of flammable vapors in air. 30-170 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCI TATION• OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSETIME: ENVIRONMENTEFFECTS: DOESIT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: REMARKS: Salen & Wicander AB Catalytic combustion Combustible gases and vapors, chlorine and freon "Salwico" type KVC-5_KVC-50 0 - 100%LEL of the gas concentration 2% LEL 115 or 240v, 60 or 50 Hz 400w Panel meter (I ma into 700 ohms) +5% full scale 100% change in 2 sec. Designed for I00 to 130 or 215 to 260v at 0 ° to 125°F and atmospheric pressure No Check zero and span monthly. No specific servicing interval. I0 years Both portable and fixed mounted models are available for multi channel systems. I0 years $500 to $I0,000 4 weeks Audible and visual alarm adjustable from 2% to I00_ LEL. --io 30-171 -_-i_ MANUFACTURE R: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : OUTPUT SIGNAL IMPE DANCE : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB !L ITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Schneider Manufacturing Company Sonic - Sonic Range No. It is an underground water and steam leak locator. Globe Geophone Stethoscope headpiece Normal atmospheric humidity and temperature has no effect on operation. No Instruments now in for repair have been out for 10-16 years and after repair (about $28.00) will last for another 10-16 years. (See above) Carried in a wooden case 4" x i0" x 12" 12 ibs. Hand carried Since 1918 - 50 years $105.00 Same day order is received Geophone is non-electrical, rugged, sensitive and easily carried. Used to locate underground water and steam leaks. 30-172 MANUFACTURER : OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: LIFE EXPECTANCY: SIZE: WE IGHT : PORTABILITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Shannon Luminous Materials Company, Tracer-Tech Division Chemical indicators - Dye (Fluorescent System, Fluorescent Tracer Concentrates). Dilutes in any solvent except water. (Water tracers available). Non-specific, detects any leakage-path through which a liquid can be transported. T-IO0/0S-31 (green) T-IO0/0S-80 (blue-white). Fluorescent Concentrates - "Tracer-Tech." Sensitivity adjustable, according to dilution. Flaws as small as 75 millimicrons can be detected. Sensitivity may be increased to about I0 millimicrons or less by a development technique. Black light lamps operate on l15v, 60 Hz, 4 to lOOw. (50 Hz and high power up to 3 kw available). Visual inspection of fluorescent leak indications (photocell readout available). ± 5% in statistical count of defects. Average penetration dwell time i0 minutes. (Depends on length of leakage path). Recommended use temperature above 40°F._ to maximum of 200°F_ i0 years (plus). Supplied in pint bottles of concentrate (Spray cans available - 12 oz. spray cans, 8 per kit). Approximately 1 lb./pint - Kit weights about 16 Ibs. Kits can be hand carried. i0 years Spray can kit $30.50. Pint bottles $8.00. Ultraviolet lamps $14.50 to $95.00. Stock - immediate shipment. Qualifies under pertinent portions of MIL-I-25135C. Several different types of kits are available. Modifications are available to meet specific requirements of liquid systems, sensitivity, etc. Calibration instrumentation is available. Patented. 30-173 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : SENS ITIVITY : OUTPLrr SiGNAL IMPEDANCE : RE FEATABIL ITY: RESPONSE TLME: ENVIRONMENT EFFECTS: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS: Shannon Luminous Materials Company, Tracer-Tech Division Chemical Indicator - Dye Indicator shows color change as result of shift in pH due to absorption of amine vapors. Specific to amine gases, an_nonia, diethylene triamine, ethylenediamine, and similar liquids and vapors. T-621 Gas-Phase System "Tracer-Tech" -7 Estimate - leaks down to 1 x i0 std. cc/sec, can be detected. Visual inspection of color change from pale blue to bright red in locality of leak. Good. Presence of Ketone vapors and electro- chemical effects of metals may interfere. Average time is a few seconds to reach equilibrium of indications. Recommended use temperature between 60°F to 80°F. Elevated temperatures may accelerate electrochemical interference effects. I0 years Supplied in pint bottles (complete kits include accessory materials, barrier film-former, protective film-former, cleaners, vapor source). Kit weights approximately 16 ibs. Kits can be hand carried. 5 years T-621 Indicator $20.00 per pint. Complete Kit - $60.00 Stock - three days. Low volatility vapor sources are supplied which have less hazard than ammonia gas. The system has the capability of locating leakage points on the inside of a pressurized chamber, as in a honeycomb fuel tank. Patented. 30-174 MANUFACTURER: OPERATING PRINCIPLE: MODEL NO. & TRADENAME: RANGES : SENSITIVITY: EXCITATION: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS : MAINTENANCE : LIFE EXPECTANCY: SIZE : WEIGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Sherwin Incorporated Chemical Indicator - Fluorescent Dye Tradename is "Dubl-Chek" - Fluorescent Dye Penetrant Nonwater-washable and water-washable Fraction micron (Capillary Attraction) Good Penetrant dwell-tlme 15 minutes; developing time 5 minutes Penetrants should be used above 60°F. Surfaces and flaws must be free of moisture and soil. Bulk materials check for brightness periodically. Indefinite Spray cans (12 oz.) and bulk - 1/5/55 gallon containers. 30 ibs. Kit w/black light Portable but requires electric source for black light 4 years $150 with black light Two weeks Fluorescent Dye Penetrant (Liquid charged w/fluorescent dye 3 penetrates defects and exposes as glowing mark under black light) Qualified under MIL-I-25135C(ASG) and MIL-I-6866B. 30-175 .. • MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME" RANGES : SENSITIVITY: EXC ITAT ION: REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : LIFE EXPECTANCY: SIZE : WEIGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Sherwin Incorporated Chemical Indicator - Dye Tradename is "DUBL-CHEK" - Dye Penetrant Nonwater-washable and Water-washable Fraction micron (Capillary Attraction) Good Penetrant dwell-time 15 minutes; developing time 5 minutes Penetrants should be used above 60°F. Surfaces and flaws must be free of moisture and soil. Indefinite Spray cans (12 oz.) and bulk - 1/5/55 gallon containers Kit (3 spray cans) weighs 5 ibs. Completely portable 4 years $13.95 for Kit of 3 spray cans Immediate Visible Dye Penetrant_ a red llquid_ penetrates defects and shows them as a red mark on white developer. Qualified under MIL-I-25135C(ASG); MIL-I-6866B; and NAVSHIPS 250-1500-1 30-170 MAN"jFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: EXCITATION: OUTPUT SIGNAL IMPEDANCE : RE PEATAB IL ITY: RESPONSE T_ME : ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: WE IGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME: REMARKS : J. & S. Sieger, Ltd. (Pools-Dorset-England) Agent: Smith-Jesse_ Incorporated Catalytic Combustion All explosive Mases except acetylene, and vapors containing sulfur compounds which will poison detector element. Sieger ME7 Series I 20-25% to 100% LEL Ii0-250v, 50/60 Hz or 12v dc via power converter Panel meter and 5 amp_ 250v alarm relay ±2% i to i0 seconds Humidity or pressure does not affect reading. Designed for use in 30°F to 130°F ambient Yes Check monthly Indefinite with normal servicing 6 Ibs. Yes 20 years From $220 up 3 - 4 weeks Also have Model P_ Portable Battery Powered Unit. Features meter readout, any super-sensititive and standard 0-100% of LEL readout. From $170 up. 30-177 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : SENS IT IV ITY: EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE : DOES IT FAIL SAFE: SIZE : WEIGHT: PORTAB IL ITY: TIME ON MARKET : PRICE : Sierra Engineering Company - Materials Research Division Tracer - Radioactive. _ermetically sealed components are placed into a chamber which is then pressurized with a Radio-tracer (Kr 85 & Nitrogen) for a specific time and pressure. Components are then removed and tested for radioactive gas penetration_ Krypton-85 (Krypton-85 and Nitrogen mixture) Radioflo Model 44-462 i x I0 -II std. cc/sec. llSv_ 25 amps, 60 Hz (50 Hz available) Scintillation Crystal Counting Station Yes 56 1/4" x 54 7/8" x 44" Complete system: 3640 Ibs. (5 gallon Activation Tank) No 12 years Price on request 30-178 IIA_FACTURER: OPERATINGPRINCIPLE• SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: DOESIT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT : PORTAB lL ITY: TLME ON MARKET: PRICE : DELIVERY TIME : REMARKS: Sloan Instruments Corporation Mass Spectrometer (partial pressure) Any between 2 to 50 Mass Model R.G.A. Masses 2 to 50 i0-I0Partial pressures to 3 x torr (I00 ppm) llTv 3 50-60 Hz Recorder output 0 to 100my Yes Periodic tube element bake-out Dependent on gas being used for leak detection 7" x 9 1/2" x i0 1/2" 12 ibs (without magnet) Yes - tube and magnet only can be installed in system R.G.A. moved anywhere Three years R.G.A. $2400 Tube $265 Magnet $300 30 days The Sloan R.G.A. is capable of measuring partial pressures to 3 x i0 "I0 torr over 2 mass range of 2 to 50. Can automatically sweep i0 mass numbers/minute or be set to scan for one gas only for leak detection or monitoring doping gases etc. Long term stability allows one peak observation for hours or even days. Signal can be generated when pressures exceed set limits. 30-179 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: SENS ITIV ITY: EXCITATION: SIZE : WE IGHT : TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Spectronics Corporation (Black Light Eastern Division) Chemical Indicators - Dye (Fluorescent) Black light sources and additives to fluids in systems. Depends on additive and ambient light. 90v dc to llOv ac for lamp 6" x 6" x 12" i0 Ibs. ii years $22.50 and up I week Various models available. Dye is added to fluid. Used for detection of leaks in condensers, reactors, etc. Small traces of additives can be detected when leaks occur. 30-180 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : LIFE EXPECTANCY: S IZE : WEIGHT : PORTAB IL ITY: PRICE : Sprague Devices, Incorporated Bubble (Liquid Applicant) "Air Push" Leak Detector Visual (bubbles) Within 5 seconds 2 years, minimum 4 oz. bottle - i pint - 1 gallon 7 OZ. Yes 4 oz. $i.00; I pint - $2.35; 1 gallon - $15.00 Pi- 30-181 MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS: Starr-Kap Engineering Company Pressure Change - Liquid Liquid appropriate to system SKEC 1-200-TAR "Leak Check" Line Unit for Production Line Standard Working Pressure 0 to 2000 psi 2000 to 15,000 psi - special application 0.015 cc/min at 2,000 psi system pressure I00 psi air pressure normal *Visual readout to gauge Absolute Immediate No effect Yes, unit is self testing Minimum, depending on usage Indefinite 20" x 15" x 13" 70 ibs. approximate For production line use i0 years $1,750 and up 3 to 4 weeks *Automatic readout available; ticket printer also available. Readout is taken on a differential pressure gage. Measurement indicates pressure difference between a pressurized liquid system and the system being tested. Diaphragm seal is used between hydraulic and air system. Built-in intensifier increases shop line air pressure to desired value. 30-182 MANUFACTURER : OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADE NAME : RANGES : SENS IT IVlTY: EXC ITAT ION : OUTPUT SIGNAL IMPEDANCE : RE PEATAB IL ITY: RESPONSE TIME : DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY: S IZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Starr-Kap Engineering Company Pressure Change - Liquid Liquid appropriate to system SKEC 2-200-TAR "Leak Check" Portable Model on wheels Standard Working Pressure: 0 to 2000 psi 2000 to 15,000 psi - special application 0.015 cc/min at 2_000 psi system pressure i00 psi air pressure normal *Visual readout to gauge Absolute Immediate Yes 3 unit is self testing Minimum, depending on usage Indefinite 22" x 42" x 20" 200 ibs. approximate For repair or laboratory use i0 years $2,750 and up 3 to 4 weeks *Automatic readout available; ticket printer also available. Similar to Model SKEC-I-200 TAR_ except can be wheeled to test site, and has tank of hydraulic fluid to fill the system being tested. 30-183 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGE S : SENS IT IVITY: EXC ITAT ION: OUTPUT SIGNAL RESPONSE TIME : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Starr-Kap Engineering Company Pressure Change - Gas Gas LC 10234 "Air Check" 0 to 500 psi Has capacity of detecting beyond one bubble in five seconds or less. I00 psi air pressure, depending on application *Visual readout on gauge Immediate. Time duration of test: 15 sec. to fill, 15 sec. to temperature stabilize, i0 sec. to test, 5 sec. to dump. Yes, unit is self testing Minimum, depending on usage Indefinite 18 1/2" x 30" x I0" (with air intensifier to 500 psi) 175 ibs. approximate (with air intensifier to 500 psi) For production or laboratory use 5 years $1,400 and up 3 to 4 weeks *Automatic readout available also; ticket printer also available. Built-in air intensifier is used to raise test pressure above shop line pressure. Primarily for production testin_ of systems. Typical system volume is 250 in _. 30-184 MANUFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADENAME: EXCITATION: OUTPUTSIGNAL IMPEDANCE: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: LIFE EXPECTANCY: SIZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Superior Signal Company_ Incorporated Tracer - Smoke. Smoke is generated by chemical reaction in a cartridge type bomb. Superior Smoke Candles and Superior Smoke Bombs None required. Flame manually applied to fuse. Visual observation and odor of escaping smoke through leak Approximately 5 minutes Should be stored below 65% humidity and 85°F Yes 18 months Four sizes from 1/2" x 1 3/8" OD to 14" x 1 3/8" OD with burning time of 30 seconds3 60 seconds_ three minutes or five minutes 1 i/2 oz. to i lb. each Yes 14 years $4.50 to $25.80 per dozen 2 weeks After the smoke device is starte_ a blower injects the non- toxic smoke into the system to be leak tested. Smoke will be observed escaping from leaks. This method can be used on large systems such as sewer lines. On smaller systems a blower may not be necessary and merely insertion of the smoke device is sufficient. Smoke volume normally should be sufficient to fill an area 5 or 6 times that of the test system. Various types of smoke devices available. Smoke will not stain clothing nor corrode metal. 30-185 _- MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSiTIV ITY: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSETIME: DOESIT FAIL SAFE: MAINTENANCE: LIr-E EXPECTANCY: SIZE: WEIGHT: PORTABIL ITY: TIMEONMARKET: PRICE: DELIVERYTIME: REMARKS: Technicon Inc. Chemical Indicater - Reagent Specific for SO., NO, NO2, formaldehyde, agone_ armmonia,cyanide, acroleln, H2S Auto Analyzer Variable from ppmupwards 1 ppm 0-10my ± 1.0%relative 3 - 5 minutes Yes i week 5 - i0 years 3 x 2 x 2 ft. cabinet 70 Ibs. Yes New $5,000 90 days A gas sample is selectively scrubbed, as programmed, for one specific constituent at a time. The liquid concentrate for each analysis is delivered to a colorimeter for quantitative analysis. The colorimeter output is normally shownon a recorder chart. °. 30-186 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIV!TY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSETIME: ENVIRONMENTEFFECTS: DOESIT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: REMARKS: Technology/Versatronics_ Inc. Flow Gases "L!NO?_ASS"MassFlowmeter 0.16 std. cc/sec, air_ through 50 ibs.min. 0.01 std. cc/sec, air llSvj 60 Hz or 28v dc Panel Meter also 5v dc _+0.1%of reading 70 ms for full step changeat 10%of flow rate +2%full scale accuracy specified over m _25°F temperature span and pressure range of _i atm. No Check zero and span every 6 months No specific servicing interval I0 yrs. 4.53" long 1.37" in diameter 8 oz. Due to light weight and small size easily portable. 6 years $1500 thru $2500 4 weeks A self-heated thermistor placed in the gas flow path 3 senses mass flow rate. A second thermistor which is not in the flow path but held at the flow stream temperature_ serves to compensate for temperature variations. Modifications are available to conform with customer's requirements. 30-187 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSETIME: ENVIRONMENTEFFECTS: DOESIT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: Technology/Versatronics_ Inc. Electrochemical Cell Oxygen p 0160 0 to 10%, 0 to 21%,0 to 40%, or anywherebetween 0 to 75 mmHgand 0 to 320 mmHg. 30 mv/n_mon Model p 0160L; 6 mv/mmon Model p OI60B Line operated l15v, 50-60 Hzj 0.3 amps. Battery operated 4 mallory RMI2Rcurrent 1.3 ma. Fanel Instrument with 10v dc on p 0160L (ac unit) and 1.5v dc on p 0160B (battery unit). ± 0.1% of reading 5 seconds ± 1%of full scale accuracy specified over temperature range of 32°F to 120°F and ± lOv ac variation. No Recharge oxygen probe every 30 to 90 days. 5 years 5" x 9.5" x 6" 5 ibs. Yes 1 1/2 years $480 for p 0160L; $490 for p OI60B price includes electrode. Off the shelf 30-188 _- MANUFACTURER: OPERATING PRINCIPLE : SPE CIFICITY: MODEL NO. & TRADENAME : SENS IT IVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: ENVIRONMENT EFFECTS : MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB IL ITY: TI_ ON MARKET: PRICE : DELIVERY TIME : REMARKS : Techsonics, Inc. Sonic - Ultrasonic Range None; depends on sound of leak II0, IIOM_ 112 "Son-Tector" Can detect 0.003" diameter hole at 25 psi at 25 feet (air) 9 volt transistor radio battery Speaker_ 8 ohm headset 3 meter movement ±5% of meter reading 0 to 50°C Periodic battery replacement (100-150 hours) 5 - i0 years 6 1/4" x 4 1/4" x 1 1/2" 15 oz. base unit, 5 pounds including case and all accessories. Normally hand carried or clipped to belt. 4 1/2 years $144.50 to $245.50 depending on accessories Stock Also available: Pole Mounting Amplifier for use in hazardous locations - complete high voltage isolation. Useful for locating leaks in gas and liquid pressure and in vacuum systems. 30-189 _- MANUFACTURER: OPERATING PRINCIPLE : SPE CIF!CITY: MODEL NO. & TRADENAME : SENS IT IV ITY: EXCITATION : OUTPUT SIGNAL IMPEDANCE : ENVIRONMENT EFFECTS : MAINTENANCE : LIFE EXPECTANCY: SIZE : WEIGHT : PORTABILITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Techsonics, Inc. Sonic - Ultrasonic Range None; depends on sound of leak i00_ I01 "Son-Tector" Can detect .003" diameter hole at 25 psi at 25 feet (air) 9 volt transistor radio battery 8 ohm headphone 0 to 50°C Periodic battery replacement (150-200 hours) 5-10 years Pistol shape - 6" x 8" 2 pounds Hand held 4 1/2 years $144.50 to $168.00 depending on accessories Stock Used to find leaks in both pressure and vacuum systems. 30-190 _- MANUFACTURER: OPERATINGPRINCIPLE: MODEL NO. & TRADE NAME : SENS ITIV ITY: EKC ITAT ION: OUTPUT SIGNAL IMPEDANCE : DOES IT FAlL SAFE: MAINTENANCE : SIZE : PORTAB IL ITY: REMARKS : Tel Air Products Corp. Sonic-Ultrasonic Range (converted to audible signal) Tel-A-Leak Model TA 700 Detects holes 0.0015" in diameter and larger. 9 v internal battery Audible signal (headphones) No (Servicing interval) 500 hours (low drain solid state circuitry) Approximately 4" x 6" x 2" Yes This unit is designed to locate pressurized cable leaks at a distance. 30-191 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENS ITIV ITY: EXC ITAT ION: O5_£PUT SIGNAL IMPEDANCE : RE PEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS: DOES IT FAlL SAFE: PORTABILITY: PRICE: REMARKS: Teledyne, Inc. (Analytical Instruments Division) Ultraviolet (Absorption of ultraviolet and/or visible radiation) Selectivity can be achieved by selection of specific light sources and filter elements. Series 600 Trace or Percent ± I% of full scale l15v, 60 Hz_ 160w. 0-5 mv dc Within 1% of full scale in 24 hours. For most applications, 90% response obtained in 5 to 30 seconds. Ambient temperature: 40 to ii0 degrees F. No Not portable Depends upon application. Noise level: less than 0.25% for most applications; up to 2% on highly sensitive applications. Pump requirements: gas flow of 30 to 60 cubic inches per minute. Optional accessories available include: recorder, alarm contacts, multiple sampling systems, calibration samples, etc. Numerous standard modifications can be made to enable unit to handle a wide variety of applications. 30-192 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFIC ITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXC ITAT ION: OUTPUT S IGNAL IMPEDANCE : RE PEATAB IL ITY: ENVIRONMENT EFFECTS : SIZE : WEIGHT: PORTABILITY: PRICE : DELIVERY TIME : REMARKS : Teledyne, Inc. (Analytical Instruments Division) Thermal Conductivity - preceeded by chromatographic columns fer gas separation. Can be made specific in many applications. Model 850 Percent only Depends on the thermal conductivity of carrier gas versus component measured. Typically is 1/2% full scale. l15v, 60 Hz, 200w 0-5 mv dc ± 1/2% of scale Ambient temperature 40-100°F Analysis Unit: 15 x 15 x 19 Control Unit: 17 1/2 x 6 x 12 Approximately ii0 ibs. No $3200 plus options 8 - I0 weeks A one to four component thermal conductivity analyzer that utilizes a separation system to give specific information relating to the components of interest in a complex gas composition. The analyzer is actually a system_ composed of a minimum of three non-explosion proof sections (analysis and control sections, and recorder). 30-193 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO.& TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: RESPONSETIME: ENVIRONMENTEFFECTS: DOES IT FAlL SAFE: MAINTENANCE : SIZE : PORTABiLITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Teledyne_ Inc. (Analytical Instruments Division) Flame lonization Hydrocarbons Series 400 Triple Range Attenuator As low as 0-2 ppm Methane equivalent l15v, 60 Hz Linear signal. Meter readout and 0-5 mv dc. Other outputs available. Flame response is instantaneous. Model 403 for analysis of samples with dew points below 125°F and Model 404 with dew points up to 175°F. Yes Replacement of support gases Approximately 16" x 17" x 9" (slightly larger for other models). Portable and panel models offered. Approximately 3 years Standard Model - $2450.00 8 - i0 weeks The analyzers are continuous monitoring devices designed to measure trace quantities of total hydrocarbon contaminants in a gaseous atmosphere. The principle of operation is based on measuring the ion current generated when organic compounds are burned in a hydrogen flame. The signal is linear over a range of 0 to I0,000 ppm hydrocarbon. 30-194 MANUFACTURER : OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RANGE S : SENS ITIV ITY: EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE : RE PEATAB IL ITY: RESPONSE TIME : DOES IT FAlL SAFE: LIFE EXPECTANCY: SIZE : WE IGHT : PORTAB IL STY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Teledyne, Inc. - (Analytical Instruments Division) Thermal Conductivity Series 200 Analyzers Single or multiple, as requested, ppm or percent Changes of 1/4 to 1/2% of scale detected reliably. l15v, 60 Hz, l15w. 0-5 my dc standard Zero drift is less than 1% full scale in 24 hours. 90% response in approximately 50 seconds No i0 years Approximately 15" x 17" x i0" From 25 to 70 ibs., depending on unit. No Approximately i0 years Dependent upon application requested. Usually 6 to 8 weeks Accuracy: ±1% full scale for most binary mixtures. Typical application: 0-1% hydrogen in air, nitrogen, or oxygen analyzer. Optional accessories available include readout indicators, automatic controls, alarms_ etc. Sample requirement flow - 5 to 25 cubic inches per minute. . . • 30-195 _- MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENS ITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY: S IZE : WE IGHT: PORTABILITY: PRICE : DELIVERY TIME : Teledyne, Inc. - (Analytical Instruments Division) Electrochemical Cell Oxygen only 306W 2 ppm to 1% 1% full scale l15v_ 60 Hz 0-5 my dc 90% in 5 sec. Temperature range 40-120°F. Cell is not sensitive to barometric pressure. No Replacement and service of electrolytical cell. Depends on cell 16" x 18" x i0" 67 ibs. Semi Standard Model $2045.00 2 to 4 weeks 30-196 MANUFACTURER : OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGE S : SENSITIVITY: EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: MAINTENANCE : SIZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Teledyne Inc. " (Analytical Instruments Division) Electrochemical Cell Oxygen Series 320 0 - 1% to 0 - 100% 1% full scale None - detector cell furnishes all power for unit. Visual reading on meter and 0-5 mv dc 90% in 5 seconds Operating temperature range 30-125°F No Cell replacement annually Approximately 7 1/2" x II" x 5 i/2" 4 ibs. Can be hand carried Approximately 4 years $525.00 and up. 2 to 4 weeks Accuracy: 1% of full scale at constant temperature. 5% of full scale throughout the temperature range. Model 330 is a pocket size unit (8 oz.) without probe or indicating instrument. 30-197 fMANUFACTURER: Teledyne, Inc. - (Analytical Instruments Division) OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : EKC ITAT ION: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS : S IZE : REMARKS : Catalytic Combustion Combustible gas and vapor #i00 Series Single or multiple ranges are available. 0 to 1% concentration and greater range. l15v, 60 Hz (50 Hz on request) 0-5 mv dc, also_ indicating intrument if requested 95% of total change in 30 seconds Temperature range: 50°F to 100°F. Voltage: llSv ± 15%, 60 Hz. 15" x 17" x i0" Sample flow rate of 200 cc/sec, is required. This analyzer comprises complete sensing equipment. Optional accessories available include readout indicators, automatic controls, alarms, sampling systems, etc. o 30-198 __ MANUFACTURER : OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION: REPEATABILITY: RESPONSE TIME: ENVIRONMENT EFFECTS: REMARKS : Teledyne, Inc. (Analytical Instruments Division) Infrared (Absorption of radiant energy) Gas selectivity is obtained by separate detectors and selective infrared beam filtering. #700 series Single or multiple as required indicated by 0-I0 ppm C02, 0-50 ppm CO full scale ranges° l15v, 60 HZ, 200w (other frequencies on special order). Better than 1/2% of full scale 90% of a change in 15 to 30 seconds. Faster response may be provided for special applications. Line voltage: 95 to 130v ac. Ambient temperature: 50°F to 100°F. Sample requirement: 30 to 200 cubic inches per minute. Components of detector are selected for optimum response to the sample component of interest and minimum interference of other sample components. Among selected detector components are: filling gases for detector and filter; sample, filter, and detector cell lengths; the cell window and rotating shutter materials. Above information is for series 700 Infrared Analyzer. This analyzer comprises the complete sensing equipment. Optional accessories available include recorder, alarm contact, multiple sampling systems, calibration samples, etc. Principle use as leak detector is with nitrous oxide tracer gas useful in detecting: cyanogen, hydrazine, hydrogen cyanide_ nitric oxide, hydrocarbons, H2S , CO, CO 2. --io _. ° 30-199 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITiVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : RE PEATAB IL ITY: RESPONSE TIME : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT : TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Tenvac, Incorporated Mass Spectrometer Helium, Neon 3 Argon TENVAC-850 Automatic Leak Tester i, 5, i0_ 50, 1003 5003 i000, 5000 & I0,000 I0 -I0 cc/sec. He and larger leaks llSv, 60 Hz, 20 amps Panel Meter & 2 amps at llOv. 0.5% full scale Less than 1 sec. Yes Calibrate and zero daily - no other specific. 5 years 55" x 42" x 32" 500 ibs. I year $113500.00 8 weeks Detects leak rates of 5 x 10-9 atmosphere cc/sec, of helium in "prebombed" components. Automatically feeds 3 tests, and accepts or rejects up to 150(i parts per hour. Designed for production applications where high rates and automation are imperative. 30-200 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSETIME: ENVIRONMENTEFFECTS: DOESIT FAlL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERYTIME: TescomCorporation, Smith Welding Equipment Division Halide Torch - Flame Color Non-combustible Halide. Refrigerant gases. NEISI-17 or NE182-17with NEI80, Handi-Heet Halide Detector 15 ppmto 13000_000ppmin air 15 ppmof halide gas in air Visual observation of flame color change Dependson visual detection of operator 2 seconds Temperature -2° to 120°F No Replace reactor element whenconsumed 40 years reactor element, i0 years detector 12" x i" 16 oz. Can be carried to job by one person I0 years $16.00 range From stock °_ 30-201 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: SENSITIVITY• EXCITATION: OUTPUTSIGNAL IMPEDANCE : RESPONSE TIME : DOES IT FAIL SAFE: LIFE EXPECTANCY: SIZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Testing Systems, Incorporated Chemical Indicator - Dye Leakage of fluorescent penetrant detected by black light. "Fluoro Finder" FL-50 System Can detect any straight through leak regardless of size of opening ll0v, 50-60 Hz black light (3660a.u.) Available also at 220v. Fluorescent glow Immediate to 30 minutes No Indefinite KL-50 Kit 12 1/4" x 7 7/8" x 3 3/8" KL-50 Kit 9 Ibs. Power Packs available to afford complete portability 2 1/2 years KL-50 Kit $49.00; Penetrant - $45.00/gallon One week Variations and modifications are available to conform with customers requirements. Power Pack for portable application $198.00. 30-202 -- MANUFACTURER: OPERATINGPRINCIPLE: MODEL NO. & TRADENAME : RANGE S : SENS IT IV ITY: EXCITATION : OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : SIZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET: PRICE : REMARKS : Texas Instruments, Incorporated Pressure change Gas (Fused Quartz Bourdon Tube) Fused Quartz Precision Pressure Gage Models 144 and 145 0-1.5 to 0-500 psi 0.001% full scale. Special units with 0.00033% full scale. 105 to 125v 3 50 or 60 Hz, 80w. Visual (digital readout) and recorder output 0.002% full scale Slew rate = 2 minutes full scale Operational temperature range: 0 to 38°C. Zero stability after warmup - 0.0005% full scale per degree C ambient temperature change. Table model - 14 1/8" x I0 i/2" x 15 1/2" Rack mount model - 19" x 14" x 15" 32 1/2 ibs. table; 41 I/2 ibs. rack Yes 7 years Model 144 - $2085. Model 145 - $2680. Model 145 is a Servo-Nulling Readout Unit. Model 144 is a Motor Driven Readout Unit with manual control. Tubes with special sensitivity ranges or in evacuated capsules are available on special order. Gages consist basically of two parts - the interchangeable capsule containing the fused quartz pressure sensitive element and the readout unit. For use in absolute 3 differential or gage applications. - 30-203 MANUFACTURER : OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SE NS IT IV ITY: EXC ITAT ION : OUTPUT SIGNAL IMPEDANCE : RE PEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE: WE IGHT : PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Thermal Industries of Florida, Inc. Tracer-Halogen (cold cathode plasma emission affected by minute traces of Halogen gas. When a leak is approached a loud, penetrating squeal is produced by the signal generator.) Halogen Gas TIF 550 Halogen Leak Detector Single Better than 1/2 ounce per year 2 standard type D flashlight batteries in parallel 1.5 volts. Audible tone Excellent Instantaneous 0°F to 120°F - same environment as ordinary flashlight. No Change batteries when needed - no specific servicing interval. Indefinite - battery life 40 hours at 4 hours per day. 5.625" x 3.25" x 1.875" 25 ounces with batteries Designed for "in hand use" 3 years $97.50 Stock - i week Supplied with practice leak; I ounce in I0 years. Complete solid state device - long flexible conductor with miniature probe. Pinpoints leaks, large or small, even in a room or fixture containing concentrations of Halogen gases. 30-204 -- MANUFACTURER : OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGE S : SENS IT IVITY: EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE : REPEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Thermal Instrument Company Flow (thermal mass flow rate) Any gas Portable Model #59 0-0.12 to 0-3 x 105 std. cc/min. 0.01 std. cc/min. ll5vj 60 Hz_ 20w. Panel meter and 0 to i0 my to potentiometric instrument. 0.2% 5 seconds Maximum effect of environmental temperature variations from 0 to 200°F is 1%. Excitation voltage variations (90-135v) have no effect. No None required (solid state electronics) i0 years Power and readout unit - 8" x 6" x 8" Sensor - 6" x 4" x 3" Power Unit - 15 Ibs. Sensor - 6 Ibs. Yes 9 years $1180 - add $80 for panel type readout instrument - add $400 for built-in amplifier. 6 to 8 weeks Standard sensor useable to 500°F. Special sensors available for llO0°F service. Standard flow wetted parts are made of 316S.S. Flow tubes made of other materials are available. 30-205 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE : RE PEATAB ILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : SIZE : Thermal Instrument Company Flow (Thermal Mass Flow Rate) For Liquids Model 60 2.0 grams/min, to 0 to 200 Ibs./min. l15v, 60 Hz, 20w. 0 to I0 my dc. Optional indicating meter. Better than 0.2% of reading. 1 second Standard working pressure: 1200 psi; available to 20,000 psi Standard working temperature: to 500°F; specials available to llO0°F. Standard - 7 1/2" x 13 1/4" x 9". v Portable - 6" x 8" x 8". 30-206 ° • MAN-JFACTURER : OPERATING PRINCIPLE SPECIFICITY: MODEL NO. & TRADENAME • RANGES : SENSiTIVITY: EXC ITAT ION: OUTOUT S IGNAL IMPEDANCE : REPEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: SIZE : WE IGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Tinker & Rasor (Detectron Division) Sonic - Sonic Range Primarily for fluid leaks Detectron LD Audio spectrum of interest Amplifier frequency response shaped to emphasize leak sounds and reduce rumble and other outside interference. Self contained 9v battery Audio (2000 ohm earphones) _ood Instantaneous Temperature range 0°F - 130°F Yes Overall height 5", diameter 2 3/4" i lb. Can be hand carried 4 years $67.50 Stock item Uses magnetic pick-up and converts mechanical vibrations into electrical impulses. These impulses are amplified and fed to a pair of earphones. 30-207 _- MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABIL ITY: RESPONSETIME: ENVIRONMENTEFFECTS : DOES IT FAIL SAFE: LIFE EXPECTANCY: S IZE : WE IGHT : PORTABILITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Tinker & Rasor - (Detectron Division) Sonic - Sonic Range Fluid Leak Detector (gas or vapor not detected) DETECTRON XL-2 Complete Audio Spectrum. One wide-band position - i0 filter selected frequencies. 3 course selections and fine tuning control to the acoustic frequency of interest. Self-contained 9v battery Visual & Audio (2000 ohm earphones) Excellent Instantaneous Temperature Range 0°F to 130°F Yes Battery life under normal conditions approximately i year. 5 I/8" x 7 i/8" x 2 I/2" (instrument only) 3 ibs. Hand carry 1 year $142.00 including carrying case Stock XL-2 consists of: Instrument with battery ready to operate, sensitive magnetic transducer, lightweight earphones, 7" probe, molded compartmented carrying case. Uses magnetic pick-up and converts mechanical vibrations _ into electrical impulses which are amplified and connected to a pair of earphones. Mute switch allows silencing of headphones without volume adjustment to allow control of repeatability. 30-208 -_ MANUFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADENAME• RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABIL ITY: RESPONSETIME: ENVIRONMENTEFFECTS: SIZE: WEIGHT: PORTABILITY: TIMEONMARKET: PRICE: DELIVERY TIME : REMARKS : Trans-Sonics_ Incorporated Gas Pressure Change - Gas (Variable capacitance- diaphragm element) Type No. 130 ° System (consists of pressure cell and electronics unit) I0_ i00, i000 torr_ absolute or differential 5 x 10 -5 torr l15v_ 60 Hz 5 and 10v dc at rated pressure 0.01% to 0.02% dependent on range 0. i second Requires correction for changes in environmental temperature. Pressure cell and electronics unit each are 3 1/4" x 5 1/4" x 5 3/4" Each unit - 4 ibs. Yes i year Pressure cell $485. Electronics unit $410. Stock item Additional instrumentation is required for reading output voltage. This equipment has been found useful for measuring gas leaks of flanges by measuring differential pressure across a capillary tube through which the leaking gas is allowed to pass. 30-209 __ MANUFACTURER: OPERATINGPRINCIPLE: MODEL NO. & TRADENAME : REPEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS : LIFE EXPECTANCY: S IZE : PORTABILITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Turco Products_ Inc., Division of Purex Corp. 3 Ltd. Chemical Indfcator- Dye "Dy-Chek" Good Penetrant should remain on test area for I0 minutes. Test Area must be clean and dry. Best penetration obtained between 70°F and 120°F. Shelf life one year minimum. 12 oz. spray cans to 55 gallon drums. Kits available for hand carry 16 years Complete kits $25.00 - penetrant $i0 to $12 per gallon. One week Qualifies under pertinent portions of MIL-I-25135C - a visible dye penetrant. 30-210 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RE PEATAB IL ITY: RESPONSE TIME : ENVIRONMENT EFFECTS : LIFE EXPECTANCY: SIZE: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS: Turco Products, Inc., Division of Purex Corp., Ltd. Chemical Indicator - Fluorescent Dye "Fluor Chek" Good Penetrant should remain on test area for i0 minutes. Test area must be clean and dry. Best penetration obtained between 70°F and 120°F. Shelf life one year minimum 12 oz. spray cans to 55 gallon drums Kits available for hand carry i0 years Penetrant: $5 per gallon ($31.28 per 12 - 12 oz. spray cans) Emulsifier: $3.50 per gallon - Developer: $9.00 per gallon. One week Qualifies under pertinent portions of MIL-I-25135C - a fluorescent inspection penetrant. Material is intended for detection of surface defects. Process requires application of penetrant, then emulsifier and then a developer solution. Surface is inspected for flaws under ultraviolet light. Several formulations available. 30-211 __ MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAlL SAFE: LIFE EXPECTANCY: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: 20th Century Electronics Ltd. Mass Spectrometer Model A Model B Model C He iium/Hydrogen He Iium/Ar gon Masses 2, 3, & 4 "CENTRONIC" LD401 Six positions (xl, x3, xl0, x30, xl00, Test) i0 "II std. cc/sec. 10 "12 tort partial pressure Helium by accumulation 200-250 v 50 Hz 3.5 amp Less than one second is required to produce 50% full scale deflection on xl scale of leak rate meter. 30 ° C maximum due to use of air cooled diffusion pump. Yes 4 to 5 years with servicing at 6 month intervals. 165 Kg. (360 lb.) On four wheels 3 years _1200. O. O. 4 weeks 30-212 - MTLNL]FACTL'RER: Union Carbide Corporation - Linde Division OPERATING PRINCIPLE: Halide Torch - Flame Color SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION : OU_PL_ S ISNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENACE : LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS: Non-Combustible halide refrigerant gases Prest-O-Lite Model No. 2 (Part #11XI6) I00 to 500,000 PPM i00 PPM in air Flame heated copper or copper alloy Change in color of flame within unit I00 PPM 2 to 3 seconds Performs within stated repeatability at ambient temperatures of -65°F to 150°F. Yes Replacement of copper or copper alloy re-action plate --I0 to I00 hours life expectancy 5 years normal usage 1 1/4" diameter x 6" long ounces Yes 23 years $8.10 list One week after receipt of order "Jnit is a leak detecting attachment to an acetylene gas torch. ° 30-213 MANUFACTURER: OPERATING PRINCIPLE : SPECIFIC ITY: MODEL NO. & TRADENAME : RANGES: SENS ITIVI TY: EXCITATION : OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE : MAINTENANCE : LIFE EXPECTANCY: SIZE : WEIGHT : PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Union Carbide Corporation, Linde Division Halide Torch Flame Color Non-Combustible Halide Refrigerant Gases Prest-O-Lite Model No. I (Part #IOX32) 20 to 500,000 PPM 20 PPM in air Flame heated copper or copper alloy Change in color of flame within unit 20 PPM 2 to 3 seconds Performs within stated repeatability at ambient temperatures of -65°F to 150°F. Yes __ Replacement of copper or copper alloy re-action plate --I0 to I00 hours life expectancy 5 years normal usage 1 1/4" diameter x 6" long 4 ounces Yes 23 years $8.10 list One week after receipt of order Unit is a leak detector attachment for an acetylene gas torch. --i- 30-214 _- MANUFACTURING: OPERATINGPRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAM_: RANGES: SENS IT iV!TY: OUTPUT SIGMAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFORTS : LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB IL iTY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Union Industrial Equipment Corporation Chemical Indicators - Reagent Reagent type detector tube chosen for specific gases of interest available for detecting nitrogen dioxide, oxygen_ carben dioxide, and many other gases and vapors. unico Model 400 - Kitagawa Detector Reagent type detector tubes available for over 50 different gases and vapors with full scale ranges varying from 20 ppm to 30%. As low as i ppm on some tubes Length of reagent discoloration in tube Less than three minutes for complete test Temperature correction information is supplied. Contamination of test area by gases and vapors can affect accuracy of measurement of specific gas to be detected. Reagent tubes are single test items Complete kit - i0" x 8" x 2" Complete kit - 3 Ibs. Can be hand carried i0 years Cost of gas detector kit is $80.00. Cost of reagent tubes is $.50 to $I.00 each and are packaged in lots of 5-10-20. Irm_ediate Gas detector kit includes all equipment and information required for making detection tests. Reagent tubes are purchased separately. Unit consists of a hand operated precision pump which draws a gas sample into a detector tube filled with a chemical reagent which changes color upon exposure to the gas of interest. The length of color change varies with gas concentration. 30-215 MANUFACTURER• OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVlTY: REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : LIFE EXPECTANCY: SIZE : WE IGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Union Industrial Equipment Corporation Chemical Indicator - Reagent Oxygen in air No. 707 2 to 30% by volume ±1% full scale ±5% full scale 1 1/2 minutes for test Temperature correction table provided Indefinite Complete kit Complete kit Complete portable 3 years $22.75 From stock 8" x 4" x 2 1/2" I ibs. Can be used in explosive atmospheres. Manually operated piston type plunger draws gas sample into reaction tube. Length of discoloration in reaction tube is proportional to oxygen concentration. 30-216 _ MANUFACTURER : OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGE S : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: RESPONSE T]2dE: ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EX2ECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE: DELIVERY TIME: REMARKS: Union Industrial Equipment Corporation Chemical Indicators-Reagent (Color change insensor is detected by photoelectric reagent cell) Carbon monoxide Model No. 777 Is a function of both exposure time and gas concentration 50 ppm 120v, 60 Hz, 3w Visual indicating instrument and audible alarm. Responds to full scale and sounds alarm in 2 to 3 minutes in a I000 ppm concentration and in 4 to 5 hours for 50 ppm. Not sensitive to ambient changes in temperature and humidity. No Replace sensing tab after tripping alarm or every 60 days of use. i0 years 8 5/16" x 4 1/4" x 3 3/16" 3 Ibs. Yes - battery pack available for power source. 4 years $124.50 From stock The detecting sensor responds to the presence of CO by changing color. The color change is detected by a photoelectric system. When the concentration reaches the t_ic level, a relay is tripped and an alarm sounded. 30-217 __ MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVlTY: EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT PAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WEIGHT : PORTAB ILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Union Industrial Equipment Corporation Chemical Indicators - Reagent (Color change in sensor is detected by photoelectric cell) Carbon monoxide Model 888 Is a function of both the exposure time and gas concentration. -50 ppm 120v ac-dc plus internal ni::_el-cadmium battery and built-in charger Visual indicating instrument and audible alarm Responds to full scale and sounds alarm in 2 to 3 min. ma I000 ppm concentration and in 4 to 5 hours for 50 ppm. Not sensitive to ambient changes in temperature and humidity. Yes Recharge batteries after i0 hours of service. Replace sensing tab after tripping alarm or every 60 days of use. i0 years 8 5/16" x 4 1/4" x 3 3/16" 3 I/2 ibs. Yes 4 years $190 From stock Automarlcally converts to battery operation in event of power line failure. The sensor responds to the presence of carbon monoxldeby changing color. The color change is detected by a photo- electric system. When the gas concentration reaches th toxic level, a relay is tripped and an alarm is sounded. 30-218 -_ MANU'FAZ._JRER: OPERATINGPRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL LMPEDANCE : REPEATABILITY: RESPONSE TIME: DOES IT FAIL SAFE: MAINTENANCE: LIFE EXPECTANCY: SIZE : WEIGHT: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Union Industrial Equipment Corporation Interferometer Gases Model #760 As low as 0 to 2% by volume - varies with gas being measured. C.1% for hydrogen 3 carbon dioxide or propane. i!5v 3 50/60 Hz. Panel indicating instrument and audible and visual alarm. _5% of full scale 3 seconds No Nominal I0 years II 7/8" x 7 1/8" x 8 5/8" 15.5 Ibs. Good portability 3 years $1500 3 - 4 weeks The displacement of interference light fringes produced by the optical path difference between the sample gas and air standard is measured by a photo- electric circuit. A built-in vacuum pump draws the sample into the analyzing chamber. No special training is required for operation. 30-219 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME : RANGES : EXCITATION : OUTPUT SIGNAL IMPEDANCE : DOES IT FAlL SAFE: MAINTENANCE : SIZE : WEIGHT: PORTABILITY: PRICE : DELIVERY TIME : REMARKS : Union Industrial Equipment Corporation Catalytic Combusion Combustible gases and vapors Model #202 0 to 100% LEL 4 standard flashlight cells (6v) Indicating instrument and audible alarm at 1/3 of LEL No Replace batteries when necessary 6 1/2" x 5" x 3 1/4" 5 1/2 Ibs. Yes $180_ With built-in battery charger $270 From stock Alarm point at 1/3 of LEL - 30-220 _- MAh"JFACTURER: OPERATINGPRINCIPLE: MODELNO. & TRADENAME: SENSITIVITY: RESPONSETIME: ENVIRONMEN_rEFFECTS: SIZE: PORTAB IL ITY: PRICE : REMARKS : United States Gulf Corporation Bubble "Detek" i x I0 -4 cc/sec. Almost instant Formulas available to -65°F and to +210°F 6 ounce plastic bottles - also available by the gallon Can be hand carried From $19.10 to $24.00 per carton (8 bottles, 6 ounces each) depending on formulation. Derek dries clean and does not require removing after testing. Detek penetrates dirt, oil films, scale and grease. It is non-corrosive, non- flammable, non-explosive and is not harmful to users or apparatus. Various formulas are available for compatibility with gases such as oxygen, nitrogen, hydrogen, refrigerant gases7 natural gas and air. . ° 30-221 MANUFACTURER: United States Safety Service Company OPERATING PRINCIPLE: Chemical Indicator - Reagent SPECIFICITY: Carbon monoxide MODEL No. &: TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: RESPONSE TIME: #300 Saf-Co-Meter (Detector kit) o to 0.04% CO 0.005% CO Gas is drawn through the indicating tube by aspirator bulb. Color change of indicating gel in tube is compared to color chart. 36 seconds exposure per tube ENVIRONMENT EFFECTS: Operating temperature range is 65 to 850 F. Can be used at altitudes up to 40,000 ft. LIFE EXPECTANCY: SIZE: WEIGHT: PORTABn.ITY: TDm ON MARKET: PRICE: DELIVERY TIME: REMARKS: (Detector kit - indefinite) (Tubes - one year) Kit: approximately 3 1/2" x 3" x 6" 1 lbs. Yes 20 years $30.00 complete with carrying case and 12 tubes Stock item Glass sealed indicating tubes developed by National Bureau of Standards and also conform to Military Spec Mn.-T-3948A. Kits also may be obtained to Military Specification MIL-D-3945A upon request for quotation. Presence of nitrogen dioxide interferes with the normal development of color in the tube. Filter tubes of activated carbon placed ahead of the sensing tube will remove this gas from the sample. 30-222 M_NUF AC %_oqlER: OPERATLNG PRINCIPLE SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS : MAINTENANCE: LIFE EXPECTANCY: SIZE : WEIGHT: PaR TABILITY: TIME ON MARKET: PRICE : DELIVERY TIME: REMARKS : Universal Controls Corporation Flow Gases Dragnet 0-30 and 0-200 PS!G 1/4" water column pressure loss. Hand Pump Visual - Flow through bubbler bottle i minute Volume displacement subject to temperature changes. Yearly 5-10 years I0" diameter x 30" 26 Ibs. Yes 15 years $IOO Stock - 3 weeka Pressure reference tank volume is approximately ii0 cubic inches. Test systems should not be significantly different in volume, System and connected storage tank are pressurized by hand pump. A system leak is measured by flow through a bubbler bottle located between the reference tank and the system. Gas is admitted into test system to make up pressure loss due to gas leak. Gas volume admitted is measured by a bubbler bottle. . 30-223 MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: REPEATABILITY: RESPONSETIME: ENVIRONMENTEFFECTS: DOES IT PAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WEIGHT: PORTABILITY: TIME ON MARKET: PRICE DELIVERY TIME : REMARKS : Uson Corporation Thermal Conductivity None (on standard unit). Custom units available with partial selectivity to helium and argon. Model 500 Series Leak Detectors Automatic range change i x 10 -3 std. cc/sec, full scale on Helium (Std.) Custom Unit available for I x 10 -4 cc/sec. Rechargeable batteries (6 volt) and/or directly from I05-125v, 50-63 Hz. Meter-100 microampere, light and audible signal. +5% Less than I second full scale, any range Voltage- I05-125v, 50-63 Hz 4 o Temperature - I0 to 130°P Humidity - 0 to 100% R.H. No No periodic servicing (one year unconditional warranty). 20 years Two units, each smaller than a telephone Two, four pound packages Easily hand carried Four years $2600- 3800 Three weeks Detects helium, hydrogen, argon, all refrigerants, fluorine_ and others. Unaffected by background gases. Available in totally explosion-proof version for Class I, Division I, Groups B & D (model 540). Explosion-proof Model 540 has FSN 4940-928-4698. 30-224 __ MANUFACTURE R : OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGE S : SENSITIVITY: EXC iTAT ION : OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: LIFE EXPECTANCY _- SIZE : WE IGHT : PORTAB IL IYY: TIME ON MARkeT: PRICE : DELIVERY TIME : REMARKS : Vacuum Instrument Corporation Mass Spectrometer Helium or Argon MD I00_ 100A, 12_ 120A, 140 Seven (XI to XI000) i x 10 -4 std. cc/seco to 5 x 10 -14 std. cc/sec. 5 x 10-14 stdo cc/sec. llSv ac_ I0 amps. Panel Meter instantaneous at test port inlet. Normal factory environment is recommended. Can be used outdoors in good weather. Yes i0 years 34" x 24" x 30" Approximately 400 ibs. Mounted on rubber casters 5 years $4675 to $6885 2 4 weeks Accessories available include: Calibrated helium leak, tracer gas sprayer kit, sampling sniffer probe° Audible leak indicator_ and test port adapters. Units do not require liquid nitrogen traps° Getter system removes all but inert gases. 30-225 __ MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: RESPONSE TIME: ENVIRONMENT EFFECTS: DOES IT FAlL SAFE: PORTABILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Vacuum Instrument Corporation Mass Spectrometer Helium MD 190 Seven (XI to XI000) 10-5 to 2 x I0 -I0 std. cc/sec. 2 x i0 "I0 std. cc/sec. l15v ac 3 I0 amps Panel Meter Instantaneous at test port inlet. Normal factory environment is recommended. Can be used outdoors in good weather. Yes Moveable table model i year $1975 2 - 4 weeks Accessories available include: Calibrated helium leak_ tracer gas sprayer kit 3 sampling sniffer probe. Portable leak detectorj and test port adapters. Units do not require liquid nitrogen traps. Getter system removes all but inert gases. 30-226 __ MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGE S : SENS IT IVITY: EXC ITAT iON: OUTPUT SIGNAL IMPEDANCE : DOES IT FAIL SAFE: MA INTE NANCE : SIZE : WE IGHT : PORTAB IL ITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS : Varian Associates (Vacuum Division) Mass Spectrometer Helium #LD-100 7 sensitivity ranges - XI to Xl000 i0-I0i x std. cc/sec. Approximately 15 amps at l15v, 60 Hz with auxiliary roughing pump system. Meter No As needed 16" wide x 27" high 350 Ibs. Is mounted on rubber wheels 2 years $5195 30 days after recipt of order This equipment includes auxiliary mechanical pump and automatic rough, test and vent valving assemblies. Accessories available. _. o 30-227 MANUFACTURING: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : RANGES : SENS IT IVITY: EXC ITAT ION: OUTPUT SIGNAL IMPEDANCE : RE PEATAB IL ITY: RESPONSE TIME : DOES IT FAIL SAFE: MAINTENANCE : SIZE : WEIGHT: PORTAB ILITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Varian Mess Analysen Technlk GmbH (Heraeus-Engelhard Vacuum, Inc. distributor) Mass Spectrometer Helium (other gases mass 2-92) Atlas Gas Detector Model C Nine ranges: X3000, XlOj000) Helium I x 10-12 std. cc/sec., Argon I x 10 -12 Freon 5 x I0-I0 std. cc/sec. Xl, X3, Xl0_ X30_ Xl00, X300, XI000, llbv, 60 Hz, 600 volt amps i0 millivolt or I00 millivolt full scale std. cc/sec. ±2% of reading Less than 0.5 seconds for 50% of leak when volume ot test sample is less than 5 liters. Yes As required 20" x 22" x 18 1/2" Approximately 210 Ibs. Cart available as standard option About 5 years Basic unit $6j080 Stock Many accessories available for use in conjuction with mass spectrometer. 30-228 -- MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES : SENS IT IVITY: EXC ITAT ION: RESPONSE TIME : ENVIRONMENT EFFECTS : DOES IT FAIL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE : WE IGHT : PORTABILITY: PRICE : REMARKS : Veeco Instruments_ inc. Mass Spectrometer Helium Model MS-9ABC 7 sensitivity ranges (1-3-10-30-100-300-1000) i x I0 -I0 std. cc/sec or I part helium in i0 million parts air. 24 amps at 115 v 60 Hz. Almost instantaneous Can be used in normal factory environment. Yes - only in automatic operation. Requires frequent daily tuning of electronics circuitry. Piping and vacuum lines cleaned approximately every 2 months to remove out gassing contaminants. No experience in this area 41" x 27 3/4" x 36 1/2" Approximately 600 ibs. Unit mounted on rubber casters. Exact price not known, unit purchased thru a rental plan. Accessories available - calibrated leak helium probe assembly sniffer kit reducers audible alarm extension cable --i- _° • 30-229 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : SENS IT IV ITY : OUTPUT SIGNAL IMPEDANCE : ENVIRONMENT EFFECTS : DOES IT FAlL SAFE: MAINTENANCE : LIFE EXPECTANCY: SIZE: WE IGHT: PORTAB IL ITY: TIME ON MARKET : PRICE : DELIVERY TIME : REMARKS • Volumetrics Volumetric Displacement VM 1 x 10 -5 std. cc/sec helium Digital indicator Requires constant gas temperature for maximum accuracy. Temperature range -65°F to + 180°F. No None normally required. 250,000 cycles Approximately 6" wide x i0" deep x approximately 3" high. 4.8 ibs. Portable when not attached to system. 2 years. $395.00 From stock Accuracy of measurement depends on accuracy and repeatibility of the pressure sensor used_ (auxiliary). System is pressurized 3 known period of time elapses_ piston is adjusted to restore original system pressure, displacement is read on counter. Pressure range: 0-i000 psia. Adjustment sensitivity is 0.0005 psi. Model VM-II (cost $14_5) is a volumetric micrometer with resolution of i x i0 -vcu in. provides adjustment range of 0.000001 to 0.880000 cu. in. Accuracy of 0.1% of reading throughout range of vacuum to I000 psia, when using pressure sensor of such accuracy. With a fused--_ quartz pressure sensor, an accuracy of 0.015% of reading is available. Volume readout is digital. 30-230 -- MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RANGES : SENS IT IVI TY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : REPEATABILITY: RESPONSE TIME : ENVIRONMENT EFFECTS : SIZE: WEIGHT: PORTABILITY: PRICE: Wallace & Tiernan, Inc. Pressure Change - Gas Series 660A Various ranges from 0-120 inches of water to 0-i00 psi absolute_ gage or differential. 0.005% of full scale l15v or 220v_ 50 or 60 Hz; i00 watts Digital readout (direct reading). 0.02% of full scale 5 to 40 seconds, depending on range (5 seconds per thousand register counts) Temperature sensitivity is .05% for 10°F Operating temperature limits are 0°F_120°F Ii" x I0" x 8" 21 Ibs. Can be carried by hand. $1000 to $1200 30-231 MANb'FACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME : OUTPUT SIGNAL IMPEDANCE: MAINTENANCE : LIFE EXPECTANCY: SIZE: WEIGHT: PORTABILITY: TIME ON MARKET: PRICE DELIVERY TIME: REMARKS : Watsco_ Incorporated Bubble (liquid Applicant) None DL-I "Search" Visual - Bubbles form in leak area None Indefinite 6" x 2 1/2" x 1 1/8" 4 fluid ounces squeeze bottle - I gal. (8 1/2 Ibs.) Pocket size 8 years $i Stock Contains no glycerin. Is safe to use with oxygen. --io 30-232 MANUFACTURER: OPERATING PRINCIPLE : SPECIFICITY: MODEL NO. & TRADENAME : EXCITATION : OUTPUT SIGNAL IMPEDANCE : SIZE : PORTABILITY: PRICE : REMARKS : The Welch Scientific Company Spark Coil (Tesla Type) For finding leaks in glass vacuum systems. Leak Detector - Catalog No. 2619 115 volts ac or dc Glow is produced in a vacuum system when a leak is approached with the spark 2" dia. x 12" long Hold in hand $16.75 Not recommended for very thin wall systems. 30-233 _- MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RANGES : SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE : ENVIRONMENT EFFECTS : WE IGHT: PORTAB EL ITY: PRICE : REMARKS : Whittaker Corporation - Pace Wiancko Division Pressure Change - Gas Model Q3403 Secondary Pressure Standard 18 ranges from 0-i to 0-I0,000 psi gage, absolute or differential. *Less than 0.05% full scale i05-125v ac, 60 Hz, 65w lOv rms (nominal) at I0,000 Hz at 0 input and 12,500 Hz at full scale. Output impedance is approximately i,000 ohms. Operating temperature: 40°F to ll0°F. Less than 25 ibs. (including plug-in pressure head) Has a carrying handle $2700 including one pressure head Two types of pressure heads are offered. One mounts in the front panel of the Secondary Pressure Standard and the other is for remote operation at distances up to 500 feet. Each head incorporates _n integral heater and thermostat to stabilize the temperature of the transducer for optimum performance. *With the optional Frequency Multiplier 3 the basic 2500 Hz full scale frequency can be multiplied by 2 or 4 increasing the pressure reading resolution. 30-234 MANUFACTURER: OPERATING PRINCIPLE: SPECIFICITY: MODEL NO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUT SIGNAL IMPEDANCE: REPEATABILITY: RESPONSE TLME : ENVIRONMENT EFFECTS : SIZE : WEIGHT: PORTABILITY: PRICE: DELI_RY: REMARKS: Whittaker Iorporation - Pace Wiancko Division Pressure Change - Gas None_Can handle corrosive liquids and gases on both sides of pressure sensor) Model DMI - Digital Manometer (4 digit presentation) Interchangeable dual range pressure heads of 0-I and 0-I0; 0-i00; 0-I00 and 0-I000 nan Hg. (Dizferential, gage or absolute) Resolution: Better than 0.001% of range l10-120v, 60 Hz Visual (Digital Indicator) and Analog output voltage 0-I0 volts dz full scale Accuracy: _I/4% range, including linearity and repeatability. No error to I000 Hz. Ambient temperature range: 32° to 150°F 6" x I0 3/4" x 7.5" 9 ibs. Yes 0 to I mm Hg range system - $12A5 All other ranges - $995 Additional pressure heads - $350 each Six weeks The pressure head may be detached and installed at a remote point using an extension cable (I0 ft.) supplied for the purpose. 30-235 MANUFACTURER: OPERATING PRINCIPLE : MODEL NO. & TRADENAME : RANGES : SENS IT IVITY: OUTPUT SIGNAL IMPEDANCE : RESPONSE TIME : LIFE EXPECTANCY: SIZE : WE IGHT: PORTAB IL ITY: TIME ON MARKET: PRICE : DELIVERY TIME : REMARKS : Winton Products Co., Inc. Bubble "Sherlock" -65 ° to plus 160°F 0.16 ounce per year (2.88 x 10 -5 std. cc/sec.) Clusters of foam or bubbles 5 seconds to 1 minute depending on size of leaks Shelf llfe I year 4 oz. dispensers to 55-gal. drums Depends on container size 4 and 8 oz. dispensers can be hand carried 16 years Depends on type of fluid ordered and container size Type I: 4 oz. $0.70 - $3.70 gal. Type II: 4 oz. $0.85 - $5.20 gal. 24 hours receipt of order Various types Regular - for use above freezing Low Temp. - for use below and above freezing Extra Low - extreme temperatures (-50°F) Type CG - for pure oxygen and compressed gases Type F - for refrigeration and air conditioning applications Type I - for oxygen (+35°F to 160°F) - meets AF Spec MIL-L-25567A (ASG) Type II - for oxygen (-65°F to +35°F) - meets AF Spec MIL-L-25567A (ASG) Various type applicators and spraying equipment available. Dries clean. 30-236 _ MANUFACTURER: OPERATINGPRINCIPLE: SPECIFICITY: MODELNO. & TRADENAME: RANGES: SENSITIVITY: EXCITATION: OUTPUTSIGNAL IMPEDANCE: RESPONSETIME: ENVIRONMENTEFFECTS: MAINTENANCE: LIFE EXPECTANCY: SIZE: WE IGHT : PORTAB IL ITY: PRICE : DELIVERY TIME : Yellow Springs Instrument Company, Inc. Electrochemical Cell Sensor is selective for oxygen except for Halogens and easily reduced gases rarely encountered. #52 0-50% oxygen 0.2% Two 7.0v Hg. batteries; one 1.3v Hg. battery Panel Instrument 90% complete within 30 seconds; stable within 45 seconds Sample should be close to ambient when collected. Analyzing cell is temperature compensated. Recharge the cell and change Teflon membrane every few months. Battery life is six months in normal operation or 500 hours of continuous use. 9 1/2" x 7 1/2" x 7 1/2" 5 ibs. Yes $245 Stock 30-237 REFERENCES SECTION I None SECTION 2 2-1 2-2 2-3 2-4 2-5 2-6 SECTION 3 3-1 3-2 3-3 3-4 Wells, F.E., "A Survey of Leak Detection for Aerospace Hardware." Paper presented at 28th National Fall Con- ference, Amerlcan Society of Nondestructive Testing, Detro&t, Michigan, October 14-17, 1968. Sax, N.I., Dan@erous Properties of Industrial Materials, 2nd edition, Relnhold Publlshlng Corporation, New York, 1963. Dushman, S., Sclentzfic Foundations of Vacuum Technique. 2nd edition, John Wiley and Sons, New York, 1962. Neilson, J.M.S., and Weisberg, H., "Analysis of Leak Detection in Industrial Silicon Rectifiers," Solid State Design, 1963, pp. 28-32. Marr, J.W., "Leakage Phenomena." Paper presented at the Valve Technology Seminar, Midwest Research Institute, Kansas City, Missourl, October 21, 1965. Weiner, R.S., Baslc Criteria and Definitions for Zero Fluid Leakage, Jet Propulsion Laboratory Report TR 32- 926, Pasadena, California, December 15, 1966. NASA Accession No. N67-15681 Howell, G.W., and Weathers, T.M., editors, Aerospace Fluid Component Designers' Handbook. TRW Systems Group Report RPL-TDR-64-25, to U.S. Air Force Rocket Propul- sion Laboratory, Contract AF 04(011)-11316, Project No. 6753, March 1967. Ansley, S.P., Jr., "Vacuum Leak Detection of Large Space Environmental Chamber." Presented at Fifth An- nual Symposium on Space Environment Simulation, Arnold Engineering Development Center, (Aerospace Environmen- tal Facil_ty), Arnold Air Force Station, Tennessee, May 21-22, 1964. AD 441 312 Oaks, A.E., "Helium Leak Testing Fuel Rods for the PWR Blanket," Nondestructive Testing, Vol. 28, 1960, pp. 319-22. Panza, P.A., Jr., "Improved Fine and Gross Leak Test Methods for Electronic Components." Paper presented R-I _ at 28th National Fall Conference, American Society of Nondestruct±ve Testing, Detroit, Michigan, October 15, 1968. 3-5 U.S. Department of Defense (Army), Test Methods for Electronic and Electrlcal Component Parts, MIL-STD- 202C, 12 September 1963. SECTION 4 4-1 Cassen, B., and Burnham, D., "A Method of Testing Her- metically Sealed Components Utilizing Radioactive Gas," International Journal of Applied Radiation and Isotopes, Vol. 9, 1960, pp. 54-59. 4-2 4-3 4-4 4-5 4-6 4-7 Roberts, J.A., "The Role of the Halogen Detector in Industrial Leak Detection." Presented at 26th National Conference, Society of Nondestructive Testing, Novem- ber I, 1966, Chicago, Illinois. American Vacuum Soczety, Glossary of Terms Used in Vacu- um Technolo@y Commlttee on Standards, 1958. Manganaro, J.L., and Hollinger, D.L., Quantitative Leak Test Desiqn Guide, Report to National Aeronautics and Space Admlnistratlon N67-37647, Contract NAS7-100; JPL-951763; August 1967. Summers, R.H., and Koch, E.F., "Bag-type Quantltative Leak Measurements Using a Helium Mass Spectrometer," Jet Propulsion Laboratory Space Programs Summary No. 37-35, Vol. IV, October 31, 1965, p. 44. Blears, J., and Leck, J.H., "General Principles of Leak Detectlon," Journal of Scientiflc Instruments, Vol. 28, 1951, Supplement No. i, p. 20. Florescu, N.A., "H_gh Vacuum Side Versus Forepressure Side Leak Detecuion, Vacuum, Vol. 12, No. 4, 1962, p. 227. 4-8 Goldback, G., "Leak Detectlon with Mass Spectrometer and Platinum Diode," Vacuum-Technlk, Vol. 5, 1956, pp. 7-12. 4-9 4-10 4-11 Cross, S.H., and SteckelmaCher, W., "Leak Detectlon by Vacuum Techniques," Research, April 1956, pp. 124-131. Garrod, R.I., and Nankivell, J.F., "Leak Testing of -_ Large Welded Vacuum Vessels, Vacuum, Vol. ii, No. 3, 1961, pp. 139-145. Turnbull, A.H., "Leak Detection and Detectors," Vacuum, Vol. 15, No. i, 1965, pp. 3-11. R-- 2 _- 4-12 4-13 4-14 4-15 4-16 4-17 4-18 4-19 SECTION 5 5-1 5-2 5-3 5-4 5-5 Florescu, N.A., Reply to "Comments on High Vacuum Side Versus Forepressure Side Leak Detection, Vacuum, Vol. 13, No. 2, 1963, p. 57. Florescu, N.A., Final Comments on "High Vacuum Side Versus Forepressure Side Leak Detection," Vacuum, Vol. 13, No. 3, 1963, p. i01. Steckelmacher, W., Comments on "High Vacuum Side Versus " Vacuum Vol 13 No.Forepressure Side Leak Detection, , . , 2, 1963, p. 57. Steckelmacher, W., Further Comments on "High Vacuum Side Versus Forepressure Side Leak Detection," Vacuum, Voi. 13, No. 3, 1963, pp. 101-i02. Santeler, D.J., Comments on "High Vacuum Side Versus Forepressure Side Leak Detection," Vacuum, Vol. 13, No. 3, 1963, p. 102. Biram, J.G.S_, and Burrows, G., "Bubble Tests for Gas Tightness," Vacuum, Vol. 14, No. 6, 1964, pp. 221-226. Ratcliffe, R.T., "The Location, Measurement and Assess- ment of Shape of Leaks by Bubble Emission," British Journal of Applied Physics, Vol. 15, January 1964, pp. 79-83. Howl, D.A., and Mann, C.A., "The Back-pressurizing Technique of Leak Testlng," Vacuum, Vol. 15, No. 7, 1965, pp. 347-352. Herbst, G.F., "The Phenomenon of a Time Lapse Effect in Predlctlon and Detection of Leaks." Paper presented at 56th Air Force/Industry Conference on Missile Systems Leaks and Spills, Los Angeles, California, February 24- 26, 1965. Sullivan, J.J., and Schultz, J.B., "Design Parameters for Welding and Brazing Vacuum Components," Research/ Development, Vol. 17, No. 9, 1966, p. 64. Pirani, M., and Yarwood, J., Principles of Vacuum En_i- neerin@, Reinhold Publishing Corporation, New York, New York, 1961, p. 146. Guthrie, A., Vacuum Technolo@y, John Wiley and Sons, Inc., New York, New York, 1963. American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Sectlon I: Power Boilers; Sec- tion III: Nuclear Vessels; Section VIII: Unfired Pres- sure Vessels, 1965. _o , R-3 5-6 5-7 5-8 5-9 5-10 5-11 5-12 SECTION 6 6-1 6-2 6-3 6-4 6-5 6-6 Olson, R.E., "Safety Hazards of High Pressure Leak Checks." Paper presented at 56th Air Force/Industry Conference on Missile Leaks and Spills, Los Angeles, California, February 24-26, 1965. Smith, G.C., "Constructing Fixtures for Using MSLD," ISA Journal, November 1963, p. 56. Shields, R.B., A Portable Leak Detector for Heav_ Water, Report AECL-2278, Atomic Energy of Canada, Ltd., Chalk River, Ontaria, April 1965. Drawin, H.W., and Kronenberger, K., "New Portable Bench- type Mass Spectrometer," Vakuum-Technik, Vol. 8, 1959, pp. 128-137. Pacey, D.J., "A Self-extracting Search Gas Probe for the Location of Leaks in Vacuum Apparatus," Journal of Scientific Instruments, Vol. 41, June 1964, p. 398. Kloepper, F.H., and others, "Leak Localizer for Van de Graff Accelerator Tubes," Review of Scientific Instru- ments, Vol. 23, May 1952, p. 245. Santeler, D.J., Private Communication from Aerovac Corporatlon, Green Island, New York. Perry, R.H.; Chilton, C.H.; and Kirkpatrick, S.D., edi- tors, Chemical En@ineers' Handbook, 4th edition, McGraw- Hill Book Company, New York, New York, 1963. Marr, J.T., Study of Dynamic and Static Seals for Liquid Rocket En@ines, Final Report Phase II, Contract NAS7-102. Report to Chief, Liquid Propulsion Technology, Rocket Pro- pulsion Laboratory, National Aeronautics and Space Ad- ministration, Washington, D.C., December 1963. Burrows, G., "Flow Through and Blockage of Capillary Leaks," Transactions of the Institution of Chemical Engineers, Vol. 39, 1961, p. 55. Edmister, W.C., "Specific Heat Ratlos for Hydrocarbons," Industrial and En@ineerin_ Chemistry, Vol. 32, i'_40, p. 373. International Crltical Tables, Vol. 5, McGraw-Hill Book Company, New York, New York, 1929, pp. 79-84. _- Santeler, D.J.; Jones, D.W.; Holkeboer, D.H., and Pagano, F., Vacuum Technolo@[ and Space Samulation, National Aeronautics and Space Administration SP-105, 1967. w R-4 6-7 6-8 6-9 6-10 6-11 6-12 6-13 6-14 6-15 6-16 Ochert, No, and Steckeimacher, W., "The Flow Character- istics of Caplilary Leaks," British Journal of Applied Physics, Vol. 2, 1951, pp. 332-333. IIT Research Institute, Permeability Data for Aerospace Appllcations, Contract NAS 7-388, Natlonal Aeronautics and Space Administration, March 1968. Kobayashi, S., and Yada, H_, "Leak Test of Rubber Gas- kets," Advances In Vacuum Science and Technolo@y, (Pro- ceedings of the First International Congress on Vacuum Techniques, Namur, Belgium, June 10-13, 1958), E. Thomas, editor, Volume I, Pergamon Press, Inc., New York, New York, 1960, pp. 248-250. Baer, E., editor, En@ineer_n_ Design for Plastics, Reinhold Publishlng Corporatlon, New York, New York, 1964. Tellier, G.F., Poppet and Seat Desl_n Data for Aerospace Valves, Rocketdyne Division of North American Aviation, Inc., Report AFRPL-TR-66-147, Canoga Park, California, July 1966. AD 488 480 Marr, J.W., Study of Dynamlc and Static Seals for Liq- uid Rocket En@ines, Contract NAS 7-102. Report to Chief, Liquid Propulsion Technology, RPL, National Aeronautics and Space Admlnistration, Washington, D.C., September 1965. Hayashi, C., "Role of Adsorption in Production and Mea- surement of High Vacuum," Vacuum Symposium Transactions, 1957, Pergamon Press, Long Island Czty, New York, p. 13. Chelton, D.B., and others, "Solid Formatlon in Flowing Cryogenic Fluids," Advances in Cryo@enic En_ineerin@, Vol. 8, Plenum Publishing Corp., New York, New York, 1963, pp. 311-314. Dahi, E., Propellent Frostin@ Effects, Final Report AFRPL-TR-66-75, April - September 1965; Alr Force Rocket Propulsion Laboratory, Air Force Systems Command, Ed- wards Air Force Base, California. AD 488 681. Gift, R.D., and others, "Clogging of Manlfolds wiuh Evaporatively Frozen Propellants." Paper presented at American Institute of Aeronautics and Astronautics, Second Propulsion Joint Specialist Conference; U.S. Air Force Academy, Colorado Springs, Colorado, June 13-17, 1966. °_ R-5 SECTION 7 7-1 7-2 7-3 7-4 7-5 7-6 7-7 7-8 7-9 7-10 SECTION 8 8-1 8-2 American Nuclear Society Standards Committee, Proposed Standard for Leaka@e Rate Testin@ of Containment Struc- tures for Nuclear Reactors, ANS 7.60, Hinsdale, Illi- nois. American Society of Mechanical Engineers, Leak Detection and Leaka@e Measurement, PTC-19.21, United Engineering Center, New York, New York. Feakes, F.; Roehrig, J.; Benner, F.; Beecher,N.; Wernlnck, L.; and Barnes, C., Research Studies Relat- in_ to the Detection of Leaks in a Lar@e Aerospace Sys- tems Environmental Chamber, Arnold Engineering Develop- ment Center Contract AF 40(600)-1076. Technical Docu- mentary Report AEDC-TDR-64-237, National Research Cor- poration, Cambridge, Massachusetts, November 1964. AD 451 008 U.S. Department of Defense, Nondestructive Testin@ Re- quirements for Metals, MIL-STD-271D, March ii, 1965. U.S. Department of Defense, Environmental Test Methods, MIL-STD-810B, June 15, 1967. U.S. Department of Defense, Iron-nickel Alloys for Seal ° in_ to Glasses and Ceramics, MIL-I-23011B, April 30, 19 _. U.So Atomic Energy Commission, Leak Rate Measurement, Mass Spectrometer Method, Process Standard 9956010, Sandia Corporation, Albuquerque, New Mexico. Symons, G.E., "Water and Wastes Engineering Manual of Practice, Number Two," Water and Wastes En_ineerin@, Vol. 4, No. 5, 1967, M 46. U.S. Department of Defense, Test Methods and Procedures for Microelectronics, MIL-STD-883, May l, 1968. U.S. Department of Defense, Standard for Weldin@ of Reactor Coolant and Associated Systems and Components _or Naval Nuclear Power Plants, NAVSHIPS 250-1500, Nov- ember 1960. Work, R.H., "Silica-glass Helium Leaks as Standards in Leak Detection," Fifth National Symposium on Vacuum Tech- nology Transactions (1958), pp. 126-128. National Aeronautics and Space Administration, Reference Technical Brief B68-10142 (1968), Technology Utilizatior Office, NASA, 4800 Oak Grove Drive, Pasadena, Californi_ R-6 8-3 8-4 8-5 8-6 8-7 8-8 8-9 8-10 8-11 8-12 8-13 Holkeboer, D°H., "An Ultra-high Vacuum Gauge Calibra- tion System," Test Engineerin@, October 1965, p. 16. Jenkins, R.O., "The Constructlon of Small Vacuum Leaks of Constant Value," Journal of Sclentific Instruments, Vol. 35, November 1958, p. 428. Kronberger, H., "Vacuum Technlques in the Atomic Energy Industry," Proceedings of the Institution of Mechanical En@ineers, Vol. 172, No. 3, 1958, pp. I13-132_ Christlan, R.G., and Leck, J.H., "The Use of a S_licon Carblde Porous Plug for the Control of Gas Flow _nto a Vacuum System Down to 1 ul torr sec -_,'' Journal of Scien- tific Instruments, Vol 43, 1966, pp. 229-233. Mathews, A.J., Evaluation of Porous Materials as Mole- cular Leaks, AEDC-TDR-64-94, ARO, Inc., Arnold Air Force Statlon, Tennessee, Aerospace Environmental Facility, July 1964. NASA Accession No. N64-26189 Haywood, W.H., and Jepsen, R.L., "A Simple High Vacuum Gauge Calibratlon System," Vacuum S_mposium Transac- tions, 1962, p. 459. Ochert, N., and Steckelmacher, W., "Leak Detection Prac- tice wlth Particular Reference to the H2-Pd Method," Vacuum, Vol. 2, 1952, pp. 125-136. Laufer, M.K., "Standard Leaks and Their Callbration by Constant Pressure Change in Volume Technlques," Trans- actlons of the 8th Natlonal Vacuum Slrm_osium and 2nd Internatlonal Congress on Vacuum Science and Technology (1961), Vol. 2, Pergamon Press, New York, New York, 1962, pp. 1086-1090. Bicknell, C.B., "An Improved Helium-only Sensltive Meth- od for Calibratlng Silica Membrane Hellum Leaks," Sixth National Symposium on Vacuum Technology, Trans- actions (1959), Pergamon Press, Inc., New York, New York, pp. 97-100. Fisher, F., "Measurement of Satellite Subsystem Leak Rates in a Thermal-vacuum Environment," Paper presented at Institute of Environmental Sciences 13th Annual Tech- nical Meeting, Washington, D.C., April 10-12, 1967 Roehrig, J.R., and Simons, J.C., Jr., "Accurate Cali- bration of Vacuum Gauges to i0 -_ Torr," Transactions of the 8th National Vacuum S_mposium and 2nd Interna- tional Con@ress on Vacuum Science and Technology (1961), Vol. i, Pergamon Press, New York, New York, 1962, p. 511. R-7 8-14 8-15 8-16 8-17 8-18 SECTION 9 9-1 9-2 9-3 9-4 9-5 9-6 9-7 9-8 Normand, C.E., "Use of a Standard Orifice in the Cali- bration of Vacuum Gauges," Transactions of the 8th National Vacuum S_mposium and 2nd International Con_res_ on Vacuum Science and Technology (1961), Vol. i, Perga- mon Press, New York, New York, 1962, p. 534. Sundheim, B.R., "An Absolute Leak," Review of Scienti- fic Instruments, Vol. 35, 1964, p. 228. Salvinski, R.J., "Advanced Valve Technology for Space- craft," Paper No. 66-MD-61. Presented at American Soci- ety of Mechanical Engineers Design Engineering Conference and Show, Chicago, Illinois, May 9-12, 1966. American Society for Testing and Materials, Tentative Method for Calibration of Helium Leak Detectors by Use of Secondary Standards, F 78-67T, ASTM, 1916 Race Street, Philadelphia, Pennsylvania. American Vacuum Society Standard (Tentative), Helium Mass Spectrometer Leak Detector Calibration, AVS 2.1- 1963, AVS, P.O. Box 1282, Boston, Massachusetts. McDowell, C.A., editor, Mass Spectrometry, McGraw-Hill Book Company, Inc., New York, New York, 1963. Ellman, R.P., "Trouble-shooting Vacuum Systems With a Mass Spectrometer," Research/Development, Vol. 15, No. 7, 1964, pp. 45-47. Skurat, V.E., and others, "Increasing Leak Detection Sensitivity by Means of Liquid Indicators," Pribory i Tekhnika Eksperimenta, Vol. ii, No. 6, Nov.-Dec. 1966, pp. 143-147 (in Russian). Weast, R.C., editor, Handbook of Chemistry and Physics, 45th edition, The Chemical Rubber Company, Cleveland, Ohio, 1964. Cossutta, D., and Steckelmacher, W., "Lens Mass Spec- trometer Leak Detector," Journal of Scientific Instru- ments, Vol. 37, 1960, p. 404. Hanley, T.E., "The Use of Thoria-coated Filaments in the Mass Spectrometer Leak Detector," Review of Scien- tific Instruments, Vol. 19, 1948, p. 369. Peters, J.L., "Mass Spectrometer Leak Detector Including a Novel Repeller-heater Assembly," U.S. Patent 3,155,826; November 3, 1964. Varadi, P.F., and Sebestyen, L.G., "A Simple Vacuum Leak Detector Using a Radio-frequency Mass Spectrometer," Journal of Scientific Instruments, Vol. 33, October 19567 pp. 392-394. R-8 9-9 Barrington, A.E. v and others, "An Inverted Magnetron Helium Leak Detector," Journal of Vacuum Science and Technology, Vol. 2, No. 4, July/August 1965, pp. 198- 202. 9-10 Nicollian, E.H., "A Laboratory Leak Detector Using an Omegatron," 7th National S_mposium on Vacuum Technolo_[, Transactions (1960), Pergamon Press, Inc., New York, New York, p. 80. 9-11 Peters, J.L., "Mass Spectrometer Leak Detector with Im- proved Sensitivity," Review of Scientific Instruments, Vol. 30, December 1959, p. 1093. 9-12 Daly, N.R., "High Sensitlvity Mass Spectrometer Leak Detector," Review of Sclentiflc Instruments, Vol. 31, No. 7, July 1960, p. 720. 9-13 Lurie, W.W., Commercial Equlpment Specification Number ERC/F-C-1001 for a Versatile Leak Detector, U.S. Nation- al Aeronautics and Space Adminlstration Electronics Research Center, Cambrldge, Massachusetts, December 8, 1965. 9-14 Lee, T.H.; Kurtz, D.R.; and Veras, D.J., "Problems in Detectlng Leaks wlth Long Time Constants in Long Life Vacuum Devlces wlth Sealed Glass Envelopes," Vacuum, Vol. 13, No. 5, May 1963, pp. 167-172. 9-15 Lineweaver, J.L., "Leak Detection - Ultrasensitive Techniques Employlng the Helium Leak Detector," IRE Transactions of Electron Devices, January 1958, pp. 28- 34. 9-16 Consolidated Electrodynamlcs Corporation, Leak Detection Manual, 992249-0008, Pasadena, California. SECTION 10 I0-i Brownell, L.E., and others, The Improvement of Leak Detectlon Techniques, Final Report N63-83879, Contract NAS8-2579, Universlty of Michigan College of Engineer- •ng, December 1962. 10-2 Briggs, W.E.; Jones, A.C.; and Roberts, J.A., "Leak Detection Techniques," 5th National S_mposium on Vacu- um Technology, Transactions (1958), Pergamon Press, Inc., New York, New York, p. 129. 10-3 10-4 Hutchins, W.C., "Production Leak Testlng of Appliances," Home Appliance Builder, October 1961, pp. 1-6. Torney, F.L., Jr., "A New Type of Vacuum Leak Detector," 4th National Symposium on Vacuum Technolo@[, Transac- tions (1957), Pergamon Press, Inc., New York, New York, pp. 115-119. - o . R-9 _- 10-5 Quisenberry, R.C., Leak Detection Technlques: Improve- ment Study for Space Vehlcles, Second Formal Report, Contract NAS8-2563, Ohlo Universlty, Athens, Ohio, June 1963. NASA Accesslon No. N63-23808 SECTION 11 ii-i H3erten, G.; Munch af Rosenchold, J.; and Rohloff, T., "Determination of Leakage in Compressed Air-Distribu- tion Systems," Jerkontorets Annaler, Vol. 140, No. 6, 1956, pp. 425-450; also The En@ineers Di_est, Vol. 17, No. 9, September 1956, pp. 385-388. ll-2 Keshock, E.G., Comparison of Absolute and Reference- system Methods of Measurin_ Containment-vessel Leaka@e Rates, National Aeronautics and Space Administration Technical Note TN-D-1588, Lewis Research Center, Cleve- land, Ohlo, October 1964. ll-3 Schumacher, G.W., "A Nondestructive Leak Detector for Production Testlng of Hermetic Enclosures for Electronic Components," Natlonal Symposium on Vacuum Technology, Transactions (19563, Pergamon Press, Inc., New York, New York, pp. 110-113. 11-4 Weinberg, M.H., Ch., Whds and Rkts. Sec., IEEB, ARD, QAD, U.S. Army P1catinny Arsenal, Dover, New Jersey, Personal Communication. 11-5 Campbell, E.G., "Why Planned Program of Leak Detection Pays Continuing Dividends," Gas Age, Vol. 108, Decem- ber 20, 1951, pp. 26-28. SECTION 12 12-i Bedwell, D.C., and Meyer, E.Ao, "Leakage Testing of Sealed Electronlc Enclosures," Electrical Manufactur- ing, Vol. 56, December 1955, pp. 127-133. 12-2 Grimes, L.E., "Laboratory Leakage Measurement Techniques on Separable Connectors." Paper presented at the 56th Air Force/Industry Conference on Missile System Leaks and Spills, Los Angeles, California, February 1965. 12-3 Muehlner, E.E., "Measurlng Hydraullc Leakage," Hydrau- lics and Pneumatics, May 1962, pp. 91-93. 12-4 Hurm, R.B., "A Simple and Inexpensive Pneumatic Leak Detector and Valve Test Unit," ISA Journal, Vol. 2, No. 7, July 1955, p. 255. --_o 12-5 Montgomery, W.J., "Indicator Detects Gas-filled Cable Leaks," Electrical World, Vol. 140, October 5, 1953, p. 112. R-10 - SECTION 13 13-1 DeCastra, J.E., and Wells, F.E., Proposed Standards Descrlblng and Estlmatln_ Leaks in Aerospace Hardware, Final Report, National Aeronautics and Space Admini- stration, February 12, 1968. NASA Accession No. N68-23467 13-2 Scheffler, H.F., Final Report on Task 511 Leak Detection, U.S. Army Signal Equipment Agency Contract DA-36-039- SC-73212, Battelle Memorial Instltute, 1959. 13-3 Guthr_e, A., and Wakerling, R.K., Vacuum Equipment and Technlques, McGraw-Hill Book Company, New York, New York, 1949. Section 14 14-I Inglis, W.W., "Methods of Leak Detection for Propellant- actlvated Cartridges," Materlals Evaluation, March 1966, p. 150. 14-2 Clark, J.E.; Jones, M.S.; and Karoly, R.F., "Evaluation of Radioactlve Gas Accumulation Leak Test for Semicon- ductor Encapsulation." Paper prepared for Electro- chemlcal Society Meeting, Washlngton, D.C., October 11-15, 1964. 14-3 Courtols, G., and Gasnaer, M., "Leak Detection by Means of Rad_oelements," Microtecnic, Vol. 17, No. i, 1963, pp. 27-33; No. 2, 1963, pp. 67-83. 14 -4 Putman, J.L. and Jefferson, S., "Application of Radio- isotope to Leakage and Hydraulics Problems," Proceed- in_s of the F&rst International Conference on the Peace£ul Uses of Atomzc Energy (Geneva, 1955), Vol. 15, Paper 462, United Na_zons, New York, New York. 14-5 Cameron, J.F., and Jefferson, S., "Method and Appara- tus for Detecting Leaks in Pipelines," Britlsh Patent 774,136. 14-6 Gemant, A., "Radioactive Leak Location in Gas-pressure Underground Cables," Direct Current, Vol. 2, Septem- ber 1954, pp. 51-53. 14-7 Black, R.E., and Kerwlck, W., "Finding Piping Leaks with Sealed Millicurie Float," Nucleonics, Vol. 18, August 1960, pp. 106-108o SECTION 15 None --i- R-11 _ SECTION 16 16-1 Allen, R.L., "Pinpointing Industrial Defects with Ultra 2_ sonic Ears," Hewlett-Packard Journal, Vol. 18, No. 9, 1967, pp. 2-10. 16-2 McElwee, L.A., and Scott, T.W., "The Sonic Leak Detec- tor," Amerlcan Gas Journal, Vol. 184, August 1957, pp. 14-17. 16-3 Industrial Electronics Department, "Underground Cable Leak Detection," Electronic Products, Vol. ii, No. 4, 1968, pp. 114, 116. SECTION 17 17-1 Balko, P.G_; Bresky, D.R.; and Coates, V.J., "IR Anal- yzer Solves Leak Detection Problem," ISA Journal, Vol. 5, December 1958, ppo 44-47. 17-2 Matheson Gas Data Book, 4th edition, The Matheson Com- pany, Inc., East Rutherford, New Jersey, 1966. 17-3 Patty, F.A., Industrial Hygiene and Toxicology, Vol. II, Interscience Publishers, New York, New York, 1949. 17-4 Neeley, A.H., Nitrous Oxide for Leak Detection, A: Chemical, Physical and Pharmacolo@ical Properties, with Results of Corrosion Tests, (Ohio Chemical Tech- nical Information Series: IA), Ohio Chemical and Surgi- cal Equipment Company, Madison, Wisconsin, May 1957. 17-5 Kaufman, J.E., "Laughing Gas Shows Value in Spotting Pipeline Leaks," Oil and Gas Journal, Vol. 58, No. 8, February 22, 1960, pp. 100-102. SECTION 18 18-1 McMasters, R.C., editor, Nondestructive Testin_ Hand- book, Volume I, Section 6-8, The Ronald Press Company, New York, New York, 1959. 18-2 Polito, A.J., "Method of Detecting Leaks in Metallic Vessels and Testing Media Therefor," U.S.Patent 2, 878,392. 18-3 Delafosse, D.; Noe, P.; and Troadec, G., "Detection of Leaks by Means of Ammonia Gas," LeVide, Vol. 15, No. 90_:. November-December 1960, pp. 442-445. 18-4 Stacy, C.E., "Locating Leaky Sewers with Smoke," Pub- lic Works, Vol. 92, 1961, p. 133. R-12 _- 18-5 Winter, P.; Bilford, H•R.; Jacob, C.E.; and Kemmerer, R.A•, "How to Find Microscopic Leaks in Process Equip- ment," Industrial and En_ineerin_ Chemistry, Vol. 50, No. 5, May 1958, p. 53a. 18-6 Hettlnger, F.C., and Hoelscher, H.E., "Leakage Tests for Sealed Instruments," Industrial and En@ineerin@ Chemistry, Vol. 47, No. 12, December 1955, pp. 2437- 2439. 18-7 Hartwlg, H.H., "Method for Locating Points of Gas Leak- age in Packages and Packaging Materials," Paper Trade Journal, Vol. 124, No. 20, May 15, 1947, pp. 47-48 (TAPPI Sect±on, pp. 225-226). 18-8 Wilby, F.V., "Acetylene as a Natural Gas Leakage Tracer," Gas A_e, Vol. 104, No. i, July 7, 1949, pp. 32-34. 18-9 McAdams, W.A., and Foss, M.H., "Leakage Testing Method," U.S_ Patent 2, 846,872; August 12, 1958. 18-10 Griffith, J.R., Leak-indicatin_ Paints for Rocket-fuel Tanks and Stora@e Areas, Report NRL-5735, U.S. Naval Research Laboratory, Washington, D.C., January 18, 1962. AD 271 001 SECTION 19 19-1 • "An Audible Vacuum-leak Indicator," Jour-Lloyd, J T., nal of Scientific Instruments, Vol. 27, March 1950, pp. 76-77. SECTION 20 20-1 Alpert, D., "New Developments in the Production and Measurement of Ultra High Vacuum," Journal of Applied Physics, Vol. 24, No. 7, 1953, pp. 860-876. 20-2 Ackley, J.W., and others, "Leak Detection Using Current Changes in Ionization Gauges and Sputter-ion Pumps," 1962 Transactions of the Ninth National Vacuum S_m- osium, The Macmillan Company, New York, New York, pp. 80-383. 20-3 Varicak, M., "Penning Gauge as Leak Detector," Review of Scientific Instruments, Vol. 27, No. 8, 1956, p._5. 20-4 Nelson, H., "The Hydrogen Gauge -- An Ultra-sensitive Device for Location of Air Leaks in Vacuum-device En- velopes," Review of Scientific Instruments, Vol. 16, No. i0, 1945, pp. 273-275• 20-5 Van Leeuwen, J.A., and Oskam, H.J., "Simple and Sensi- tive Leak Detector," Review of Scientific Instruments, Vol. 27, No. 5, 1956, p. 328. _. ° R-13 20-6 20-7 20-8 20-9 20-10 20-i1 20-12 20-13 20-14 20-15 SECTION 21 21-i 21-2 Botden, Th. P•J., "The Silica Gel Leak Detector," aAd- vances in Vacuum Science and Technology (Proceedings of the First International Congress on Vacuum Techniques_, Namur, Belgium, June 1958), Vol. i, pp. 241-244• • "A Sensitive Leak DetectorBeck, A_H , and King, G., Using Magnetron Ionization Gauges," Vacuum, Vol. 4, No. 2, 1954, pp. 147-158. Perkins, G.D., and Robinson, C.F., "Combined Leak De- tector and High Sensitivity Vacuum Gauge," Review of Scientific Instruments, Voi. 39, No. 3, 1968, pp. 361-362. Lawton, E.J., "More About Vacuum Testing," Review of Scientific Instruments, Vol. ii, No. 4, 1940, p. 134. Nelson, R.B., "An A.C. Operated Leak Detector and Ioni- zation Gauge," Review of Scientific Instruments, Vol. 16, No. 3, 1945, pp. 55-57• • "An Instrument for Leak Detection andLeger, E G., Pressure Measurement in High Vacuum Systems," Cana- dian Journal of Technology, Vol. 32, No. 6, 195 ,_--pp. 199"205. Barton, R.S., The 1441A Oxygen Leak Detector, United Kingdom Atomic Energy Research Establishment Report GP/M-189, Harwell, England, January 1957. Bloomer, R.N•, and Brooks, W.C., "Simple Detector for Small Leaks Using a Thoriated Tungsten Emitter with Oxygen as Probe Gas," Journal of Scientific Instru- ments, Vol. 37, August 1960, pp. 306-307. Barrington, A.E., "Sensitivity of an Ion Pump Leak De- tector," Review of Scientific Instruments, Vol. 33, No. i0, 1962, pp. 1045-1046. Young, J.R., "Use of an Ion Pump as a Leak Detector," Review of Scientific Instruments, Vol. 32, No. i, 1961, p. 85. Steckelmacher, W., and Tinsley, D.M., "Thermal Con- ductivity Leak Detectors Suitable for Testing Equip- ment by Overpressure or Vacuum," Vacuum, Vol. 12, No_ 3, 1962, pp. 153-159. Contractor's Independent Research and Development Pro- gram (CIRP) Final Report 1965, DB 66A138, Apollo Sup- port Department, General Electric Company. R-14 21-3 NASA Tech Briefs Department, "Portable Detector Shows Helzum Leakage Rates," Electronlc Desi@n, Vol. 15, July 19, 1967, p. ll0. 21-4 Stine, P.T , and Koncen, R.E., Operational Performance of the NRL Thermlstor-brld@e Gas Leak Detector and Its Sens±tzv_ty to Varzous Gases, Equipment Research Branch, Radar Dlvls_on, U.S. Naval Research Laboratory, Wash- Ington, D.C., June II, 1962. AD 277 410 21-5 Minter, C.C., "Vacuum Leak Testzng w_th Liquids," Re- view of Sczentlflc Instruments, Vol. 31, No. 4, 156_, pp. 458-459. 21-6 Alers, G_A.; Jacobs, J.A.; and Malmberg, P.R., "In- creased Sensltlv_ty of Leak Detectlon wlth Hydrogen," Review of Sczentific Instruments, Vol. 24, No. 5, 1953, pp. 399-400. 21-7 Kent, T.B., "A Hydrogen Plranl Leak Detector Using a Charcoal Trap," Journal of Sczentlfic Instruments, Vol. 32, April 1955, pp. 132-134. 21-8 Ishil, H., "A Dzfferential Piranz Type Leak Detector With a Charcoal Trap," Advances in Vacuum Science and Technology (Proceedlngs of the First Internatlonal Con- gress on Vacuum Technlques, Namur, Belgium, June 1958), Vol. i, Pergamon Press, Inc., New York, New York, pp. 245-247. 21-9 Hafnez, A , A Portable Thermistor-brld@e Gas Leak De- tector, Report NRL-5647, Equipment Research Branch, Radar D_vislon, U.S. Naval Research Laboratory, Wash- ington, D.C., J_ly 3, 1961. AD 260 385 SECTION 22 22-1 Van Lu_k, F.W., Jr., and Rlppere, R.E., "Condensation Nuclei, A New Technzque for Gas Analysis," Analytical Chemzstr_, Vol. 34, No. Ii, 1962, pp_ 1617-1620. 22-2 Impellitterl, V.J., "Condensatlon-nuclei Techniques," Bureau of Ships Journal, Vol. 10, No. 3, 1961, p. 16. 22-3 Pink, W.V., "Inspection, Malntenance and Monitoring of ,! Ultra-clean Work Stations, Contamlnation Control, Vol. 6, No. i0, 1967, pp. 10-12, 14-16. SECTION 23 23-1 Hamlen, R.P.; Marr, J.W.; and Murphy, C.B., "Fuel Cell Membrane Permeation Measurements Using a Gas Chromato- graph," Industrlai and En@_neerin_ Chemistry Product Research and Development, Vol. 4, 1965, p. 251. R-15 23-2 23-3 23-4 23-5 23-6 23-7 Girard, F.L., "Finding Leak IC's on p-c Boards," tronics, Vol. 41, No. 13, 1968, pp. 127-128. Elec- Juran, W., "Leakage Detection by Temperature Sensing," 9th Liquid Rocket Propulsion Symposium, vol. I, Septem- ber 1967, pp. 145-154, CPIA Publication No. 155. Shaver, P.J., "Activated Tungsten Oxide Gas Detectors," Applied Physics Letters, Vol. ii, No. 8, 1967, pp.255-257. Industry and Economic News Department, "Hydrogen Makes Sensitive Sensor Blush Blue," Chemical En@ineerin@, Vol. 74, No. I0, 1967, p. 102. New Chemicals and Materials Department, "Wrap-on Leak Detector," Chemical En_ineerin@, Vol. 74, No. 15, 1967, p. 114. Quisenberry, R.C., personal communication from Ohio University, Athens, Ohio. - R-16 Appendix A PROPERTIES OF TRACER GASES PRECAUTIONARY MEASURES FOR USING VARIOUS TRACER GASES a-J, o . PROPERTIES OF TRACER GASES Thern%al Diffusion Conductivity viscosity Coefficient Chemical Molecular BTU/hr ft a poise x 10" ftA/hr at Name Formula _ F/ft at 20"C at 0°C 1 arm and 0"C Acetylene CaH _ 26 0.01128 93.5 0.55 Air mixture 29.9 0.01478 170.8 Ammonia NH a 17 0.01333 91.8 0.66 Argon A 39.9 0.01016 209.6 0.61 Benzene C6H" 78 0.00538 70.9 0.30 Butane C,H_ 58 0.00822 84.04,14.7C 0.33 Carbon dioxide CO_ 44 0.00873 139.0 0.52 Carbon disulfide CS_ 76 0.00410 91.I 0.36 Carbon monoxlde CO 28 0.01360 166 0.67 Ethane C_H I 30 0.01102 84.8 0.49 Ethylene C_H, 28 0.01025 90.66,0.05C 0.52 Halogenated hydrocarbon F-If CClaF 137.4 0.00470 96.0 0.30 Halogenated hydrocarbon F-12 CCI_F, 120.9 0.00542 328, 5F 0.32 Halogenated hydrocarbon F-21 CHCI_F 102.9 0.00554 101.0 0.33 Halogenated hydrocarbon F-22 CHCIF_ 86.5 0.00660 286, 5F 0.37 Halogenated hydrocarbon F-If3 CCI_F-CCI_F 187.4 0.00438 93.0 0.25 Halogenated hydrocarbon F-ll4 CCIF_-CCIF 170.9 0.00629 102.0 0.28 Helium He 4 0.08740 186 2.7 Hydrogen H a 2 0.10770 83.5 2.6 Hydrogen sulfide H_S 34 0.00770 116.6 0.53 Krypton Kr 83.8 0.00540 232.7 0.51 Methane CH, 16 0.01872 102.6 0.72 Neon Ne 20.2 0.02660 297.3 1.1 Nitric oxide NO 30 0.01180 178 0.70 Nitrogen N_ 28 0.01462 166 0.68 Nltrous oxide N,O 44 0.00925 136.2 0.52 Oxygen O 4 32 0.01490 189 0.68 Propane C_H, 44 0.00925 79.5,17.9C 0.39 Sulfur dioxide SO a 64 0.00514 117 0.42 Water vapor H_O 18 0.01087 90.4 0.85 Xenon Xe 131.3 0.03000 210.1 0.42 Heat Capacity Molecular Ratio Diameter Cp/Cv cm x 10" 1.26, 15C 1.403, 0C 1.31, 25C 2.97 1.67, 25C 3.67 i.i0, 90C 7.65 i.ii, 15C 7.06 1.29, 25C 4.65 1.63,99.7C 1.404, 15C 3.19 1.19 5.37 1.255, 15C 1.124,160F 1.157,160F 1.077,160F 1.080,160F 1.67, 25C 2.18 1.41 2.75 1.32, 15C 1.68, 19C 4.15 1.31, 15C 4.19 1.64, 19C 2.60 1.4, 15C 1.40 3.15 1.303, 15C 1.40 2.92 1.13 6.32 1.29, 15C 1.324,100C 1.66, 19C 4.91 A-I PRECAUTIONARY MEASURES FOR USING VARIOUS TRACER GASES* AMMONIA At room temperature and atmospheric pressure, ammonia is a colorless, alkaline gas having a pungent odor. Ammonia dissolves readily in water. It is shipped as a liquefied gas under its own vapor pressure of 114 psig at 70°F. The pungent odor of ammonia provides ample warning of its presence. The American Conference of Governmental Industrial Hygienists has recommended 100 parts per million as the maximum allowable concentration for an eight-hour daily exposure. How- ever, concentrations in the range of 50 to i00 ppm, although not harmful, will be of considerable nuisance. It is therefore un- likely that an individual would unknowlngly become overexposed. The physiological effects of various concentrations of am- monia are: Atmospheric Concentration Physlological Effects 20 ppm First perceptible odor 40 ppm A few individuals may suf- fer sllght eye irrltation 100 ppm Noticeable irritation of eyes and nasal passages after few minutes exposure 400 ppm Severe irritation of the throat, nasal passages, and upper respiratory tract 700 ppm Severe eye irritation. No permanent effect if the exposure is limited to less than one-half hour 1700 ppm Serious coughing, bronchial spasms, less than a half hour of exposure may be fatal 5000 ppm Serious edema, strangula- tion, asphyxia; fatal almost immediately *Courtesy of Mr. R.J. Roehrs, Nooter Corporation, St. Louis, Missouri A-2 The corrosive action of high concentration of ammonia (above 700 ppm) can cause extensive injuries to the eyes, causing severe irritation, hemorrhages, and swollen lids. If it is not treated immediately, partial or total loss of sight may result. The mu- cous lining of the mouth, throat, nose and lungs is particularly sensitive to ammonia attack. One percent ammonia in the atmosphere is mildly irritant to moist skin; two percent has a more pronounced effect; three percent produces a stinging sensation and may produce chemical burns with blisters after a few minutes. Liquid ammonia in con- tact with the skin will produce severe burns, and the freezing effect due to rapid evaporation from the skin surface can cause frostbite. Anyone working with ammonia should wear rubber gloves, chemical goggles, and a rubber or plastic apron. Cylinders should never be dropped or be permitted to strike each other violently. No part of a cylinder should be subjected to a tem- perature higher than 125°F. Ammonia cylinders should never be directly heated by steam or flames. Uncontrolled heating of a cylinder can cause the liquid to expand to a point where dan- gerous hydrostatic pressure will be developed. Any heating should be done in a thermostatted water or oil bath. The tem- perature should not be allowed to exceed 125°F. Cylinders con- taining less than 165 pounds of ammonia are not equipped with safety devices. Although ammonia does not represent a serious flammability hazard, mixtures of air and ammonia containing from fifteen per- cent to twenty-eight percent ammonia by volume will ignite when sparked or exposed to temperatures exceeding 1200°F. Therefore, flames and sparks should nct be allowed in the area where am- monia is being used. Iron and steel are recommended for all equipment coming in contact with ammonia. Copper, tin, zinc, and their alloys are attacked by moist ammonia and should not be used. Piping should be rigid steel except where short connections are needed, such as between cylinders and manifold or pipe lines. For these ap- plications reinforced, flexible neoprene line is recommended. A/mnonia can combine with mercury to form explosive compounds; therefore, instruments containing mercury that will be exposed to ammonia should not be used. ARGON Argon is a colorless, odorless, and tasteless gas, somewhat soluble in water (4 volumes in i00). It is normally supplied as a nonliquefied gas compressed into cylinders at a pressure of approximately 2200 psig at 70°F. Argon is nontoxic, but can act as a simple asphyxiant by displacing the amount of air necessary to support life. A-3 Argon is a chemically inactive gas. It will not react with other elements or compounds. While a few compounds of argon and other rare gases are reported to have been prepared, the results obtained may be considered of scientific interest only. CARBON DIOXIDE Carbon dioxide is a nonflammable, colorless, odorless, slightly acid gas. It is approximately one and one-half times as heavy as air. One volume of carbon dioxide will dissolve in approximately one volume of water at atmospheric pressure and 15°C. In high concentrations it has an acidic taste. Carbon dioxide is shipped in Interstate Commerce Commission approved, high-pressure steel cylinders as a liquid under its own vapor pressure of approximately 830 psig at 70°F. In high concentrations carbon dioxide can paralyze the re- spiratory center. It is, therefore, an industrial hazard. It is heavier than air and does not diffuse readily; consequently, it may collect in confined, unventilated areas. Where persons are working in confined spaces, the amount of carbon dioxide formed by breathing may assume dangerous proportions. Carbon dioxide is the regulator of the breathing function; an increase in the carbon dioxide inhaled will cause an increased rate of breathing: Carbon Dioxide in Air (volume percent) 0.i-I Increased Lun@ Ventilation Slight and unnoticeable increase 50% increase 100% increase 300% increase, breathing becomes laborious Ten percent carbon dioxide in air can be endured for only a few minutes. Twelve to fifteen percent soon causes uncon- sciousness. Twenty-five percent may cause death in exposures for several hours. A generally recommended maximum allowable concentration for an eight-hour day is 5000 ppm. The normal concentration of carbon dioxide in the air is 0.03 percent, or 300 ppm. Carbon dioxide is not a chemically active compound. High temperatures are generally required to promote its reactions. Carbon dioxide is stable under normal conditions, but at tem- peratures above 1500"C carbon dioxide almost completely disso- ciates into oxygen and carbon monoxide according to the follow- ing formula: 2 CO_-_ 2 CO +Om A-4 DICHLORODIFLUOROMETHANE (F-12) Dichlorodifluoromethane iFreon 12, Genetron 12, Isotron 12, Ucon 12} is a colorless, nonflammable gas at normal temperatures and pressure. In concentrations of less than 20 percent dichloro- difluoromethane is odorless; in higher concentrations its odor is mild and somewhat ethereal, and similar to that of carbon tetrachloride. It is readily llquefied and is shipped in steel cylinders as a liquefled gas under its own vapor pressure of about 70 psig at 70°F. Dichlorodifluoromethane is practically nontoxic. It shows no toxic effects In guinea pigs in concentrations up to at least 20 percent (by volume} for two hour exposures. In higher con- centrations, it may produce some physlological action, caused primarily by oxygen deficiency. The generally accepted maximum allowable concentration for an eight-hour daily exposure is 1000 parts per m_lllon. No part of a cylinder should be subjected to a temperature higher than 125°F. Temperatures in excess of 125°F may cause excessive hydrostatlc pressure buildup. Never permit a flame to come in contact wlth any part of a compressed-gas cylinder. In general, gasket materials should not contain natural rubber. Neoprene or isoprene rubber, pressed fibers, including asbestos, with a number of insoluble binders and metallic gaskets may be used. Dichlorodifluoromethane zs thermally stable. It is non- flammable in any mixture with air and will not explode or pro- pagate a flame. It is hydrolytically stable. It is noncorro- sive under normal conditions to all common metals of construc- tion, but it is corrosive at elevated temperatures. HELIUM Helium is the lightest member of the rare gas family. It is an inert, colorless, odorless, and tasteless gas, and is only slightly soluble in water (0.87 part in 100 parts). Helium is compressed into cylinders at a pressure of approximately 2200 psig at 70°F. Helium is nontoxic but can act as an asphyxiant by dlsplac- ing the necesssary amount of air to support life. Helium is a chemically inactive gas. It will not react with other elements or compounds under ordinary conditions. HYDROGEN CHLORIDE Anhydrous hydrogen chloride is a colorless, pungent, corro- sive gas having a suffocating odor. Hydrogen chloride is heavier than air; it fumes strongly in moist air. It is very soluble in A-5 water and alcohol, and in ether. While in the cylinder under pressure, hydrogen chloride is in the form of a gas over liquid, the cylinder pressure being about 613 psig at 70°F. As long as liquid is present in the cylinder, the pressure will remain fair- ly constant. Hydrogen chloride is a highly toxic gas; it is severely ir- ritating to the upper respiratory tract and corrosive to the eyes, skin, and mucous membranes. The acid formed neutralizes the al- kali of the tissues and causes death as a result of edema or spasm of the larynx and inflammation of the upper resplratory system. According to Walsh-Healey legislation the threshhold limit value for hydrogen chloride gas is 5 ppm by volume in air. This is a ceiling limit and cannot be time-weighed. The short expo- sure tolerance is 50 ppm and the atmospheric concentration im- mediately hazardous to life is i000 to 2000 ppm. Hydrogen chlo- ride provides adequate warning for prompt voluntary withdrawal from contaminated atmospheres. Workers who handle hydrogen chloride should wear protective clothing such as rubber or plastic aprons, rubber gloves, and suitable gas-tight chemical safety goggles. Outside clothing of wool or other acid-resistant fabrics is also recommended. Hydrogen chloride is essentially inert to metals and does not attack the commonly used structural metals under normal con- ditions of use (room temperature and atmospheric pressure). In the presence of moisture, however, hydrogen chloride will corrode most metals other than silver, platinum, and tantalum. When used at higher pressures, it is necessary to use extra-heavy black- iron pipe throughout. No galvanized pipe or brass or bronze fittings should be used, since these will corrode. High-pressure monel or aluminum-iron-bronze valves should be used throughout. Hydrogen chloride lines should always be shut off from the use end, backward to the cylinders. Hydrogen chloride is thermally stable. It is stable to oxidation except at elevated temperatures. Hydrogen chloride is extremely soluble in water; its aqueous solution is a strong acid. HYDROGEN Hydrogen is colorless and odorless, and is the lightest gas known. Hydrogen is only very slightly soluble in water (1.93 volumes in i00 volumes of water). Hydrogen is usually shipped in high-pressure steel cylinders, 2000 psig at 70°F. Hydrogen is nontoxic, but can act as an asphyxiant by dis- placing the amount of air required to support life. Cylinders of hydrogen should never be used in areas where flames, excessive heat, or sparks may occur. Only explosion- A-6 proof equipment and spark-proof tools should be used in areas where hydrogen is handled. All equipment and lines used with hydrogen should be grounded. A flame should never be used to detect hydrogen gas leaks. Reserve stocks of hydrogen should never be stored wlth cyl_nders containing oxygen or other highly oxidizlng materlals. Hydrogen, although relatively inactive at ambient tempera- tures, reacts with almost all the other elements at high temper- atures. The reaction between hydrogen and oxygen at high tem- peratures is usually violent. Hydrogen will reduce metallic oxides at elevated temperatures. KRYPTON Krypton is an inert gas, and one of the rarest gases known. Krypton exlsts in minute traces in the atmosphere (i ppm by vol- ume of air). Krypton is a colorless and odorless gas, and only slightly soluble In water. Krypton is available in small cylin- ders at various pressures up to 800 psig, and in Pyrex liter flasks. Krypton is chemlcally inert under all normal conditions, and does not combine chemically with other elements or compounds. METHANE Methane is a flammable, colorless, odorless, and tasteless gas. It is the major constituent of natural gas. The material is normally shipped as a nonllquefied gas in high-pressure cyl- inders, approximately 2265 psig at 70°F. Methane is not considered a toxic gas. Physlologically, it is a simple asphyxiant; in high concentrations it can displace the oxygen required to sustain life. Miners frequently breathe air containing nlne percent of methane and do not appear to suf- fer. When the percentage rises above this point, pressure on the forehead and eyes is noticed. However, this pressure disap- pears when fresh air is again breathed. The hazards due to the handling of methane stem mainly from its extreme flammability. Although methane is generally inert at room temperature and atomospheric pressure, it can undergo re- action under certain conditions. Cylinders of methane should be stored in a well-ventilated area away from heat and all igni_ion sources. Flames should never be used to detect flammable gas leaks. Methane should not be used around sparking motors or other non-explosion-proof equipment. Reserve stocks of methane cylinders should never be stored with cylinders containing oxy- gen, chlorine, or other highly oxidizing or flammable materials. NEON Neon is a rare inert gas that exists in the atmosphere. Neon constitutes 0.00182 percent, by volume, of air. Neon is A-7 --L- ,a colorless and odorless gas; it is normally available in com- pressed cylinders at varying pressures up to 1800 psig, and also in Pyrex flasks at atmospheric pressure. Neon is nontoxic but can act as an asphyxiant by displac- ing the amount of air necessary to support life. Neon is chemically inert under all normal conditions. NITROGEN Nitrogen comprises approximately 79 percent, by volume, of the air. It will not burn and will not support combustion. Ni- trogen is normally available in cylinders compressed to 2200 psig at 70°F. Nitrogen is nontoxic but can act as an asphyxlant by dis- placing the amount of air necessary to sustain life. Nitrogen is extremely inert, except when heated to very high temperatures, where it combines with metals to form nitrides. NITROUS OXIDE Nitrous oxide is a colorless, nonflammable, nontoxic gas with a slightly sweetish taste and odor. It is shipped as a liquefied compressed gas under its own vapor pressure of about 745 psig at 70°F. It is somewhat soluble in water and more soluble in alcohol. Nitrous oxide is nonirritating and is extensively used as an anesthetic in medicine and dentistry. It is a rather weak anesthetic, and must be inhaled in high concentrations mixed with air or oxygen. When inhaled without oxygen, it is a simple asphyxiant. Inhalation of small amounts often produces a type of hysteria; hence its trivial name, laughing gas. Nitrous oxide is stable and comparatively unreactive at ordinary temperatures. At elevated temperatures nitrous oxide decomposes into nitrogen and oxygen, the rate of decomposition being appreciably above 565°C. At elevated temperatures, ni- trous oxide supports combustion and oxidizes certain organic compounds, the alkali metals, etc. OXYGEN Oxygen is a colorless, odorless, and tasteless gas. Its outstanding properties are its ability to sustain animal life and to support combustion. It is somewhat soluble in water. is usually shipped as a nonliquefied gas at 2200 psig at 70°F. It The inhalation of 100 percent oxygen at atmospheric pressure for periods up to 16 hours per day, for many days, has caused no observed injury to man. Long periods of exposure to higher pres- sures can adversely affect neuromuscular coordination and power of attention. A-8 --L- Oil, grease, or other readily combustible substances should never contact oxygen cyl_nders, valves, regulators, gages, and fittings. Oxygen valves, regulators, gages, or fittings should never be lubricated with oil or any other combustible substance. In welding shops and industrial plants using both oxyacetylene and electric welding apparatus, care should be taken to avoid the handling of these equipments in any manner which may permit the compressed-gas cylinders to come in contact with electrical circuits. Manifolds should never be used for oxygen cylinders unless constructed by a qualified engineer under the standards of a recognlzed safety authority. Oxygen should not be allowed to enter the cyllnder or valve. Cyllnders of oxygen should not be stored near cylinders of acetylene or other combustible gases. Unless they are well separated, there should be a fire-resistant partition between oxygen and acetylene or other cylinders of combustible gases. SULFUR DIOXIDE Sulfur dioxide is a highly irritating, nonflammable, color- less gas at room temperature and atmospheric pressure. It is soluble in water, forming a weak solution of sulfurous acid. It is readily liquefied and is shipped in steel cylinders as a liq- uefied gas under Its own vapor pressure of about 35 psig at 70°F. Sulfur dioxide is a highly irritating gas in the vapor form; it is readily detectable an concentrations of three to five parts per million, providing ample warning of its presence. In higher concentrations, the severely irrltating effect of the gas makes it unlikely that any person would be able to remain in such a contaminated atmosphere unless he were unconscious or trapped. Liquid sulfur dioxide may cause skin and eye burns upon con- tact with those tissues. This results from the freezing effect of the liquid on the skin or eyes. Acute exposure to sulfur dioxide has the following effects: Atmospheric Physiological Concentration Effects 8-12 ppm 150 ppm 500 ppm Causes throat irritation, coughing, constriction of the chest, tearing, and smarting of the eyes Causes extreme irritatlon; can be tolerated only for a few minutes So acutely irritating that it causes a sense of suffocation There are no known systemic effects of acute exposure to sulfur dioxide. The generally accepted maximum allowable con- A-9 centration of sulfur dioxide for an eight-hour daily exposure is ten parts per million. Sulfur dioxide should be handled only in a well-ventilated area, preferably a hood with forced ventilation. Personnel han- dling sulfur dioxide should wear chemical safety goggles and/or plastic face shields, approved safety shoes, and rubber gloves. In an emergency, gas masks approved by the U.S. Bureau of Mines for sulfur dioxide should be worn as required. Additional gas masks, air-line gas masks, and self-contained breathing appara- tus should be conveniently located for use in emergencies. In- stant-acting safety showers should be available in convenient locations. Sulfur dioxide forms both sulfite and bisulfite salts. A-lO Appendix B LEAK TESTING SPECIFICATIONS American Vacuum Society -- AVS 2.1-1963 American Nuclear Society -- ANS 7.60 AMEI_ICAN VACUUM SOCIETY STANDARD (tentative) AVS 2.1-1963 Helium Mass-spectrometer Leak-Detector Calibration 1. INTRODUCTION 1.1 Scope. This standard prescribes pl_cedures to be used for calibrating leak detectors of the mass- spectro,neter type, that is, for dctelanining a sensi- tivity figure for such leak detectors. The procedures require the use of a calibrated leak and a standard mixture; thc preparation and standardization of these is outside the scope of this standard. Refer to the appropriate AVS standards. While various leak-tracing gases have been used in conjunction with mass-spectrometer leak detectors, the present standard has reference only to the use of helium-4. The application of this standard is restricted to leak detectors with rated sensitivity corresponding to leak rates larger than l0 _ atm cc/sec. Factors that are unimportant for larger leaks may becon|e significant for gas flows that are substantially less than 10-_ arm cc/sec; consequently, a separate standard will cover the calibration of detectors designed for leaks mnallcr than this figure. 1.2 Mode of Presentation. Sections 2-4 deal with preliminary matters such as definitions. The dctermination of sensitivity (Sees. 6 and 7) in- volves a figure referred to as the minimum detectable signal. The procedure for determining this figure is covered in Sec. 5 for the determination in See. 6, and in Sec. 7.2 for the determination in See. 7. Section 6 covers two procedures for determining mini- mum detectable leak, the second procedure being fob lowed if rubber or other polymeric substances are present in the connections to the standardizing leak. Section 7 presents the procedure for determining mini- mum detectable concentration ratio. 2. DESCRIPTION OF LEAK DETECTOR The helium-leak detector is essentially a gas analyser, employing the mass-spcctro|neter principle. In the mass-spectrometer tube, a mixture of gases to be analyzed is first ionized, then separated into a series of ion beams or group_, each grotlp ideally represent- ing a single species of gas. (Strictly speaking, the ions in cach beam havc the same mass-to-charge ratio.) In the hclium-leak detector, means are provided for "tuning" the instrument, so that only the beam duc to helium hits an ion collector. (The detector can gen- erally bc tuned to respond to other gases.) The cur- rent produced by the beam is amplified, and its mag- nitude is a measure of the partial pressure of the helium gas in thc incoming sample. It will be assumed that the gas ionization is produced by the electrons from a hot filament. Mass-spectrometer leak detectors consist of a mass- spectrolneter tube, a high-vacuum system for main- taining the tube under suitable vacuum with a flow of gas sample through or into the tube, suitable voltage supplies, and an ion-cur|'cnt amplifier. The OUtlmt of the amplifier is displayed on an output meter, and means al_ provided for reducing the output so that a large range of leak sizes can be detected and meas- ured. In other words, the leak detector may be set at one .of a number of different detection levels, here- after referred to as sensitivity settings. Since the spectrometer tube must be able to receive a gas sample from the system under test and must also be kept under vacuum, a line is provided for leading gas from the outside into the spectrometer tube, and this line must have an isolation valve in it. In this standard, the line is referred to a_ the sample inlet line. 3. DEFINITIONS 3.1 GeneraL Many of the technical cxpressions used in this standard are defined in Glossary o.f Terms Used in l'acuum Technology, issued by tim American Vacuum Society (Pergamon Press Inc., New York, 1958). Starred definitions are not from the AVS Glos- sary. 3.2 Channel Leak. A hole, or pores, in the wall of an enclosure, capable of passing gas from one side of the Approved by American Vaccum Society, Inc., October 1963 Additiomd copie_ of this Standard arc available at $1 each from the _cretary of AVS, P. O. Box 1282, Bo.-lon, Ma._s.0'2014. __ o 230 AV$ StandiMI wall to the other under action of a pressure or con- centration differential existing across the _all. *3.3 Calibrated Leak. A device that permits leakage through it at a specified rate, of a specified gas, under specified conditions, the downstream side of the device being exposed to a pressure sufficiently low to have negligible effect on the leak rate. *3.4 Standard Leak Rate. The rate of flow of at- mospheric air of dewpoint less than -25°C through a leak under standard conditions specified as follows: the inlet pressure shall be 1 standard atmosphere ±5%, the outlet pressure shall be less than 0.01 of 1 atmosphere pressure, and the temperature shall be 23°C -" 3. *3.5 Viscous Leak. A leak, the flow through which is controlled by viscosity. *3.6 Membrane Leak. A leak that produces a gas flow by permeation of the gas through a nonporous wall. For helium, this wall may be of glass, quartz, or other suitable material. 3.7 Concentration Ratio. In this standard, the ratio of partial pressure to total pressure. 3.8 Sensitivity. $.8.1 In the case of a leak detector, the smallest leak that can be detected. The leak is specified in terms of its standard leak rate (see 3.4). A synonym used in this standard is minimum detectable leak. $.8.£ In the case of a leak detector, the minimum concentration ratio of helium gas in a helium-air mix° ture that can be detected by the device. 4. TEST CONDmONS AND APPARATUS 4.1 Ambient Temperature. Ambient temperature shall be 23°C ± 3. 4.2 Ambient Pressure. Ambient pressure shall be 760 Torr ± 5%. 4.3 Calibrated Leaks.. Two calibrated leal_ may be required: one with a relatively small leak rate and the other with a relatively large leak rate. The small leak is used for determining minimum detectable leak, the larp leak for minimum det_table oonmmtratton ratio. The small leak may be of the channel type or of the membrane type. The leaks are specified as fol- lows: 4_J 3_ Channel Leak. This shall have a leak rate such that when helium, at 1 standard atmosphere pressure, is fed to the leak and thence into the leak detector under test, a deflection is produced on the output meter of not less than 100 times the minimum detectable signal (see teetor shall have been 4a_ 8maU Membrane at a rate to produce a deflection as specified under See. 4_.1. above. Its leak rate shall be specified in terms of eqmvaLent air leakace rate. The equ/valent air leakage rate shall be taken as 0.37 times the helium leakage rate through the membrane under specified conditions. A temperature correction shall be specified for the leak, and the correction applied for the difference between the temperature of the leak at the time of use and the temperature specified in the calibration. _M.3 Large Calibrated Leak. This shah be a viscoua leak of such leakage rate that, when connected to the leak detector with ambient air at the inlet side of the leak, the pressure in the leak detector rises to the op- timum (high) operating pressure specified by the manufacturer. 4.4 Helium. This shall be at least 99.9% helium (available from commercial dealers in cylinder gases). 4.5 Helium Mixture. This shah be a helium and air mixture of a known concentration such that it pro- duces a deflection of at least I0 times the minimum detectable signal (see See. 7_) when fed at a pres- sure of 760 Torr "'5% and at ambient temperature to the large calibrated leak (See. 4_ above) and thence into the leak detector under test. Where applicable, atmospheric air may be used as the helium mixture; _ in any ease, the mixture air shall be obtained from a point at least 5 ft outside the walls of the building housing the test equipment. Helium concentration ratio shall be expressed as a fraction with numerator reduced to unity, and this ratio will be represented by the symbol C. Alternatively, the concentration ratio may be expresed in parts of helium per million parts of mi_zre (parts per million by volume). The concentration ratio of helium in air shall be taken arbitrarily as 1/200000 or 5 parts per million, and this figure shall be taken into account when preparing mixtures containing more helium. [Note: The latest data indicate 5.24 parts per million of helium in air by volume, z] 4.6 Leak Detector. 4_.I The leak detector shall have been connected to a power source conforming in voltage, frequency, and regulation to the manufacturer's specifications. 4_J_ The leak detector shall have been "warmed up" as specified by the manufacturer, prior to all test proeedures. -:- z E. Glueekauf, "Compendium of Meteorology," T. F. Ma- lone, ed., (American Meteorological Society, Boston, IMI), pp. 3-10. 8eo. 5_ below). The leak de- adjusted as in See. 4.8 below Leak. This shall leak helium-- ,4.6.3 The leak detector under test shall have been adjusted far tlctecting helium in the manner specified by ttle manufacturer. 4.7 Chart Recorder. This shall be an instrument of at least l-h recording time suitable for recording the output of the leak detector under test and adjustable so that full scale on the recorder equals full scale of tim leak-detector output meter W]lCn tile leak detec- tor is set at its most sensitive detection setting. Tho time constant nf the recorder shall not be greater than that of the leak-detector output meter. In the absence of a suitable recorder, visual observations of the out- put meter may be used. 4.8 Test Setups. These are illustrated diagrammati- cally in Figs. 1.0 and 1.1. 5. TEST PROCEDURE--MINIMUM DETECTABLE SIGNAL _ 5.1 Drift Determination 5.1.1 The output of the leak detector is connected to the recorder, the leak detector being at its maxi- muln sensitivity settiag and the inlet valve being closed. 5.1_ The loak detector is adjusted so that the re- corder reads less than 10% of full scale, the electron- producing filament being, on. 5.1.3 The output is recorded for 60 rain or until the output indication has reached full scale. 5.1._, Generally, the recorded-output curve will show spikes. If spikes do appear, the curve is to bc faired in standard engineering fashion. 5.1.5 From the faired curve, the output is deter- mined initially and at the end of each minute, in scale divisions. 5.1.6 The change in output is calculated for each l-rain period and tho largest of tbese changes is deter- mined. This largest change shall be called the driIt (scale divisions). If the change of output per minute ST&NOARO SAMPL( INU[T LEAR LINE LEAK lVALVE PUMP T_ ALVE LEAK Dt[TECTOR PUMP FmtrR,, 1.0. a As used here, minimum detectable signal refers to the per- formance'of a particular leak detector; it is determined by _purious outputs of the device that _t a lower limit to the elium flow rate which rate will produce an unamhiguoua output signal. _ - ,3 STANOARD LEAK AVS Standard LEAK DETECTOR 231 PUMP l "A VlSI__1 PUMP Fm fJr_: 1.1, is always less than ½ of 1% of full scale, the total change in the 60-rain observation period is deter- mined. The total change divided by 60 shall be called the dri]t. 5.2 Noise Determination. The recorded output curve is examined to determine thc two spikes, one on each side of the faircd curve, that extcnd furthest from the curve. The departures are measured (in scale divi- sions) and the two figures are added. The sum shall be called the noise. If the output is such that spikes appear only on one side, the noise shall be taken as twice the largest departure from the curve (scale di- visions). 5.3 Minimum Detectable Signal The minimum de- tectable signal shall be taken to be equal to the sum of the drift and the noise (scale divisions}. If the sum is less than the scale divisions corresponding to 2,e,o of full scale, then the scale divisions corresponding to 2% of full scale shall bc called the minimum detecta- ble signal. 6. TEST PROCEDURE--MINIMUM DETECTABLE LEAK 6.1 General. In the procedures below, a calibrated leak is connected to tile leak detector under test. Preferably, the connections should contain no rubber or other polymeric surfaces between the leak and the leak valve (see Fig. 1.0); if such is tile case, the pro- cedure under Scc. 6.2 is followed. If rubber or poly- meric surfaces arc prcscnt, the procedure under See. 6.3 isfollowed. 6.2 SensitivityDetermination I. The leak detector is prepared as in Sec. 4.8 and cotmected to the recordcr. 6.2.1 The small calibrated leak (scc Scc. 4.3) is con- nected to the leak detector in a manner specifiedby the manufacturer. Refer to Fig. 1.0. Specificd conncctions shall include a valve (prefera- bly all-metal) that does not act as a source of hclium, located bctwcen the leak and the leak detector.Thi.-: valve willbe referred to as the leak valve. Specified connections shall include a pumping line to permit evacuation of said connections. The pumpi,lg lineshall include a valve hereafter referred to a._the pump valve, which shall be located adjacent to the pump. --_o 2.q2 AVS Standard Specified connections shall contain a minimum of rub- bet or other polymeric surface(s). Preferably, such surface(s) shall consist only of the exposed partial surface(s) of O ring(s). 8.2._ The output is zeroed, with the filament on. 6._ The leak valve is opened. 6_._ The pump valve is opened. 6_ Helium at 760 Torr premure is applied to the leak. If the leak has its own supply of helium, this step is omitted. 6.t.6 The atmospheric air present in the connections between the leak and the leak detector is evacuated to protect the leak detector. 8.2.7 The pump valve is closed. 6._.8 The inlet valve in the leak detector sample line is opened promptly after See. 6._.7. [Note: The fila- ment of the mass spectrometer tube may be turned off before See. 6_,.7 above.] The pressure in the leak detector is allowed to reach a steady value, shewing no observable change in 1 rain. 6.8.9 Turn on filament of mass-spectrometer tube if it is not on. 6_.10 At this point, it may be necessary to change the sensitivity settin_ When the output signal has reached a steady value, showing no observable change in 1 min, the reading is noted (scale divisions). 8J.ll The stop watch is started and simultaneously the leak valve is closed aa rapidly am]easible. 6J.1_ The output is observed continuously, and the stop watch is stopped when the reading has decreased to 37_ of the reading obtained in Sec. 6-2.10 above. The reading of the stop watch is noted (T see). T is a measure of the time required to remove the out- put signal initially caused by the helium input; this time figure is referred to as the c/eonup t/m_. It is assumed, for the purpose of this standard, that the leak detector is so constituted that the cleanup time and response time are equal, the respoau t/me being a measure of the speed of response of the leak detector to an incoming helium sample. Hereafter, T will be called theresponsetime. 6J.IS When the output signal has reached a steady reading, showing no observable change in 1 rain, the reading is noted. 6.S.I_ The signal due to the calibrated leak shall be taken as the differeaee between the reading noted in See. 6.2.10 above and that noted in See. 6-2.13 above. If the leak detector has been set at reduced sensi- tivity, the difference shall be converted into equiva- lent _ale divisions at full-sensitivity setting. minimum detectable leak shall be calculated by t_ formula below and shall ahool/s be stated together with the response time, T. M.Z]N1M_ DR'FJ_F_JUg LIAr, WITH lUWPOlq'am TIMa' _ _._ L,l_rl. R&TIIqG X MINIMUM DIMr_F?_[JI SI_]NAJr_ SlON_b DUB TO C_,IJ/LLTI_ L/L_K 6.3 _msitivity Determinttion II. 8_.1 The leak detector is prepared as in Sec. 4.8 and connected to the recorder. (a) A stainless-steel plug is connected to the leak detector, in place of the calibrated leak shown in Fib 1.0. Refer to See. 6-2.1. (b) The output is zeroed, with the filament on. (c) The leak valve is opened. (d) The pump valve is opened. (e) The atmospheric air present in the connec- tions between the plug and the leak detector is evacuated to protect the leak detector. (f) The pump valve is closed. (g) The inlet valve is opened promptly after See. 6.3.1f above. [Note: The filament of the mass- spectrometer tube may be turned off before See. 6.3.1f]. The pressure in the leak detector is allowed to reach a steady value, showing no observable change in 1 min. (h) Turn on filament of mass spectrometer tub, if it is not on. -" (i) When the output has reached a steady value, but in any case not longer than 3 n_in after See. 6.3.1g above, the output reading is noted. If the leak detector has been set at reduced sensitivity, the reading shall be converted to the equivalent scale divi,ions for full-sensi- tivity setting. (j) Close the leak valve. (k) When the output has reached a steady value, showing no observable change in 1 rain, the output reading is noted. As in Sec. 6.3.1i, con- vert the reading if necessary. (1) The difference between the readings in Secs. 6_.1i and 6_.1k, abo_e, is calculated and will be considered a correction figure in See. 6.3.2m below. (m) Close the inlet valve. _.# The plug onl_l is removed from the inlet line. All connections are to remain in place. (a) The small calibrated leak is put in place of the plug removed in Sec. 6_ above, the leak -_ being inserted the same distance into the con- - nections as the plug had been. The output is seroed , with the filament on. The leak valve is opened. (b) (_) d-'-/ (d) Tile pump valve is opened. (e) The atmospheric air present in the connections between the plug :md the leak detector is evacuated to protect the leak detector. (f) The pump valve is closed. (g) The inlet valve is opened promptly after See. 6.3.2f [Note: The filament of tile mass-sl)ee- trometer tube may be turned off before See. 6.32f above.] The pressure in the leak detec- tor is allowed to reach a steady value, show- ing no observable change in 1 min. (h) Turn on filament of mass-spectrometer tube if it is not on. (i) When the output has reached a steady value, but in any ease not, longer than 1 rain after step 6.3.2g above, the output reading is noted. If the leak detector has been set at reduced sensitivity, the reading shall be converted to the equivalent scale divisions for full-sensi- tivity setting. (j) Close the leak valve. (k) When the output has reached a steady value, showing no observable change in 1 rain, tile output reading is noted. As in See. 6.3.2i, con- vert tile reading if necessary. (l) The uncorrected signal due to calibrated leak shall be taken as the difference between the reading noted in Sec. 6.3.2i above and that noted in Sec. 6.3.2k above. If the leak detector has been set at reduced sensitivity, the differ- ence shall be converted into equivalent scale divisions at full-sensitivity setting. (m) The signal due to the calibrated leak shall be taken as the difference between the uncor- rected signal, See. 6.3.21 above, and the cor- rection in See. 6.3.11 above. The minimum detectable leak shall be calculated by the formula below and shall always be stated to- gether with the response time, T. MINIMU_,f DIgTgL_ABLI_ LEAK, WITH RF_I_-_SE TIMZ _ -_ SIGNAL DUZ TO CALIBN.4TED LI_4K CAL/stRATEi) LF_IL R_TINO MINIMUM DETECTAU_ .qlG.%'AL 7. TEST PROCEDUREmMINIMUM DETECTABLE CONCENTRATION RATIO 7.1 General. A significant determination of mini- mum-detectable concentration ratio requires means within tile leak detector under test for scanning the helium peak. This refers to the ability to tulle or ad- just the detector for detecting helium (see See. 2.) and thereby to attain a maximum or peak output for a given helium input, and the ability to detune either side of the peak adjustment until a minimum signal AVS Standard 233 is produced. The process of adjusting a leak detector from one side of tile correct adjustment fol' helium, to the correct adjustment, and then past the correct ad- justment, is referred to as seanniTig the (helium) pcctk. The leak-detector adjustment referred to above is al- most always an adjustment of the accelerating volt- age, and it will be assumed that this is the case. When leak-detector output (scale divisions) is plotted against accelerating voltage, a curve is ol)tai_md whose general features are illustrated I)y the solid line in Fig. 2.0. (Note that voltage may be plotted in the reverse direction and this will give a reverse slope to tile curve.) The rise in the curve to a peak at B is duc to tile presence of helium. The faired curve indicated by a broken line is due to a varying backgro_,nd sig- nal contributed by other ions than helium. With helium present, and in the absence of background, the curve obtained would be symmetrical, tailing to zero on either side of the peak voltage. The curve shown in Fig. 2.0 is very nearly a direct superposition of the background curve and the symmetrical pure-helium curve. It will be noted that, as one varies the voltage from the left side of the graph to tile right, the output first decreases, then increases, and finally decreases again. This reversal in direction, indicati,ag the presence of helium, is very easily detected when the scan is being observed visually on a meter. As the helium input signal becomes smaller, the reversal becomes, smaller. At some point, a curve such as is shown by the solid line in Fig. 2.1 is obtained. At this point, the output never reverses; it "stands still" for a very short in- terval. Such a condition will just barely be detected by the usual visual observations. Accordingly, in the absence of noise,and drift, the concentration ratio of helium which produces this condition determines the minimum-detectable concentration ratio. Under practical conditions, it is not possible to make a rigidly correct deternfination of the mininmm detec- table concentration ratio as defined above. In the fol- lowing, somewhat arbitrary determinations are used for ealeulating a sensitivity figure. The sensitivity so obtained is one that is reasonable in light of practical experience. , /\ _. ° 234 AVS Standard ! VOLTA_IE F:avu 2.1. 7._ Test Procedure--Minimum Detectable Signal s 7_.I Dri]t Determination. (a) The output of the leak detector is connected to the recorder, the leak detector being at its maximum sensitivity setting and the inlet valve closed. Refer to See. 4.6. (b) The large calibrated leak (see Sec. 4.3.3) is connected to the leak detector in a manner specified by the manufacturer. Refer to Fig. 1.1. Specified connections shall include a pumping line to permit evacuation of said connections. The pumping line shall include a valve,here- after referred to as the pump valve, which shall be located ad)aecnt to the pump. Specified connections shall contain a minimum of rubber or other polymeric surfaces. Prefera- bly, such surfaces shall consist only of the exposed partial surfaces of O rings. (c) Atmospheric air (see Sec. 4.5) is fed at 760 Torr ---570 to the leak. The feed line shall not of itself act as a source of helium, and should preferably be of all-metal construction. (d) The pump valve is opened. (e) The atmospheric air present in tile connections between the leak and the leak detector is evacuated. (f) The pump valve is closed. (g) The valve in the leak detector sample inlet line is opened. [Nots: The filament of the mass spectrometer may be turned off before Sec. 7.2.1f above.] The pressure in the leak detector i8 alrowed to reach a steady value. (h) Turn on the filament of the mass spectrometer if it is not on. (i) Observe the leak-detector output. If the re- corder is no scale, dstune until the recorder reads half-scale. If the recorder is off scale, slowly tune the leak detector o]] the helium peak setting until the recorder comes just on scale. Then detune further until the recorder reade half-scale. • As treed here, minimum detectable aignni refers to the per- formanee of a particular leak detsctor; it is determined by qmrious outputs of the device that set s lower limit to the helium.eoneestratioa ratio, which ratio will lxoduee an unam. biguous output ,_gnsl. (j) The output is recorded for 30 rain or until the recorder has reached the end of its scale. (k) Generally, the recorded output curve will sh,.__ spikes. If spikes do appear, the curve i._ to be faired in standard engineering fashion. (I) From the faired curve, the output is deter- mined initially and at the end of each minute, in scale divisions. (m) The change in output is calculated for each l-rain period and the largestof these changes is determined. Tltis largest change shall be calledthe drift(sealodivisions).If the change of output per minute is always lessthan _ of I% of fullscale,the totalchange in the 30-rain observation period is determined. The total change divided by 30 shall be called the drift. 7J.t Noise Determination. The recorded output curve is examined to determine the two spikes, one on each side of the faired curve, which extend furthest from the curve. The departures are measured (in scalc divisions) and the two figures arc added. The sum shall be called the no/as. If the output is such that down-scale spikes cannot be observed, tlze noise shall be taken as twice the largest departure from the curve (scale divisions). 7._ Minimum Detectable Signal. The minimum ctc- tectable signal shall be taken to be equal to the sum of the drift and the noise (scale divisions). If the sum is less than the scale divisions corresponding to 2_ oi full scale, then the scale divisions corresponding to- 2% of full scale shall be called the minimum detecta- ble signal. 7.3 Helium Background 7.3.1 With the inlet valve closed, turn on the fila- ment of the mass-spectrometer tube if it is not al- ready on. 7.3._ Set the leak detector for the greatestsensitivity that gives on-scale readings. 7.3.3 When the output signal has reached a steady reading, showing no observable change in 1 rain, the helium peak is scanned as specified for the instrument. Provision is to be made for measuring the accelerating voltage u the scan i8 performed, and the correspond- ing outputs are to be observed and recorded. 7.3._, Plot the output against the voitag_ and draw a smooth curve through the plotted points. The curve is also faired as shown by the dotted line in Fig. 2.0. The ordinate AB is taken as a measure of the helium background, B being located at the maximum of the _:. curve. 7'.3.5 If AB is different than zero, the scanning is to be repeated at 16-rain intervals until AB has become zero or has not changed over a 2-h period. 7.$.6 If AB is ultimately different than zero, its mag- nitude is determined and is referred to as the helium background (scale divisions). If the leak detector is at reduced sensitivity setting, the background shall be converted to equivalent scale divisions st full-sensi- tivity setting. Helium background will be abbreviated HB. 7.4 $_udt/vity Determinatioa 7._.I Directly after See. 7.3, the large calibrated leak (see See. 4.3.3) is connected to the leak detector in a manner specit_ed by the manufacturer. Refer to Fig. 1.1. Specified connections shall include a pumping line to permit evacuation of said connections. The pumping line shall include a valve hereafter referred to M the pump valve, which shall be located adjacent to the pump. Specified connections shall contain a minimum of rub- bet or other polymeric surfaces. Preferably, such sur- faces shall consist only of the exposed partial surfaces of 0 rin_. 7._._ The helium mixture (see 4.5) is fed at 760 tort ±5% to the Leak. The feed line shall not of itself set as a source of helium, and should preferably be of all- metal construction. 7.4.3 The pump valve is opened. 7.,_.4 The atmospheric air present in the conneetions between the leak sad the leak detector is evacuated. 7_.5 The pump valve is closed. AVS Stanclsrcl 23S 7._,.6 The valve in the leak detector sample inlet line is opened. [Note: The filament of the mass spec- trometer may be turned off before See. 7.4.5 above.] The pressure in the leak detector is allowed to reach a steady value. 7._.7 Turn on the filament of the mass spectrometer if it is not on. 7._.8 When the output signal has reached a steady reading, showing no observable change in I rain, the helium peak is scanned as specified for the instrument. Record the scanning voltage and the corresponding output (scale divisions). If the leak detector is at reduced sensitivity setting, the output shall be con- verted to equivalent scale divisions at full-sensitivity setting. 7._ Plot the output against the voltage and draw a smooth curve through the plotted points. The curve is also faired as shown by the dotted line in Fig. 2.0. 7._.I0 Mark on the curves the point B (scan maxi- mum), point A, point D (scan minimum), and point C directly below D. Measure the distances of these point_ from the voltage axis (scale divisions), and de- note these ordinates, respectively, by b, a, d, and c. 7._.II The minimum-detectable concentration ratio shall be calculated by the following formula: MDCR = C,, × (c - a)/(b - a -ItB), where MDCR is the minimum-detectable concentra- tion ratio C, is the concentration ratio of helium mix- ture (see See. 4.5) HB is the helium background (see See. 7_.6) Or, if c - a is less than the MDS (mini- mum-detectable signal, see See. 7.2.3), use the formula MDCR -- C, × (MDS)/(b - a - HB). _o . ANS 7.60 Proposed Standard for Leakage Rate Testing of Containment Structures for Nuclear Reactors Approved for Publication for Comments June 15, 1964 ANS Standards Committee --2- _.. Foreword (This foreword is not a part of the proposed standard.) This proposed standard was prepared by Evan F. Wilson of the Allis-Chalmers Manufacturing Company in his capacity as a member and, pres- ently, Chairman of Subcommittee ANS-7, Reactor Components, of the American Nuclear Society Standards Committee. The work was initiated early in 1959, and the standard has undergone some ten or more reviews and revisions. Correc- tions and additions were incorporated into four formal revisions of which this is the latest. Rep- resentatives of 16 companies involved in nuclear research and development and other companies involved in the fabrication and construction of containment vessels participated in the reviews of this standard. The following are presently mem- bers ot Subcommittee ANS-7: E. F. Wilson, Chairman, Allis-Chalmers Manu- facturing Company S. F. Bacharach, Aerojet-General, Azusa E. S. Brown, Phillips Petroleum Company, NRTS S. Davis, United Nuclear Corporation K. H. Dufrane, The Martin Company A. W. Flynn, Ebasco Services, Inc. L. W. Fromm, Argonne National Laboratory W. R. Gall, Oak Ridge National Laboratory R. Hobson, Westinghouse Atomic Power Divi- sion K.C. Hoffman, Brookhaven National Laboratory Arne B. Holt, U. S. Atomic Energy Commission H. Hopkins, General Atomic R. L. Koontz, Atomics International R. C. Lovington, Bechtel Corporation D. A. Mars, Babcock & Wilcox Company W.J. McGonnagle, Southwest Research Institute A. W. Savolainen, Oak Ridge National Labora- tory W. R. Smith, General Electric Company, APED L. E. Steele, Naval Research Laboratory N. O. Strand, General Electric Company, Han- ford T. H. Thomas, Lockheed Nuclear Products Following review and discussion in the June 15, 1964 meeting of the ANS Standards Committee, a vote was taken that was in favor of publication of this draft for comment by ANS members. The vote was not unanimous; the dissenting members were of the opinion that Section 8 should be a sep- arate standard. This proposed standard is issued for review and comment by ANS members and other interest- ed persons. Comments will be accepted until February 1st and should be addressed to: O. J. Du Temple Executive Secretary American Nuclear Society 244 East Ogden Avenue Hinsdale, Illinois, 60521 with copies to Evan F. Wilson Allis-Chalmers Manufacturing Company Atomic Energy Division 6939 Arlington Road P. O. Box 5976 Washington, D. C., 20014 and Ralph G. Chalker Atomics International P. O. Box 309 Canoga Park, California, 91306 American Nuclear Society It is the policy and practice of the Standards Committee of the American Nuclear Society through its subcommittees to formulate and promulgate proposed standards for the nuclear industry. This standard was prepared on the consensus principle and is based on the experi- ence and knowledge available at the time. This standard is intended as a guide to aid the manufacturer, the consumer, and the general public. The existence of a standard does not in any respect preclude any party from manufacturing, selling, or using products, processes, or proce- dures not conforming to the standard. This standard is subject to peri- odic review and reaffirmation or revision. The existence of this stand- ard does not relieve its user from the requirement that he exercise good judgment in its application, and that he provide himself with tech- nical competence commensurate to his activities, nor does compliance with ANS Standards assure acceptability to federal, state, or local authorities. -/0 Contents SECTION PAGE 1. Purpose and Scope ................................... 7 1.1 Purpose ...................................... 7 1.2 Scope ........................................ 7 2. Conjunctive Standards ................................ 7 2.1 Conditions of Applicability .......................... 7 2.2 Conjunctive Standards ............................. 7 3. Definitions and Descriptions of Terms ..................... 7 3.1 Containment Structure ............................. 7 3.2 Leak ........................................ 7 3.3 Leakage ...................................... 8 3.4 Leakage Rate ................................... 8 3.5 Maximum Allowable Leakage Rate ..................... 8 4. Preliminaries to Leakage Rate Testing ..................... 8 4.1 Sequence of Tests ................................ 8 4.2 Pressure Tests for Strength ......................... 8 4.3 Integral Pneumatic Leak Detection Tests ................ 8 4.4 Local Leak Detection Tests ......................... 8 4.5 General Preparations for Test Pressurizing .............. 8 4.6 Time Scheduling of the Leakage Rate Test ............... 8 5. Leakage Rate Test Methods ............................. 9 5.1 Applicable Test Methods ........................... 9 5.2 Description of Methods ............................ 9 5.3 Leakage Rate Pressures ........................... 9 6. Test Equipment and Facilities ........................... 9 6.1 Pressurizing Facilities ............................ 9 6.2 Temperature Measurements ......................... 9 6.3 Pressure Measurements ........................... 9 6.4 Atmospheric Humidity ............................. 9 7. Test Procedures .................................... 9 7.1 The Absolute Method .............................. 9 7.2 The Reference Vessel Method ........................ 10 7.3 Leak Minimization ............................... 10 7.4 Pressurizing ................................... 10 7.5 Temperature Measurements ......................... 10 7.6 Personnel Access to Pressurized Containment Structures ..... 10 7.7 Period of Test .................................. 10 7.8 Humidity ...................................... 10 7.9 Recording of Data ................................ 11 7.10 Computation of Leakage Rate, The Absolute Method ......... 11 7.11 Computation of Leakage Rate, The Reference Vessel Method . . . 11 8. Reinspection and Recheck of the Containment Structure .......... 11 8.1 Reinspection ................................... 11 8.2 Local Leak Detection Retests ........................ 11 8.3 Leakage Rate Retests ............................. 11 6 -// . L SECTION Appendix A. Local Leak Testing Procedures ................... A1. Applicability of Local Leak Tests .... . ................ A2. Water Submersion Test ............................ A3. Vacuum Test ................................... A4. Air-Ammonia Test ............................... A5. Halogen Sniffer Test .............................. Appendix B. Derivation of Formulas for Containment Structure Leakage Rates ............................. B1. Definition of Symbols ............................. B2. Determination of Leakage Rate, The Absolute Method ........ B3. Determination of Leakage Rate, The Reference Vessel Method . . PAGE 11 11 12 12 12 12 12 12 13 13 _- ° Proposed Standard for Leakage Rate Testing of Containment Structures for Nuclear Reactors 1. Purpose and Scope 1.1 Purpose. The purpose of this standard is to specify uniform methods for determining the abil- ity of a reactor container to retain, within the lim- its of permissible leakage rates, any gases, va- pors, liquid, or other fluid materials which would be of a hazardous nature if not contained and which might be present in the containment struc- ture as a result of an energy release, rupture, or leak in the nuclear reactor components or acces- sories. The need for restriction of leakage from the containment structure is based on the mainte- nance of public health and safety, the protection of operating and maintenance personnel, and the preservation of property. 1.2 Scope. The provisions of this standard specify the preferred practices and test require- ments for the quantitative determination of gas leakage rates of containment structures for the housing of operating nuclear reactors. The provi- sions apply to containment structures for nuclear power, test, research, and training reactors, wherever a gas-tight containment structure is specified as a condition for operation. 2. Conjunctive Standards 2.1 Conditions of Applicability. This standard shall be applied in conjunction with other stan- dards and codes as they may apply and are also specified. Acceptance of a containment structure with respect to the requirements of this standard shallbe contingent upon compliance with the spec- ified codes for design, fabrication,construction, inspection,proof testing,and maintenance, as sub- sequently listedin 2.2. 2.2 Conjunctive Standards. Standards or codes which are conjunctiveto the present standard are the following: 2.2.1 ASME Boiler and Pressure Vessel Code, Section 3, Nuclear Vessels. 2.2.2 ASME Boiler and Pressure Vessel Code, Section 2, Material Specifications. 2.2.3 ASME Boiler and Pressure Vessel Code, Case Interpretations, 1962 and later revi- sions. 2.2.4 ASA N 6.2: Proposed Safety Standard for Design Fabrication and Maintenance of Steel Containment Structures for Stationary Atomic Power Reactors. 2.2.5 ASA Standard A57.1: American Insti- tute of Steel Construction, Specifications for the Design, Fabrication and Erection of Structural Steel for Buildings. 2.2.6 ASA Standard A58.1: Building Code Requirements for Minimum Design Loads in Buildings and Other Structures. 2.2.7 ASA Standard A89.1: Building Code Requirements for Reinforced Concrete. (ACI-318) 2.2.8 National Fire Codes, National Fire Protection Association. 2.2.9 American Petroleum Institute, Rec- ommended Rules for the Design and Construction of Large, Welded, Low-Pressure Storage Tanks. 3. Definitions and Descriptions of Terms To assure common understanding of the terms employed inthis specification,the following deft- nitionsshall apply. 3.1 Containment Structure. A containment structure, within the nmaning of this standard, shall be an erected vessel, building, or under- ground location thatprovides an outer housing for the reactor system, including the primary vessels, components, and accessories. The function of the containment structure shall be the emergency and secondary retention of fluids and ob]ects in the event of their accidental release from the reactor vessels or system. 3.2 Leak. A leak, in the context of this stan- dard, shallconstitutean opening, however minute, which allows the passage of a fluid and which is detectable by the means and methods specified herein for leak detection or leakage measurement. 3.3 Leakage. Leakage shall be interpreted as the measureable quantity of fluid escaping from a leak. For the purposes of this standard, air shall be used as the reference fluid. 3.4 Leakage Rate. Leakage rate is that leakage experienced during a specified period of time. For the purposes of this standard, leakage rate shall be reported as the percentage by weight of the original content of air by weight pressurized to the leakage rate test pressure which could escape during a 24-hour period. The leakage rate shall be that experienced at the outside atmosphere and containment structure air conditions prevailing during the period of leakage rate testing. 3.5 Maximum Allowable Leakage Rate. The maximum allowable leakage rate governing the acceptability of the containment structure by those responsible for its reliability shall be that stipu- lated in the specification for the individual con- tainment structure. 4. Preliminaries to Leakage Rate Testing. 4.1 Sequence of Tests. Leakage rate testing should be conducted after the inspection and test- ing of welded Joints, penetrations, and mechanical closures; completion of repair measures for the minimizing of leakage; and corr@letion of contain- ment structure pressure tests for strength. Where the containment structure is to be subsequently covered with concrete or wilt otherwise be inac- cessible to direct examination, particular care should be given to inspection of these areas prior to such coverage. Integral or local leak detection should preferably precede leakage rate tests. 4.2 Pressure Tests for Strength. Hydrostatic or pneumatic pressure tests to determine whether the containment structure complies with specified strength and design requirements shall precede leakage rate testing. Also, the results of pressure tests shall meet the stipulated requirements be- fore leakage rate tests are initiated. 4.3 Integral Pneumatic Leak Detection Tests. The detection of individual leak locations, preliminary to leakage rate testing, may be effec- ted by local or integral pressurizing of the con- PROPOSED STANDAR_ tainment structure or both. and the use oa] solution to provide air-bubble indications O_ex- terior surfaces. In the initial integral testing fo: location of leaks, the air pressure should be be- tween 85% and 100% of the design pressure for th_ containment structure. Repairs or adjustment_ should be made as the leak detection results ind_- cats. The use of integral pneumatic leak detectior_ methods is particularly adapted to the examinatio_u of welded joints, gaskets, threaded connections and mechanical closures, such as air locks, vaive_¢ vacuum breakers, and ducts, where local leak de- tection methods are not conveniently applicable. 4.4 Local Leak Detection Tests. Locaiizec pressure tests may be advantageously employed in some circumstances where the part or area is especially susceptible to leakage or it is wished to, employ higher pressures than in the integral- pressurizing detection test. Local leak detectior: methods may include the pneumatic soap-bubble test, vacuum testing, air-ammonia and haioger. sniffer tests, or other tests developed for special examinations. Local tests are particularly suit- able for inspection of equipment prior to installa- tion in the container and for inspection of mf -- ately small but complex assemblies where _-aks are difficult to locate and where the leakage rate is especially slow. Descriptions of local leak de- tection methods are given in Appendix A. If the local leak detection test is carried out with inter- nat pressurizing, a pressure of at least 5 peig shall be used if the design pressure of the con- tainment structure is above 10 psig; and at least one half of the design pressure, if this pressure is 10 psig or less. 4.5 General Preparations for Test Pres- surizing. Preparatory to test pressurizing for leakage rate determination, contents of the con- tainment structure that are sensitive to damage by a pressure differential, such as some instruments, should be removed or otherwise protected. Thin also applies to fan and blower motors employed for air circulation where the load is a function of air density. The protection of the structure from damage, such as by underpressure, should be as- sured by checking the operative reliability of Vac- uum breakers. The vacuum release devices should operate within 10% of their design pressures for internal or external loading. 4.6 Time Scheduling of the Leakage h Test. To assure favorable test conditions f'or leakage rate tests without large or abrupt changes PROPOSED STANDARD in atmospheric temperatures or barometric pres- sures, the scheduling of the test should be planned insofar as feasible in accordance with advance weather predictions. Final weather checks to as- sure safety of the containment structure should be made just prior to and during the test. To mini- mize temperature fluctuationscaused by solar ra- diation, wind effects, or appreciable changes in temperature, a relatively windless day during a period of relativelystable weather conditions is to be preferred. The anticipatedweather conditions during the test should indicate littleor moderate barometric pressure variations in order to im- prove the reproducibilityof leakage rate results. 5. Leakage Rate Test Methods 5.1 Applicable Test Methods. Leakage rate test procedures applicableto this standard may be either the absolute method or the reference vessel method. The choice of either method shall be a matter of agreement between parties who axe charged with responsible acceptance of the vessel and those in charge of the leakage rate test proce- dures. 5.2 Description of Methods. The absolute method of leakage rate testing shallconstitutethe determination and calculation of air losses by containment structure leakage over a stated peri- od of time by the means of direct pressure and temperature observations during the period of test with temperature detectors properly located to provide an average air temperature. The refer- ence vessel method shall constitute the deter- mination and calculation of air losses by observa- tions of the pressure differentials between the containment structure and a gas-tight reference system, with the reference vessels located so as to represent, with reasonable accuracy, the aver- age temperature of the aggregate containment air. 5.3 Leakage Rate Pressures. Leakage rate determinations shall be conducted at the pressure at which the leakage rate was specified and after all other pressure testing required in the specifi- cation. 6. Test Equipment and Facilities 6.1 Pressurizing Facilities. Pressurizing facilities for containment structure leakage rate tests should be of sufficient capacity to bring the structure pressure to the test level within a suffi- to favorable weather conditions. Valves and re- pressurizing facilitiesshould be available for ad- justingto subsequent atmospheric changes, as ap- propriate to specific test requirements. 6.2 Temperature Measurements. All ther- mometric equipment shall be compared over a normal range of atmospheric variations with a reference thermometer of established calibration. Corrections based on the reference thermometer shall be available before the leakage rate test is started. Thermometers, thermocouples, and ther- mographs employed in the leakage rate tests shall be reproducibly readable to 0.2°F, or equivalent, or to the extent specified as the tolerable error for the maximum allowable leakage rate of the structure subject to test. 6.3 Pressure Measurements. Mercurial or aneroid barometers for the observation of contain- ment structure and outside atmospheres shall be reproducibly readable to 0.1 mm or less (0.004 in.) or to the extent specified as the tolerable error for the maximum allowable leakage rate. Barographs for the recording of the outside at- mospheric changes need be only of such accuracy as will indicate gross barometric changes perti- nent to the scheduling of tests. ALl barometric equipment shall be compared with a single preci- sion mercurial barometer equipped with vernier and shall be correctable for temperature and readable to 0.1 ram. Manometers for the reading of pressure differentials shall be of precision bore and plainly readable to 1 mm (0.04 in.) or less of water by marked graduations. 6.4 Atmospheric Humidity. Hygrometers or psychrometers shall be available to determine relative humidities during the period of test within and outside the containment structure when re- quired. 7. Test Procedures 7.1 The Absolute Method. The absolute meth- od of leakage rate determination depends on the measurement of the temperature and pressure of a constant volume of containment structure air with suitable correction for changes in tempera- ture and humidity control under a nearly constant pressure difference wt_ respect to the atmos- phere outside the structure. R is assumed that the temperature variations during the test will be in- sufficient to effect significant changes in the in- ternai volume of the structure or the partial pres- cientperiod of time for scheduling with referent./ffsure of water vapor in the contained air. ° , 10 7.2 The Reference Vessel Method. The refer- ence vessel method of leakage rate determination depends on the changes in pressure of a constant volume of contained air compared with that of a hermetically closed reference vessel which may be at the same pressure as the contained air at the start of the test or may have a small differential. The reference vessels shall be so placed and of such a geometry that they will assume the tem- peratures of the contained air within a reasonable time lag. The reference vessels shall be subject to leakage rate determination in accordance with the absolute method prior to their use for con- tainment structure testing according to the appUc- able procedures of this standard or may be check- ed by the halogen sniffer test or by retention of vacuum. 7.3 Leak Minimization. Before pressurizing for leakage rate testing, all discernible leaks in the container shall be revealed by local and inte- gral leak detection tests and shall be repaired or corrected. AU openable closures and vacuum breakers shall be checked for leak tightness. 7.4 Pressurizing. Pressurizing for the leak- age rate test shall be carried out under atmos- pheric conditions which provide relatively low air humidity in order to avoid moisture condensation within the containment structure. Any moisture that condenses out of the pressurized air and col- lects at the bottom of the structure shall be drained off prior to the start of the test to prevent re-evaporation. Reference vessels should be sim- ilarly drained. To provide low humidity and to im- prove pumping efficiency, cool night air is usually preferred for pressurization. The structure shall be pressurized to as near the design pressure as is possible under prevailing conditions or to pres- sures stipulated as a condition for test acceptance. 7.5 Temperature Measurements. Area sur- veys within the structure shall be made in advance of leakage rate testing to establish any tendencies to regional variations in temperature. Additional- ly, thermometers and thermocouples shall be lo- cated at different parts of the structure wherever local variations may be expected in the course of the test. Fans or other means for air circulation may be used to equalize temperatures in any re L_ gion where representative temperature measure- ments are. taken and appreciable temperature variations exist. .- E PROPOSED STANDARD The temperature pattern revealed by the ,_T,r- vey shall be employed in connection with the n representative temperature determination for the absolute method of leakage rate testing. Location oi reference vessels shall be made with consider- ation of the temperature pattern in order to reflect representative temperatures. Where test- ing experience with vessels oi various configura- tions has established appropriate locations for reference vessels, temperature surveys may be eliminated /or those vessels having similar pro- portions. 7.6 Personnel ,Access to Pressurized Con- tainment Structures. Exposure of personnel to pressurized air and return to normal atmos- pheric pressures during the course of containment structure leakage rate testing shall be governed by approved decompression procedures involving a controlled depressurizing rate and waiting peri- ods at intermediate pressures. For exposures of no longer than 200 rain at pressures not greater than 14.3 psig, no intermediate holding periods or decompression stops are required provided that the time rate of pressure reduction in the air lock to atmospheric level is not less than 30 sec. For exposures to pressurization in excess of 14.3 p; "- and for exposure periods including repetitive _- posure within 12 hr, the practices should conform to those stipulated in Section 1.5, Diving Tables of the U. S. Navy Diving Manual, NAVSHIP 250-538_ January 1959. 7.7 Period of Test. The leakage rate test period shall extend to not less than 24 hr of re- tained internal pressure. Completion of the test should be scheduled to coincide with atmospheric temperatures and pressures close to those at the start of the test, as far as is possible. Check tests or repetition of tests shall be a matter of agreement between those responsible for the ac- ceptance of the containment structure and those in charge of the leakage rate testing. 7.8 Humidity. The relative humidity of the con- iainment structure shall be monitored during the course of the leakage rate test to assure that the dew point is not reached and that there is no con- densation of moisture in any part of the structure. Concrete structures within the containment struc- ture should be properly cured prior to testing to minimize high humidity from moisture release; however, where appreciable evaporation may o_- cur from exposed surfaces of incompletely cu, concrete, such surfaces should_ be covered with PROPOSED STANDARD plastic sheeting, or other suitable precautions should be taken. Open pools of water may be sim- ilarly covered. To minimize the effect of variation in the partial pressure of water vapor, it is desir- able to maintain the containment structure air at a reasonably constant temperature level, particu- larly near the completion of the test. Air condi- tioning, prior to testing, may be employed to approach this condition. Any moisture condensa- tion occurring during the course of the test will result in an apparent leakage rate in excess of actual. 7.9 Recording of Data. Pressure, tempera- ture, and humidity observations shall be made within the containment structure and recorded during the course of the leakage rate test at hourly or more frequent intervals. Pressure and tem- perature measurements of the outside atmosphere shall also be made and recorded at corresponding intervals and times. The times of observations shall be denoted in hours and minutes. A dated log of events and pertinent observations shall also be maintained during the test, and the correctness of data shall be attested to by those responsible for the test and, where specified, by a competent wit- ness. Records of the leakage rate tests shall be maintained in accordance with the terms of agree- ments with those responsible for the acceptance of the containment structure. 7.10 Computation of Leakage Rate, The Ab- solute Method. For the absolute method of leak- age rate testing, the calculation of the per cent leakage of air from the containment structure in terms of the original amount contained and that which escaped during a 24-hr period shall be made in accordance with the following formula: 24 ( T, Pa_Per cent leakage in 24hr =-_- 1-_] 100, where T_ = mean absolute temperature of the con- tainment structure air at the start of the test, T2 = mean absolute temperature of the con- tainment structure air at the completion of the test, P_ = absolute pressure of the containment structure air at the start of the test, P2 = absolute pressure of the containment structure air at the completion of the test, H = time period of the leakage rate test, in hours. ._'-/7 11 The derivation of this formula is given in Appen- dix B. 7.11 Computation of Leakage Rate, The Reference Vessel Method. For the reference vessel method of leakage rate testing, the calcula- tion of the per cent leakage of air from the con- tainment structure in terms of the original amount contained and that which escapes during a 24-hr period, shall be made in accordance with the fol- lowing formula: Per cent leakage in 24 hr = __ 24 [ rl (P; - P2) (P[ -P01 -- H _ T2PI PI j 100, where P' and P2' are, respectively, the absolute pressures of the reference vessel at the start and completion of the test. 8. Reinspection and Recheck of the Containment Structure 8.1 Reinspection. Annual reinspection is rec- ommended to determine whether visual evidence of deterioration of the structure has occurred and whether this might affect its tightness with re- spect to the leakage rate. Such inspection should include evidence of unequal settlement of the foun- dations, significant corrosion, significant weath- ering of sealing compounds or other nonmetallic materials, cracking at weld areas or other re- gions of stress concentration, and damage result- ing from operations or accidents. Penetrations and closures should be examined and their func- tional reliability determined. 8.2 Local Leak Detection Retests. Localized pressure tests, such as those described in 4.4, should be made whenever annual inspection tests or other circumstances show deterioration or otherwise indicate the desirability of such retests. Localized pressure tests shall be made whenever repairs or new construction are involved. A record of lo_cal leak tests results should be main- tained for reference. Appendix A. Local Leak Testing Procedures. (This material is informative only and is not a part of the Standard for Leakage Rate Testing of Containment Structures for Nuclear Reactors.) AI. Applicability of Local Leak Tests. Lo- cal leak tests may be selected for the qualitative ° 12 inspection of specific materials or components where methods other than air pressurizing are not objectionable and provide a more searching and convenient method. Such tests are particularly applicable to parts of or accessories to the con- tainment structure. A2. Water Submersion Test. The water sub- mersion test consists of covering an area which may contain a leak with clean water on the low pressure side of a differential pressure. The water should be such as to provide full submerg- ence with convenient observation of bubble forma- tion. Repeated bubble formation occurring within 5 min after a previous bubble has been wiped away will indicatea leak. A3. Vacuum Test. The vacuum test employs a vacuum box which can be placed over an area to be tested and evacuated to at least a 5-psi pres- sure differentialwith the atmospheric pressure where the edge seals provide a tightseating clo- sure. Air leakage through the area tested may be revealed by changes in a manometer level after the absence of seating leakage is determined by soap-suds indicators. Ifa soap solution isapplied to the test area before covering with the vacuum box, leaks may be revealed by bubble formation visible through a glass-covered opening in the box within a 5-min examination period. A suitable soap solution for air leak indication is one consisting of equal parts of corn syrup, liquiddetergent, and glycerin. The solutionshould not be prepared more than 24 hr preceding the test and bubble formation properties should be checked with a sample leak every halfhour during the test. A4. Air-Ammonia Test. The air-ammonia test is an air-pressurizing method employing an- hydrous ammonia as an indicator. Where leaks are present, the leakage permeation of ammonia is revealed by a white chemical fog on probing the atmosphere with a swab wetted with 0.1 N hydro- chloric acid. Sulphur dioxide, such as frown a sul- phur candle, can also be used as the revealing reactant. Other methods employing ammonia use 1.0% phenolphthalein in a solutionofequal amounts ofwater and ethyl alcohol. A cloth dampened with the phenolphthalein solution and placed over the test area shows the location of leaks by a pink discoloration. The ammonia indicator can be in- troduced as an anhydrous gas or by placing a cloth saturated with ammonia solution within the pres- surized space. _-/ PROPOSED STANDARD A5. Halogen Sniffer Test. The halogen sn, _ fer test employs a halogen compound leak ind, tot, such as freon gas, in the pressurized air/_ About 0.3 ounces per cubic foot of air is common- lyused. Leakage is revealed by traversing the test area with a detector that senses the effectsofthe halogen compound on ion emission from a heated metal surface. Locating the leak is best accom- plished by holding the snifferat about I/2 in.from the surface to be examined and traversing this at a rate of 1/2 in./sec. A leak is indicated by a milliammeter pointer movement or audible signal. Detection is also made by flame coloration from halogen indicator additions to the contained air. It should be realized that halogen detectors are sen- sitive to cigarette smoke or vapor from dry cleaning fluidsin recently cleaned clothing. Also, ifhalogen compounds are used with stress-corro- sion sensitive materials, chloride attack ispossi- ble unless thorough-cleaning follows this test. Appendix B. Derivation of Formulas for Containment Structure Leakage Rates. (This material is informative only and is not a part of the Standard for Leakage Rate Testing of Containment Structures for Nuclear Reactors.) BI. PI P2 Tl T2 W t = V = R = H I ? ,rT ,P ,V Definition of Symbols. = absolute pressttre of containment structure air at the start of the leakage rate test, = absolute pressure of containment structure air at the end of the leakage rate test, = mean absolute temperature at the start of the leakage rate test, OF + 459.7° or °C + 273 °, mean absolute temperature at completion of test, original weight of contained air at the start of the test, final weight of contained air at the end of the test, internal volume of containment structure/ assumed to remain constant, gas constan_ for a perfect gas, applicable to air for the testconditions employed, time length of test,in hours, = reference vessel conditions. /

Quantitative leak test design guide

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Quantitative leak test design guide

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