A Theoretical Based Valve Noise Prediction Method for Compressible Fluids,"

Introduction The noise generated by control valves and regulators in chemical, petrochemical, and steam power plants has received much attention over the last 10 years because of the potential health and communication hazards to workers inside the plants and the objectionable noise levels which are radiated into surrounding communities. Typical noise levels inside large stream power plants can range up to 120 dBA in the vicinity of the large piping arrangements. Such levels are in excess of the OSHA limits for typical exposures of workers. The valve industry has responded to this problem by, on the one hand, developing valve noise prediction methods to aid the plant designers, and on the other hand, developing quieter valves which are based on concepts of multiple series and parallel expansion or tortuous path approaches. However, such quiet valves are far more complex than conventional valves, such as globe, butterfly, and simple trim configurations, and may cost as much as 10 times more and, in several instances, result in reduced reliability. Most attention has been given to the aerodynamically generated noise situations, since the dominant noise generation process in the hydrodynamic case is cavitation. Cavitation almost always is accompanied by serious physical damage to the metering elements in the valve, due to cavitation erosion. Properly designed and used valves with liquids avoid cavitation conditions. This paper, therefore, deals only with aerodynamically generated noise. A discussion of the background to valve noise prediction, with an extensive bibliography, is given in references fl] an