PRE-001 METHOD _- DIRECT MEASUREMENT OF GAS VELOCITY AND VOLUMETRIC FLOWRATE UNDER CYCLONIC FLOW CONDITIONS (PROPELLER ANEMOMETER)

1.1 Applicability. This method applies to the measurement of gas velocities in locations where cyclonic flow conditions exist and gas temperatures range from O ° to 50°C (e.g., cooling tower exhausts). 1.2 Principle. A propeller anemometer is used to measure gas velocity directly. The area of the stack cross section at the sampling location is used to calculate volumetric flowrate, and temperature and pressure measurements are used to correct volumes to standard conditions. 2. Apparatus Specifications for the apparatus are given below. 2.1 Propeller Anemometer. A vane axial propeller anemometer capable of measuring gas velocities to within 2 percent. The manufacturer’s recommended range (all-angle) shall be sufficient for the expected minimum flow rates at the sampling conditions. Temperature, pressure, moisture, corrosive characteristics, and sampling locations are factors necessary to consider in choosing a suitable propeller anemometer. 2.2 Data Output Device. A digital voltmeter, analog voltmeter, stripchart recorder, data-logger, or computer capable of displaying a propeller anemometer output to within 1 percent and at a minimum frequency of one reading per minute