A method is described of measuring the bulk mass-flow rate in steady and pulsating air streams with the aid of a suitable tracer gas such as carbon dioxide. The method briefly involves controlled injection of the tracer into the main flow, mixing of the two flow media, and analysis of the mixture to determine the concentration of the tracer. The main flow is derived from the injection flow rate and from the concentration of the tracer in the sample mixture. An inexpensive infrared analyzer was constructed for determining mass concentrations of carbon dioxide in air ranging from 1/2 to 3 per cent. Results obtained by the gas-tracer method in both steady and pulsating streams were compared with those obtained by other methods of mass-flow measurement. A few possible practical applications of the measuring technique are discussed.
Theoretical and Practical Comparison of the Potassium Iodide Tracer Method (KI–Discus) for Assessing the Containment Efficiency of Fume Cupboards with the Gas Tracer Method Described in BS 7258: 1994: Part 4