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This handbook describes the use of tracer-gas techniques for measurement of airflow in ducts. Initial measurements were carried out in the laboratory to examine the accuracy of these techniques. The mixing of tracer gases (eg, sulphur hexafluoride, SF6) in ducts of various shapes and sizes was examined using different types of tracer injector. Airflow estimated using tracer-gas techniques (eg, constant-injection, pulse-injection) was compared with measurements made with traditional instrumentation such as pitot-tubes and hot-wire anemometers. Work also involved the development of tracer gas equipment for balancing airflow in HV AC systems. This equipment was used to balance airflow in a small-scale HV AC system.
Research also involved the development of a perfluorocarbon (PFT) tracer gas sampling system. The PFT was injected using a thermostatically controlled injection unit and a fast-response sampling system, using stainless steel tubes packed with adsorbent, was employed to collect tracer gas samples. The samples were analysed in the laboratory using a thermal desorber and gas monitor. The PFT system was tested successfully in the laboratory. Airflow measurements were carried out in the HV AC system of an office building using tracer-gas techniques and the new PFT technique.
Tracer-gas techniques were used in other applications including measurement of airflow through a porous medium in a rectangular duct and determination of the air-tightness of ductwork.