TRACER GAS TECHNOLOGY FOR AIR-FLOW MEASUREMENTS IN HVAC SYSTEMS

This paper describes the use of tracer gas techniques for airflow meas urement in ducts. The author had carried out extensive work in both th e laboratory and the field to test the accuracy and viability of these techniques. Preliminary measurements were carried out in the laborato ry to examine the accuracy of these techniques. The mixing of tracer g as (e.g. sulphur hexafluoride, SF6) in ducts of various shapes and siz es was examined using different types of tracer injectors. Measurement s of airflow estimated using tracer gas techniques (e.g. constant-inje ction, pulse-injection) were compared with measurements made using tra ditional instrumentation such as pitot tubes. Field testing on a large -scale heating, ventilation and air-conditioning system was carried ou t and tracer gas techniques were used to determine airflow rates in ai r handling units serving a library building.