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.
Parking garages require ventilation because the exhaust fumes produced by the vehicles have to be discharged. This can be achieved with a mechanical or a natural ventilation system. A natural ventilation system has several important advantages compared with a mechanical system. As a rule natural ventilation systems arc simpler, cheaper and have fewer breakdowns, furthermore a natural system requires less maintenance and uses no energy (for air transfer).