An automated air infiltration measuring system using SF6 tracer gas in constant concentration and decay methods

Describes a system which measures the rate of air infiltration in buildings using sulphur hexafluoride as a tracer gas. Discusses two methods for evaluating the infiltration rate,the decay method and the constant concentration method. The system automatically operates a portable electron capture detector /chromatograph and samples air on a one-minute cycle. In the decay method the slope of concentration vs time on a semilogarithmic plot can be used to compute infiltration rate. In the second method the infiltration rate is proportional to the rate at which tracer gas must be injected to maintain a constant concentration.