DE-2553 -- An Automated Air Infiltration Measuring System Using SF Tracer Gas in Constant Concentration and Decay Methods PDF

One method of measuring rate of air infiltration in buildings involves t'he use of small amounts of a tracer gas. The concentration of the gas, which is measured at regular intervals, provides the basis for evaluating the infiltration rate. In the following paper, two bases for such evaluations are discussed -. the decay method and the constant concentration method. A system is described which automatically operates a portable electron capture detector/chromatograph and measures parts per billion concentrations of sulphur hexafluoride (SF6) in air. It samples air on a 1-min. cycle. In the decay method, the slope of concentration vs time on a semilogarithmic plot can be used to compute the infiltration rate. In the second method, the system injects SF6 at the rate required to maintain the tracer gas at a fixed, predetermined level. The infiltration rate is proportional to the rate at which the tracer gas must be injected.