United States Environmental Protection Agency Air and Energy Engineering Research Laboratory Research Triangle Park, NC 27711 Research and Development EPA/600/SR-95/013 February 1995 EPA Project Summary Air Infiltration Measurements Using Tracer Gases: A Literature Review MaxM. Samfield The report gives results of a litera- ture review of air infiltration measure- ments using tracer gases, including sulfur hexafluoride, hydrogen, carbon monoxide, carbon dioxide, nitrous ox- ide, and radioactive argon and kryp- ton. Sulfur hexafluoride is the commonest tracer gas, primarily be- cause its presence may be accurately measured in the parts per billion range, while most of the other gases used may be accurately measured in the parts per million range. The re- port describes a computer-controlled injection system. This Project Summary was developed by EPA's Air and Energy Engineering Research Laboratory, Research Triangle Park, NC, to announce key findings of the research project that is fully docu- mented in a separate report of the same title (see Project Report ordering infor- mation at back). The use of tracer gases for the mea- surement of air infiltration into structures and interzonal flows within a structure is not new. This technique has been investi- gated over the past 15 years. Numerous tracer gases have been used, among which are sulfur hexafluoride, hydrogen, carbon monoxide, carbon dioxide, nitrous oxide, and radioactive argon and krypton. Sulfur hexafluoride is the most common tracer gas of choice—primarily because its presence may be accurately measured in the parts per billion range using elec- tron capture/gas chromatography tech- niques. Most of the other gases used may be accurately measured in the parts per million range using infrared technology. There are generally three types of methods used: tracer gas decay, con- stant concentration, and constant injec- tion. Investigations comparing tracer gases have led to the following conclu- sions: (a) Even though sulfur hexafluo- ride is appreciably heavier than air, mixing is not a problem; and (b) The inherent uncontrollable variables present in tracer gas work limit the accuracy of determinations to +5-10%. There is thus no reason why one tracer gas should be selected over another provided other criteria are met. In the case of hydro- gen, diffusion of the gas through the surrounding walls can pose a problem. Tracer gases may be used in air flow measurements in large buildings where the building may be treated as several coupled zones. In such a case, the decay technique can still be used by having the system repeat the injection at regular in- tervals. A computer-controlled injection system is described in the full report. ------- Max M. Samfield, Durham, NC 27701, is an independent consultant. David C. Sanchez is the EPA Project Officer (see below). The complete report, entitled "Air Infiltration Measurements Using Tracer Gases: A Literature Review,"(Order No. PB95-173225; Cost: $17.50, subject to change) will be available only from National Technical Information Service 5285 Port Royal Road Springfield, VA22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 United States Environmental Protection Agency Center for Environmental Research Information Cincinnati, OH 45268 Official Business Penalty for Private Use $300 BULK RATE POSTAGE & FEES PAID EPA PERMIT No. G-35 EPA/600/SR-95/013 ------- |