Describes a system which automatically operates a small gas chromatograph and measures parts per billion concentrations of sulphur hexafluoride in air. It samples air on a 10-minute cycle and records the response on a strip chart recorder. When SF6 in distributed in the air of a building, data is obtained from which air infiltration rates may be determined.
Reports experiments using sulphur hexafluoride as a tracer gas to obtain quantitative data on actual residence time distributions in rooms and hallways and contamination caused by reentry of laboratory fume hood exhausts into a building. Defines a factor k which gives a measure of the mixing of fresh withstale air in part of a room. Measured values of k varied from 0.3 to 0.7 insmall rooms without fans. Discusses two experiments to find the amount of exhaust fumes reentering the ventilation system of a building.
Reports measurements of air change rates carried out in the living rooms of 39 flats built during the last 20 years using Freon 12 as a tracer gas. Ventilation rates ranged from 0.3 to 2.9 changes per, hour, the average being 1.3 changes per hour. Air temperature, humidity and wind speed were recorded and the ventilation rates corrected for wind speed and temperature. Notes large ranges in ventilation rates for similar flats.
Suggests use of an electron capture detector for the routine estimation of the SF6 content of a mixture of gases without preliminary chromatographic separation. Gives chromatogram illustrating method.
Discusses the two methods for calculating air infiltration given in the ASHRAE handbook. These are the air change method, a gross estimate based on the number of windows and doors in each room, and the crack method based on measurements of flow through the cracks around windows and doors. Presents comparisons of tracer gas measurements with calculations by both air change and crack methods for test houses in California and Minnesota. Find agreement is adequate for sizing equipment but that the crack method underestimates infiltration at low wind velocity.
Reviews tracer gas methods for measuring ventilation rate and discusses the diffusion of gases. Describes four tracer gas methods; rate of decay, equilibrium concentration, transfer index and constant concentration. Discusses the analysis of results. Describes an experimental room and series of measurements of air change rate using two methods a) rate of decay, where a balloon filled with gas was burst as a point source and b) equilibrium concentration where tracer gas was released continuously at a constant rate.
Reports measurements of natural ventilation and leakage rates in two test rooms in a university building. Describes rooms and instrumentation. Gives results of pressurization tests with windows closed but not sealed, sealed, and weatherstripped. Gives results of measurements of ventilation rate using N2O as a tracer gas. Discusses the analysis of results and experimental errors. Compares measured rates with ventilation rates calculated using crackand ASHRAE methods.
Describes use of a radioactive tracer for measuring ventilation rates. Finds krypton 85 is the most suitable gas although xenon 133 and argon 41 have been used. Mentions various studies using radioactive tracers made in both France and England. Suggests commercial sources for krypton 85.
Reports air leakage measurements made in a mobile home using sulphur hexafluoride as a tracer gas. The home was located in an environmental chamber where it was possible to measure and control the temperature outside the home. The effect on infiltration rate of inside-outside temperature difference, simulated wind, installation of storm windows, opening of doors and operation of the furnace for was investigated. Also reports pressurization measurements which showed that the installation of storm windows had little effect on air leakage.
Describes air infiltration measurements made in three apartment houses in the Chicago area using SF6 as a tracer gas. Two were in tenement districts and one was suburban. Data were collected in selected apartments in each building, and these data were used to estimate the infiltration rate for the entire building.
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