tracer gas

The problem of describing quantitatively the effective ventilation in a room when the air within the room is imperfectly mixed is discussed. It is suggested that the protection afforded by the ventilation to any given position against air

This paper describes the experimental techniques devised to measure the necessary parameters on installed heating systems. With these data the seasonal performance of a heating system can be computed. The effectiveness of various operating and system modifications can then be predicted. Thecalculated effects of some modifications are presented in a companion paper.

Air infiltration rates are important in determining greenhouse heating requirements. Design recommendations usually suggest one to two complete air exchanges per hour under calm conditions. Tests made in 10 commercial ranges showed no greenhouse in excess of one exchange per hour, with one as low as 0.34 per hour, and an average of 0.56. However, additional tests at CSU showed marked variation, depending upon greenhouse size and heating methods, as well as type of structure and outside wind velocity.

A comprehensive computer program for the prediction of air flow and smoke migration in the building was applied to the 11 story administration building of the National Bureau of Standards. Natural air leakage rates under various climatic conditions for several ventilation system operations were obtained. The computed results were compared with measured air leakage rate by using the sulphur hexafluoride tracer gas technique. Smoke migration was simulated for the selected pressurization conditions.

The air change rate in a single story office building was measured using atracer gas technique. The air change rate was determined by the rate of decay method using sulfur hexafluoride as the tracer gas. A total of eight tests were conduc

The heating of air infiltrating through cracks around doors and windows forms an important part of the heat balance of buildings. The complexity of the problem makes it difficult to calculate. Describes the development of an insitu method for measuring the infiltration of buildings.

Describes validation of a simple technique for infiltration measurement in large, multicelled, naturally ventilated buildings by reference to a computer model study and by field measurements in two naturally ventilated office buildings. The salient features of the technique are: 1) a single tracer gasis used, 2) measurements need only be carried out in part of the building, 3) an initially uniform distribution of tracer is not needed, and 4) artificial mixing of the tracer with the internal air is not essential.

The multiple tracer gas technique of I'Anson et al. has been improved, in order to increase the rate at which samples can be taken. Using parallel gas chromatographic separation columns and an electron capture detector, it is now possible to take an air/tracer gas sample every thirty seconds in the case of a two-zone ventilation and air movement test. Rapid sampling enables a new,simplified analysis of the air movement between two connected zones to be employed. This analysis derives ventilation rates and intercell airflows simultaneously.

This paper reports on measurements of air change rate in dwellings during occupancy. The occupants were shown to exert a considerable influence on the total air change. The air change rate for occupied dwellings is, on average, 3-4 times greater than the air change rate in sealed dwellings (with air escape valves, doors, windows, and ventilation system closed). The measurements also reveal a tendency for higher air change rates in mechanically ventilated dwellings than in naturally ventilated dwellings.

Although infiltration of outside air across the envelope of a building has been considered of prime interest in relation to energy conservation and indoor air quality, it also important to understand the way in which air moves between zones within a building. A knowledge of the air movement pattern enables the transfer of pollutants or heat to be determined. In order to achieve this, a number of experimental methods have recently been developed, using either single or multiple tracer gases. (See, for instance, references 1,2,6,7,9) .