The development of tracer gas methods for measuring air changes. Utveckling av spargasmetoden for matning av luftvaxling.

Notes principle of air change rate measurement using natural growth exponential equation to measure concentration of tracer gas. Experience shows that period required for satisfactory measurement is often periodicity of air change rate. Diagram relates linear and logarithmic scales used in air change equation. Describes use of pre-programmed gas analysis equipment allowing extrapolation to forecast results. Uses microprocessor for evaluation. Also discusses importance of instrument calibration. Block diagram and graph illustrate measurement time required as function of air change rate forecast.