Abstract

The use of either a variable voltage transformer (Variac) for regulating the fan speed or resistances has been widely accepted for varying the air flow through a high-volume sampler during calibration. Calibration data for the Staplex high-volume sampler demonstrate that significant differences exist between the calibration results obtained by the two metheds. Calibration curves obtained with a bellows-type dry gas meter and a rotating vane anemometer clearly illustrate that resistances should be used as the standard procedure for varying the flow rate during calibration of the Staplex high-volume sampler. A simplified calibration procedure utilizing a rotating vane anemometer at the sampler inlet is described.