Performance of electronic flow rate meters used for calibration of air sampling pumps.

Electronic flow rate meters (EFRMs) have been used by industrial hygienists for more than 20 years and are useful because they reduce the time required to calibrate air sampling pumps. This study compared the variability of the traditional bubble burette meter with electronic flow meters and simultaneously compared several EFRMs under different calibration conditions. The flow rates of air sampling pumps were set using a standard bubble burette meter at flow rates of 2 or 50 mL/min using two pressure drops, 2 inches water and 10 inches water. Four airflow rate meters (Bios DryCal, A.P. Buck mini-Buck, MSA Accuflow, and Sensidyne Gilibrator) were concurrently compared at each of the pump flow rate and pressure drop combinations. Results indicated that the standard bubble burette method is more variable than the EFRMs and that the flow rates given by the EFRMs were significantly different (p<0.0001) at both the high and low flow rates. Although the calibrators gave significantly different flow rates, the difference was within the acceptable air sampling pump error of +/- 5%.