Accuracy of gas flowmeters determined by the bubble meter method

THe accuracy of 15 oxygen and nitrous oxide flowmeter units in daily use was investigated using the bubble meter method. At preset oxygen flow rates of less than 1 litre min-1 unacceptable errors were found. At flow settings greater than 1 litre min-1 the deviations varied within closer limits, but the actural flows were inaccurate irrespective of the presettings and of the gas delivered, and independent of the indicator being adjusted to be opposite or between the graduation marks on the flowmeter.