気体流量計の校正

抄録

For gaseous substances, mass flowrate is more essential than volumetric flowrate because the measurement of density at a point is very difficult. Strictly speaking, flowrate of a gas is not known until its mass flowrate has been obtained.
The method of calibration of gas flowmeters at present is to utilize the critical flow in a flow nozzle, the so-called sound-velosity nozzle. However, this method of calibration meets with considerable difficulties.
In addition to the sound-velosity nozzle method, there exists a method of calibration using a movable-tube flowmeters. Absolute measurements of the flowrate of a gas can be accomplished with a movable-tube flowmeter and therefore it enable us to calibrate other gas flowmeters. However, this method also involves some difficulties.
The objective of this paper is to discuss and compare the above two methods of calibr-ation, from the standpoint of calibration of gas flowmeters. It is concluded that the movable-tube flowmeter is more reliable than that of the sound-velosity nozzle.