A constant pressure low range flowmeter

In this pap re the design principle and selection rules of the parameters of the constant pressure low range flowmeter are intoduced.The ezperiment results are given.The measurement range is 3.49~1.97×10-5pa·L/:,and the uncertainty is less than 2.25%·The flowmeter has been used in the dynamic flow method system for calibration and the cryopump speed measurement。