AVS 47th International Symposium
    Vacuum Technology Wednesday Sessions
       Session VT-WeP

Paper VT-WeP1
Study of Uncertainty of a Constant Volume Flowmeter

Wednesday, October 4, 2000, 11:00 am, Room Exhibit Hall C & D

Session: Poster Session
Presenter: D. Tian, Lanzhou Institute of Physics, P.R. China
Authors: D. Tian, Lanzhou Institute of Physics, P.R. China
X. Wen, Lanzhou Institute of Physics, P.R. China
Correspondent: Click to Email
A constant volume flowmeter was built in Lanzhou Institute of Physics (LIP). It can calibrate mass flow meters. In order to find and reduce the systematic errors, its uncertainty is calculated and analyzed at first. The range of the flowmeter is 1.7x10@super-3@-85 Pam@super3@/s (1 sccm-50 slm) with uncertainty (1@sigma@) less than 1.2%. Then, a lot of experiments are accomplished by calibrating the mass flow meters. The measurement data of two mass flow meters prove that the flowmeter has good repeatability and long-term stability. Because the systematic errors are still under discussion, we have to prove our supposition by comparison study at last. The range of constant pressure flowmeter developed in our laboratory formerly is 1x10@super-3@-10@super-8@ Pam@super3@/s, with uncertainty less than 2%. For carrying out the comparison between these two flowmeters, an accurate mass flow meter whose range is 1-10 sccm is used as transfer standard. The mass flowmeter is calibrated by two flowmeters respectively. The result shows that the agreement of these two standards is better than 1.5%. The comparison is mainly dependent on the linearity and stability of spinning rotor gauge, and the uncertainty resulting from these two factors is about 0.5%. The short-term repeatability of the mass flow meter is also an error source of comparison, and the uncertainty resulting from this factor is approximately 0.2%. The big systemic error is not found in the tests and calibration reliability has been ensured through the above discussions.