The comparison of the gas flow standards at high pressure

Abstract

The first formal comparison of gas flow primary and working standards was conducted in China during 2016 ∼ 2020. There were 4 participants from China, and PTB was invited as the link lab to connect this comparison with the serial key comparisons of CCM.FF.K5. For the primary standards, there were 4 sets of sonic nozzles as the transfer meters, with which there were totally 105 set of measured results were conducted with the Reynolds range (4.8 × 104 ∼ 1.1 × 107). Based on the flow range of the existing working standards of participating laboratories, 3 turbine flow meters were used as transfer standards. Totally 298 sets of measured data were obtained with Reynolds number range of (6.3 × 104 ∼ 1.4 × 107). A nonlinear theoretical equation of discharge coefficient for sonic nozzle was presented with only one parameter, which was used to evaluate the discharge coefficient at the exact same Reynolds number of the measured points. The curve fitting based on the relationship between meter deviation and the Reynolds number for each turbine meter was obtained. The degree of equivalence of En was finally evaluated. For the primary standards, there were 96 of results with En ≤ 1.0, while there were 8 sets of results with 1 < En ≤ 1.2, and one set of result with En = 1.41. For the working standards, there were 282 sets of results with En ≤ 1, while there were 9 sets of results with 1 < En ≤ 1.2, and 7 sets of result with En > 1.2.