Improvements in the Implementation of Laminar and Sonic Based Gas Flow Meters in the Range of 2 X 10-5 G(centre dot)S-1 (1 Ncc Min-1) to 100 G(centre dot)S-1 (5000 Nl(centre dot)Min-1)

摘要

During the middle of the last decade, DH Instruments (now Fluke Calibration) developed an improved primary calibration chain based on dynamic gravimetric measurements and a successive addition technique to provide significantly lower uncertainty in gas flow from 2 X 10-5 g(centre dot)s-1 (1 Ncc min-1) to 100 g(centre dot)s-1 (5000 Nl(centre dot)min-1) [1]. Recently, in order to disseminate the lower uncertainties achieved to the flow measurement community, significant improvements were made to the laminar and sonic based flow meters supported by the gas flow references. The improvements include the use of NIST (USA) Refprop gas property data, a new Reynolds number and pressure characterization, lower uncertainties in absolute and differential pressure monitoring, and filtration designed directly into the meter. These improvements decreased the uncertainty of the population of these instruments and should also improve their reliability. This paper discusses these advances and the benefits to gas flow metrology.