Comparisons by PTB, NIST, and LNE-LADG in Air and Natural Gas With Critical Venturi Nozzles Agree Within 0.05 %

Published

May 16, 2006

Author(s)

B Mickan, Roland H. Kraemer, D Dopheide, Hans-Jurgen Hotze, Heino-Michael Hinze, Aaron Johnson, John D. Wright, J-P Vallet

Abstract

The PTB, NIST, and LNE-LADG conducted a comparison of gas flow measurement standards in air and natural gas in the pressure range from 0.9 to 42 bar. The artifacts used in the intercomparisons were four critical venturis with ISO standard toroidal shape. Flow calibrations made on the four nozzles at four facilities were used to produce discharge coefficient (Cd) versus Reynolds number (Re) curves at Re from 2 105 to 2 107. Three of the facilities used air and the fourth facility flowed natural gas. The calibration data clearly show the laminar to turbulent transition at throat Re between 1 106 and 2 106. All of the laboratories discharge coefficients agreed within 0.15 % or less, well within the uncertainty of the comparison. The geometry of the nozzles was measured by coordinate measuring machines at NIST and PTB. The throat diameter measurements from the two institutes agreed within 4 mm or better. The dimensional measurements were used to generate theoretical Cd curves, for both the laminar and turbulent regimes, for air and natural gas. The theoretical Cd curves agree with the experimental measurements within 0.15 % or less.The results suggest that it is feasible to calibrate critical nozzles in air, then use them as working standards in natural gas with uncertainty less than 0.2 %, if the gas composition and properties are know to sufficient accuracy.

Proceedings Title

Annual International Symposium on Fluid Flow Measurement | 16th | | CEESI

Conference Dates

May 16-18, 2006

Conference Location

Queretaro, 1, MX

Conference Title

International Symposium on Fluid Flow Measurement

Pub Type

Conferences

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Keywords

comparison, critical nozzles, discharge coefficient, natural gas

Citation

Mickan, B. , Kraemer, R. , Dopheide, D. , Hotze, H. , Hinze, H. , Johnson, A. , Wright, J. and Vallet, J. (2006), Comparisons by PTB, NIST, and LNE-LADG in Air and Natural Gas With Critical Venturi Nozzles Agree Within 0.05 %, Annual International Symposium on Fluid Flow Measurement | 16th | | CEESI, Queretaro, 1, MX, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=830965 (Accessed October 13, 2025)