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Bilateral Comparison between NIST and PTB for Flows of High Pressure Natural Gas

Published

Author(s)

Aaron N. Johnson, B Mickan, H. Toebben, Tom Kegel

Abstract

In 2009 NIST developed a U.S. national flow standard to provide traceability for flow meters used for custody transfer of pipeline quality natural gas. NIST disseminates the SI unit of flow by calibrating a customer flow meter against a parallel array of turbine meter working standards, which in turn are traceable to a pressure-volume-temperature-time (PVTt) primary standard. The calibration flow range extends from 0.7 actual m3/s to 10.7 actual m3/s with an expanded uncertainty as low as 0.23 % at high flows, and increasing to almost 0.35 % at the lowest flows. Details regarding the traceability ladder and uncertainty analysis are documented in prior publications. The current manuscript verifies NIST’s calibration uncertainty via a bilateral comparison with the German national metrology institute PTB. The results of this bilateral comparison are linked to the 2006 key comparison results between three Euramet national metrology institutes (i.e., PTB, VSL, and LNE). The bilateral results demonstrate NIST’s natural gas flow measurements are within their specified uncertainty and are metrologically equivalent to the key comparison reference value established by the Euramet national metrology institutes.
Proceedings Title
2012 Measurement Science Conference
Volume
50
Issue
07004
Conference Dates
March 19-23, 2012
Conference Location
Anaheim, CA

Keywords

bilateral comparison, flow measurement, flow standards, high pressure natural gas, key comparison, traceability
Created April 6, 2012, Updated November 10, 2018