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Bilateral Comparison Confirms NIM’s and NIST’s Gas Flow Capabilities



Aaron N. Johnson, CHUNHUI LI


The bilateral comparison between NIM and NIST for gas flow was conducted from June 2008 to October 2009. Two critical flow venturis (CFVs) with nominal throat diameters of 10 mm and 20 mm, respectively, were selected as transfer standards. The CFVs were calibrated on NIM’s 20 m3 pVTt system and then on NIST’s 26 m3 pVTt system. The results confirm NIM’s and NIST’s gas flow measurement capabilities for flows ranging from 1000 liters per minute to 4000 liters per minute at reference conditions of 101.325 kPa and 293.15 K. The experimental data also showed good agreement with existing theoretical models (i.e., better than 0.07 %). The ISO 9300 empirical equation consistently underpredicted the experimental results, but was within the specified ± 0.3 % uncertainty tolerance.
Conference Dates
October 13-15, 2010
Conference Location
Conference Title
15th Flow Measurement Conference (FLOMEKO)


critical flow venturi (CFV), NIM and NIST bilateral flow comparison, pVTt facility, sonic nozzle


Johnson, A. and Li, C. (2010), Bilateral Comparison Confirms NIM’s and NIST’s Gas Flow Capabilities, 15th Flow Measurement Conference (FLOMEKO), TAIPEI, -1 (Accessed April 25, 2024)
Created October 15, 2010, Updated June 2, 2021