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Title: Realistic Pipe Prover Volume Uncertainty
Author: Paul Martin
Source: 2009 North Sea Flow Measurement Workshop
Year Published: 2009
Abstract: Traceability for liquid turbine metering systems is generally achieved via a calibrated pipe prover volume used to verify the meter K-factor in situ. This paper demonstrates how incompatibility between an arbitrary tolerance set for the calibration of a pipe prover and the achievable uncertainty in measurement when determining the prover volume can lead to practices which may result in measurement bias. This paper presents a robust method of estimating the pipe prover volume uncertainty determined using the master meter/master pipe prover calibration method. The individual uncertainty components used in the estimate, and the method of combining them, are included along with a comparison of the gravimetric and volumetric calibration methods for determining the compact prover volume. The traceability chain relating to the calibration of the pipe prover and the importance of accreditation for measurements are also discussed. The paper concludes by examining the tolerances in place in the North Sea and how the practices which have evolved to meet the tolerances may compromise good metrology and lead to measurement bias.