Gas Oil Piston Prover,primary reference values for Gas-Volume

The paper describes the design, measurement results and uncertainty analyses of the hydraulic driven piston-prover system which has been in operation at VSL since 2008. The 12-meter long, 0.6 m bore piston-prover is used for the realization of Reference Values for Gas-Volume at pressures between 1 and 65 bar(a) at several gases. The principle is based on the displacement of a piston acting as a Gas–Oil separator. The standard has a flow-rate range from 5 to 230 m³/h. The system is designed to calibrate reference meters. The Calibration and Measurement Capability (CMC) of the system is proven to be smaller than 0.1% (k=2). The paper also explains the coherence between the Gas–Oil piston-prover and other traceability generators and ‘flow rate bootstrapper systems’.