An Uncertainty Analysis for a Positive Displacement Liquid Flow Calibrator Using the Water Draw Technique

by Wesley B. England

This paper is an uncertainty analysis performed by the Liquid Flow Lab of the Army Primary Standards Laboratory (APSL) for the calibration of positive displacement piston prover using a volumetric water draw. The water draw calibration is conducted to establish a precise relationship between translator pulses and the volume of liquid displaced by the draw and is known as the K-Factor (given in pulses/unit volume). For the APSL the term “Water Draw” is a misnomer, because the APSL uses hydrocarbons that are already in the flow calibrator at the time of the draw calibration.