Method and apparatus for in situ calibration of gas flowmeters

Abstract

The focus of this paper is to introduce a novel method for calibrating natural gas flowmeters. This new method can accommodate very large flow rates and it avoids common problems associated with current techniques for meter proving. In this method, the amount of gas accumulated in a vessel of fixed volume is determined by measuring the change in capacitance of the vessel with respect to time. Because the accumulator has a fixed volume the problems inherent with the mechanical motions involved in volumetric provers such as bell provers, piston provers and ball provers are eliminated. Accurate measurements can also be made in larger vessels than would be feasible for gravimetric provers, especially for in situ calibrations. Along with avoiding the fundamental problems associated with current provers, initial studies indicate that accuracies of ±0.1% are possible, even for flow rates in large pipelines.