U.S. National Standards for High Pressure Natural Gas Flow Measurement

摘要

NIST plans to establish a calibration service for flow meters used in the custody transfer of high pressure natural gas. These calibrations will provide internationally recognized flow traceability for the U.S. natural gas industry over a flow range from 0.25 m~(3)/s (3.2 X 10~(4) acfh) to 9 m~(3)/s (1.1 X 10~(6) acfh) at a nominal pressure of 7500 kPa and at ambient temperatures. Flow meter calibrations will be performed at CEESI's Iowa facility under NIST's metrological control, using working standards that are traceable to NIST's primary flow standards. The measurement uncertainty of these calibrations range from 0.25percent to 0.27percent (with a 95percent confidence level) depending on flow rate. This manuscript documents the five-stage scale-up process used to establish traceability between NIST's low-pressure, air-flow primary standard to flowmeters calibrated at CEESI's Iowa facility in natural gas at up to 54 times the volumetric flow and 10 times the pressure.