A primary high-pressure air flow measurement standard in Taiwan

A high-pressure air-flow national measurement standard is constructed in Taiwan with a capacity of 8400 Nm{sup 3}/h and a projected measurement uncertainty of {plus_minus}0.2% in the pressure range of 1 {approximately} 84 bars. it is a blow-down type facility, and its main purpose is to serve as the primary standard of a larger-flowrate natural gas flow measurement facility to be built in the future by Chinese Petroleum Company (CPC). The system has a gyroscopic weighing platform suitable for high precision gravimetric measurements and several sonic nozzles with different throat diameters situated in a chamber to be the reference flow meters. A set of two turbine meters, 50mm and 100mm, are sued as the transfer standard. The facility has two test sections separated by the nozzle chamber and four different calibration modes could be arranged. To make calibration, the storage tank, the temperature control loop, and two sets of pressure regulating valve establish a pressurized air flow with stable temperature and pressure in the test section. The control of the air-flow diversion, connect-disconnect mechanism, sonic nozzle array is made through a hydraulic power unit operating at 200 bars. Real time measurements of temperature, pressure, flow signal, and time are collected throughmore » a Honeywell 9000-series PLC and a FIX DMAC data acquisition/control software. This paper describes the key components of the test facility and presents the preliminary results of performance assessment.« less