LAUSR

Abstract A new mass-time primary standard for high pressure natural gas, which is based on electromagnetic balance and hydraulic fast-acting valves, was set up at the beginning of 2017 in Chengdu, China. The full load of the electromagnetic balance is 3 tons and the measurement uncertainty of mass is better than 1.0g(k = 2). The opening and closing time of the hydraulic fast-acting valves can achieve 33 ms±3 ms.The operation pressure and flowrate range of the facility is (4–60)bar.a and (5–410)m3/h respectively. In accordance with the preliminary tests, the estimate uncertainty of sonic nozzles calibration is between 0.10% and 0.12%(k = 2). The operation principle, testing results and the uncertainty evaluation are presented in the paper as well as some improving ideas.