气体活塞式压力计基准量值传递自动化研究

Research on Automated Dissemination of Primary Standard for Pneumatic Piston Gauges

研制和改进了基于传感器辅助方法的活塞式压力计自动化校准系统,介绍了基于LabVIEW编制的校准软件的组成和功能。通过与传统方法的比对,实验研究了自动校准系统应用于气体活塞式压力计国家基准量值传递工作的可靠性。研究表明,传感器系数γ与1的偏差和相对压差β的乘积小于10^(-6)时,γ可作为1处理;测量上限为7MPa的反压型气体活塞,全量程和半量程的拟合数据表明活塞的压力形变具有一定的非线性,因此对于高压活塞应进行全量程校准;PG7607活塞底座发热导致0.33℃的活塞温度测量误差,由此产生3×10^(-6)的压力测量误差,对于压力基准是不可忽略的;180 kPa、360 kPa和3 MPa活塞的2种方法校准结果偏差分别约为标准不确定度的10%、1%和2%,验证了自动化校准系统的高可靠性。

Based on the transducer-aided crossfloat( TAC) method,an automated calibration system for piston gauges has been developed and improved. The components and function of the calibration software based on the LabVIEW are introduced. The reliability of applying the automated calibration system on the dissemination of primary standard for pneumatic piston gauges is studied by comparison test against the traditional crossfloat method( CF). The transducer coefficient( γ) could be treated as 1 if the deviation is so small that the product of the deviation and the relative pressure difference( β) is less than 10;. For the counter-pressure pneumatic piston gauges with the measurement upper limit of 7 MPa,the fitting data of the full-scale and half-scale indicate that the pressure deformation of the piston has a certain degree of nonlinearity,so full-scale calibration should be carried out for the high-pressure piston;The thermal effect of the PG7607 piston base causes a piston temperature measurement error of 0. 33 ℃,resulting in a pressure measurement error of 3 × 10^(-6),which is non-negligible for the primary standard;The calibration results for the 180 kPa,360 kPa and 3 MPa piston gauges determined by the automated system and the traditional method differ from each other are about 10%,1%and 2% of the standard uncertainty,which verify the high reliability of the automated calibration system.