Research On Gas Flow Standard Facility By Parallel Master Meter Method

The gas flow standard facilities by master meter method are widely usedin the field of flow measurement because of its advantages of short constructionperiod, high efficiency, wide flow range and high accuracy. As the wide applicationof gas flow meter，the verification and calibration of the meters increase rapidly. Inorder to improve the verification efficiency of gas flowmeter, expand the calibrationflow scope and tackle the regional demand of flow instrument verification, a gasflow standard facility by parallel master meter method is designed. Four parallelRoots flowmeter as master meters are used to meet the large flow range. Anautomation control system is adopted in order to calibrate different kinds of gasflowmeters quickly.The principle of the gas flow standard facilities by master method is introducedin the paper as well as domestic and foreign research status. The overall design of thedevice including working principle, verification processes, mathematical models,hardware design and so on, is briefly described,. The flow regulation pattern whichcombines regulate valve and adjusting the fans frequency is analyzed, on the basis ofwhich, a fast, accurate, small overshoot and energy saving flow regulation pattern areput forward by using AMESim model and simulation and tested through experiments.The HMI based on LabVIEW and industrial automation control system based onPLC have been established to satisfy the requirements of verification, which canaccomplish various functions automatically such as the control of verificationprocess and valve switch, the data acquisition of temperature and pressure, the flowregulation, the data processing and the report generation. According to JJG663-2003Verification Regulation of Flow Standard Facilities by Master Meter Method andJJG1033-2008Rule for the Examination of Measurement Standard, the measurementperformance of the standard facility is tested through the experimental data, whichincludes the evaluation of uncertainty, the assessment of stability and repeatability,the comparison of verification results and so on.At present, the gas flow standard facility by master meter method is applied practically. The performance can reach the requirements of design. The system canprovide stable standard gas flow quickly and accurately with friendly HMI system,simple and efficient verification process. The expand uncertainty is0.31%(k=2), andthe flow stability is better than0.44%. It can automatic accomplish the verification ofspeed flowmeter such as turbine flowmeter, vortex flowmeter and gas volumetricflowmeter such as Roots flowmeter whose flow range is between0.5~2000m3/h,diameter between15~200mm.