An experimental intercomparison of gas meter calibrations

Abstract

This paper presents four calibrations carried out in four different, independent, metrological accredited laboratories, on six diaphragm gas meters for domestic use (G4). The aim of this study is to evaluate the degree of metrological agreement among different calibration results, by means of the assessment of suitable factors (compatibility index, also known as normalized error). This application study is quite interesting in the field of “legal metrology”, when often conformity assessment are requested in order to assure the adequate behavior of a domestic gas meter. The six gas meters were calibrated in four different laboratories, each of them characterized by different values of the calibration uncertainty (also called CMC=Calibration and Measurement Capability, or BMC=Best Measurement Capability, or Minimum Uncertainty). Two alternative approaches about the metrological compatibility are introduced: a quantitative approach and a qualitative approach. The calibration results show that for diaphragm gas meters for domestic use, the metrological agreement should be preferable by means of the qualitative approach.