A practical method to assess the performance of gravimetric flow test rigs by using the timing error

This paper proposes an improved method to assess the performance of a gravimetric flow test rig. It addresses the study of two of the most important measurement systems: the weighing scale and all mass-related corrections, and the time measurement system. By performing a regular diverter test according to ISO 4185:1980 several times and under different conditions, it was possible to determine not only the statistical variances of the diverter system, but also the variances of the meter under test and of the flow test facility separately. The proposed method allows also under special conditions the determination of systematic errors in the mass determination. The method has been successfully applied at the large water flow calibration facilities of PTB in Braunschweig and Berlin and is recommended as a routine to test the performance of gravimetric flow test facilities.