New Methods for the Validation of Liquid Flow Measuring Systems

摘要

Maximum-accuracy metering of media flowing into pipes requires standard measurement calibration rigs in which the volume flowing is metered, usually by means of gravimetric or volumetric systems. The author explains the calibration of flow meters and the various operating and test modes of gravimetric systems, in order to then introduce new methods of validating standard flow measurement systems. The measurement of liquids in closed conduits with high measurement accuracy requires liquid flow standards, if the measurement of the flowing liquid is done with a volumetric reference or a gravimetric weighing system. The quantitative value of the measurement accuracy is usually expressed by a measurement uncertainty, which includes the influences of the system on the measurement process and the influences of the meter under test . The influence of the reference measuring system should be smaller than 1/5 of the total measurement uncertainty of the measurement. To achieve this for measuring systems with the highest requirements on the measurement uncertainty a very detailed and complete analysis of the measurement process and each influence has to be done. For liquid flow reference standards this is usually done by National-Metrology Institutes for example the Physikalisch-Technis-che Bundesanstalt in Germany. In addition, each influence has to be checked carefully for the estimation of the measurement uncertainty.