New metrological capabilities for measurements of dynamic liquid flows

The capability to calibrate flow and volume devices dynamically has gained increasing interest over the years. Within the scope of the EMPIR project 17IND13 'Metrology for real-world domestic water metering', several test rigs were developed with which dynamic flow profiles can be generated and measured that reflect characteristics of real-world drinking water consumption. The dynamic component of the test rigs is realized based on different technologies such as valves, cavitation nozzles or piston provers. For validation purposes, an intercomparison of the test rigs was carried out in the scope of an EURAMET pilot study no. 1506. Between September 2020 and February 2021, a transfer standard specially developed for the intercomparison was calibrated at eight laboratories. The measurement error was determined for three dynamic flow profiles representative of drinking water consumption in Europe. In addition to determining the measurement errors and the degree of equivalence, five additional key parameters were derived to characterize the test rig properties: (1) repeatability of the profile measurements, (2) mean value of the residuals, (3) deviation between measured total mass and total mass resulting from the given profile and (4) duration of the flow change for an increasing change (5) and duration of the flow change for a decreasing change. These key parameters comprehensively describe the quality with which the dynamic flow profiles were generated and measured on the test rigs and can be used for evaluations in future intercomparisons of this kind. A main outcome of the intercomparison is that there is no technology to be preferred in terms of technical implementation. All test rigs agree well with each other, taking into account their expanded measurement uncertainties.