No additional correction or adjustment was required, and the weighted mean error (WME) was only -0.13% during the scheduled calibration of an ultrasonic flow meter Vympel-500 after two years of operation.

An 8-beam ultrasonic flowmeter Vympel-500 DN300 passed scheduled calibration on a QBig high-pressure facility in Germany after two years of operation at a Gazprom Transgaz Belarus facility. This was the first experience of evaluating the long-term measurement stability of Vympel-500 flow meters during primary and secondary calibrations at a German facility. No additional adjustment was required and the weighted mean error was only -0.13%! It is noteworthy that the primary calibration was carried out at another facility in Germany: Pigsar. This confirms the high traceability of a consumption unit of German metrological calibration benches with an uncertainty of 0.17%. In addition, the tests prove the possibility of using an 8-channel Vympel-500 flowmeter as an inter-comparison standard.