Operating and calibration conditions of flow meters vary considerably and have been the subject of various investigations over the years. Based on the knowledge gained and the development of test capabilities that has taken place in the meantime, the investigation of operational influences on the measurement behaviour of the devices can be further advanced. These efforts are driven by stricter requirements on the part of the users of flow measurements, who use these measurements for process optimisation or to prove compliance with given limit values. In the EMPIR project 20IND13 “Safest” infrastructure has been developed enabling a dynamic characterization of flow meters linked to different kinds of flow meter applications. In addition, eventual effects on flow measurements due to changes in ambient and fluid temperatures or deviations between them were investigated. The results for different types of flow meters such as Coriolis and screw spindle meters are presented and discussed.