In addition to accuracy, the traceability of a given measuring device is of essential importance, in particular with respect to the general guarantee of uniformity and comparability of measurements. The practical realization of this traceability requires, as a crucial prerequisite, reliable and highly stable transfer devices. In gas flow measurement, the so-called critical nozzles have been widely established as such an efficient transfer standard during the last two decades. Comparable solutions for liquid flow measurement do not exist to this day. Looking at several analogies observed in experiments with venturi nozzles using gas or liquids as working fluids, PTB started more detailed investigations of cavitating nozzle flows. The intention was to clarify their applicability in liquid flow measurement comparable with the use of critical nozzles for gas metering.