A coriolis effect mass flow meter was tested under conditions of single-and two-phase refrigerant (R-22) flow to determine the effect of refrigerant quality on the accuracy of the meter. The meter was found to perform well for single-phase flow measurement, but measuring accuracy decreased drastically with the addition of a second phase. For the particular meter and flow rate tested, refrigerant vapor mass fractions from 1 to 72% produced a zero flow indication. The ability of a turbine flowmeter to measure liquid refrigerant mass flow rate in conven­tional refrigerating cycle systems was also examined.