[en] The results of measurements show that the Rice frequency is a good integral parameter characterizing the mechanical condition of rotating parts of circulating pumps. Another advantage worthwhile mentioning is that Rice frequency can be measured with a simple device with low capital cost. A portable Rice frequency meter was developed for the measurements, powered from the 220 V/50 Hz mains. Monitoring the Rice frequency with occasional on-line or off-line spectral analysis of mechanical vibrations can be recommended as a reliable diagnostic method. (Ha)