Force-balance type differential pressure transmitter has liquid in its connecting pipes when it is used to measure a flow rate of liquid, a flow rate of corrosive gas with substituting liquid or a liquid level. Described in this paper is an analysis of self-excited oscillations of the same transmitter in such a condition. The method of judging the stability of a system consisting of the liquid and the differential pressure transmitter is given on an actual example. It is proved that the result of experiments is in good coincidence with that of judgment.
