In an electromagnetic flowmeter one of two electrodes mounted on a measuring pipe is impressed with an electrical pulse synchronous with the switching of an excitation currrent, thereby detecting the voltage drop across the electrical resistance of a fluid, such that both the conductivity and the flow...http://www.google.com/patents/US4969363?utm_source=gb-gplus-sharePatent US4969363 - Electromagnetic flowmeter capable of simultaneous measurement of flow rate and conductivity of fluid
