An instrument used to measure the volumetric rate of flow of a fluid and is based on the principle that the velocity is directly proportional to the frequency at which vortices are shed from a body in a flow stream. One design relies on a body that lies in the direction of flow to generate vortices that are detected with the aid of a capacitive transducer, which consists of two electrodes separated from two welded diaphragms by a dielectric of fluid. When the fluid flows, vortices cause asymmetric movement of the diaphragms varying the capacitances generating a current output.