A device that measures flow by sensing the movement of vortices in a pipe or conduit. The instrument usually is constructed with a partial barrier (vortex shedder) inserted perpendicular to the flow to allow formation of vortices, and sensor(s) to detect the passing vortices. The vortices are shed from one side of the shedder and then the other side as the fluid flows around the shedder. The sensor counts the number of vortices generated per unit of time and the velocity of the fluid can then be calculated.