The SOREL / Grundfos VFS sensor combines the established vortex principle (von Karman, 1912) with the unique metal-glass coating, Silicoat® from Grundfos an affordable, accurate and direct flow sensor for aggressive media is now available. The flow sensor is without any moving parts, which can deteriorate or commence clogging. The Vortex Street generates two series of turbulence (vortices) shedding behind a bluff body By increasing flow the frequency of the vortices will increase and the frequency increases directly proportional to the flow in a full pipe. The Vortex Flow Sensor consists of a sensor, Vortex Tube and element. The sensor detects the pressure pulsation generated by the vortices, and converts the pulsation into an electrical output signal. The frequency of the pressure pulsation is a measurement of the velocity and in the defined flow pipe the actual flow is measured.