FVX700S is based on Karman vortex effect to work. A columnar object that goes through the entire cross-section of the meter tube creates a vortex when a flow ispresent. The frequency of the vortex is proportional to flow. FVX700S is specially designed for food sanitation industry and widely used in gas, steam and liquid applications. No moving part; Integral display for instantaneous and tatal flow;4...20mA or pulse output.