Alternate vortices rotating in opposite directions are generated behind a bluff body immersed in a flow. The vortices detach from the edges of the bluff body and form a Kármán vortex street in the fluid stream. The distance between the single vortices is constant. The frequency of the vortices flowing past a sensor depends on the flow rate and is proportional to the flow. The sensor detects these vortices which are then converted to an electrical frequency signal.     
Some of the advantages of this measuring principle:

• Almost free pipe cross section > low pressure drop  
• Wide range of applications in terms of pressure, temperature and density
• Independent of the conductivity of the medium
• High long-term stability / no zero drift

Our Vortex VVX series flow sensors offer the following compelling features:

• Solid state flow sensor with no moving parts for liquids → no mechanical wear
• Rugged glass fibre reinforced plastic ensures highest strength and performance
• Completely encapsulated piezoceramic sensor to detect the vortices → thus no direct contact with the medium
• Wide measuring span (1:20)
• Temperature sensor integrated
• Output signals: an analogue voltage signal and / or pulse signal is available for the flow, and a resistance or analogue signal is available for the temperature.
• High interference resistance
• Wetted parts metal-free

Highlights

• Increased efficiency of the heat pump by controlling even at low flow rates
• The low pressure drop of the sensor can help to reduce the power consumption of the pump
• The compact design allows the use even if only little space is available