SFX Paddle Flow Switch

Proper equipment operation that require fluid flows can benefit from flow switches that will work to provide positive flow/no-flow indication.  Flow switches include paddle type and thermal dispersion technologies.

There are many applications where knowing whether there is flow or no-flow conditions of a fluid in a pipe is important.  A thermal flow switch is an option to consider to provide such positive indication of flow or no-flow conditions.  Detecting flow conditions also can be accomplished using a electromechanical paddle type flow switch.  However, a thermal flow switch operates without any moving parts and therefore is more reliable.


Application and use of the thermal flow switch can be found in water power plants, steel production, marine use, food processing, pharmaceutical manufacturing, semiconductor manufacturing and many industries where flow sensing in pipes is required.

Higher sensitivity, less installation limits and no wear and tear of moving parts compared to paddle type
flow switches.
• Choice of wetted materials for a wide range of
• Can be set for use with a wide range of liquids
having different densities and amount of impurities.
• Extended probe lengths up to 7.9” (200mm).
• Local LED indication
• Adjustable sensitivity and alarm setpoint.
• Solidstate NPN/PNP or Relay outputs available.
• Explosionproof version available.

A thermal flow switch, also known as a thermal dispersion flow switch,  is a precise flow sensing device.  The principle sensing method is that of heat diffusion.  According to Wikipedia, "The operation of thermal dispersion flow sensing is attributed to L.V. King who, in 1914, published his famous King's Law revealing how a heated wire immersed in a fluid flow measures the mass velocity at a point in the flow. King called his instrument a "hot-wire anemometer". However, it was not until the 1960s and 1970s that industrial-grade thermal dispersion devices finally emerged."