TW Series Trailing Wire Flow Switch


  • Unique Trailing Wire Flow Sensor 
  • 0 to 500V AC 15 Amp S.P.D.T Switch Standard (‘H’ models)
  • Low Voltage option available (‘RL” models)
  • 1” BSP or NPT models available 
  • Option of 316 Stainless or Polypropylene Connection
  • Easily Serviceable 
  • 400 Bar 5800psi Rated Models Available 
  • Built In Manual Override (TW-H models only)
  • Seal-less Magnetic Drive 
  • Adjustable Sensitivity 
  • IP67 Weatherproof


The TW Series flow switches are available with various lengths of the flexible stainless steel wire from 50mm to 300mm (2” to 12”). The required wire length must be specified when ordering. The flexible stainless wire sensor offers major advantages over conventional paddles in applications where solids or semi solids are present, such as in sewage pumping. They are also suitable for use in slurry and mining applications and in many normal pumping situations where the flow velocity is high and conventional paddle type switches are unsuitable.

The flow rate required to actuate the TW flow switch will depend on many variables such as turbulence, liquid viscosity and the exact surface area of sensor wire exposed to the flow.

The TW-H models are the standard models in the TW Series. The TW-RL models are the low voltage options specifically designed for use in Ex applications and with low wetting currents.

See the data sheet linked below for more information on the available models in the TW Series and the ordering codes.

More Information

Wire Trimming Calculator

As with our Paddle Flow Switches,  the Trailing Wires for our TW Series can be cut down in length to suit your pipework if needed. Please refer to our Paddle Trimming Calculator to find the correct wire length for your application. The width of the wires is 2mm.

Please note that if you do cut down the length of your trailing wire, you must either silver solder or tig weld the end of the wire to prevent fraying.


For assistance in choosing the correct product for your needs, check out our Product Selection Guide. 

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