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Magnetrol Thermatel TD1/TD2 Thermal Dispersion Switch

ABLE Instruments are the authorised representative for Magnetrol in the UK, including the Thermatel Model TD1/TD2 switch, which is employed in flow, level and interface applications. The TD1/TD2 is perfect for pump protection, specifically low flow detection with its unique spherical tip design, preventing pumps from running dry. Continuous diagnostics with fault indication, temperature compensation and fast response time make the TD1/TD2 the latest in thermal dispersion technology.

The thermal switches are based on convective heat transfer. One sensor is at the process temperature and the other is being heated by a constant power. As the flow rate increases, the temperature difference between the sensors decreases. A set point is established so when that specific temperature difference is reached the relay changes state. This can be on either increasing or decreasing flow or flow/no flow. When used in a level or interface application it is primarily the thermal conductivity of the fluid that will provide the difference in heat transfer.

Have a particular application / project in mind? We’d welcome a call on +44 (0) 1189 169 420, or email us now at [email protected]


  • Temperature compensated to provide repeatable alarm under varying process temperatures
  • Continuous diagnostics detect sensor fault
  • Non-linear mA output signal can be used for trending, diagnostics and repeatable flow/level indication
  • Detects minimum flow or presence / absence of flow
  • Excellent low flow sensitivity
  • Simple calibration / installation
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Price: POA Contact 247ABLE