Advantages of Thermal Dispersion Switches for Pump Protection

Thermal dispersion switches use similar measurement principles to thermal mass flow meters. Fluid carries heat away from the probe tip reducing the temperature difference between a heated resistance temperature detector (RTD) and a reference RTD. As the temperature difference increases or decreases due to heat transfer, the set point is reached and the relay de-energizes. Manufacturers will refer to the switch being in “alarm” at set point. How the relay is wired (NC-CO or NO-CO) depends on the needs of the application.