In a refrigeration system that uses a refrigerant liquid pump to force a liquid supply cycle to the evaporator, if the pump does not go up late, it will cause cavitation damage to the refrigerant liquid pump and burn the motor. The pressure difference controller is used to detect the difference of the fluid pressure before and after the pump. If the pressure difference does not reach the normal value for 8~15s, the pump is stopped.
Cooling water pumps and cold water pumps are also used in the cooling water system and the cold water system outside the refrigeration system. These pumps will encounter the same problem in operation and also use the differential pressure controller to perform the same protective control.