Differential Pressure Gauge with a switch is set to signal an alarm at a preset value of pressure differential.
Diaphragm type differential pressure instruments are used on heat exchangers to measure pressure differential in a transformer oil cooling system. The oil passing through the heat exchanger is kept at a higher pressure than the water that is used as a cooling medium to prevent water contamination of the oil in the case of a tube leak. The differential pressure gauge is used to monitor the pressure drop of the oil across the heat exchanger and the switch is set to signal an alarm if the differential pressure gets too high, signaling the possibility of a tube leak and water contamination of the oil.