Johnson Controls P74FA-5 SPDT Differential Pressure Switch 8-60 PSI 1/4" FNPT

The Johnson Controls P74FA-5 is a long-lasting SPDT differential pressure switch designed for use in HVAC applications. It measures the variation in pressure within two points of the system, for example, on either side of a filter or between the supply and return ducts. By turning an external wheel, you get a pressure range of between 8-60 PSI. The switch has a fixed differential pressure of 1.5 PSI as is incorporated in the switch. This means that the switch will open or close the electrical circuit only if the pressure difference between the two ports that the switch is monitoring above your setpoint. Prevents filter blockage by turning off the system when a high-pressure difference across the filter means restricted airflow.