Model FS-751 Air Pressure Sensing Switch is an airflow proving switch designed for duct heater, oven, and other HVAC or Energy Management applications that require a nonadjustable switch with a conduit enclosure for protection against accidental contact with the switch terminals. Model FS-751 is especially suitable for surface-mounting in areas where internal access is limited. This switch can be used to sense positive, negative, or differential air pressure.

The plated housing contains a diaphragm and a snap-acting SPDT switch. The convenient sample line connections located on each side of the diaphragm accept 1⁄4″ OD metallic tubing via the integral compression ferrule and nut.

The electrical connection consists of screw-type terminals with cup washers. The SPDT snap action switch operates on pressure rise of 0.05 ± 0.02″ w.c.