Model AFS–240 Air Pressure sensing switch is a general purpose proving switch designed for HVAC and Energy Management applications. It can be used to sense positive, negative, or differential air pressure.

The plated housing contains a diaphragm, a calibration spring and a snap-acting SPDT switch. The 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 top terminals with cup washers. An enclosure cover guards against accidental contact with the live switch ter- minal screws and the set point adjusting screw. The enclosure cover accepts a 1⁄2″ conduit connection.