Model AFS-228 Air Pressure Sensing Switch is a general purpose proving switch de- signed for HVAC and Energy Management applications. It may 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 connections located on each side of the diaphragm accept 1⁄4″ OD metallic tubing via the integral compression ferrule and nut.