Model AFS-145 Air Pressure Sensing Switch is a general purpose proving switch designed for package burner, furnace, fuel-burning equipment, HVAC and other Energy Management applications. It can be used to sense positive, negative, or differential air pressure. The AFS-145 has a field adjustable set point range of 0.05″ wc to 12.0″ wc. The screw terminals are protected by an enclosure that accepts 1/2″ conduit. This switch has an SPDT contact arrangement. The two ⅛”–27 NPT female sample line connectors located on either side of the diaphragm accept ⅛” pipe.