The Model AFS-460–137 is a general purpose airflow proving switch designed for 24 V ac HVAC and Energy Management applications where a manual reset switch with DPDT contacts is desirable. It may be used to sense positive, negative, or differential air pressure. The plated housing contains a diaphragm, a calibration spring, a snap-acting switch with manual reset button and a DPDT relay. The AFS-460-137 has a field adjustable set point range of 0.40″ wc to 12.0″ wc. The screw terminals are protected by an enclosure that accepts a 1/2″ conduit connection. This switch has DPDT form-C contacts rated 8 amp @ 250 V ac. It is equipped with two compression ferrule and nut sample line connectors that accept ¼” OD rigid tubing.