The model AFS-304 is a general purpose proving switch with gold contacts designed for HVAC, Energy Management and DDC (Direct Digital Control) applications. Gold- contact switches are used in computer environments, direct digital control, or wherever low ampere currents are wired. AFS-304 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 with gold contacts. The sample connections located on each side of the diaphragm accept 1⁄4″ OD metallic tubing via the integral compression nut and ferrule.