The Model DDP-109 is a general purpose proving switch designed for HvAC and Energy Management applications. the DDP-109 provides dual switching action: two separately-operated, independently-adjustable SPDT snap-acting switches are mounted on a common foot bracket.

Differential pressures up to 2 inches w.c. can be measured. Because the two snap switches are set independently, an adjustable “deadband” can be established for control circuits requiring both high and low actuation points. Many control and alarm functions are possible: for instance, monitor two pressure sources and sense the differential for actuation at two independent set points.

Each of the two plated housings contains a diaphragm, a calibration spring and a snap-acting SPDT switch. there are two low pressure sample connections (one for each switch assembly), and a common high pressure sample connection (located on the foot bracket between the two low pressure connections). All three sample connections accept 1⁄4” OD metallic tubing via integral compression ferrule and nut fittings.

An enclosure cover is provided for each switch assembly to guard against accidental contact with the live switch terminal screws and the set point adjusting screws. the enclosure covers accept a 1⁄2” conduit connection.