These differential pressure switches are used to remotely sense over pressure, vacuum, and differentials of pressure. Typical applications include sensing fan or blower operation in ducted ventilation systems, sensing pressure drop across filters, and sensing frost build-up on coils. The SPDT switch allows remote status/alarm indication or operation of electrical circuits to other control devices. The models have three different pressure ranges to meet nearly any need. Sensor probes, tubing, and screw terminal adapters are included. The housing contains a diaphragm, a snap-acting SPDT switch, range adjustment knob with inches water column and Pascals increments. The sample connections located on the side accept 6.35 mm (0.25 inches) OD tubing An enclosure cover guards against accidental contact with the live switch terminal screws and the setpoint adjusting dial Three optional pressure ranges Includes mounting screws, terminal screw connection adapters, two sensor probes, and PVC tubing