A Differential Pressure Switch (DPS) is an electro-mechanical device which is used for sensing a difference in pressure between two points, cut-in and cut-out pressure. The cut-in is the pressure of the system when the pressure switch closes. The cut-out is the pressure of the system when the pressure switch opens. The range of a control is the operating range of the
system-for example: the overall pressure over which the switch can operate.
When connected to two pressure sources, the differential pressure switch can be used as an alarm to make or break a circuit as the pressure rises or falls beyond the preset value. The internal diaphragm within the differential pressure switch deflects under pressure to make the contact; this could be either a SPST or SPDT contact. The set point can be factory preset or field adjustable.