Honeywell Pressure Switches are durable, reliable electromechanical gauge pressure on/off switches that are available with either single pole single throw (SPST) normally open or normally closed circuitry, or single pole double throw (SPDT) circuitry. Their IP67 environmental sealing and high proof pressure and burst pressure ratings allow for use in many rugged applications that require the making or breaking of an electrical connection in response to a pressure change of the system media.
The media (gas or liquid) pressure is applied via the port of the switch to a diaphragm or sealed piston. A pre-tensioned spring on the other side of the sealed piston or diaphragm controls the set-point pressure. If the force resulting from the pressure is greater than the tension on the spring, the electrical contacts within the switch will change state. If the contacts are normally open when no pressure is applied, they close on increasing pressure when the set point is reached. On decreasing pressure, the contacts will open again at a pressure somewhat less than the set switching point. The difference between the activation point on increasing pressure and the deactivation point on decreasing pressure is called hysteresis. The set point pressure for the switch can be configured such that the switch will actuate on increasing or decreasing system pressure.