The pressure switch is an instrument that opens or closes an electrical circuit, depending on the change of a preset pressure value, in a pneumatic circuit. It is also known as a pressure switch.
In general, pressure switches are mechanical instruments. Its adjustment is made by means of a screw or a small cam, which increases the pressure it exerts on a central spring and this in turn, on the contact or contacts. When the system pressure exceeds that of the spring, the contacts vary in position and conversely, when the system pressure is low and that of the spring is higher, the contacts vary again. With this maneuver, the contacts open or close and allow the central control of the compressor or the corresponding compressed air equipment to carry out the maneuver for which it was designed.
A typical application for pressure switches is starting and stopping small piston compressors. For large compressors and rotary compressors, the pressure switches open or close the contacts so that the central control puts the compressor in charge or discharge, acting on the depressurization valves, in the case of the pistons or on the suction valve, in the case of newspapers.
Pressure switches have also been used for other applications. In security systems controlling high pressure values, such as alarm equipment to activate signals remotely or simply to detect the presence of air pressure in a certain circuit.
In compressed air, pressure switches have been widely used, but little by little they are being banished from industrial applications and replaced by pressure transmitters. These teams have smaller sizes, fewer breakdowns, being simpler mechanics and much higher in operation.