Understanding Pressure Switches

A pressure switch contains a capsule, bellows, Bourdon tube, diaphragm or piston element that deforms or displaces proportionally to the applied pressure of a fluid. The resulting motion is applied via a mechanism to a set of switch contacts.

The pressure switch may be adjustable by moving the contacts or adjusting a counterbalance spring. Industrial pressure switches may have a calibrated scale and pointer to show the set point of the switch. A pressure switch will have a differential range around its set point in which small changes of pressure do not change the state of the contacts. Due to this some types allow adjustment of the differential.

You can arrange the pressure sensing element of a pressure switch to react to two different pressures. Such switches are useful when the difference is significant, for example, to detect a clogged filter in a water supply system.

The switch contacts may be rated up to around 15 amps with smaller ratings found on more sensitive switches. Often they will operate a relay but some types can directly control small electric motors or other loads.

Benefits of Using Pressure Switches In Hazardous Locations

The internal switch materials have to be compatible with the application media. This is due to the media entering the pressure switch. For example, Nitrile diaphragms are suitable in contact with water, however, they would quickly degrade if in a system containing oil.

Switches designed for use in hazardous areas have enclosures designed to prevent arcing contacts from igniting the surrounding gas. If there is a requirement, an enclosure can be weatherproof, corrosion resistant, or submersible.

An electronic pressure switch incorporates some variety of pressure transducer (eg strain gauge or capacitive element) and an internal circuit. The internal circuit compares the measured pressure to a set point. As a result, such devices may provide improved repeatability, accuracy and precision over a mechanical switch.

V-Flow Pressure Switches

In conclusion V-Flow Solutions Ltd supply a wide range of high-quality instrumentation products including pressure switches manufactured by global company Ashcroft.