What is a Pressure Switch?

This article will explain what a pressure switch is, how it works and how to select one.

What is a Pressure Switch?

Pressure switches are used to monitor pressure in pneumatic systems by providing an output when a set pressure is reached, as well as improving operation and safety. For example, an air pressure switch is used to maintain a constant pressure,  and can turn the compressor off once the tank reaches the required air pressure level.  If the air pressure drops and more is required, the switch can also turn the compressor on.

How do pressure switches work?

An electro-mechanical pressure switch works by applying pressure to either a diaphragm, bellow or a piston to exert motion. The motion can create electrical contact in a microswitch launching an alarm or creating an action, for example switching off a compressor. An electronic pressure switch generally uses a piezo-electric crystal; when deformed a piezo crystal emits an electric current.

How do I select a pressure switch?

Choosing the right switch will depend on the pressure requirements of the air compressing unit you’re using, as well as the following considerations:

  • Operating pressure range

  • Switching pressure difference

  • Repeatability

  • Medium – for example air, hydraulic or ‘allfluid’

  • Environment for operation – for example ATEX requirement, temperature etc

  • Switching current – for example, gold contacts allow lower currents

  • Outputs required

Types of pressure switches

There are two different types of pressure switches available:

  • Electro-mechanical pressure switches – Strong and simple, these switches are often used in less complex operations. The Norgren range includes the 18D product which houses an electro-mechanical diaphragmatic operation, and a microswitch with gold-plated contacts. Electro-mechanical pressure switches are available in a range of port sizes and pressure ranges, and have a high switching rate. 

  • Electronic pressure switches – These tend to be very robust and are often used in more complex applications. These pressure switches are ideal for applications that require high repeatability and greater accuracy, with an analogue output option if required. The range includes the 33D pressure switch, which offers remote or pre-set programming and the option of digital or analogue outputs.

Typical applications of pressure switches

Pressure switches are used in a range of industrial and manufacturing applications, including compressors and pumps. Many process applications require the monitoring of pressure to ensure optimum operation.

Do I need anything else to make a pressure switch work?

Fittings, tubing, electrical wires and plugs are all required. Even though pressure switches are very durable, regular testing should be carried out to check for leaks. 

Visit our Pressure Switch section to find out more.

Do you have an Industrial Automation Challenge or Application you would like to discuss?

Please enter your details and we will be in touch.

* All fields are compulsary