What is a pneumatic valve?

Pneumatic systems work on the basis of air pressure. This means that compressed air is the medium that transfers energy to different users in the system. For example, to a cylinder to achieve a movement or to a gripper to achieve both a movement and a gripping force.

The structure and operation of pneumatic systems can be made clear by means of a pneumatic diagram. This contains all relevant components, ranging from air supplies and air pipes or hoses to consumers (actuators), controls and valves.

Construction of the valve

Pneumatic valves play an important role in a pneumatic system. They determine how much air passes through and in which direction. This means that they can be used as control valves, but also as safety valves that shut off the air supply in dangerous situations or that depressurise the system.

Every valve basically consists of three elements:

Typically 2, 3 or 5 connections which are also called ports. The minimum of two ports provides power to the valve and work. A third port is used for exhausting the valve or actuator if necessary. If five ports are available, this is usually to control a double-acting cylinder. One port remains available for supply, two ports are used for working and two for exhausting. A port is nothing more than an opening with a thread into which a coupling can be inserted. Often a push-in coupling with which a direct hose connection can be made.

A housing containing the switching mechanism directs the compressed air to the correct working port. Various switching technologies allow for different functions and applications.

Finally, the controller ensures that the valve switches at the right time. It can be operated manually, mechanically, pneumatically or electrically.

Automation ladder

During the last few decades, pneumatic valves have undergone far-reaching developments. The first variants were operated mechanically, manually or pneumatically. These versions are still widely used today because of their simplicity and reliability.

This was followed by the introduction of electrically operated valves. In these valves, a magnetic coil and a control signal initiate the switching of the valve. Because the current generation of machines uses PLC technology, electrically operated valves are currently the most widely used. In our blog 'How a valve works' all possible controls are explained in more detail.

From valve island to Motion Terminal

A true revolution was unleashed when the first valve island was introduced. It combined several valves into a single component that is faster to install and more compact.

The next version also bundled the controls, replacing individual or parallel wiring with multipin connections. This saved a lot of time on wiring and connecting the valve islands.

The most recent versions of the valve island even integrate bus systems, IO-Link or a PLC. Changing from a multipin connection to a bus system again results in cost savings, because it makes wiring and connecting even faster. In addition, any malfunctions can be detected more quickly.

The most recent trend in valve technology is the Motion Terminal. This development opens the door to Digital Pneumatics. Based on software apps, any valve position can be assigned a function that can be changed on the fly. This provides a range of new possibilities. For more information: read our blog about the VTEM.

Festo valve programme

The developments in valve technology are clearly recognisable in the Festo programme. Starting with individual valves that are switched manually or pneumatically up to the most advanced motion terminal with integrated PLC. The higher the program, the more versatile the automation possibilities.

July 2022