How Does a Pneumatic Control Valve Work?

Pneumatic control valves are among an array of components used to control the rate and pressure of air that moves through a pneumatic system. But, how does a pneumatic control valve work? API UK is here to explain everything you need to know about pneumatic control valves, including how and why they are used, and why you should choose API valves. 


Pneumatic valves, which are also known as directional control valves, are used to modulate and control the flow of air and other inert gases in pneumatic systems. 

Pneumatic control valves are categorised in various ways. These include the number of inlet and output ports, the type of actuator (manual, mechanical, electromagnetic or pneumatic), the valve’s status when deactivated (normally open or normally closed), and the number of flow ways or switching positions. 

Typical configurations include 2/2, 3/2, 4/2, 5/2 and 5/3.


Pneumatic control valves divert the flow of control air from one port to another, which feeds other pneumatic valves with signals, or openss and closess pneumatic actuators. In a 3/2 normally closed valve, compressed air enters the valve at port 1 and is held there until the valve receives a command to change position. The command can be either from a pneumatic signal (in the case of a pilot operated valve), an electrical signal for a solenoid valve, or a mechanical signal (in the case of manual or mechanically operated valves).

Once a signal is received, a spool within the valve moves across and allows air to travel to port 2 and then to a spring return actuator, which will then operate. Upon removal of the signal, the spool returns to its original position and air exhausts from the actuator. This occurs as the spring forces it back to its start position into port 2 and out of port 3.

The same principle applies to 5/2 valves. However, these valves have two outlet ports: one with air passing and one with air exhausting. Actuating the valve will change over the air to the opposite port and exhaust the previously pressurised port, enabling a double-acting cylinder to move back and forth.  


Pneumatic control valves are versatile, from simple tasks like switching a single flow path on and off to more complex functions like proportional flow control. Like many other pneumatic components, pneumatic control valves are durable, reliable and require less maintenance than electromotive equivalents. 

They are also safe, simple and cost-effective, making them a desirable proposition for any manufacturers seeking to maximise the efficiency and longevity of their pneumatic systems.


Due to their various advantages and configuration options, pneumatic control valves are ubiquitous across all industries. As a result, they are used far and wide in many everyday applications, from automation to medical, chemical, metallurgy and more. 

It’s little wonder that many industries are choosing to use pneumatic systems consisting of pneumatic control valves when you consider that compressed air is a readily available resource that is not only clean but is also easy to use.


As a leading industrial valve supplier, API UK can supply a wide selection of industrial and process control valves. Constructed from lightweight aluminium, our industrial valves feature rugged anodised aluminium spools to ensure long service life.

Available in various sizes, API industrial valves can be tailored to suit your application requirements. We supply a range of high-quality process control valves, including the following:

  • Solenoid Valves
  • Actuated Ball Valves
  • ISO Control Valves
  • Pneumatic Valves
  • Manual and Mechanical Valves
  • Ancillary Valves


We supply electric solenoid valves and electrically-operated solenoid spool valves that deliver impressive performance and durability. Our selection of solenoid valves includes direct, indirect, ISO and stainless steel valves to suit many pneumatic applications. All are available at affordable prices on a next-day delivery basis.


We offer actuated ball valves made from hardened and anodised aluminium, brass, or corrosion-resistant stainless steel. Selected ball valves are available in single and double-acting versions. At the same time, we also offer robust single and double-acting rotary actuators with a double rack for automating ball and butterfly valves.


Our selection of pneumatic control valves includes ATEX-certified ISO 5599/1 control valves in two different sizes (ISO 1 and ISO 2) to suit your needs. The electrically-operated ISO control valves at API UK come with either an inline electro pilot or a CNOMO electric pilot. We also supply a wide range of manual and mechanical ISO valves.


Our ISO 5599/1 conforming pneumatic valves are used with compressed air, with or without lubrication.

Furthermore, our A1 series pneumatic spool valves come with the option of panel or sub-base mounting for high flow applications. Whatever your process requirements, our pneumatic valves will exceed expectations.


Our manual and mechanical valves provide the broadest range of operating options available. We have a solution for every application with a wide range of manual and mechanically operated pneumatic valves. From wide or roller lever to top-level and push-pull, our manual and mechanical valves are designed to perform.


API UK offers a range of ancillary valves for use with compressed air. Our selection includes uni-directional valves for single direction control and manually operated nickel-plated brass miniature ball valves, or full bore ball valves for control in both directions. We also provide slide valves, safety valves and quick exhaust valves.


Pneumatic control valves are essential components in any pneumatic system. Available in a wide range of configurations, at their core, pneumatic control valves all serve a similar purpose: to control and modulate airflow in a pneumatic system. Their reliability, simplicity, durability, and affordability make pneumatic control valves a must-have component for any forward-thinking manufacturer.

To find out more about our pneumatic control valves or arrange a free on-site visit, speak with our technical team today. As expert pneumatic control valve manufacturers, we can help you understand the full range of options available and guide you towards the best system solution for your compressed air application. Call us on 01782 206 995, email [email protected], or complete our contact form.