What are Pneumatic Valves?

There are various power sources used across systems in numerous industries, and each system is named for its power source. For example, a pneumatic system depends on pneumatic power which is generated by compressed air. The energy generated by this air powers movement in other parts of the pneumatic system, such as the spring inside of an actuator. The exact pressure and rate of airflow inside a pneumatic system must be regulated carefully because this directly determines the amount of power running through the system. Therefore, the very important function of a pneumatic valve or directional control valve is to regulate the air powering the entire system.

There are two main ways that pneumatic valves function to operate industrial machinery. They either regulate air flow directly or they regulate a secondary substance which, in turn, regulates the air flow. The first type meets air or gas at the source and divides it across the system. The opening or closing of the valve is controlled by an actuation movement accomplished manually, electrically, or pneumatically depending on the system. In indirect air flow control, the valve controls a fluid other than air. To achieve this action, air flows through a pneumatic actuator which, in turn, lifts the valve in and out of a port, allowing a separate liquid or gas to flow.

Directional control valves can be classified based on four main factors. The first involves the number of exit and entry ports they possess, such as two-way, three-way, or four-way valves. In a two-way port, liquid can pass through the first and second port in either direction when open, and flow is halted entirely when ports are closed. A three-way valve has one port connected to an actuator or device, another connected to the flow system, and a third connected to an exhaust exit. The first and second valve can open together to allow flow or the first and third valve can open together to vent exhaust. A four-way valve uses its fourth port to connect to a second actuator. These are common given their ability to switch flow in either direction, enabling reverse motion. Occasionally, a fifth port might also be added to provide dual pressure or a secondary exhaust exit.

Pneumatic valves can also be classified by how they switch airflow. A common example is the spring offset classification which depends on a valve connected to an actuator. A spring within the actuator moves a valve spool in and out of a default position which can either be open or closed depending on the position of the spring relative to the pressure source. The number of switching positions is also part of the classification system, and the combinations of valve configurations are written by the number of ports followed by a slash and the number of switching positions. For example, a valve with five ports and two switching positions would be written as a 5/2-way valve.

Yet another important classification is the non-actuated state or default position of the valve. In spring offset valves, the non-actuated state refers to where the valve will be positioned when actuation is removed. In detonated valves, the valve remains in the position it held when the device was shut off. Pneumatic valves vary in pressure range, operating mediums, port size, and additional factors not discussed in depth within this blog. It is important to find the correct design for your pneumatic valve to ensure successful power regulation.

For any questions, reach out to our always available team members at NSN Target. We are a state-of-the-art parts purchasing platform owned and operated by ASAP Semiconductor, and we are here to supply you with the highest quality products for your projects. All of our parts are subject to rigorous quality assurance tests and are sourced from over 5,000 global manufacturers that we trust. For all shipments, parts are sent out following strict adherence to FAA AC 00-56B, AS9120B, and ISO 9001:2015 accreditations.


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