Pneumatic Valves: Everything You Need To Know

Pressure, flow rate, direction, and amount of air moving through a pneumatic system are controlled by pneumatic valves. In numerous industrial applications, pneumatic systems are used to control power sources, and although the medium of the system is fluid (as in a hydraulic system), how it is controlled and delivered is different. Pneumatic valves can also be used to control fluid pressure and flow. Pressure relief valves, flow control valves, and directional control valves are the most common.

Pressure Relief Valves

There has always been a need to create a safe and efficient way to manage steam and pressure when boiling water. The pressure relief valve, also known as the safety valve, has a spring-loaded valve that opens at a specified pressure setting and releases fluid until the pressure returns to a safe level. Air storage devices and large centralized compressors use these types of valves for compressible and incompressible fluids.

Flow Control Valves

It is common for pneumatic systems (as well as hydraulic systems) to include flow control valves. These types of pressure valves regulate the pace at which the fluid flows through a system. They respond to signals from a control meter or temperature gauge and are usually equipped with actuators and positioners. In both configurations, either the valve opens or closes based on a variable restriction or the valve allows one direction of flow while restricting the opposite direction.

Directional Control Valves

The directional control valve is a fundamental part of pneumatic machinery that controls the flow. A pneumatic valve can be as simple as a check valve or as complex as a valve with multiple ports. Quite simply, they allow fluid to flow in different directions from various sources. Valve operators shift the valve between positions using the directional valve. The mechanism consists of a spool inside a cylinder that can be controlled either electrically or mechanically.

Poppet Valve

An engine's poppet valve (also known as a mushroom valve) regulates how much and when gas or vapor is pumped into the engine.

An open-ended chamber with a hole or stopper, typically a disk-shaped disk at the end of a shaft known as a valve stem, makes up a valve stem. A 45° bevel is commonly ground into the valve face, which seals against a matching valve seat in the chamber rim. A valve guide keeps the shaft aligned.

The differential pressure on both sides of the valve may help or hinder its function. Exhaust applications require higher pressure against the valve, while intake applications require lower pressure.