Legris Pneumatic Non-Return Valves

Pneumatic non-return valves are one of the simplest types of pneumatic valves available. They allow compressed air to flow in one direction and prevent or block it from flowing in the opposite direction. Also known as a check valve these simple but effective devices help to eliminate any potential damage that may be caused by backflow pressure. RS offer a range of high-quality valves from leading brands including Festo, SMC, Legris, Norgren and of course RS PRO.

How does a Pneumatic Non-Return Valve Work?

Non-return valves work automatically, which means that most valves don’t need human intervention external control to work. The valves will have two openings or ports, an inlet and an outlet port. An internal spring will lift when the pressure upstream is great enough to overcome the tension of the spring. This is referred to as the ‘cracking pressure’.

What is Cracking Pressure?

Cracking pressure refers to the minimum pressure differential needed between the inlet and outlet of the valve at which the first indication of flow occurs. When cracking pressure is reached, the valve will open to allow flow, when it drops the valve will close.

What are the different types of Pneumatic Non-return valve?

Pneumatic non-return valves are available in two main types. Push in tube-to-tube or Push-in tube to threaded.

Tube-to-Tube Non Return Valves

This type of non-return valve will have a push-in connection port at either end. They are available with different body materials, including brass and aluminium. Hose sizes ranging from 4 mm to 12 mm

Tube to Threaded Non Return Valves

This type of non-return valve will have a tube connection on one end and a threaded connection on the other. They are available with different body materials including brass and aluminium. Hose sizes ranging from 4 mm to 12 mm. Threads are typically BSPP (G), BSPT (R), NPT, and Metric.