Pneumatic Non-Return Valves

Pneumatic non-return valves are among the simplest pneumatic valves available. They allow compressed air to flow in only one direction while preventing reverse flow. Also known as check valves, these straightforward yet effective devices help protect systems from potential damage caused by backflow pressure. Pneumatic Resources offers a selection of high-quality valves from the trusted brand, SMC.

How Does a Pneumatic Non-Return Valve Work?

Non-return valves operate automatically, meaning they generally require no external control or manual intervention. Each valve features two ports—an inlet and an outlet. Inside, a spring holds the valve closed until the pressure on the inlet side exceeds the spring tension. This threshold is called the ‘cracking pressure.’

What is Cracking Pressure?

Cracking pressure is the minimum pressure difference between the valve’s inlet and outlet at which flow begins. When this pressure is reached, the valve opens to allow air through; if the pressure falls below this point, the valve closes to prevent backflow.

What Are the Different Types of Pneumatic Non-Return Valves?

Pneumatic non-return valves come in two primary styles: push-in tube-to-tube and push-in tube-to-threaded.

Tube-to-Tube Non-Return Valves

These valves feature push-in connection ports on both ends. They are available with bodies made from materials such as brass and aluminum, and support hose sizes from 4 mm to 12 mm.

Tube-to-Threaded Non-Return Valves

These valves have a push-in tube connection on one end and a threaded connection on the other. Body materials include brass and aluminum, with hose sizes also ranging from 4 mm to 12 mm. Common thread types include BSPP (G), BSPT (R), NPT, and Metric.