What Is a BIFOLD Check Valve?

A BIFOLD check valve (such as the PCV series) is a non-return valve that permits flow in one direction only and automatically blocks reverse flow. It protects pumps, actuators and compressed-air circuits from backflow, pressure spikes and cross-contamination.

How to Select the Right Check Valve

• Port size and thread: Match the line (G1/8 – G1/2 typical) and choose BSP or NPT to suit existing fittings.
• Cracking pressure: The minimum upstream pressure needed to open the valve. Standard springs are ~0.1–0.3 bar; use a low-crack version for gravity/drain lines and a higher one where back-pressure must be held.
• Pressure rating: Confirm maximum working pressure and burst margin for your system.
• Body and seal material: Brass or stainless for corrosion resistance; NBR/FKM seals for air, water or oil compatibility.
• Mounting style: In-line or cartridge; cartridge types save space in manifold blocks.

Installation Notes

1. Respect the moulded flow direction arrow — fitting it backwards permanently blocks the line.
2. Install where accessible so the valve can be removed for inspection.
3. For vertical air lines, confirm the spring orientation supports the expected flow.
4. Avoid sudden downstream closure that can cause water hammer; pair with a soft-close or accumulator where needed.

Maintenance and Inspection

Check valves are largely maintenance-free. Inspect during planned shutdowns for seal wear, scoring on the seat, or debris preventing full closure. Symptoms of failure include reverse leakage, chatter (loose spring or contamination) and restricted forward flow. Replace the cartridge or complete unit rather than attempting seat lapping in the field.

Common Application Tips

• Use a check valve on each pump discharge in parallel-pump sets to stop backflow through the idle unit.
• Fit one on instrument air taps to keep calibration gas from leaking back into the main line.
• In hydraulic power units, a suction check prevents drain-back and primed-pump loss after stop.