304 Stainless Steel Vertical Check Valve H42W

A vertical check valve is an automatic valve that opens and closes automatically by medium flow, to prevent reverse flow of fluid. Also known as non-return valve, one-way valve, back-flow preventer and back pressure valve.

It belongs to the category of automatic valves, core functions include preventing medium backflow, protecting pumps and drive units from reverse rotation, and avoiding medium discharge from containers. Widely installed at pipeline outlets of pressure systems and pressure compensation auxiliary supply circuits.

Check valves are mainly divided into swing check valves (rotating around a fixed pivot) and lift check valves (moving along axis). This type of valve only allows medium to flow in one direction and completely blocks reverse flow. Normally working automatically: under fluid pressure in forward direction, disc opens; when fluid flows backward, disc closes by its own weight and medium pressure to cut off backflow.

Threaded vertical check valves and wafer check valves fall into this category, including swing type and lift type structures.

- Swing check valve: Equipped with hinge chain and door-like disc, which freely leans against the tilted valve seat surface. To ensure the disc can reach full seating position accurately, the disc is mounted on hinge mechanism for sufficient swing stroke to achieve full, reliable contact with valve seat. Disc can be made of full metal, or with rubber/soft composite lining on sealing face. When fully open, fluid resistance is minimal.

- Lift check valve: Disc sits on the seat located below valve cavity. Besides free up-down movement of the disc, identical structure to globe valves. Fluid pressure pushes disc upward to open; backflow makes disc fall back onto seat and shut off pipeline. Disc can be all-metal, or with rubber gasket/ring mounted on sealing face.

Similar to globe valves, the passage bore of lift check valves is relatively narrow, resulting in larger pressure drop than swing check valves. Meanwhile, flow capacity of swing check valves is limited.