How does the check valve work

A check valve is designed to allow flow in one direction. When the flow is forward, the valve disc should open, and when the flow is reversed, it should block the passage.

In all types of check valves, opening occurs due to the pressure difference across the disc, and closing occurs:

• by gravity - for valves with heavy discs and lever mechanisms
• by spring force in spring-loaded check valves
• by reverse pressure difference on the disc.

When the flow is forward, the pressure at the valve's inlet exceeds the pressure at the outlet, and the disc is displaced, lifted, or rotated, opening the passage for flow.

When the flow is reversed, the pressure at the outlet exceeds the pressure at the inlet, and the greater the pressure difference, the more the disc is pressed against the seat, blocking the passage.

The operation of the check valve does not require external power sources, making it a direct-acting protective fitting.

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