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The principle of non-return valve and common troubleshooting methods

The role of this type of valve is only allowed the media to flow in one direction, and stem the flow direction. This valve is normally automatically, in a direction of flow of fluids under pressure, the valve opens; fluid flowing in the opposite direction, the fluid pressure and weight of the flap valve disc on the seat, so as to cut off the flow.
The check valves are examples of this type of valve, which includes swing check valves and lift check valves. Swing check valves have a hinge, and doors as a free flap valve in leaning on the seat surface. In order to ensure that the disc can reach every seat position, valve flap hinge, so that the disc has a sufficient swing space and disc real, full contact with the valve seat. All disc can be made of metal or metal studded leather, rubber, or synthetic coverage, depending on the use of performance requirements. Swing check valve is in fully open condition, fluid pressure almost unhindered, through the valve pressure drop is relatively small. Lift check valves the valves located on the valve body valve seat sealing surface. The top of valve disc is free to lift, and the rest as well as valve, fluid pressure on the valve from the valve seat sealing surface lifts, medium back bringing the disc back into the valve seat, and cut off the flow. According to the conditions of use, the valve can be an all-metal structure, can also be rack mounted disc rubber mats or rubber ring form. As well as valve, fluid through a lift-type check valves channel is narrow, so by lifting type check valve swing check valve pressure drop, and swing check valve flow subject to few restrictions.
Common faults are:
① valve broken; II medium back.
Cause broke the disc is: check valves before and after the media pressure is close to equilibrium and mutual "see-saw" State, the valve seat on a regular beat, some brittle materials (such as cast iron, brass, etc) disc is made of smashed.
Prevention method is to select the disc check valve of ductile materials.
Media is back because:
① sealing surface damaged the second dirt inclusion. Reconstruction of sealing and cleaning impurities and to prevent backflow.