Ⅰ. Introduction of check valve

The function of the check valve is to only allow the medium to flow in one direction and prevent the flow in the opposite direction. Usually this kind of valve works automatically. Under the action of the fluid pressure flowing in one direction, the valve flap opens; when the fluid flows in the opposite direction, the fluid pressure and the self-coincidence of the valve flap act on the valve seat, thereby cutting off the flow.

Ⅱ. The failure of the check valve and its treatment method

Common failures of check valves include:

①The valve disc is broken;

1The reason for the disc breaking is: the pressure of the medium before and after the check valve is close to equilibrium and they are in a state of “seeing” each other. The disc often beats against the valve seat, and some brittle materials (such as cast iron, brass) are made of The finished valve disc was broken. The preventive method is to use a non-return check valve whose disc is a flexible material.

②The medium flows back.

The reasons for the backflow of the medium are:

1. The sealing surface is damaged;
2. Clamp in impurities.

Repairing the sealing surface and cleaning impurities can prevent backflow.

Ⅲ. The principle of check valve

A check valve is a valve that automatically opens and closes the disc depending on the flow of the medium itself, and is used to prevent the medium from flowing back. It is also called a check valve, a one-way valve, a reverse flow valve, and a back pressure valve. Its main function is to prevent the medium from flowing backwards, to prevent the pump and drive motor from reversing, and to discharge the container medium. Check valves can also be used to supply pipelines for auxiliary systems where the pressure may rise above the system pressure.

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Ⅰ. Introduction of check valve

Check valve is an automatic valve. It relies on the pressure of the flowing medium in the pipeline to push the disc to close and open the valve. When the medium stops flowing, the check valve disc closes, it can be effective to prevent the medium in the pipeline from flowing back, which plays a great role in ensuring the safety of the pipeline.

 Ⅱ. The installation position of the check valve

The check valve is installed to ensure the flow direction of the water flow inside the water pump, so as to ensure the normal operation of the water pump. Therefore, regarding the installation position of the non-return check valve, whether it is installed before the pump or after the pump, there are two situations:

• 1. One is installed at the end of the vertical suction pipe in front of the water pump, also called a bottom valve. The purpose is to fill the pump without pumping water once, because when there is no water in the pump and the suction pipe in front of the pump, the pump can only run idling and cannot pump water, so the pump must be filled with water to pump out water. The installation of this kind of water pump is a method when it is higher than the liquid level, also called negative pressure method.
• 2. The other is installed behind the pump. This installation method is that when the liquid level is higher than the water pump, it is convenient to start and stop the water pump without closing the water pump outlet valve, especially for the main control water pump system to prevent backflow.

The non-return check valve must be installed at the outlet of the pump and before the outlet control valve in order to check the check valve. Generally, the first outlet of the pump is the soft connection (shock absorber), the next is the check valve, and then the isolation valve (such as butterfly valve, gate valve, stop valve)

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