FUNCTION AND CLASSIFICATION OF CHECK VALVE

Check valve definition

Check valve refers to the valve that automatically opens and closes the valve disc depending on the flow of the medium itself to prevent the backflow of the medium, also known as check valve, one-way valve, reverse flow valve, and back pressure valve.

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Check valve action

The check valve is an automatic valve. Its main function is to prevent the reverse flow of medium, the reverse rotation of pump and drive motor, and the discharge of container medium. The check valve can also be used on the pipeline to supply the auxiliary system whose pressure may rise above the system pressure.



Classification of check valves

Check valves can be divided into:

1. swing check valve

The disc of the swing check valve is disc-shaped and rotates around the rotating shaft of the valve seat channel. Because the channel in the valve is linear, the flow resistance is smaller than that of the lift check valve. It is suitable for large-diameter occasions with low flow rate and infrequent flow changes, but it is not suitable for pulsating flow. Its sealing performance is not as good as that of the lift check valve. Swing check valves are divided into three types: single disc, double disc and multi half. These three types are mainly divided according to the valve diameter, so as to prevent the medium from stopping or reversing flow and reduce the hydraulic impact.



2. lift check valve

For the check valve whose disc slides along the vertical center line of the valve body, the lift check valve can only be installed on the horizontal pipeline, and the disc on the high-pressure small-diameter check valve can adopt a ball. The body shape of the lift check valve is the same as that of the stop valve (which can be common with the stop valve), so its fluid resistance coefficient is large. Its structure is similar to the stop valve, and the valve body and disc are the same as the stop valve. The upper part of the valve clack and the lower part of the valve cover are machined with a guide sleeve. The guide sleeve of the valve clack can rise and fall freely in the guide sleeve of the valve cap. When the medium flows downstream, the valve clack is opened by the thrust of the medium. When the medium stops flowing, the valve clack falls on the valve seat by itself to prevent the reverse flow of the medium. The direction of the medium inlet and outlet channel of the straight through lift check valve is perpendicular to the direction of the valve seat channel; For the vertical lift check valve, the direction of the medium inlet and outlet channel is the same as that of the valve seat channel, and its flow resistance is smaller than that of the straight through type.

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