Classification and precautions for use of check valves

A check valve refers to a kind of valve with a round valve disc as the opening and closing part and acting by its own weight and medium pressure to block the reverse flow of the medium.

Here is the content list:

• Classification of check valve

• Precautions for use of check valve

• Troubleshooting of check valve

Classification of check valve

The valve that the opening and closing parts automatically open or close by the force of media flow to prevent media backflow is called a check valve. The check valve belongs to the automatic valve category, which is mainly used in the pipeline with a one-way flow of the medium. Only one direction of medium flow is allowed to prevent accidents.

Structure classification

According to structure, it can be divided into a lift check valve, swings check valve and butterfly check valve:

1. Lift check valves are divided into vertical, and horizontal types.

2. Swing check valves are divided into three types: single-disc, double-disc, and multi-disc.

3. Butterfly check valve is straight-through type.

Material classification

1. Cast iron check valve

2. Brass check valve

3. Stainless steel check valve

4. Carbon steel check valve

5. Forged steel check valve

Precautions for use of check valve

1. Do not allow the check valve to bear the weight in the pipeline system.

2. During installation, the direction of medium flow shall be consistent with the arrow direction marked on the valve body.

3. The lifting horizontal disc check valve shall be installed on the horizontal pipeline.

4. Prevent excessive piping stress due to temperature change, minimize temperature change, and add U-shaped expansion joints before and after the valve.

5. It is forbidden to use the pull rod to switch the check valve. Observe the switch indication position and limit the device of the check valve. Do not force it to close after the switch to avoid premature damage to the fluoroplastic sealing surface.

6. During the use of the check valve, due to the soft material of the sealing surface of the fluoroplastic, the crystal and solid particles of the medium will damage the sealing surface and cause sealing leakage. Once found, repair or replace the seal immediately.

7. When the rotation of the handle and handle is not flexible, or the check valve cannot be opened or closed, the push nut can be properly loosened. Rotation is not flexible. The cover may tilt, please adjust the positive pressure cover. After adjustment and locking, if the check valve cannot be opened and closed flexibly, it must be disassembled and checked to remove dirt and eliminate faults. When disassembling this check valve, please pay attention to whether the medium in the check valve piping is used or newly installed, so as to avoid accidents during disassembly and avoid accidents.

Troubleshooting of check valve

The reason why the valve disc is broken is that the medium pressure before and after the check valve is nearly balanced and "sawing" with each other. The valve disc often beats the valve seat, and the valve disc made of some brittle materials is broken.

The prevention method is to use the check valve with a disc made of tough material.

The reasons for media backflow are: ① the sealing surface is damaged; ② Inclusion of impurities.

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