Lift check valves are an important fluid control device, and the following is a detailed description of them:

1、Definition and alias

Lift check valve, also known as check valve, check valve, backflow valve, backpressure valve, is a kind of relying on the flow of the medium itself and automatically open and close the valve flap, used to prevent the medium backflow valve. It only allows the medium to flow in one direction, and prevent reverse flow.

2, the principle of work

When the medium flows in the specified direction, the valve is opened by the role of the media force; when the medium flows backward, due to the self-weight of the valve flap and the role of the media reverse force, so that the valve flap and the sealing surface of the valve seat closed to prevent the purpose of the media backflow. Specifically, when the fluid is introduced from the low end, due to the pressure difference between the valve and the valve fluid generated by the thrust is greater than the gravity of the valve flap and the valve flap topped up, the fluid from the valve flap and the sealing ring through the high end of the flow out of the valve body. However, when the fluid backflow occurs, the pressure at the outlet end is greater than the pressure at the inlet end, and the valve flap falls under gravity and differential pressure and seats in the sealing ring, preventing the fluid from flowing in the reverse direction.

3、Structural characteristics

The valve flap of lift check valve is located in the valve body on the seat sealing surface. In addition to the valve can be free to lift the valve, the rest of the valve as a globe valve. The upper part of the valve flap and the lower part of the valve cover are processed with guiding sleeve, and the valve flap guiding cylinder can be lifted and lowered freely in the valve cover guiding cylinder. According to the conditions of use, the valve can be all-metal structure, can also be in the valve frame inlaid rubber gasket or rubber ring form.

4、Advantages and disadvantages

Advantages
Easy to install: lift check valve structure is simple, easy to install, does not require a large number of pipeline connections and ancillary equipment, saving installation time and cost.
Easy to operate: lift check valve can be manually, electrically or hydraulically controlled to realize the valve opening and closing, convenient and reliable control.
High reliability: lift check valve adopts piston structure, has better sealing and stability, can ensure the unidirectional flow of fluid, and prevent backflow liquid damage to the valve.
Wide range of application: lift check valves can be used in a variety of pressures, flows and media of the hydraulic system, a wide range of applications.
Disadvantages
Large pressure drop: the valve hole of the lift check valve is small, and there will be a certain loss of fluid pressure when the fluid passes through, resulting in a large pressure drop.
Need for storage space: Lift check valves need a certain amount of storage space to realize the opening and closing of the valve, which will be limited if the installation space is small.
Leakage problems: lift check valves in the sealing aspect although better, but in the process of use there are still some leakage problems, especially in high pressure, high temperature, strong corrosion and other special conditions are prone to leakage phenomenon.

5、Application field

Lift check valves are widely used in oil fume purifiers, petrochemical plants, metallurgical industry, electric power engineering, textile industry and other production areas, used in industrial pipelines as a device to stop the medium backflow.

6、Installation and maintenance

Before installation, the valve should be cleaned and defects caused during transportation should be eliminated.
Installation must be carefully check the valve on the logo and nameplate whether it meets the requirements of use.
Lifting vertical flap check valves should be installed on horizontal piping, while lifting horizontal flap check valves should be installed on vertical piping.
Do not subject check valves to weight in the pipeline, and large check valves should be independently supported so that they are not subject to pressure generated by the piping system.
Installation of check valves, special attention should be paid to the direction of media flow, the normal flow direction of the medium should be made to indicate the direction of the arrow on the body of the valve in line with the direction of the arrow, otherwise it will cut off the normal flow of the medium.

In summary, lift check valve plays an important role in the fluid control system, but at the same time there are some problems that need attention. When selecting and using, comprehensive consideration should be made according to the actual needs and conditions.