Lift check valve is an important fluid control device, and the following is a detailed introduction to it:
1. Definition and Alias
Lift check valve, also known as check valve, one-way valve, reverse flow valve, back pressure valve, is a type of valve that automatically opens and closes the valve disc based on the flow of the medium itself, used to prevent the medium from flowing back. It only allows the medium to flow in one direction and prevents reverse flow.
2. Working principle
When the medium flows in the specified direction, the valve disc is opened under the action of the medium force; When the medium flows back, the sealing surface between the valve disc and the valve seat is tightly closed due to the self weight of the valve disc and the reverse force of the medium, achieving the purpose of preventing the medium from flowing back. Specifically, when fluid is introduced from the lower end, the thrust generated by the pressure difference between the fluid in front of and behind the valve is greater than the gravity of the valve disc, causing the valve disc to lift. The fluid flows out of the valve body through the annular gap between the valve disc and the sealing ring at the higher end. However, when the fluid reverses, the Pressure at the outlet end is greater than the Pressure at the inlet end, and the valve disc drops and seats on the seal ring under the action of gravity and pressure difference, preventing the reverse flow of fluid.
3. Structural characteristics
The valve disc of the lift check valve is located on the sealing surface of the valve seat on the valve body. This valve is like a globe valve, except for the valve disc which can be freely raised and lowered. The upper part of the valve disc and the lower part of the valve cover are processed with guide sleeves, and the valve disc guide cylinder can be freely raised and lowered inside the valve cover guide cylinder. According to the usage conditions, the valve disc can be made of all metal structure or embedded with rubber pads or rubber rings on the valve disc frame.
4. Advantages and disadvantages
advantage
Easy installation: The lift check valve has a simple structure and is easy to install, without the need for a large number of pipeline connections and ancillary equipment, saving installation time and costs.
Easy to operate: The lift check valve can be controlled manually, electrically, or hydraulically to open and close the valve, making control convenient and reliable.
High reliability: The lift check valve adopts a piston structure, which has good sealing and stability, ensuring one-way flow of fluid and preventing backflow liquid from damaging the valve.
Wide scope of application: lift check valve can be used in various hydraulic systems with Pressure, flow and medium, and has a wide scope of application.
shortcoming
Large pressure drop: the valve hole of the lift check valve is small, and the fluid Pressure will be lost when the fluid passes through, resulting in a large pressure drop.
Storage space required: Lift check valves require a certain amount of storage space to achieve valve opening and closing. If the installation space is small, it will be limited.
Leakage problem: Although lift check valves have good sealing performance, there are still certain leakage problems during use, especially under special conditions such as high pressure, high temperature, and strong corrosion, which are prone to leakage.
5. Application Fields
Lift check valves are widely used in production fields such as oil fume purifiers, petrochemical plants, metallurgical industry, power engineering, textile industry, etc. They are used as devices on industrial pipelines to prevent medium backflow.
6. Installation and maintenance
Before installation, the valve should be cleaned thoroughly and any defects caused during transportation should be eliminated.
During installation, it is necessary to carefully check whether the markings and nameplates on the valve meet the usage requirements.
Lift type vertical flap check valves should be installed on horizontal pipelines, while lift type horizontal flap check valves should be installed on vertical pipelines.
The check valve shall not bear weight in the pipeline. Large check valves shall be independently supported so that they are not affected by the Pressure generated by the pipeline system.
When installing a check valve, special attention should be paid to the direction of medium flow. The normal flow direction of the medium should be consistent with the direction indicated by the arrow on the valve body, otherwise it will cut off the normal flow of the medium.
In summary, lift check valves play an important role in fluid control systems, but there are also some issues that need to be noted. When selecting and using, comprehensive consideration should be given to actual needs and conditions.
