How check valve works
The check valve is used in the pipeline system, and its main function is to prevent the backflow of the medium, the reverse rotation of the pump and its driving motor, and the discharge of the medium in the container.
Check valves may also be used on lines supplying auxiliary systems where the pressure may rise above the main system pressure. Check valves can be applied to pipelines of various media according to different materials.
The check valve is installed on the pipeline and becomes one of the fluid components of the complete pipeline. The opening and closing process of the valve disc is affected by the transient flow state of the system in which it is located; in turn, the closing characteristics of the valve disc are It has an effect on the fluid flow state.
Check valve classification
The disc of the swing check valve is in the shape of a disc and rotates around the shaft of the valve seat channel. Because the channel in the valve is streamlined, the flow resistance is smaller than that of the lift check valve. It is suitable for low flow rates and infrequent changes in flow. However, it is not suitable for pulsating flow, and its sealing performance is not as good as that of the lifting type.
The swing check valve is divided into three types: single-lobe type, double-lobe type and multi-lobe type. These three forms are mainly divided according to the valve diameter.
2. Lift check valve
A check valve in which the valve disc slides along the vertical centerline of the valve body. The lift check valve can only be installed on a horizontal pipeline, and a ball can be used for the valve disc on a high-pressure small-diameter check valve. The valve body shape of the lift check valve is the same as that of the globe valve (it can be used in common with the globe valve), so its fluid resistance coefficient is larger. Its structure is similar to the globe valve, and the valve body and disc are the same as the globe valve.
A check valve in which the disc rotates around a pin in the seat. The disc check valve has a simple structure and can only be installed on the horizontal pipeline, and the sealing performance is poor.
4. Pipeline check valve
A valve in which the disc slides along the centerline of the valve body. Pipeline check valve is a new valve. It is small in size, light in weight and good in processing technology. It is one of the development directions of check valve. However, the fluid resistance coefficient is slightly larger than that of the swing check valve.
5. Compression check valve
This kind of valve is used as boiler feed water and steam cut-off valve, it has the integrated function of lift check valve and globe valve or angle valve.
In addition, there are some check valves that are not suitable for pump outlet installation, such as foot valve, spring type, Y type, etc.
Post time: Jul-06-2022