Check valve refers to rely on the medium itself flow and automatically open and close valve disc, used to prevent media backflow of the valve, also known as check valve, check valve, counterflow valve and back pressure valve.
Check valve belongs to an automatic valve, its main function is to prevent the backflow of the medium, prevent the pump and the drive motor from reversing, as well as the discharge of the container medium. Check valves can also be used to feed pipes where the pressure may rise to exceed the system pressure. Check valves can be mainly divided into swing check valves (rotating according to the center of gravity) and lifting check valves (moving along the axis).
The purpose of this type of valve is to allow the medium to flow in only one direction and to prevent the flow in the opposite direction. Usually the valve works automatically. The disc opens under the action of fluid pressure flowing in one direction;
When the fluid flows in the opposite direction, the fluid pressure and the self-recentdisc of the disc act on the seat to cut off the flow.
1. In order to prevent the medium countercurrent, check valves should be installed on the equipment, devices and pipelines;
2. The check valve is generally suitable for clean media, should not be used for media containing solid particles and larger viscosity;
3. Generally, horizontal lifting check valves should be selected on horizontal pipelines with nominal diameter of 50mm;
4. Straight through type lifting check valve can only be installed in horizontal pipeline;
5. For the water pump inlet pipeline, should choose the bottom valve, the bottom valve is generally only installed on the vertical pipe of the pump inlet, and the medium bottom-up flow;
6. Lifting type is better than swing type sealing, fluid resistance, horizontal should be installed on the horizontal pipe, vertical installed on the vertical pipe;
7. Swing check valve installation position is not restricted, it can be installed in the horizontal, vertical or inclined pipeline, such as installed in the vertical pipeline, medium flow to from the bottom up;
8. Swing check valve can be applied to any working medium and any working temperature range according to the material of the shell and seal. Media for water, steam, gas, corrosive media, oil, medicine, etc.
Medium operating temperature range between -196--800℃;
9. Swing check valve is suitable for low pressure and large diameter, and installation occasions are limited;
10. Butterfly check valve installation position is not limited, can be installed in the horizontal pipeline, can also be installed in the vertical or inclined pipeline;
Check valves can be divided into lifting check valves, swing check valves and butterfly check valves according to their structure.
Lift check valves can be divided into vertical and straight through two types.
Swing check valves are divided into single -, double - and multi-disc types.
Butterfly check valve is butterfly double flap, butterfly single flap, the above types of check valve in connection form can be divided into threaded connection, flange connection, welding and clamp connection four.