Check valve: the guardian of system safety

1. The basic principle and function of check valve
Check valve, also known as one-way valve or non-return valve, is a valve that automatically opens and closes by the force of the fluid itself. When the fluid flows forward, the valve disc is pushed open to allow the fluid to pass; when the fluid tries to flow in the opposite direction, the valve disc is closed due to fluid pressure or deadweight, effectively preventing the occurrence of backflow. This feature makes the check valve play a vital role in preventing medium contamination, protecting pump equipment from reverse impact, and maintaining system pressure stability.

2. The role of the bottom valve in the pumping device
In the pumping device, especially the centrifugal pump system, the check valve is often used as a bottom valve. The bottom valve is installed at the bottom of the pump suction pipe, close to the water source. Its main function is to prevent the water in the water source from flowing back into the pump through the pipe after shutdown. If this phenomenon occurs, not only will the pump fail to establish the necessary suction pressure due to idling when it is started next time, but it may also cause damage to the pump body and pipeline due to the water hammer effect. By installing a foot valve, the water flow can be effectively cut off even after the water pump stops working, avoiding the above problems, thereby extending the service life of the pump and improving the overall reliability of the system.

3. Double protection: combined application of check valve and stop valve
In some occasions with extremely high safety requirements, a single type of valve may not be able to meet all the needs of the system. At this time, the combined use of check valves and stop valves becomes an ideal choice. The stop valve is a valve that can completely cut off the flow of fluid. Through the manual operation handle, the flow of the medium in the pipeline can be precisely controlled. Installing the check valve and the stop valve in series can form a solid safety line of defense.

Under normal operating conditions, the check valve is responsible for automatically preventing the backflow of the fluid, while the stop valve is in a fully open state, which does not affect the normal circulation of the fluid. Once the system needs emergency shutdown or maintenance, the operator can quickly close the stop valve and completely cut off the fluid channel. Even if the check valve fails for some reason, it can effectively prevent the fluid from continuing to flow or backflow, avoiding potential safety risks and property losses. This dual protection mechanism is particularly important in high-risk industries such as chemicals, petroleum, and electricity. It ensures that the system can remain in a relatively safe state even in extreme situations.

4. Selection and maintenance of check valves
In order to ensure that the check valve can fully play its protective role, correct selection and maintenance are also critical. When selecting, it is necessary to consider factors such as the properties of the medium (such as temperature, pressure, corrosiveness), pipeline size, system working pressure, and expected service life. In terms of maintenance, regular inspection of the wear of the valve disc, cleaning of impurities inside the valve body, and inspection of the integrity of the sealing surface are all essential steps. In addition, for check valves installed in key positions, it is also necessary to consider installing bypass pipes and vent valves so that manual intervention can be performed when necessary to ensure the flexibility and safety of the system.