Introduction of check valve

Check valves can be used to supply pipelines where the pressure of the auxiliary system may rise above the pressure of the main system. According to different materials, check valves can be applied to pipelines of various media. When the check valve is installed on the pipeline, it becomes one of the fluid components of the complete pipeline. The opening and closing process of the valve flap is affected by the transient flow state of the system in which it is located; conversely, the closing characteristic of the valve flap is again It has an effect on the fluid flow state. The working characteristics of the check valve are the large load change, the small opening and closing frequency, once it is put into the closed or open state, the applicable period is very long, and the movement of moving parts is not required. But once the "switching" requirement is repeated, it must be flexible. This requirement is more demanding than common mechanical movements. In most practical applications, check valves are qualitatively determined to be used for fast closing. At the moment when the check valve is closed, the medium flows in the direction. As the valve flap is closed, the medium quickly drops to zero from the maximum backflow velocity. , And the pressure rises rapidly, that is, the phenomenon of "water hammer" that may have a destructive effect on the pipeline system is generated. For high-pressure piping systems where multiple pumps are connected in parallel, the water hammer problem of check valves is more prominent. Water hammer is a kind of pressure wave in the transient flow in the pressure pipeline. It is the hydraulic shock phenomenon of the pressure rise or fall caused by the change of the fluid velocity in the pressure pipeline. The physical reason is the combined effect of fluid incompressibility, fluid motion inertia and pipeline elasticity. In order to prevent the hidden danger of water hammer in the pipeline, for many years, people have adopted some new structures and new materials in the design of check valves to ensure the applicable performance of the check valve while minimizing the impact of water hammer. Gratifying progress has been made. Check valve refers to the valve that automatically opens and closes the valve flap depending on the flow of the medium itself, and is used to prevent the medium from flowing back. It is also called check valve, one-way valve, reverse flow valve, and back pressure valve. The check valve is a kind of automatic valve, its main function is to prevent the back flow of the medium, prevent the pump and the drive motor from reversing, and the discharge of the container medium. Check valves can also be used to supply pipelines for auxiliary systems where the pressure may rise above the system pressure. Check valves can be divided into swing check valves (rotating according to the center of gravity) and lift check valves (moving along the axis).