Check valves are characterized by their large load variations and relatively low opening and closing frequency. Once a check valve is in a closed or open state, its service life is long, and it typically requires no movement of moving parts. However, when a "switching" requirement arises, the check valve must be able to operate flexibly, a requirement even more stringent than common mechanical movements.
In practical applications, check valves are usually characterized as fast-closing valves. At the moment of closure, the medium flows in a directional manner. As the valve disc closes, the backflow velocity of the medium rapidly drops from maximum to zero, while the pressure rises sharply. This phenomenon is called "water hammer," which can damage the pipeline system. Water hammer is particularly prominent in high-pressure pipeline systems where multiple pumps operate in parallel.
Water hammer is a pressure wave caused by transient flow in a pressure pipeline, resulting from a pressure surge or drop caused by changes in fluid velocity. Its physical cause lies in the combined effects of the fluid's incompressibility, fluid inertia, and pipeline elasticity. To address this issue, designers have incorporated various new structures and materials into the design of check valves, aiming to ensure valve performance while minimizing the impact of water hammer.
