Cast iron wafer check valves are used in piping systems. Their main functions are to prevent medium backflow, reverse pumps and their driving motors, and discharge of medium in containers. Stainless steel check valves can also be used in pipelines to supply auxiliary systems where pressure may rise to more than the pressure of the main system. Stainless steel check valves can be used in pipelines of various media according to different materials.
The working characteristics of cast iron wafer check valves are that the load varies greatly and the small frequency of opening and closing. Once closed or opened, the service cycle is very long, and the movement of moving parts is not required. But once there is a "switch" requirement, it is necessary to move flexibly, which is more stringent than the common mechanical movement.
Because check valves is used in many practical occasions, check valves are qualitatively determined to be used for quick closure. At the moment of the check valve closure, the medium moves in the direction. Following the closure of the valve disc, the medium drops rapidly from the maximum backflow velocity to zero, while the pressure rises rapidly. This results in the phenomenon of "water hammer" which may damage the pipeline system.
The water hammer problem of check valves is more prominent for high-pressure pipeline systems with multiple pumps. Water hammer is a kind of pressure wave in the transient activity of pressure pipeline. It is a hydraulic shock phenomenon caused by the pressure jump or drop caused by the change of fluid velocity in pressure pipeline.
The physical reasons are the combination of the incompressibility of fluid, the inertia of fluid motion and the elasticity of pipeline. In order to prevent the hidden danger of water hammer in pipeline, some new structures and materials have been adopted in the design of check valves for many years. Great progress has been made in minimizing the impact force of water hammer while guaranteeing the combined function of check valves.