Introduction to Power Station Exhaust Check Valve

Introduction to Power Station Exhaust Check Valve
Check valves are also known as reverse flow valves, check valves, back pressure valves, and check valves. This type of valve is automatically opened and closed by the force generated by the flow of the medium itself in the pipeline, and belongs to an automatic valve.
Check valves are used in pipeline systems to prevent reverse flow of media, reverse rotation of pumps and their drive motors, and release of media from containers. Check valves can also be used on pipelines to supply auxiliary systems where the pressure may rise above the main system pressure.

Check valves can be applied to pipelines with various media depending on the material. A check valve installed on a pipeline becomes one of the fluid components of the complete pipeline, and its valve disc opening and closing process is affected by the transient flow state of the system it is in; Conversely, the closing characteristics of the valve disc have an impact on the fluid flow state. The working characteristics of check valves are large load changes, low opening and closing frequency, long applicable cycle once put into the closed or open state, and no requirement for moving parts. But once there is a "switching" requirement, it must be flexible, which is more demanding than common mechanical movements.
Due to the fact that check valves are qualitatively determined to be used for quick closure in most practical applications, the medium flows in a directional manner at the moment of valve closure. As the valve disc closes, the medium rapidly drops from the rated reverse flow velocity to zero, and the pressure rapidly increases, resulting in a "water hammer" phenomenon that may have a destructive effect on the pipeline system. For high-pressure pipeline systems with multiple pumps connected in parallel, the water hammer problem of check valves is more prominent. Water hammer is a pressure wave in transient flow in pressure pipelines, which is a hydraulic shock phenomenon caused by changes in fluid velocity in pressure pipelines, resulting in pressure jumps or drops. The physical cause of its occurrence is the combined effect of the incompressibility of the fluid, the inertia of fluid motion, and the elasticity of the pipeline. In order to prevent water hammer hazards in pipelines, over the years, new structures and materials have been adopted in the design of check valves. While ensuring the applicability of check valves, gratifying progress has been made in reducing the impact force of water hammer to a very small extent.