Reversed flow of qi check valve is how to play its role?

Extraction non-return valve is mainly used in thermal power plant steam turbine extraction system, prevent the backflow medium or water, water pumps and other important facilities protection for steam turbine, its performance requirements for the pipeline medium backflow, power outages, accidents are very state, the instantaneous close the valve, closing time is less than 0. 5 seconds. Extraction non-return valve is also known as reflux valve, non-return valve, back pressure valve, check valve. This type of valve is to rely on the force created by the flow of the medium itself in the line of open and close automatically, belongs to a kind of automatic valve. Extraction non-return valve used in pipeline system, its main function is to prevent the backflow medium, to prevent the pump and its pattern in reverse driving voltage, and the discharge of the containers within the medium. Extraction non-return valve can also be used to give the pressure could rise to more than the main system of auxiliary system supply line. According to different material, the extraction check valve can be applied to all kinds of medium on the pipeline. Extraction non-return valve installed in the pipeline, which become one of the full line of fluid components, the valve opening and closing process will be affected by it in system is influenced by transient flow state; On the other hand, the disc in closing feature and have hair effects on fluid flow state. The working characteristics of extraction non-return valve is load change is big, open-close frequency is small, in closed or open, apply cycle is very long, and does not require moving parts movement. But once again the 'switch' requirement, you must move flexibly, the requirement of the more common mechanical movement is more demanding. Due to extraction non-return valve in the most practical use, qualitatively determine for fast shut down, and at the instant of the check valve closed, medium is a direction, with the disc in closing, the medium from the rapid rate of maximum back down to zero, while the pressure rise rapidly, generating possible damage to pipeline system of 'water hammer' phenomenon.