Check valves are also known as backflow valves, backstop valves, back pressure valves and check valves. These valves are automatically opened and closed by the force generated by the flow of the medium itself in the pipeline; it is an automatic valve. Check valves are used in piping systems, and their main role is to prevent backflow of media to prevent the pump and its driving motor reversal, as well as the release of media in the container. Single-valve rotary check valve, the closing member of the valve flap around the valve seat outside the pin rotation, you can realize the opening and closing process of the valve.