Flap valves are used at the exit end of the discharge pipeline of a pumping system where water is pumped from a river / reservoir to a canal. The purpose is to prevent the back flow of water from the canal having high silt or foreign material flowing back into the discharge pipeline of pump, when the pump trips. The flap of the valve is designed in such a way that

	It opens with the working pressure of the pump and also due to the moment exerted by the dead weight arrangement which is provided on the same shaft where the flap of the valve is located / supported.