Structure and Working Principle of Cast Iron Flap Valve: It consists of a flap valve seat, a flap door plate and other components. The cast iron flap valve is only used for one-way flow circular and square water outlets. It has a compact structure and reliable operation, requiring no manual operation. The opening and closing force comes from water source pressure: it opens when the water pressure inside the flap valve is greater than the external pressure, and closes otherwise. 1.Used for pipeli