Foot Valve
Foot valve belongs to the lift check valve, installed in the bottom of the suction pipe of centrifugal pumps, so it is called "foot valve". Before the pump starts, the valve flap is closed due to self-weight, which can fill the suction pipe on the top of the bottom valve with water. After the pump starts, the suction in the suction pipe will bottom valve flap lift, so that the water flow into the pump. After stopping the pump, the suction disappears and the bottom valve closes by itself.
Overview
Principle:
The principle of a foot valve depends primarily on the difference in fluid pressure and the force of the spring. When the fluid pressure exceeds the spring force, the valve is pushed open, allowing fluid to pass. When the fluid pressure drops below the spring force, the flapper is pushed toward the seat by the spring, closing the fluid passage. In this way, the foot valve prevents backflow and ensures that the fluid in the piping or vessel is directed in the same direction.
Drawing:
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