プライムを保持するためにフットバルブが使用されます

フートバルブは、真空に依存して吸入流体をポンプの入口開口部まで上昇させるポンプシステム内で呼び水を保持するために使用されます。 It is common in rural shallow well water systems, or in private water systems which provide lake water to a summer cottage, where the water level is within perhaps 8 meters vertically of the pump installation location and it is not convenient to place the pump down in the well or below the lake surface, to depend on external air pressure to push water up the intake pipe into the pump’s impeller by evacuating all air from the intake pipe and allow external air pressure pushing on the surface of the water to push water up the pipe.

問題は、ウォーターポンプが空気を送り込むことができず、インペラが十分な効果を発揮できるほど速く回転しないことです。 Often venturi jets are used ahead of the impeller to recirculate a small amount of water internally in the pump housing because the venturi jets are able to move a proportion of air from the intake to the outlet, bypassing the impeller, but the process of pumping all the air out of the standing intake pipe is very slow.

So the solution is to put a one-way check valve at the bottom of the intake pipe which allows water to freely flow into and up the pipe when the pump is running, but will not let any water flow out of the pipe to be replaced by air when the pump is shut off. But rather than using simply a standard check valve, what is usually used is a foot valve which is designed to operate in the vertical position and which has screens designed to keep unwanted solids or debris out of the intake pipe.

フットバルブは、ポンプが作動していないときにシステムからの液体の排出を停止します。はい、システムのプライミングを維持しますが、いいえ、キャビテーションは停止しません。

吸引力が大気圧に達するとキャビテーションが発生し、真空気泡が発生します。キャビテーションは、吸引ラインに制限があるときに発生します。フートバルブはキャビテーションを引き起こす可能性がありますが、それを防ぐことはできません。