What is the primary reason for using a foot valve at the submerged end of a suction pipe?

Using a foot valve at the submerged end of a suction pipe is primarily to keep the pump primed. A foot valve is a type of check valve that allows for water to flow into the pump while preventing it from flowing back out when the pump is not operating. When the pump is turned off, gravity can cause water to siphon back down the suction line, leading to potential loss of priming.

By having a foot valve installed, it remains submerged in the water source and keeps the suction line filled with water. This continuous presence of water helps maintain the necessary conditions for the pump to start up again without needing to re-prime, which can be time-consuming and labor-intensive. In summary, the foot valve’s role in maintaining the pump’s primed state is crucial for operational efficiency and longevity.