What is the function of a foot valve in a suction line?

• A. It prevents backflow at discharge
• B. It holds prime in the suction line
• C. It regulates pressure
• D. It vents air from the line

Answer: (B)

The element being tested is how a suction-line valve preserves the pump’s ability to draw water. A foot valve is a one-way valve placed at the end of the suction line (often with a screen). It opens to let water flow into the line as the pump draws, and it closes to prevent water from flowing backward toward the source when the pump stops. This keeps the suction line filled with water, maintaining prime so the pump can start quickly again without re-priming. It isn’t about discharging backflow, regulating pressure, or venting air—the foot valve’s main job is holding prime in the suction line.