Why are check valves used in the discharge system?

• A. They speed up water flow.
• B. They reduce wear on hoses.
• C. They prevent air from entering the system.
• D. They prevent reverse flow, help maintain pressure in the lines, and protect equipment from backflow damage.

Answer: (D)

Check valves act as one-way gates that allow flow in the discharge direction and automatically close if flow tries to go backward. In a discharge system, this prevents backflow when the pump stops or downstream pressure pushes against the line, which helps keep the line pressure more stable and maintains the pump’s prime. It also protects equipment—pumps, seals, hoses, and fittings—from damage that can occur if liquid reverses direction, such as pressure surges or backflow into components not designed to handle it. They don’t speed up flow or primarily prevent air entry; their main job is to control flow direction, stabilize pressure, and guard the system against backflow damage.