What is the purpose of a discharge check valve in a fire pump system?

• A. To monitor flow.
• B. To regulate suction pressure.
• C. To prevent backflow and help maintain discharge pressure when the pump stops.
• D. To drain the discharge line.

Answer: (C)

The main idea is that the discharge check valve stops reverse flow and keeps the discharge side charged when the pump isn’t pumping. When the fire pump shuts off, water in the discharge piping would tend to push back toward the pump and potentially drain away, causing a drop in discharge pressure and making restart slower. The check valve prevents that backflow, preserving pressure in the discharge line so water is ready at the required pressure when the system is needed again. This also helps reduce water hammer and protects against loss of prime. It’s not used to monitor flow or regulate suction pressure—that’s handled by other devices—and it isn’t a drain device; a separate drain path is used if the line needs to be vented or emptied.