What is installed on recirculating line downstream from turbine-driven fire pumps?

• A. Check valve
• B. Pressure gauge
• C. Venturi
• D. Relief valve

Answer: (D)

When a turbine-driven fire pump runs, the recirculation line returns water back toward a point where it isn’t being discharged to the main system. If the discharge valves are closed or blocked, pressure in that line can rise quickly. A relief valve on the recirculation line opens at a set pressure and bypasses the excess water back toward the suction side, preventing overpressure and protecting the pump and piping. This keeps the pump from overheating and ensures the system remains safe and ready for use. A check valve would only stop backflow, not limit pressure. A pressure gauge simply reads pressure, and a Venturi is used to measure flow or create a pressure drop, not to relieve excess pressure in this setup.