What is a relief valve on a pump and why is it used?

• A. A relief valve controls flow rate to the nozzle
• B. A relief valve on a pump automatically opens at a set pressure to bypass water and prevent overpressure
• C. A relief valve increases discharge pressure when needed
• D. A relief valve filters debris from the water

Answer: (B)

A relief valve is a safety device in a pumping system that automatically opens when system pressure reaches a preset limit, allowing fluid to bypass the pump or return to suction. This prevents overpressure that could damage the pump, piping, seals, or other components, and helps keep operating pressure within safe bounds as flow demand changes or downstream conditions vary. It closes again once pressure drops below the set point, resuming normal operation. It does not control flow to a nozzle, increase discharge pressure, or filter debris—those are handled by other components like flow control valves, pressure regulators, or filters.