What is the purpose of a pressure-relief device on the discharge line?

• A. To filter debris from the pumped fluid.
• B. To protect piping and equipment from excessive discharge pressure when required by design.
• C. To increase discharge pressure during demand surges.
• D. To automatically shut down the pump when pressure is too low.

Answer: (B)

Prevent overpressure in the discharge piping. A pressure-relief device on the discharge line is there to limit how high the system pressure can rise. It monitors the discharge pressure and, once the preset limit is reached, opens to vent fluid to a safe path (such as back toward the pump suction or to a designated drain/recirculation route). This keeps the piping, valves, fittings, and downstream equipment within the design’s pressure rating, preventing damage from surges, closed-discharge conditions, or other conditions that could drive pressure too high. It’s not meant for filtering debris, it doesn’t purposefully increase pressure, and it isn’t an automatic shutdown for low pressure—those functions are handled by other devices.