Relief valve prevents excessive pressure.

• A. Relief valve prevents excessive pressure.
• B. Relief valve prevents backflow.
• C. Relief valve controls throttling.
• D. Relief valve seals the line permanently.

Answer: (A)

Overpressure protection is the idea here. A relief valve stays closed under normal pressure and automatically opens when the system pressure reaches a safe preset limit, venting excess fluid to a safe discharge path. When the pressure drops back down, it reseats and stops venting. This keeps piping, pumps, and equipment from being damaged by too much pressure. It isn’t intended to prevent backflow— that’s the job of backflow prevention devices. It also isn’t meant to regulate or throttle flow— that’s what control valves do. And it isn’t a permanent seal; it’s a safety valve that relieves excess pressure and then closes again once it’s safe.