Which device prevents overpressure by releasing fluid when the pressure exceeds a set limit?

• A. Relief Valves
• B. Check Valves
• C. Gate Valves
• D. Isolation Valves

Answer: (A)

This is a pressure-relief device. Its job is to protect a system from overpressure by venting fluid automatically when the pressure reaches a preset limit. In normal operation it stays closed; once the set pressure is reached, a mechanism (often spring-loaded) opens, releasing fluid through a relief path to lower the pressure back toward safe levels. When pressure drops, it re-seats to stop venting.

This differs from the other options: a check valve prevents flow in the reverse direction but doesn’t relieve overpressure; gate valves and isolation valves are shut-off devices that block flow and don’t automatically vent pressure.