Which valve is used to regulate pressure and is often attenuated by a spring?

• A. Relief valve
• B. Safety valve
• C. Globe valve
• D. Check valve

Answer: (A)

The main idea here is how a pressure-relief device keeps a system from overpressurizing by using a spring to set its opening point. A relief valve is designed to hold the line at a chosen pressure; when the system pressure rises above what the spring is set to resist, the valve pops open and lets fluid escape. This venting continues until the pressure drops back to the spring setting, at which point the valve reseats. The spring is essential because it provides the adjustable reference force that defines the pressure at which the valve begins to relieve.

Globe valves are used for throttling and regulating flow, not to limit pressure, so they aren’t the device that maintains a set pressure. Check valves prevent backflow and don’t regulate pressure at all. Safety valves are also spring-loaded and relieve overpressure, but they are typically used for protection against sudden spikes, often venting to atmosphere and not continuously regulating system pressure like a relief valve does. In the context of regulating pressure with a spring-defined set point, the relief valve is the best fit.