At what pressure range does a safety valve set to pop at 71-300 psig operate?

The correct response indicates that a safety valve set to pop at a pressure in the range of 71-300 psig will operate at 3% over the set pressure. This means that if the valve is set to a specific pressure within that range, it is designed to open at a pressure that slightly exceeds the setpoint, helping to prevent dangerous overpressure conditions in the boiler system.

Safety valves are critical components in maintaining the integrity of high-pressure boilers. They are calibrated to release pressure automatically when it exceeds a predetermined limit to ensure the safety of the boiler and prevent potential catastrophic failures.

The specification of operating at 3% over is a widely accepted industry standard, ensuring that there is a defined margin to account for any fluctuations in pressure within the system. For instance, if a valve is set at 200 psig, it would be expected to open at approximately 206 psig (which is 3% over 200). This margin is essential for reliable safety performance, providing a balance between allowing normal operation while ensuring that pressure limits aren't exceeded.

Understanding this operating characteristic is crucial for anyone involved in boiler operation, as it illustrates the importance of properly calibrated safety devices and their role in protecting against overpressure incidents.