How do pressure relief valves function in a boiler?

Pressure relief valves are essential safety components in a boiler system. They function primarily to open and release excess pressure from the boiler when it reaches a predetermined limit, which helps prevent potentially catastrophic failures such as boiler explosions. The design and operation of these valves ensure that if the pressure within the system exceeds safe levels, the valve activates to vent steam or fluid, thereby reducing the pressure to within safe operating parameters.

The critical aspect of pressure relief valves is their role in maintaining safety. If the pressure were to continue to rise without any means of release, it could lead to a failure of the boiler, resulting in significant damage and safety hazards. Therefore, option A accurately encapsulates the vital safety function of pressure relief valves in boiler operation.