What is the role of the pressure relief valve in a boiler?

The pressure relief valve in a boiler plays a crucial safety role by preventing the boiler from exceeding its maximum design pressure. When the boiler’s pressure surpasses a safe threshold, the pressure relief valve automatically opens, allowing steam or water to escape. This action helps to reduce the pressure within the boiler system, thereby protecting the integrity of the boiler and preventing potential explosions or failures.

Maintaining a safe operating pressure is vital for the efficient and safe functioning of a boiler. Hence, option B is correct as it accurately describes the function of the pressure relief valve in alleviating excess pressure to ensure that the boiler operates within safe limits. The other options do not accurately represent the valve's purpose, as the pressure relief valve does not serve to increase pressure, maintain constant pressure during operation, or directly prevent temperature fluctuations. Its primary role is specifically focused on pressure management for safety.