What is the purpose of a high-limit switch in boiler operation?

The high-limit switch in boiler operation plays a critical safety role by monitoring the temperature of the boiler system. Its primary purpose is to shut down the boiler if temperatures exceed safe limits. This feature is crucial because excessive temperature can lead to dangerous conditions, including the risk of boiler explosion or damage to the boiler components.

When the system detects that the temperature has surpassed the pre-set safe threshold, the high-limit switch activates, interrupting the operation of the boiler to prevent potential hazards. This automatic safety mechanism ensures that the boiler operates within safe parameters, protecting both the equipment and the facility.

In terms of the other options, controlling water levels is managed by different components such as the water level control systems; maintaining optimal temperature levels is part of the broader control strategies that include the low-water cut-off, but is not the sole purpose of the high-limit switch itself; and managing fuel supply levels pertains to controls associated with fuel feed or combustion operations, which operate independently from the temperature safety mechanisms.