What safety devices prevent a boiler from operating once the underground side becomes interrupted during an isolation transfer?

Control and limit devices play a crucial role in ensuring the safe operation of boilers. These devices are designed to monitor various operational parameters, such as pressure, temperature, and flow. When an interruption occurs on the underground side during an isolation transfer, these devices can detect unsafe conditions and shut down the boiler to prevent potential hazards such as overheating, overpressure, or system failure.

For example, if the pressure or temperature exceeds predetermined limits due to an interruption, the control and limit devices will initiate a shutdown sequence. This is vital for maintaining safety standards and preventing accidents in boiler operations.

While pressure relief valves are essential for relieving excess pressure in a system, they do not actively prevent operation in response to interruptions. Flow sensors are designed to monitor flow conditions but may not directly lead to a system shutdown in the event of an isolation interruption. Temperature control devices monitor temperatures but could not be relied upon solely for managing isolation transfers. Therefore, the most appropriate answer regarding preventing boiler operation under these specific conditions is indeed the control and limit devices.