What occurs during the "burner shutdown" process?

During the "burner shutdown" process, fuel flow is stopped and the flame is extinguished. This action is crucial for ensuring safety and efficiency in the operation of the burner. When a burner is no longer required to produce heat, stopping the fuel flow is essential to prevent ongoing combustion and potential hazards such as gas leaks or overheating.

When the fuel flow is halted, the burner naturally extinguishes the flame, leading to a safe shutdown state. This process helps in maintaining control over the combustion process, ensuring that the burner does not continue to operate unintentionally, which could pose safety risks.

The other options involve processes that are either not directly related to shutting down the burner or are performed during different maintenance or operational phases. For example, increasing fuel flow occurs during operation to maintain heat output, cleaning the burner pertains to maintenance and efficiency optimization, while checking the ignition system is part of routine checks but is not a step in the burner shutdown procedure.