What is the initial method to turn off the system?

The initial method to turn off the system involves closing the cylinder and then opening the valve. This method is a systematic approach to ensure that the flow of the substance being controlled is halted effectively. By first closing the cylinder, you prevent any further input of the material into the system, which is critical for safely managing the operation. Once the cylinder is closed, opening the valve allows for any existing pressure or contents to safely vent or be controlled, thereby stabilizing the system.

In fire safety practices, it’s crucial to ensure that all potential hazards are mitigated in a controlled manner, and this method provides a logical sequence to achieve that. It also emphasizes the importance of following safety protocols to prevent accidents during system shutdowns.

Other options may not provide the assurance needed for a safe and effective shutdown, and some methods could potentially result in unwanted pressure build-up or operational hazards if not executed in the correct order.