Which action must the AFS take if a CNG cylinder is deemed an immediate danger?

When a CNG cylinder is identified as an immediate danger, the necessary action is to require immediate removal or disconnection. This response is crucial because allowing a potentially compromised cylinder to remain in service poses significant risks, including gas leakage or explosion, which can jeopardize the safety of personnel and the surrounding environment.

Immediate removal or disconnection ensures that the dangerous cylinder is taken out of service promptly, preventing any further risk while safeguarding both the operator and the public. This action is in line with safety protocols and regulations for handling hazardous materials, emphasizing the importance of quick and decisive measures when dealing with situations that could lead to emergencies.

The other options do not adequately address the urgency of the situation. Renaming or sealing the cylinder would not mitigate the immediate risk, while conducting regular maintenance is more of a proactive measure rather than an emergency response. In scenarios where there is a clear and present danger, swift action is paramount, making immediate removal or disconnection the correct response.