Under what condition must persons be withdrawn if the gas monitoring system fails?

• A. If there is a SOP and sufficient portable gas detectors to continuously monitor the area.
• B. If there is no SOP or insufficient portable gas detectors to continually monitor the part, making risk unacceptable.
• C. Only if methane concentration exceeds 5%.
• D. Never withdraw until a supervisor approves.

Answer: (B)

When gas monitoring equipment fails, the key issue is whether there is a plan and enough portable detectors to keep a continuous watch on the area. If there is no SOP to guide how to handle the failure, or if there aren’t enough portable detectors to monitor the space continuously, the risk becomes unacceptable and workers must be withdrawn to stay safe. If an approved SOP exists and there are sufficient portable detectors to maintain continuous monitoring, operations can continue under those arrangements with appropriate controls. The decision isn’t based on a fixed gas concentration like 5% methane, and waiting for supervisor approval would delay a necessary safety action.