If more than one detector fails, what procedure is required?

• A. Nothing, operations continue
• B. Move between detectors to monitor CH4 with PGD
• C. Immediately shut down the mine
• D. Replace all detectors immediately

Answer: (B)

When methane monitoring coverage from fixed detectors is compromised by multiple failures, the immediate priority is to maintain real-time awareness of CH4 levels as you move through the mine. Using portable gas detectors to monitor CH4 between the fixed detectors provides continuous, location-specific readings and offers an early warning if methane begins to accumulate. This keeps workers safe by enabling timely decisions about ventilation adjustments, work sequencing, or evacuations as needed, while maintenance can repair or replace the failed detectors later. The other options either ignore the hazard, impose unnecessary downtime, or assume a complete reset of the system without maintaining monitoring coverage.