Which equipment detectors must be replaced or repaired immediately if they fail in service?

• A. 243 - Main return airway and return airway in a ventilation split
• B. 244 - Intake airway intersecting with longwall face
• C. 243A - Longwall return airway generally (150m TG sensor)
• D. All of the above

Answer: (D)

In underground coal mining, detectors are there to spot dangerous conditions and you must act fast if any of them fail. The locations described are all critical monitoring points, so a failure in any one of them creates a gap where gas levels or fire risk can go undetected.

In the main return airway and the return airway within a ventilation split, detectors track gas concentrations and air quality as the air moves back toward the surface. If one fails, you lose timely information on whether methane, CO, or other hazards are rising in that important path.

Where the intake airway intersects the longwall face, gas can accumulate or migrate toward the working area. A failed detector here means you might not notice a dangerous gas buildup near the face, which is a high-risk zone.

The longwall return airway with a sensor placed at intervals (such as every 150 meters) provides ongoing monitoring across that extended section. If this detector fails, a large portion of the return path goes unchecked, increasing the risk to workers.

Because each of these locations serves as a critical monitoring point, any detector failure must be addressed immediately—repaired or replaced—to maintain continuous safety coverage. That’s why all of the above detectors must be repaired or replaced without delay.