If the detector located between the LW face and intake airway exceeds 2%, what must be tripped?

• A. Electricity supply to LW equipment in LW face and intake airway
• B. Alarm only
• C. The ventilation fans
• D. The central control room

Answer: (A)

When methane in the zone between the longwall face and the intake airway reaches a hazardous level, safety systems are designed to automatically remove potential ignition sources. Reaching the 2% threshold triggers cutting the electricity supply to the longwall equipment located in that area. This rapid de-energization reduces the risk of an ignition turning into an explosion, which is the primary reason for tripping power in response to a high gas reading.

An alarm by itself alerts personnel but does not eliminate the ignition source, so it isn’t sufficient on its own. Ventilation fans and the central control room play important roles in managing safety, but the required immediate action in response to the detector reading is to trip the electrical supply to the relevant equipment to stop potential ignition sources.