Read the passage about underground mine ventilation systems. Complete the concluding statement with the word that reflects the only logically supported outcome.
Answer:Deep-mine ventilation systems use dual-fan bulkheads to maintain positive air pressure in active drift headings, preventing explosive methane gas from seeping out of abandoned shafts. If one fan trips offline, an automatic counterbalanced louver closes over its exhaust port to prevent the remaining active fan from pulling air backward through the disabled housing. If this louver jams open during a single-fan failure, the running fan will circulate air in a closed loop within the fan house rather than drawing air through the mine. Under these specific conditions, the air pressure in the active drift headings will 【decrease】.
Answer
decrease (or drop / fall / decline)
The passage establishes that positive air pressure in the headings requires active airflow through the mine. When one fan fails and the isolation louver jams open, the operating fan circulates air only in a localized loop within the fan house. Because fresh air is no longer drawn through the mine, positive pressure cannot be sustained, meaning heading pressure will decrease or drop.
Step-by-Step Solution
Key Concept
Synthesizing Systemic Mechanical Failures to Deduce Environmental Effects
Estimated Time:1m 0s