Experimental study of fire behaviors influenced by sealing time in coal mine blind roadway fires

Firefighting effectiveness of sealing and the safety of rescue personnel are closely related to emergency response time. The emergency response time can be reflected by the sealing time, which refers to the time when sealing walls are built initially after a fire occurs. This study experimentally investigated the fire behaviors and smoke temperature of coal mine blind roadway fires under different sealing times in a small-scale model. It was found that the mass loss rate continues to increase, and the mass loss of the fuel still exists after the fire is extinguished. Besides, when sealing time - t⩾150 s, self-extinction time - T1 increases linearly with sealing time. For the 6 cm × 6 cm and 8 cm × 8 cm oil pans, burning time after sealing begins- T2 decreases with increasing sealing time, which is opposite to the case when the size of the oil pan is 4 cm × 4 cm. A blind roadway fire inevitably undergoes a transition from a fuel-controlled fire to a ventilation-controlled fire, during which the CO concentration will significantly increase. In the sealed condition, the CO concentration is significantly higher at the sealing time of 0 s than at other sealing times. In addition, the temperature inside the blind roadway is higher when it is not sealed compared to the sealed condition. In the sealed condition, the overall temperature in the roadway increases with the sealing time. The research conclusions provide theoretical guidance for extinguishing fires in blind roadways.