In his written presentation, Sapko produced a chart that showed barrier requirements in many other mining countries, including Australia, Germany, Poland and the Soviet Union.
His report also listed examples where barriers had proven successful:
| At the Fenton Colliery in the U.K. in 1963, barriers controlled the spread of a methane explosion at the working face of the mine.
"There was clear evidence that the flames had actually reached the barrier," the report said. "A [coal] transfer point was located just [beyond] the barrier where there were ample deposits of coal dust, and there was little doubt that without the operation of the barrier the explosion would have increased in intensity and traveled much further."
| Also in 1963, at the Mainsforth Colliery in Durham, U.K., a rock-dust barrier on the mine intake airway "was completely discharged and without doubt arrested the spread of flame."
| In March 1984 at a mine in Belgium, water barriers helped contain the damage from an explosion that killed seven men.
"The investigation indicated that the first five sets of distributed barriers operated ... and arrested the explosion," the report said. "This was suggested as the reason why men who were located 290 meters from the face were not injured."
| On July 16, 1986 at the Moura Mine in Australia, water barriers helped stop an explosion that had already killed 13 miners, preventing even more deaths.
Sapko notes that barriers are more difficult to use in smaller mines with "low coal" seams, and in some mines using "room-and-pillar" mining configurations. But, he said, they can be more effective in more mechanized mines, especially those using longwall machines. Research on the devices continues to help them improve, he said.
"The overall direction in research on mine explosion prevent seems to be headed in the right direction," he wrote. "But it is disappointing that quantum improvements in the practice of rock dusting do not appear imminent."
Reach Ken Ward Jr. at kw...@wvgazette.com