The Upper Big Branch mine data recorder has not give any indication of a sudden methane build up before switching off 98 seconds prior to the explosion which killed 29 men in the coal mine.
Ideally the methane recorder would sound an alarm and shut down mining activities if the methane gas approached explosive levels.
The company which owns the Upper Big Branch coal mine is Massey Energy. The mine had been cited at least 17 times by federal mine inspectors for not having methane monitors in proper working order. The Mine Safety and Health Administration agency said that it was concerned when a mine is cited for improperly working methane monitors.
Two such devices were recovered from close to the explosion site. The methane data recorder is now at the Joy Mining Equipment headquarters in Franklin, Mercer County. It will be tested over the weekend to check if the data inputs for methane were functioning properly.
Shortly before the explosion three foremen had reported zero methane in the area, but after the blast high levels of methane were recorded. This is being suspected due to a crack in the mine floor near the longwall.