National Public Radio posted a story last night reporting on some of the results of the methane monitor testing being done by investigators looking into Massey Energy’s Upper Big Branch Mine Disaster.

The story is online here.

Howard Berkes, NPR’s rural affairs correspondent, has been closely following developments since the April 5 disaster and has reported on questions surrounding how Massey operated the methane monitoring system at Upper Big Branch.

Last evening’s story reports:

This weekend’s testing of two methane monitors from the Upper Big Branch coal mine in West Virginia has not detected any evidence of tampering, NPR has learned.

The methane monitors were removed from the longwall mining machine believed to be a possible ignition source of the April 5 explosion that killed 29 mine workers. Investigators have been anxious to inspect and test the monitors, given reports that similar safety devices had been disabled on other mining machines in the mine.

Disabling methane monitors permits continued mining of coal even if the monitors malfunction or they detect levels of methane that approach explosive concentrations. The practice is considered dangerous and illegal because monitors are designed to display warnings and shut down mining machines when methane levels get too high.

But, the story adds:

Testing continues next week on a 1,000-foot-long cable, or “tensioner,” that ran between the gas “sniffing” sensor at one end of the longwall machine to a digital readout device at the other end.

Investigators are also testing a data recorder from the longwall mining machine. It contains information about the operation of the mining machine and the monitors at the time of the blast and at least six days before. That testing is taking place at a Joy Manufacturing facility in Franklin, Pa. Joy is a major producer of mining machines.

Berkes observed:

The fact that the monitors are in working condition and do not appear disabled deepens one of the mysteries about the explosion. The blast is believed to have been triggered by the ignition of methane gas, which naturally occurs in coal mines and is especially prevalent in the Upper Big Branch mine. But if the monitors were working properly, the mining machine should have shut down before its cutting blades or other equipment could have provided the spark that presumably ignited the gas.

But, he added:

Investigators are keenly interested in recovering and inspecting two other methane monitors installed on two other mining machines also in portions of the mine hit by the explosion.

These monitors are mounted on much smaller continuous mining machines, and they’re also considered possible sources of ignition. But flooding in the mine has kept investigators from reaching those mining machines so far.

And as we reported the other day in the Gazette, there are a variety of reasons that investigators remain focused on the methane monitoring system at Upper Big Branch.

MSHA is scheduled to provide the Upper Big Branch families with an update on its investigation during a meeting Tuesday night … so stay tuned.