On August 27 the Associated Press reported a handheld gas monitor had documented explosive methane levels associated with the April 5 UBB blast that killed 29 workers.
“The detector referenced in the Associated Press report was one of two detectors previously discussed by Massey and described in a report by the Wall Street Journal on August 10, 2010,” a company spokesperson said Monday afternoon.
“The company also provided information on the handheld detectors to UBB family members in a family meeting held on August 2.”
The producer pointed out that the detectors located underground at the Raleigh County operation during the federal investigation of the blast were actually recovered just after the incident and tested by US Mine Safety and Health Administration staff on July 8.
The monitors are designed to continuously evaluate methane levels as well as carbon monoxide, oxygen and temperature.
The highest readings for each of those factors are recorded on the unit every three minutes.
The maximum reading for methane specifically on the monitors is 5%, as well as 500 parts per million of carbon monoxide.
Methane is considered explosive in a 5% to 15% concentration, and carbon monoxide is caused by incomplete combustion.
“Recorded data show that both detectors surged from zero to maximum readings for methane (5 per cent) and carbon monoxide (500 parts per million) within a three-minute span near 3pm on April 5, 2010,” Massey officials said.
“Actual levels of methane and carbon monoxide could have been higher, as these detectors do not record levels higher than 5 per cent for methane or 500ppm for carbon monoxide.”
Another feature of the detectors used at UBB, the company noted, is the recording of alarms every 15 seconds.
They range from “low range” alarms at 0.5% methane and 35ppm carbon monoxide to “high range” alarms at 1% methane and 100ppm carbon monoxide.
Conversely, “over range” alarms are triggered at 5% methane and 500ppm carbon monoxide.
“Testing indicates that one detector, found at the longwall face, went from no alarm to an ‘over range’ alarm for methane and carbon monoxide in less than 15 seconds near 3pm,” Massey said.
“The second detector, found around 3000 feet from the first detector, recorded a ‘high range’ alarm of 1 per cent for methane and an ‘over range’ alarm of 500ppm for carbon monoxide. Within 16 to 30 more seconds, the detector recorded an ‘over range’ alarm for methane [and] this also occurred near 3pm.”
As it continues to investigate cause and keep the families informed about the latest details, Massey said it chose to publicly provide the “very important” information and details.
“The data strongly suggest that these detectors were exposed to a sudden inundation of methane and a simultaneous or near simultaneous fire or explosion, as measured by high levels of carbon monoxide,” the producer said.
