Rescue Chambers Feasible for Most Underground Coal Mines: NIOSH
A new report from NIOSH's Office of Mine Safety and Health summarizes progress to date at fashioning refuge chambers that will protect underground coal miners in emergencies, allowing them to stay alive until escape or rescue is possible. No documentation is available at this point to illustrate successful use of a refuge chamber, but there is no evidence to suggest they are impractical, the office writes in the 16-page report. It is available at www.cdc.gov/niosh/mining/mineract/pdfs/Report_on_Refuge_Alternatives_Research_12-07.pdf.
The report calculates costs, recommends design and performance parameters, and details how four manufacturers' designs performed in 96-hour tests done to see whether they could meet West Virginia's performance standards for chambers to be used in its coal mines. Oxygen flow, carbon dioxide concentration, deployment time, and heat dissipation inside the chambers were tested. Three of the four chambers tested could not maintain carbon dioxide below the level specified by West Virginia's criteria, but their levels were within a range recommended by this report (a maximum concentration of 1.0 percent, not to exceed 2.5 percent for any 24-hour period). Two of the four tested chambers could not supply oxygen for the duration of the test. "In most cases, but not all, these shortcomings should be correctable, or have already been corrected, with minor technical changes, the addition of clear instructions, and/or improved engineering," the report says.
It concludes that the cost to move shelters inside a mine is the largest cost component -- anywhere from $256,400 to $341,200 in present value, based on 30 to 90 moves in a year. It is not economically feasible to move in-place shelters, which would be connected through boreholes to the surface and thus to essential services, but their strengths compared to portable chambers "are so significant that consideration should be given to allowing extended distances, if in-place shelters are used to provide refuge for [coal] face workers," the report says. Approval or certification of all refuge chambers is needed and should be based on lab or field testing, it says, while in-place chambers should be inspected and certified to meet at least the applicable requirements in this report's Table 1.