Two years of testing have found a critical defect in a certain model of emergency breathing devices used in U.S. coal mines, but federal regulators have no immediate plans to remove the more than 70,000 air packs that could remain in use.
The SR-100 self-contained self-rescuers are belt-worn air packs about the size of three cake-mix boxes. They hold chemicals that help recycle exhaled breath, giving miners about an hour of oxygen and, hypothetically, time to seek refuge or escape from a fire or explosion.
The Charleston Gazette said the National Institute for Occupational Safety and Health issued a report concluding the model manufactured by CSE Corp. of Monroeville, Pa., failed too many tests and therefore has a critical flaw.
NIOSH says five out of 500 randomly sampled SR-100 units had oxygen starters that failed. Under federal rules, no more than three in 500 can fail for NIOSH to remain confident.
The failure rate, the report said, means the units “no longer conform to the minimum requirements for the certification.”
CSE “could not identify a systemic cause or otherwise confine the failure to within certain lots,” the report said. “Therefore, the failure could exist among all field-deployed units.”
CSE President Scott Shearer said the company voluntarily stopped production of the SR-100 when internal quality-control teams identified problems. It has since redesigned the starter system and replaced the device with the SRLD model.
“We changed out the guts of the unit,” Shearer said, “and made further improvements to internal and external parts so the engine is beefed up.”
The new model holds more chemicals, he said, and provides more oxygen at a faster rate.
NIOSH said it’s discussing the problem of the old air packs with the Mine Safety and Health Administration, which didn’t immediately comment.
In 2010, CSE said it had recalled about 4,000 suspect units but later acknowledged it hadn’t ordered coal companies to stop using them.
Shearer reiterated his commitment to working with the federal agencies but said he’s had no directives from either so far.
He also said the number of SR-100s in use is now likely fewer than 70,000. Some have likely been replaced with competitors’ devices, he said, while operators have likely removed others because of “normal wear and tear and attrition.”
The old units are believed to have failed in at least one major mine disaster.
Sago Mine survivor Randal McCloy told investigators that several SR-100s his crew was carrying failed after a 2006 explosion that trapped 13 men. Only McCloy survived the 40-hour wait for rescuers.
The device has long been the focus of complaints from miners who worried that it either started slowly or wouldn’t start at all.
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