The agencies have been conducting a long-term investigation of the company’s SR-100 rescuers, one of the most popular models in underground mining.

“The NIOSH Long-Term Field Evaluation program has identified some SR-100 units with end covers that can be extremely difficult to remove, particularly units manufactured between October 2008 and December 2008,” the agencies said Friday.

In the event the top or bottom covers cannot be removed from the SCSR once the security band has been released, or if it is difficult to remove the pieces, miners should set the unit aside and get a secondary SCSR.

Doing so, officials said, may provide the quickest protection in the event of an emergency.

Under the regulations of the MINER Act of 2006, all underground coal operations must maintain caches of additional SCSR units.

Late last month, NIOSH announced another issue it had found with the SR-100 after a failure analysis on the units’ oxygen starters. The agency feels the problem could stem from manufacturing tolerances in the pipe thread and the application of the sealant used in the assembly of the oxygen starter, thus creating the potential for some starter assemblies to leak.

“The failure rate of the oxygen starter is not well-characterized in the field deployed units,” researchers said.

“NIOSH and MSHA feel it is necessary to accurately determine this failure rate within the population of field-deployed units,” they said, adding that they would collect samples from units in use at US operations.

Earlier this year, MSHA issued an instruction letter to its enforcement personnel outlining a temporary production halt of the SR-100 SCSRs.

In an August 31 alert distributed to the industry via its web site, the agency said that CSE was investigating the potential that the units’ breathing bag might not receive the optimum amount of necessary oxygen to fully inflate when started via the oxygen cylinder.

The issue was discovered through the company’s quality control program. It noted that the possible issue with the component involved a shipment of oxygen cylinders from its supplier.

“Until the root cause is determined and corrected, CSE Corporation is temporarily suspending sales of the SR-100 SCSRs,” MSHA said in the procedure instruction letter, or PIL.

“Mining companies utilizing these units may need to make adjustments to provide miners with the required number of SCSRs to comply with 30 CFR Part 57 and 75. Purchasing units from a different manufacturer to meet the required number of SCSRs is acceptable, provided all miners have received required training on the new units.”

Should all SCSR developers exhaust inventory and operations are not able to obtain the adequate number of supplies, MSHA said it would accept purchase orders with a 60-day confirmed delivery date.

A printable, distributable copy of last week’s announcement is available on the MSHA web site.