The meeting was the fourth of five held since mid-2005 to gather input on where the industry is heading with regards to SCSR innovations; a fifth has been scheduled for March 12 in Denver, Colorado.

Representatives of the US Mine Safety and Health Administration as well as the National Institute for Occupational Safety and Health provided a history of the research done, including the latter's Long Term Field Evaluation (LTFE), which began more than two decades ago when the agency was known as the US Bureau of Mines.

While filter self-rescuers were the most commonly found units before 1981, a consistent need for smaller, lighter units over the years has brought the current group of approved rescuers down to five: Ocenco M-20 and EBA 6.5, the CSE SR-100, Draeger's Oxy K Plus, and the Life Saver 60 by MSA.

Additionally, random testing of SCSRs since the LTFE kicked off in 1983 has grown from 50 yearly from a limited pool of only mines that cooperated with the agency to current random sampling of about 400 emergency respirators annually for review.

The groups' public workshop meetings have also been incorporated into research efforts; NIOSH representatives noted many of the comments received in the last few years have been taken to a peer-review level so that they can be integrated into a report by the agency.

From the last 25 years of research, its partnerships with other industry groups such as the United Mine Workers of America, manufacturers and others have allowed many lessons to be learned. Among them: a miner's confidence in SCSRs depends on two vital factors the unit's reliability and the amount of training he has had on using the rescuer.

Another key item is one that has seen a resurgence of discussion amid a growing rescue chamber market -- that escape is the primary strategy for survival. In some cases, miners may need more than one unit per person to make it safely to the surface, and workers need to be educated on barricading as a last resort when traveling out is not possible.

New technology

Two SCSR and emergency respirator producers were on hand at the workshop to discuss new technology being evaluated, Pennsylvania firms Technical Products (TPM) and CSE. Both said their work was not merely paper-based.

TPM's Doug Kimball presented information on the company's dockable self-rescuer, on which it has teamed with Micropore for scrubber development. Its design includes multiple safeties, including an inability to detach a "live" supply of air.

The donning of a dockable unit, he noted, allows for on-demand use and an unlimited supply of air for escape with cartridges transfer that can be completed without breaking a seal. The heat generated by the unit will also be less than that of current offerings and it will not be susceptible to moisture.

The company is currently undergoing adjustments in the unit's design to make it the most ergonomically feasible for the industry. Kimball said the company hopes to be in testing within several weeks and in full production by the third quarter of this year.

CSE representative Sean Tremba discussed the company's Advanced SCSR project, a conceptual hybrid self-rescuer unit based on its very popular SR-100. It has put a prototype through the paces on its breathing simulator and anticipates the resulting technology will be capable of aiding workers for an indefinite duration providing a sufficient scrubber supply is available.

Tests performed by CSE include a two-hour drill at a work rate equivalent to a 3mph walk and assuming 5% carbon monoxide concentration underground. Results lead to an enhanced scrubbing design that keep levels in check while the worker uses the split-designed (filter and SCSR compartments) rescuer; the miner will not be required to switch between the two sides.

Looking ahead, Tremba said CSE would be finalizing the design of the filter compartment and the chemical bed to meet the requirements for outside airflow. It also wants to develop criteria for the unit's performance and testing, and anticipated NIOSH testing will begin within 3-5 months; the final unit will be about two-thirds the size of its SR100.

For more information on the research and development underway by TPM and CSE, check out the May edition of Coal USA Magazine.