Federal regulations require the installation of refuge alternatives (RAs) in underground coal mines to ensure miners’ survivability after a fire or an explosion where escape is impractical or even impossible. Both fires and explosions can generate dangerous or even lethal levels of carbon monoxide (CO) in a mine. As part of their function, RAs must be able to isolate miners from a CO-contaminated mine environment and to purge any CO that might enter the RA as miners enter it. In 2018, researchers from the National Institute for Occupational Safety and Health (NIOSH) conducted purging research in a built-in-place (BIP) RA with a borehole air supply by testing 12 different mixing ventilation system configurations (MVSCs). Recently, NIOSH researchers evaluated the use of a thermal displacement ventilation system configuration (TDVSC) to purge a 60-person BIP RA using a borehole air supply. As in previous research, NIOSH researchers tested the TDVSC with the flow rates of 750 SCFM and then 1,000 SCFM. For each of the flow rates, the results showed that the average purge time for the more expensive TDVSC is within two minutes of the average purge times of previously tested MVSCs. Manufacturers can use this information to not only pursue 30 CFR Part 7 approval from the Mine Safety and Health Administration (MSHA), but also to determine the most practical method to purge contaminants inside RAs.

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