Mining Contract: Efficiency Improvement Study of Mine Rescue Breathing Apparatus and Development of an Improved Prototype CCBA

Contract Status & Impact

This contract is complete. To receive a copy of the final report, send a request to mining@cdc.gov.

This contract was funded as part of an interagency agreement program, which provides a formal means for federal government agencies to share and further technology that could apply to and benefit mine safety and health. Through this program, the Office of Mine Safety and Health Research (OMSHR) identifies other government agencies with the knowledge, skills, and abilities relevant to a health and safety gap and works collaboratively with these agencies to identify the type of technology solution desired and to determine specifications for this technology.

The NIOSH-certified closed-circuit oxygen breathing apparatus (CCBA) currently used for mine rescue is a semi-closed type device that contains an oxygen source, a constant mass metering system in conjunction with a demand valve for injection of breathing gas, and an integral chemical scrubber to remove carbon dioxide. With this type of design, oxygen is added at a preset rate not less than 1.5 liters per minute regardless of the user’s actual breathing rate, up to activation of the demand valve. Once the demand valve is activated, gas is added as required by the user.

Under this contract, Naval Sea Systems Command developed an improved mine rescue breathing apparatus. The two current mine rescue rebreathers currently on the market were tested to evaluate their work-of-breathing (WOB) performance. This comparison showed a very low resistive effort relative to industry standards and was not an area of concern for improvement in this development. Existing mine rescue rebreathers use ice for cooling capacity. Mine rescue team training was observed and members were interviewed. It was determined that this rebreather design effort should focus on temperature control without ice and ergonomic issues.

A demonstrator unit was designed and constructed with modular phase change material, a vertical high-pressure oxygen cylinder, and symmetry about the user’s spine. An additional feature of the demonstrator design is the leveraging of a commercial ergonomic harness system and positive pressure demand regulator from a Scott firefighting apparatus.

Based on unmanned testing of the demonstrator unit, the unit was further refined and an engineering development model (EDM), suitable for human testing, was designed and constructed. Unmanned evaluation of the WOB for the EDM was performed at all NIOSH and Navy standard work rates in relation to respiratory minute volume. Recommendations were made for future improvements to the EDM.

Finally, manned testing of the engineering development model was performed by the Navy Experimental Diving Unit (NEDU). The test results and recommendations for future improvements are included as an appendix in the final report.