Mining Contract: Development of Components for Breathing Escape Apparatus (DSOV/HMC/VHPC)

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Contract # 200-2012-52624
Start Date 9/1/2012
End Date 9/1/2015
Research Concept

The objective of this research is to deliver working prototypes of a docking/switch-over valve (DSOV) and a hood/mask with passive communication elements (HMCs). The DSOV allows for seamless changeover between breathing air apparatus without exposing the miner to harmful gases. The HMC allows the user to more effectively communicate while breathing naturally through the nose and mouth. This research also delivers very high-pressure oxygen cylinders (VHPCs) for use in the next generation of escape breathing apparatus.

Topic Area

Contract Status & Impact

This contract is complete.

This three-part contract—part 1 for the DSOV, part 2 for the HMC, and part 3 for the VHPCs—has generated two final reports. To receive a copy of the final reports for parts 1 or 2, send a request to The final report for part 3 will be available in 2018.

Following a catastrophic event, mine workers and rescue teams may be exposed to harmful gases in the mine atmosphere. Breathing air supplies (BAS) technologies are used to isolate the lungs from this atmosphere. BAS for underground mining refer to a range of mobile devices and stationary systems that offer respiratory protection to miners in the event of an emergency. Some examples of BAS are self-contained self-rescuers (SCSRs), closed-circuit oxygen breathing apparatus (CCBAs), and gas supplies for refuge alternatives. Advanced BAS technology could improve a mine worker’s chances of surviving a mine disaster.

Under this contract, Carleton Technologies conducted research to determine the feasibility of developing one common DSOV and HMC design with adaptors for connection to the selected MSHA-approved SCSRs and a NIOSH-approved self-contained breathing apparatus (SCBA).

Carelton produced a prototype DSOV that is compact and easy to use in a mine emergency situation by minimally trained users. It enables the simultaneous connection of two breathing apparatus, allowing for a seamless transfer from one device to the other so that when one breathing air supply is becoming spent the next can be used to replace it. A prototype HMC was also developed and demonstrated with the selected SCSRs and SCBA. The HMC is easier to use than current SCSRs fitted with a mouthpiece, because it allows for natural breathing through the nose and mouth as opposed to breathing only through the mouth. The HMC also has a speech diaphragm, enabling the wearer to communicate verbally during escape, which is not possible in current SCSR designs.

All components were designed and developed with due consideration to ease of use, compact size, durability, and adaptability to the selected breathing apparatus. For both the DSOV and HMC research, the goal was to produce technology demonstrators that could be incorporated into a breathing device able to meet the criteria set forth in CFR 42 part 84, “Approval of Respiratory Protective Devices.”

Finally, VHPCs are used in some current SCSRs to store and deliver pure oxygen to the user through the device. These oxygen cylinders are designed to 3,000 psi service pressure, but higher pressures are now achievable with new manufacturing techniques. This VHPC research goal was to design and produce, for a mining SCSR, two Department of Transportation cylinder designs certified to 10,000 psi working pressure and to contain oxygen volumes of 70 liters and 140 liters when expanded to standard ambient temperature and pressure. The success of the VHPC research will be updated when the final report is delivered.

Page last reviewed: July 18, 2016
Page last updated: July 18, 2016