Mining Contract: Cryogenic Life Support Technology Development Project

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. 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.

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 or provide refuge alternatives where the atmosphere is controlled. Breathing air supplies for underground mining refer to a range of devices and 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.

Research under this contract will explore cryogenic breathing air and oxygen technology used by NASA for application to mining breathing air supplies suitable for use in refuge alternatives. This research involves five projects, as detailed below.

Cryogenic Air Breathing Apparatus (CryoBA)

A two-hour, low-profile, liquid air self-contained breathing apparatus prototype termed cryogenic air breathing apparatus (CryoBA) will be developed for use in escaping from an underground mine. The liquid air will be stored in a twin dewar arrangement, attached to a frame/harness assembly together with the delivery pneumatics and will be carried on the user’s back. The apparatus will operate in an open-circuit mode with the user breathing through a facemask. It will be refillable with liquid air while worn. Two CryoBAs will be built with the intent of meeting the provisional certification criteria under CFR 42 Part 84.

Advanced Cryogenic Air Breathing Apparatus (ACryoBA)

The advanced cryogenic air breathing apparatus (ACryoBA) is a further development of the CryoBA to have additionally standby capability for use in escaping from an underground mine. The ACryoBA will be maintained in a ready status at all times underground by having active cooling to prevent cryogen loss. This will be done either by having a built-in mini cryocooler on the apparatus or by connecting to a standby station that provides active cooling. Two ACryoBAs will be built with the intent of meeting the provisional certification criteria under CFR 42 Part 84.

Low Retrofit Kits for Closed-Circuit Breathing Apparatus (LOXK)

A liquid oxygen supply system for the next generation of closed-circuit breathing apparatus (CCBA) will be developed as an alternative to the compressed oxygen gas cylinder supply normally used in this type of CCBA. These "kits" will consist of a refillable oxygen dewar, heat exchangers valves, and piping to be installed onto the CCBA, replacing the high-pressure gas system. It is expected that the LOXK system will lighten the CCBA, relieving some of the weight on the user.

Cryogenic Air Storage and Filling Station (CryoASFS)

A cryogenic air storage and filling station is being developed to store, maintain, and refill the CryoBA. It includes a large dewar where the liquid air is stored with a cryocooler to prevent loss of the cryogen when in a standby mode. The CryoBA is filled via filling lines with quick connects from the CryoASFS. Two prototypes will be built—the first for lab testing in a lightweight frame with a vertical dewar and the other in a mine-hardened frame with a horizontal dewar for underground mine tests.

Cryogenic Refuge Alternative Supply System (CryoRASS)

A cryogenic refuge alternative supply system (CryoRASS) will be designed for fitting into or attaching to existing portable and built-in-place refuge alternatives. This system utilizes stored liquid nitrox (nitrogen/oxygen mixtures) as the sole gas supply to replace high-pressure gas cylinder systems currently used in refuge alternatives. This system not only provides breathable air but a measure of cooling as well. Major components of the CryoRASS are large storage dewars, a cryocooler, and an air handler box. Two prototypes will be built—the first for lab testing in a lightweight frame with a vertical dewar and the other in a mine-hardened frame with a horizontal dewar for underground mine tests.