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An Auxiliary Gas Supply to Improve Safety During Aborted Dives with the Canadian Underwater Mine Countermeasures Apparatus (CUMA) (Un Systeme Auxiliaire D'approvisionnement en gaz Augmente la Securite des Plongeurs Utilisant L'appareil Canadien de Deminage Sous-marin (ACDSM) lors des Remontees D'urgence)

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Technical rept.

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The Canadian Underwater Minecountermeasures MCM Apparatus CUMA was introduced into CF service in 1991 and is widely used by other Navies under the commercial name of SIVA. Despite its success, both within the CF and abroad it is now apparent that emergency procedures were not fully researched at the time of its introduction. Subsequent research into Severe Decompression Accidents SDA has shown that previous emergency procedures were not sufficient to safely decompress a diver during an emergency ascent from deep or long, shallow dives. As a result of this, other decompression procedures have been instituted, based on research and practices adopted from other nations. Another option is to give the diver the option of decompressing safely in the water. This will be done using a completely independent and alternative breathing system known as the Auxiliary Gas Supply AGS in case of complete diving set failure. The AGS will allow the diver to decompress using existing operational tables rather than extended emergency tables. The AGS will deliver a 40 Oxygen and 60 Nitrogen mix, which will facilitate Helium off-gassing following the same proven principal used in CF Surface Supply diving. Validation experiments were conducted between June 2002 and November 2003 over four series of dives. Doppler scores from the 202 man dives showed no significant difference in observed bubble scores between those dives that had used the AGS to decompress and the data from previous dives using normal in-water or surface decompression. There was only one incident of surface interval stress and no incident of DCI. The results indicate that a CUMA diver can be safely decompressed from a dive requiring decompression using the in water AGS.

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  • Life Support Systems

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