Purging Procedures for the Draeger LAR V Underwater Breathing Apparatus.

Abstract

The U.S. Naval SEAL teams currently utilize the Draeger LAR V closed-circuit oxygen Underwater Breathing Apparatus (UBA) for clandestine combat swimmer operations. Prior to beginning a dive with a closed-circuit oxygen UBA, a purge procedure is carried out to remove inert gas (nitrogen) from the breathing mixture. This study seeks to establish an optimal purging procedure for the Draeger LAR V. Twenty-four purges were conducted using the current Standard three fill/empty cycle purge procedure; the average oxygen percentage obtained in the breathing mix was 85percent with a high of 96percent and a low of 73percent. Fifty-four Single Fill/Empty Cycle (SFE) purge procedures resulted in an average oxygen percentage of 74percent with a high of 89percent and a low of 50percent. Forty No Fill/Empty Cycle (NFE) purge procedures resulted in an average oxygen percentage of 55percent with a high of 82percent and a low of 20percent. Eighteen 2-hour dives using the two experimental purge procedures showed no significant inert gas buildup during the course of the dive.