Diver one of sixteen to die using high-tech gear

[FMT]

Were talking about the breathing loop here. A semi-closed circuit rebreather recycles most of the breathing gas on each pass through the breathing loop while a closed circuit rebreather recycles all of the gas. The gas is scrubbed (meaning CO2 is taken out) and fresh O2 or other gas is added to make up for that used. A CCR uses O2 and a diluent gas and must use complicated electronics to control the process. This is what DRE means about the CCR mixing gas on the fly at 300ft. An SCR uses "back gas" containing everything you breathe appropriate to the max depth and adds gas on a small constant basis. This results in the SCR "burping" gas from the loop occasionaly to control the process and hence they are only semi-closed. The SCR requires very little electronics to control the process. There are differences in how they can fail and what can fail and how you handle the failure because of the different gases involved and the control processes involved. O2 CCRs do not have the problems of multiple mix CCRs because they only have O2 and the control process is therefore very simple - scrub the CO2 and make up for the O2 used by the body - but they are then limited to 20-30ft depth. As well as the military having very developed team based skills, they also maintain their CCRs extemely well (its gov't - they can afford it).
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