By Cedric Verdier

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Bailing out to Open Circuit is like falling in the snow when you learn skiing.

By Ron Micjan

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How to identify, correct and bailout from the various BOOM type failures

Howard Packer, J. D.

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Carbon Dioxide and the Rebreather Diver
Howard Packer, J. D.
For peer review
Abstract
Humans produce carbon dioxide during the metabolism of oxygen and nutrients. Since exposure to high concentrations of this metabolic waste product can be fatal, the normal human body eliminates excess amounts of this poisonous gas through exhalation from the lungs. Survival depends upon proper carbon dioxide elimination and the avoidance of exposure to high carbon dioxide doses.

During open circuit SCUBA diving, the chance of becoming exposed to dangerous levels of carbon dioxide exists but is relatively limited for normal, healthy individuals using properly serviced, modern equipment. This is because the open circuit diver expires this waste gas into the water from the SCUBA unit.

Rebreathers, on the other hand, recirculate expired gas back to the diver for inspiration. Were it not for a carbon dioxide absorbent component of the breathing loop, the rebreather would also recirculate carbon dioxide back to the diver, allowing the accumulation of this toxic gas to dangerous levels.

By Dr Mike

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Dr Mike's CCR Cave Course in Florida

By Dr Mike Clarke - Molecular Products Ltd

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In order to better understand the factors that effect the duration of the absorber it is helpful to have a basic understanding of how the process works. The basic process is that sodalime is used to absorb carbon dioxide gas by chemically reacting it with calcium hydroxide (hydrated lime) to form calcium carbonate (chalk). This reaction occurs in the absorber of a diving re-breather set.

http://www.rebreatherworld.com/photopost/data/508/medium/fig11.jpg
Figure 1 - reaction zone moves through the absorber

The rate of reaction of the carbon dioxide gas with the sodalime and the amount of carbon dioxide produced by the diver will both effect the available duration but, less obviously, so will the gas flow rate.

In use the absorber consists of three zones shown in Figure 1. The unused material shown in green which has an intrinsic carbon dioxide capacity that is not dependant on the rate of reaction or the size of the absorber; a reaction zone shown in blue that essentially has no carbon dioxide capacity and the used or exhausted material shown in red.

The reaction zone (blue) moves forward into a volume of unused Sofnolime (green) and continues until the reaction zone reaches the end of the absorber when breakthrough of the carbon dioxide starts to occur. It leaves behind it a volume of exhausted or used material (red) made up of mostly calcium carbonate.

By Cedric Verdier

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I know it's not politicaly correct. GI3 will never like that. Nobody should endorse Solo rebreather diving.
But the fact is: there's quite a lot of Solo rebreather divers!

By Lisa

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Three Outlaw Divers take to the Cornwall coast to complete their Inspiration MOD1 with Dive Action!

By Cedric Verdier

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CCRs are a nice tool for cave diving, as long as they have some necessary features...

By wedivebc

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CCR Cave Training at Protec - Ron, Mike and Dave learn about diving in the inky darkness of Mexican Caves

By Neil Holden

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Flash cards for learning the HUD signals on the Inspiration Vision and Evolution CCR. May also be used to indicate faults while training if laminated first!