onetime

I know the discussion of CO2 break through can get technical fast. Some members here can whip out charts, quote research, and detail the methods of measuring and warning for CO2 presence, and that's a good thing.

But, as I sit here, reading through a bunch of threads discussing recent (and past) deaths, unanswered questions, and potential fundamental flaws of Rebreather designs I wonder if we aren't missing some simple solution(s) to one potential flaw.

There's no doubt that most Rebreather makers take scrubber design very seriously and a properly packed scrubber combined with following sorb replacement guidelines from the manufacturer will cut the odds of CO2 break through immensely. However, with the very real potential that CO2 is the starting point for some of the deaths, posts about the presence of CO2 after the scrubber in some cases (I believe I recall this discussion from one of AD_Ward's insightful posts), and the reality that many manufacturers are testing scrubber duration in a, potentially, flawed way (constant flow of CO2, and/or testing at surface pressures) would there be a benefit to the integration of a secondary, smaller scrubber after the main RB scrubber to "mop up" residual CO2 when exertion or other factors allow CO2 into the inhale segment of the loop?

e.g., an inline scrubber placed in or after the inhale counterlung (on rigs with IH CL's, of course), the inhale hose, or even at nearer the inhale portion of the mouthpiece? Perhaps even something as simple as filling the inhale hose with sorb. Obviously there are drawbacks to this like an increased risk of a caustic cocktail as the sorb is closer to your mouth, probably increased WOB, and more weight on one side of the kit, but having a little extra assurance that CO2 that might slip by the main scrubber may well be worth it.

Thoughts? Ideas on how much sorb might be necessary to provide an adequate protection from this "stealth CO2"?