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I think an important point here is "shallow". In shallow water it's MUCH easier to independently verify that your loop gas is life-sustaining by means other than electronic sensors - such as manually mixing gases in the loop and maintaining O2 input based on loop volume changes. For example, at 20 feet, the FO2 in the loop can be anywhere from 100% down to about 15% and still be life sustaining. That's a huge range - 85% of the entire loop volume for margin for error. Even at 60 feet, you have more than 40% loop volume margin for error (anything from 10% to 50% O2 is fine). In deep water, however, there is a much narrower tolerance for FO2 in the loop. At 300 feet, you need to keep the FO2 somewhere between about 2% and 16% or so, which is only 14% loop volume margin for error. That's a bit harder to maintain over long periods of time without electronic assistance. Rich On Wed, 2 Oct 1996, Roderick Farb wrote: > Esat, you misunderstand. If I am diving and I see that two sensors are off > and one is on (by my belief system), then I am comfortable diving that one > sensor shallow forever or deep as I move shallow. In other words, I > wouldn't bail out of a shallow dive if I have a 1.0 setpoint and sensor > one = 1.0; sensor 2=0; sensor 3=0. If I was deep, I would move to shallow. > Same as if sensor 1=1.0, sensor 2=5 and sensor 3=4. If you lose faith in > the ability of buffers to buffer, then you'd best give up lab science and > do computer dive simulations. Same for my sensors. Rod > > On Wed, 2 Oct 1996, EE Atikkan wrote: > > > [Much rebreather philosophy snipped] > > , I would turn > > >off electronics and manually dive it for whatever time was appropriate > > for > > >the depth- shallow forever, deep until I got shallow. For > > non-rebreather > > >divers and for non-diving-scientist-rebreather experts, this is a hard > > >concept to swallow. A physiologist/biochemist must know and trust > > buffers; > > >a CC rebreather diver must know and trust sensors. > > > > Though knowledge of suitability of buffers is essential to run an > > experiment, trusting them is another matter. > > > > The buffer capacity of a given sol'n is conc. dependent, which is > > checked using elecronics & primary standards. Thus it is not trusting > > the buffer as much as trusting the parameters that are measured vis a > > vis that buffer. I would proffer that the same would apply to sensors > > & if one, by gut feeling, is deemed accurate & used, while the other > > two R rejected, some re-evaluation of the method should be considered. > > > > Regards > > > > Esat Atikkan > > > > -- > > Send mail for the `techdiver' mailing list to `techdiver@terra.net'. > > Send subscription/archive requests to `techdiver-request@terra.net'. > > > > -- > Send mail for the `techdiver' mailing list to `techdiver@terra.net'. > Send subscription/archive requests to `techdiver-request@terra.net'. > Richard Pyle deepreef@bi*.bi*.ha*.or* ******************************************************************* "WHATEVER happens to you when you willingly go underwater is COMPLETELY and ENTIRELY your own responsibility! If you cannot accept this responsibility, stay out of the water!" *******************************************************************
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