Lutz Vieweg lvml at 5t9.de
Mon Jan 14 07:46:28 PST 2013

On 01/13/2013 07:57 PM, Jan Schubert wrote:
> - EAD: Equivalent Air Depth considering N2 and (!) O2 narcotic

BTW, has anyone ever seen any scientific evidence that for the
purpose of "avoiding DCS when diving" it is valid to assume that
the saturation of N2 in the human tissues depends only on the N2
partial pressure, and is reasonably independent from the partial
pressure of other gases and the absolute pressure around the body?

And if such evidence exists, wouldn't that mean that the same
assumption / simplification should also be used for de-saturation,
so the decompression stops should be done at different depths when
using EAN > 21 than with air?

The literature I have seen so far makes the first assumption
(N2 saturation depends only on the pN2) but doesn't make the second
(decompression stop depths are independent of the pN2, only the length
of the stops differs according to the accumulated N2 saturation).

Without having dug deeply into the topic, this seems somewhat
implausible to me.


Lutz Vieweg

PS: Has anyone ever been asked to do a "safety stop" at != 5m when
     diving EAN instead of air? :-)

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