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On 19 Apr 99, at 10:24, Jsuw@ao*.co* wrote: > In a message dated 4/16/99 2:51:33 PM Eastern Daylight Time, > dikndi@me*.ne* writes: > > > A smart arsed student asked if it is possible to use Nitrox (on the ead > > concept) for reverse profiles. > > I said that theoretically it could be done, but reverse profile diving is > > not ........Blah blah > > > > My question is, does anybody know of any scientific study's done on this. > > I don't know about the studies, but based on the EAD concept, the use of > nitrox makes a dive "shallower" as far as the nitrogen absorption goes. If > tanks with different mixtures are being used for repetitive dives, then the > dives with the deepest EAD would be done first. > > To use a non-technical example, based on the breathing mixtures used, it is > possible that a dive to 100' might have a shallower EAD than a dive to 80'. > This would mean that the 80' dive should be performed prior to the 100' dive. > > When deciding the order to perform repetitive dives, the resulting EAD with > the gas being used should be considered. If the same gas is used for both > dives, then the deepest dive would always be done first. If the gases are > different, then the dive with the deepest EAD would be performed first. This is not a clear cut issue. Your argument makes sense from the point of view that (for a similar gas on consecutive dives) tables can be whacked by a shallow then deep dive. In this instance, using the EAD as the 'depth' does make sense. Physiologically, the opposite may be true. On any dive, bubbles are formed on ascent. The 'deepest dive first' rule insures that these bubbles are not crushed to below their initial size, possibly dislodging them from the lungs. In this case EAD is irrelevant. Absolute pressure is the controlling factor. Probably best to follow whichever is more pessimistic. Brian. -- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ + grnbrg@cc*.um*.ca* + NETDOC Developer, Libraries Electronic + + PGP public key available. + Technologies and Services + ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ + 83% of all statistics are made up. + -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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