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Alain, Counter diffusion is when a heavier gas diffuses slower than a lighter gas, i.e.. nitrogen/heavier gasses on-gas slower than helium off-gasses. That is why it is good for decompression purposes: the helium off-gasses much faster than nitrogen/heavier gas on-gasses. Don't blame George for being right. There is a reason the WKPP is the best. Jim ----- Original Message ----- From: "Alain Tésio" <alain@on*.or*> To: "Techlist" <techdiver@aquanaut.com> Sent: Friday, April 20, 2001 4:12 AM Subject: Re: RE: Counter diffusion > Is there a real hyperbaric specialist who can back me up ? > I'm bored to read always the same replies for wkpp > guys who are full of themselves and shout louder. > > > > --------------------------- Contents of original message -------------------------- > > Subject: RE: Counter diffusion > Date: Fri Apr 20, 2001 04:53 AM > From: Trey <trey@ne*.co*> > > > > Total and complete bullshit. This is the stupidest thing I have read on here > > in years. Partial pressures are not going to create bubbles, only absolute > > differentials. Otherwise we would all get bent going to oxygen, right? You > > obviously do not dive, do you. > > > > This is a fairy tale used to explain why misfits get bent. It is total and > > complete bullshit. We in WKPP do dives involving five gas changes and the > > fastest deco from saturation on the planet, and nobody gets bent in any > > fashion. > > > > If this horseshit were even close to true, we would not be using deco gases, > > now would we. > > > > -----Original Message----- > > From: Alain Tésio [mailto:alain@on*.or*] > > Sent: Thursday, April 19, 2001 6:38 PM > > To: scottk@nw*.co*; Techlist > > Subject: Re: Counter diffusion > > > > > > Counter diffusion occurs when switching gases, the common > > picture is "isobaric counter diffusion" because bubbles > > appear though you don't change the depth, which can't happen > > in theory with no gas change : > > when you change from nitrox to heliox, as helium diffuses > > faster than nitrogen gases out, for some time the total > > partial pressure of inert gases will increase which can > > mean bubbles. > > > > It isn't something which is absolutely required to know > > for tech diving, at least if you follow the common > > procedures and don't play the random gas wizard, but it's > > a must for hyperbaric specialists. > > > > They know how to deal with decompression illness with gases > > other than air, at least in Europe when professional divers > > use heliox for 30 years, however it may be a problem > > in areas having experience only with recreational > > diving. > > > > If there is one thing to remember, it is that you shouldn't > > breath nitrox when you go to the chamber after of a > > trimix accident. > > > > The other way is ok though, it's essentially a specialist > > affair, but using heliox 50 for air accident is ok. > > > > Alain > > > > ----- Original Message ----- > > From: "Scott" <scottk@nw*.co*> > > To: "Techlist" <techdiver@aquanaut.com> > > Cc: "Trey" <trey@ne*.co*> > > Sent: Thursday, April 19, 2001 6:38 PM > > Subject: Counter diffusion > > > > > > > George, > > > > > > Can you put the issues of "counter diffusion" into language a Jarhead can > > > understand? > > > > > > I was accosted this past week by a "Master Diver" who warned us that "If > > you > > > have to take a chamber ride after breathing that shit (helium) it will > > kill > > > you." > > > > > > I was so stunned by his position and attitude that I just nodded and > > > listened. > > > > > > Plus, I have no idea what counter diffusion is, or if or why it is an > > issue > > > to SCUBA divers. > > > > > > Scott > > > > > > -- > > > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. > > > Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. > > > > -- > > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. > > Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. > > > > -- > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. > Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. > -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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