Girliegills, Thanks for the information!
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Girliegills, Thanks for the information!
And the guy at Jackson Blue who died on his "oxygen" tank at deco that was actually full of Helium. http://www.iucrr.org/20011026_01.htmQuote:
Originally Posted by Cindy
The girl at Ginnie I think might have been somewhat rich on O2 but for the dive she did it is surprizing that she woud tox - (if you are talking about the March 09 2002 incident). http://www.iucrr.org/20020309_01.htm
Admittedly 36% or 37% is pretty high and after 90 minutes she could have been pushing some limits - but I can plug 38% into my computer simulator for a 90 minute Ginnie dive and still not max out the O2 bar - at least for any dive in the front half of the cave. Anyway it is clear that she did tox.
One time I checked my tanks before filling them for my next dive and found my stage bottle had 38.6% in it! before the dive I had analyzed it at the shop and labled 36.7%. Pretty rich for a Friedman's dive but luckily I guess the depths and times really weren't all that bad (actually even then my max PO2 was only 1.41 for the dive) - still a wake up call to pay atention to what's in the tank. At another location or another dive that might have been a very important thing to have known.
GaryQuote:
Originally Posted by Gary
There used to a time that 36% was fairly standard for Ginnie,and I remember being there on 37-38%. In retrospect pretty stupid due to the current and depth. It is a good thing that we got smarter about PPo2
I think the incident that was mentioned at Ginnie was found later not to be due to toxing,but a heart anomoly.
It is still speculation that Judi did not analyse her tanks (or performed the calculations incorrectly); the isolator being closed could cause problems if changing posts during the filling process, and at the time of analysis.
Speculation by on-site experts is still speculation. The truth will not be know until a proper report is made, or Judi can tell us what happened.
Keith
You are correct. But it is a good reminder to check our isolator valve and do gas analysis.Quote:
Originally Posted by kgault
Which is the ultimate problem here (whatever the facts) and ever repeated warning: always analyze your mix.Quote:
Originally Posted by Kelly Jessop
Know what you expect it to be, how to mix it, and what actually goes into your tank.
Analyze it to make sure it i what you expected.
Smell it to make sure the gas is clean and free of hyrdocarbons.
If you are mixing normoxic trimix your O2 is going to be 21% thoughout the top off regardless of the % of Helium in the final mix. I almost got boned once on an underfill even after I watched the O2 and Helium added. It analyzed fine but the mix ended up like 21/60 instead of the planned 21/40 - the O2 analyzed the same either way.
This would be fairly easy to have happen if you were mixing hypoxic (say, 11/50 or something similar) as there is no O2 added.
You stick the He in the left post with the isolator closed, then top with air on the right post. The gauge reads correctly.......
However, there is no oxygen in the left tank. If you switch to it underwater....
To have this happen you'd have to make multiple mistakes, including not having a contents label on the tank recorded as the result of an analysis. Even a simple O2 check (no He meter) would reveal either abnormally low or abnormally high numbers, depending on which post you checked.
Even with just an O2 meter its going to be off - even for Normoxic - if you stuck the helium into one tank and the other gas(es) into the other. Exception would be if you stuffed the Helium and O2 into the left post and then topped air into the right - that'd show 21% O2, but the O2 on the left side would be way off - but it would be HIGH, not low, and at 130' would be breathable (a quick "back of the calculator" check shows that mixing 21/25 would leave you with a 26% FO2 if you didn't top it due to going into the wrong post.)
Mixing Hypoxic still doesn't do it - stick the O2 and He for 10/60 into the left post, then top the right with air. Your gauge is right but the resulting FO2 (on a 3500 psi final pressure) is 3.5%. At 130' (~5 ATA) you have a 0.17 PO2 - that's breathable - not great, but breathable.
From this I surmise that analysis wasn't done, if the reports are correct.
I think we need to wait for more info on this one.... the required mistakes to jive with the reported "facts" are so many in number that I'm having trouble getting my arms around it. FO2 isn't something you take for granted on a deep dive..... do you?
My prayers are for her recovery.
As you know, some people are less tolerant of high PO2's than others.....it all depends on the conditions and the person.Quote:
Originally Posted by Gary
I talked to a guy one a dive boat one day that had a VERY low tolerance for high PO2's. After doing his OW Nitrox training, he toxed on a dive with a 1.4 PO2 for less than 5 minutes. He admitted the workload was high(strong current), but it's still suprising that somebody would tox less than 10 minutes into a dive, and at 1.4 for only 5 minutes. He was lucky he had a good buddy that got him topside(without embolizing him, amazingly).
Once he got back to diving a few months later, he said he started to feel a tingling in his lip with a 1.2 PO2 for 15 minutes. He remembered feeling a tingling lip the last time he toxed, so he aborted the dive and surfaced immediately.
They then did an experiment with him in a chamber. Put him on O2, and took him to 20'. Less than 10 minutes into it, he toxed. Non smoker, social drinker, very fit. Some people are simply more susceptible than others.
He dives only air now, to depths of less than 60', and less than 30 minutes.
Mike
Kelly said that he thought that it turned out that it wasn't a tox, but rather a heart anomoly in her case. That at least relieves me somewhat since she should have fallen within NOAA standard limits despite the unexpectedly high fO2.Quote:
Originally Posted by MikeH
You are right some people are more sensitive and it's always wise to be careful but I got the impression the NOAA limits were set well within the bounds of what testing found could cause a tox.
So why would 21/60 vs. 21/40 be a bad thing? More HE is not going to hurt you is it? I'm just starting down the normoxic path and my impression was that more helium won't hurt given that it just displaces the nitrogen. (No one taught me this, I'm just learning stuff) I'm thinking maybe it's a problem for extreme depths or it changes the deco a bit?Quote:
Originally Posted by Gary