Weird experience today - ox tox warning

[Natasha]

Scubaholic:
You're right. What Michael meant was, when the thread was pulled, by the Moderator that sent you a PM, it was moved to our mgmt. forum, and there was a glitch there.
It took me coming in, fixing the glitch, and then editing it, to bring it back down.
I hope that explains it for all to understand now.
Please continue on the subject, whatever it may be..without insults and eveyone can live happily ever after.

 

[reubencahn]

I didn't want to. I thought our first spot was shallower, I believe around 128 - 131. It turned out deeper. I would have been absolutely fine with a 30% EAN at 131, and probably not cause my console computer to freak out.

But, your question raises a good point, and I meant to add a "4" to the list, and that is to bring a rich mix for my deco stops, or even just for offgassing on safety stops (non-mandatory decompression stops). The Vytec allows up to three gases, so that will also allow me more bottom time by being able to track OLF and Nitrogen.

If you're diving regularly at those depths, perhaps its time to consider trimix or rec triox training.

 

[Atticus]

I think he's planning a 1.5 ppO2 bottom mix. The industry has pretty much moved away from such rich bottom mixes (due to accident analysis, theories, speculation, etc). 1.4 is taught in almost all agencies, and I've been convinced that 1.2 is a good choice.

With respect to people who have done much higher ppO2's all I can say is that we're working against an accident curve -- we each need to choose where we want to be on that curve. It's far riskier to run at 2.0 than it is at 1.4 (or insert your own numbers here, 1.4 isn't magical). The choice is yours. If 9 out of 10 people do it for a year without incident, all I can say is who wants to be number 10?

 

[Scubaholic]

Ok, here is the math. A dive to 131fsw on 30% 02 renders partial pressure of 1.49. What makes that situation "unreal?" Really, please enlighten us.

Yes, the 1.49 is above the recommended PPO of 1.4. I have planned many dives for a max partial pressure of oxygen to 1.5. I think many people plan into their contingency. If you think planning a dive with a PPO 1.5 is dangerous or not advisable, then by all means tell us why. But to just show-up in a thread hurling an insult is completely classless on your part. We have already had some highly competent divers state that they'll do a 1.6 PPO on their deco stop. Is their analysis also "unreal?"

 

[Scubaholic]

I think he's planning a 1.5 ppO2 bottom mix. The industry has pretty much moved away from such rich bottom mixes (due to accident analysis, theories, speculation, etc). 1.4 is taught in almost all agencies, and I've been convinced that 1.2 is a good choice.

With respect to people who have done much higher ppO2's all I can say is that we're working against an accident curve -- we each need to choose where we want to be on that curve. It's far riskier to run at 2.0 than it is at 1.4 (or insert your own numbers here, 1.4 isn't magical). The choice is yours. If 9 out of 10 people do it for a year without incident, all I can say is who wants to be number 10?

Merlin,

Yes, as stated above, that was planning a 1.5. Certainly, there are good reasons for just planning to stay within the 1.4 PPO limit. I am not on this board trying to tell anyone to plan their dive to 1.5 or 1.6. All I said earlier in the thread is that my computer would not have freaked on a 1.5.

My PPO on the first dive was 140fsw and was 30% EAN, and thus a PPO of 1.57 (still under the 1.6 contingency, but too close to the max contingency for my liking). The second dive was almost an identical PPO of 1.56 (128fsw w/ 32% EAN).

Neither dive violated 1.6, but they were both close. The second dive cause the computer (Suunto Cobra) to register 100% OLF explosure.

I like the idea of planning the dive at 1.4PPO, and then using a higher mix for the safety or mandatory decompression stop. This obviously requires training and would be considered advanced nitrox. People have died grabbing the wrong regulator, etc.

 

[Rick Murchison]

Y'all are down to nothing but repetition and bickering now...
Closing the thread.
Rick