Accumulated 02 following a large number of repetitive Nitrox dives over 3 days.
- Thread starter Astran
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GJC
Contributor
Looks like I've wasted a lot of time in this thread!
GJC
Contributor
Diver below 83
Contributor
GJC
Contributor
Absolutely correct about pulmonary, but the exposure over time may also make you more susceptible to a CNS hit if you do another nitrox dive or have to take a chamber ride.
???
Something going in in the background?
While he was vigorously defending a position I strongly disagree with, I didn't notice any lines crossed.
GJC
Contributor
Something from another thread maybe?
I didn't think any lines were crossed either.
And I am one of probably many who learnt a quite a bit as well.
But a few of the recent posts have confused me. My EAN course was from PADI in Dec 2010, let me declare that up front.
1. In post # 182 Tursiops says "AT PPO2 (not PO2) of ....". My question is not related to the meat of the post, just on the PPO2 vs PO2. I thought they were the same (?).
2. In post # 176 rjack321 says
"there are 3 parts to oxygen and nitrox use
the depth mod
the CNS has a 90min half-life while the oceanic uses a 24hrclock
the daily pulmonary limits do not have a half life - and you exceeded those"
a. I am under the impression that there is no half life with respect to CNS toxicity.
b. I am under the impresion that there may well be a half life with respect to pulmonary toxicity. Maybe 90 minutes, maybe 120 minutes. Some computers take this into account explicitly, some may explicitly not, and some may be silent as to what they do.
Could someone please advise?
3. With respect to what Manatee Diver said in post # 192
"Not only that but those numbers are for pulmonary not for CNS. Recreational computers don't even bother calculating the pulmonary numbers because it is very very hard for non-occupational divers to hit it."
and what GJC confirmed in post # 197
"Absolutely correct about pulmonary, but the exposure over time may also make you more susceptible to a CNS hit if you do another nitrox dive or have to take a chamber ride."
a. I am under the understanding that the so called "oxygen clock" tracks oxygen loading with respect to pulmonary toxicity. The NOAA tables refer to pulmonary toxicity, not CNS toxicity. Divers and various computers (to my regret, even Shearwater) are using a misnomer by referring to a "CNS clock". It is not primarily CNS related.
b. Just so that I clearly understand this, let me go out on a limb and say that CNS toxicity is related only to depth for a given EAN%. You can spend unlimited time within 1.4 ATA, and consider that safe diving practice with respect to CNS toxicity. (I understand about diver to diver and day to day variation, I am specifying "safe diving practice", acknowledging that "things happen".)
Could someone please advise?
And I am one of probably many who learnt a quite a bit as well.
But a few of the recent posts have confused me. My EAN course was from PADI in Dec 2010, let me declare that up front.
1. In post # 182 Tursiops says "AT PPO2 (not PO2) of ....". My question is not related to the meat of the post, just on the PPO2 vs PO2. I thought they were the same (?).
2. In post # 176 rjack321 says
"there are 3 parts to oxygen and nitrox use
the depth mod
the CNS has a 90min half-life while the oceanic uses a 24hrclock
the daily pulmonary limits do not have a half life - and you exceeded those"
a. I am under the impression that there is no half life with respect to CNS toxicity.
b. I am under the impresion that there may well be a half life with respect to pulmonary toxicity. Maybe 90 minutes, maybe 120 minutes. Some computers take this into account explicitly, some may explicitly not, and some may be silent as to what they do.
Could someone please advise?
3. With respect to what Manatee Diver said in post # 192
"Not only that but those numbers are for pulmonary not for CNS. Recreational computers don't even bother calculating the pulmonary numbers because it is very very hard for non-occupational divers to hit it."
and what GJC confirmed in post # 197
"Absolutely correct about pulmonary, but the exposure over time may also make you more susceptible to a CNS hit if you do another nitrox dive or have to take a chamber ride."
a. I am under the understanding that the so called "oxygen clock" tracks oxygen loading with respect to pulmonary toxicity. The NOAA tables refer to pulmonary toxicity, not CNS toxicity. Divers and various computers (to my regret, even Shearwater) are using a misnomer by referring to a "CNS clock". It is not primarily CNS related.
b. Just so that I clearly understand this, let me go out on a limb and say that CNS toxicity is related only to depth for a given EAN%. You can spend unlimited time within 1.4 ATA, and consider that safe diving practice with respect to CNS toxicity. (I understand about diver to diver and day to day variation, I am specifying "safe diving practice", acknowledging that "things happen".)
Could someone please advise?
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