LOL, ok how should I rephrase that?
Cutaneous Decompression Sickness
- Thread starter wylerbear
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It would have been correct to say: "Basically if you were to go to 80' for 40 mins on air you'd take on ~ 17% more inert gas (nitrogen) than the same dive on EAN 32."
And if you made an direct ascent following that what would a likely outcome of that be?
Likely outcome of 80' for 40 minutes on air is... nothing special whatsoever. 40 mins is the US Navy table limit for 80'.
Even if you stayed for 50 minutes, chances are you won't get bent.
The proper thing to say is "if you stay at 80' for 40 minutes on air, you've exceeded PADI's NDL time.. but you don't exceed the NDL time if you do that dive on EAN32."
Even if you stayed for 50 minutes, chances are you won't get bent.
The proper thing to say is "if you stay at 80' for 40 minutes on air, you've exceeded PADI's NDL time.. but you don't exceed the NDL time if you do that dive on EAN32."
The old rule of thumb for square profile dives was depth + time = 120 (from the USN air tables as well as early PADI tables.) Done it many times on air with no ill effect. I much prefer EAN32 and multilevel dives.
Folks,
I hate to get mixed up in this, because some of the points are ephemeral, and thus can be argued back and forth until the bovines return.
It boils down this way. IF you dive on nitrox and use air tables, you are "slightly" safer, in terms of statistics. The percentage change is minute, however, and in the end not significant. I am sure that UP and Jon at least are well aware of this, since they have so stated previously in other posts.
The assumption is, of course, that if you go to a particular depth on nitrox, but only stay as long as you would if you were on air, you will have absorbed less nitrogen, because there is less of it in the mix.
IF you use nitrox, and nitrox tables (or wet-computer), you will be able to stay longer at a particular depth because you are NOT absorbing as much nitrogen (there is less of it in the mix).
Most folks dive on either NOAA NITROX I (NN32), at 32% oxygen, which gives you a Maximum Operating Depth of 130 fsw, or on NOAA NITROX II (NN36), at 36% oxygen, which gives you a MOD of 110 fsw.
Either way, if you use the PADI Nitrox tables, or a computer set to your mix, it is a simple process.
The only other thing to watch is your oxygen exposure. You use a CNS chart to run your oxygen clock, and for extended exposure to high oxygen concentrations, such as in repetitive technical diving, you run an OTU table to check long term (i.e. whole body, or pulmonary) exposure.
In the normal run of the mill recreational diving, neither one is much of a problem.
There is anecdotal evidence that, even running Nitrox on Nitrox tables, at the end of the day, you just feel better!
Take your pick!
P.S.--If you use the standard mixes, none of your equipment needs changing in any way, EXCEPT......
if your shop blends Nitrox through the Partial Pressure method, your TANK AND TANK VALVE needs to be cleaned, o-ringed, and lubed for oxygen service. This is because those items will see 100% oxygen at high pressure. The rest, once the mixing is done will not.
I hate to get mixed up in this, because some of the points are ephemeral, and thus can be argued back and forth until the bovines return.
It boils down this way. IF you dive on nitrox and use air tables, you are "slightly" safer, in terms of statistics. The percentage change is minute, however, and in the end not significant. I am sure that UP and Jon at least are well aware of this, since they have so stated previously in other posts.
The assumption is, of course, that if you go to a particular depth on nitrox, but only stay as long as you would if you were on air, you will have absorbed less nitrogen, because there is less of it in the mix.
IF you use nitrox, and nitrox tables (or wet-computer), you will be able to stay longer at a particular depth because you are NOT absorbing as much nitrogen (there is less of it in the mix).
Most folks dive on either NOAA NITROX I (NN32), at 32% oxygen, which gives you a Maximum Operating Depth of 130 fsw, or on NOAA NITROX II (NN36), at 36% oxygen, which gives you a MOD of 110 fsw.
Either way, if you use the PADI Nitrox tables, or a computer set to your mix, it is a simple process.
The only other thing to watch is your oxygen exposure. You use a CNS chart to run your oxygen clock, and for extended exposure to high oxygen concentrations, such as in repetitive technical diving, you run an OTU table to check long term (i.e. whole body, or pulmonary) exposure.
In the normal run of the mill recreational diving, neither one is much of a problem.
There is anecdotal evidence that, even running Nitrox on Nitrox tables, at the end of the day, you just feel better!
Take your pick!
P.S.--If you use the standard mixes, none of your equipment needs changing in any way, EXCEPT......
if your shop blends Nitrox through the Partial Pressure method, your TANK AND TANK VALVE needs to be cleaned, o-ringed, and lubed for oxygen service. This is because those items will see 100% oxygen at high pressure. The rest, once the mixing is done will not.
Not trying bust you on this one MM... but facts is facts.
*we're not worthy, we're not worthy*
Thank you for the corrections Jon and Pug. P. poor wording.
But in the case of WylerBear, considering her predisposition Type I hits and her biological factors, I would say her chances look fairly bleak for having no ill effects from that profile. More so when you consider that USN tables are for young(er), athletic males.
Thank you for the corrections Jon and Pug. P. poor wording.
But in the case of WylerBear, considering her predisposition Type I hits and her biological factors, I would say her chances look fairly bleak for having no ill effects from that profile. More so when you consider that USN tables are for young(er), athletic males.
I agree. Wouldn't be wise for someone with a predisposition to sub-q to be doing square 120 profiles on air... probably not wise on EAN32 for that matter.
Best to multilevel the dive (as she evidently does), use nitrox and spend plenty time shallow for time spent deeper.
Best to multilevel the dive (as she evidently does), use nitrox and spend plenty time shallow for time spent deeper.
OP
Which is exactly what I plan to do. Thank you all so much for all the info. I'll be diving tomorrow. Will let you know how it goes.
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