o2pp 1.4ata+?

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Rick Inman

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Nitrox divers. Do you or will you ever exceed 1.4ata?

Would you bop down to 1.6 to get a picture? Or 1.8 to get the light you dropped?

Or maybe you don't have a problem planning dives to 1.5.

Would you dive 32% to 120' (I have, and will)?

Why? Why not?


***Warning. Only dive mixed gases based on the certifying agencies guidelines, not based on what people on Scubaboard say, or you will die "a horrible death."
 
I don't have a problem with 1.6 - it was the original 'safe' limit before it was revised to 1.4 by most agencies. In fact it is still the standard limit from IANTD with an advisory of 1.4 if it is a dive with heavy exertion or thermal stress (my cert is from IANTD). I probably woudn't stay there for very long though. I'd also have no problem with a quick dip to 1.8 to pick something up that I'd dropped. That said - Oxygen Toxicity is very dramatic and sudden and will cause your death quite easily unless you have someone there to help you out, so I generally stay away from the limits - although I don't really consider 1.4 a limit.

DISCLAIMER: This is purely what I do and I do not suggest that anyone else should follow it as advice!
 
I plan all dives not to exceed 1.4 on the dive and deco up to 1.6 and I never exceed 75% of my O2 clock.
 
Rick Inman:
Nitrox divers. Do you or will you ever exceed 1.4ata?

Would you bop down to 1.6 to get a picture? Or 1.8 to get the light you dropped?

Or maybe you don't have a problem planning dives to 1.5.

Would you dive 32% to 120' (I have, and will)?

Why? Why not?


***Warning. Only dive mixed gases based on the certifying agencies guidelines, not based on what people on Scubaboard say, or you will die "a horrible death."
I just took ANDI CSU a few weeks ago so I only have two nitrox dives under my belt.

According to ANDI, 1.45 ata is considered to be the normal "working limit". 1.6 is the maximum dosage for "normal dives or open-water decompression". 2.0 is considered the limit for bailout ("extremely brief and decreasing dosage") where there is no overhead environment.

Since I dive in cold water and there can be current, I will be planning around 1.35 for "backgas" and 1.5 for the sling bottle. I may become somewhat less conservative when I get more dives under my belt.
 
I'm not a nitrox diver yet so please set me straight if I'm wrong.

From my limited understanding, a diver wouldn't automaticly tox because they went over 1.6. I thought the duration of exposure, and previous exposure (o2 loading?) is the significant factor.

Given that it would take one minute to retrieve a light, would this be present a significant risk of an oxtox? Would you ascend above your planned depth (say, pp02 of <1.2) to limit additional exposure?
 
I have done dive in the past were I exceeded a PO2 1.4 for the working part of the dive. It not something I do regularly but if I know that there will be not current I will go up to 1.5 I don't know if I would take the risk to go up to a PO2 1.6, it would have to be for something special that for sure. I know that exceeding 1.6 for a short period of time is not the end of the world (I was subjected to an oxygen tolerance test, breathing 100% O2 for 30 minutes , at 60 feet in a hyperbaric chamber on my commercial diving course) Not something anybody would do in the water.

Like you Rick I have done 32% at 120' (PO2 1.48) and have no problem with that.

I do however use 1.6 for deco all the time.
 
Rick Inman:
Nitrox divers. Do you or will you ever exceed 1.4ata?

Would you bop down to 1.6 to get a picture? Or 1.8 to get the light you dropped?
Yes, I'll go to 1.6 to get a picture or even stay at 1.6 on a leisurely dive for a brief period of time.

Rick Inman:
Or maybe you don't have a problem planning dives to 1.5.
Nope, I don't have a problem with that.

Rick Inman:
Would you dive 32% to 120' (I have, and will)?
Yes, I have too. Even in tough conditions the dives aren't really "working" dives for me. In my head, the loop plays: relax, breathing is easy and regular, heart rate is low...

So, 1.5 is still pretty comfortable and 1.6 is ok for a short period - for me.

Rick Inman:
***Warning. Only dive mixed gases based on the certifying agencies guidelines, not based on what people on Scubaboard say, or you will die "a horrible death."

-ditto!-
 
Rick Inman:
Nitrox divers. Do you or will you ever exceed 1.4ata?

Would you bop down to 1.6 to get a picture? Or 1.8 to get the light you dropped?

Or maybe you don't have a problem planning dives to 1.5.

Would you dive 32% to 120' (I have, and will)?

Why? Why not?


***Warning. Only dive mixed gases based on the certifying agencies guidelines, not based on what people on Scubaboard say, or you will die "a horrible death."

These days I use 1.6 routinely for deco (~1.8 - 1.9 under special circumstances with proper eqpt).. When I started diving nitrox it was normal to use 1.6 as a bottom gas (and I used it that way for many years) with 1.8 as a deco po2..

these days my normal working po2 starts at a 1.45 and gets decreased as adders are increased.. my deco is a 1.6
 
Despite Rick's warning, this conversation in this particular place is dangerous. There are a lot of new divers here.
 
jiveturkey:
Despite Rick's warning, this conversation in this particular place is dangerous. There are a lot of new divers here.
Fair enough. Tell us why.
 
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