Nitrox question

[sharpenu]

Holy cow, they soak you on fills. Air is $2 here, EANx is $7

 

[whitedragon13]

Heck...it's $4 for air here (unless you're in the club, then it's free). EAN32 is $12 whether or not it's your own tank and custom mixes are higher.

 

[wedivebc]

]To achieve 1.6 you have to have your bottom time at 18 minutes

Not sure what you're getting at here but partial pressure is not time related and the NOAA CNS exposure table allows 45 min at that pressure.

 

[D_O_H]

Not sure what you're getting at here but partial pressure is not time related and the NOAA CNS exposure table allows 45 min at that pressure.

Seconded (seeing as how I'm studying this at the moment and it's fresh in my mind). The deepest dive PADI allows you to plan on 32 is 110' with a PPO2 of 1.39. 130' puts you at 1.58. Doesn't matter how long you're going to be there.

 

[wedivebc]

Seconded (seeing as how I'm studying this at the moment and it's fresh in my mind). The deepest dive PADI allows you to plan on 32 is 110' with a PPO2 of 1.39. 130' puts you at 1.58. Doesn't matter how long you're going to be there.

That is probably true, the nitrox course I normally teach ANDI CSU allows a 1.45 exposure for warm water, non-working dives. Some agencies allow up to 1.6 for same conditions. ANDI allows 1.6 for deco where the diver will not be moving around too much.
I personally don't think OE2Xs statement about short 1.6 during a dive exposures was particularly dangerous as long as one is aware of the limits.
Remember toxicity is a function of pressure and time

 

[Sideband]

What is the deepest you will go on air? Why?

You are going to do two dives with a one hour SI. One tank has 32% and one has air. Your plan is to do do the deep dive as your first dive - staying within rec limits. Which gas will you choose? Why?

Yesterday as an example I dove with a buddy who was using air. We dove to 110' and had around 21 minutes of bottom time. He had 5 minutes of deco obligation while I still had about 9 minutes of NDL. If something had happened and one of us had to surface, which person would you have wanted to be?

FWIW - I now dive almost exclusively on 30 -32%.

Did you actually plan a dive in which one of you would exceed NDL?
Joe

 

[OE2X]

That is probably true, the nitrox course I normally teach ANDI CSU allows a 1.45 exposure for warm water, non-working dives. Some agencies allow up to 1.6 for same conditions. ANDI allows 1.6 for deco where the diver will not be moving around too much.
I personally don't think OE2Xs statement about short 1.6 during a dive exposures was particularly dangerous as long as one is aware of the limits.
Remember toxicity is a function of pressure and time

And that was the point that I was trying to make. You won't necessarily tox by dropping to 130' for a short amount of time on 32%.

 

[OE2X]

Did you actually plan a dive in which one of you would exceed NDL?
Joe

Yes.

 

[D_O_H]

That is probably true, the nitrox course I normally teach ANDI CSU allows a 1.45 exposure for warm water, non-working dives. Some agencies allow up to 1.6 for same conditions. ANDI allows 1.6 for deco where the diver will not be moving around too much.
I personally don't think OE2Xs statement about short 1.6 during a dive exposures was particularly dangerous as long as one is aware of the limits.
Remember toxicity is a function of pressure and time

PADI allows you to go to 1.6 as a "contingency", whatever that means, so I'd imagine planning to go to 1.6 for short periods is probably fine (so long as you don't need further "contingencies" from there). Where the statement would become dangerous, in my newbie opinion, is if you followed its logic to think it was safe to plan even higher PPO2s for short periods, thinking you don't actually hit that PP02 until you've been at depth for a certain period.

 

[D_O_H]

And that was the point that I was trying to make. You won't necessarily tox by dropping to 130' for a short amount of time on 32%.

Sorry - this was posted after I started typing. Am I mistaken? Is it safe to plan dives with high (>1.6) PPO2s for short periods?