Nitrox to an OOA Diver?

[Sas]

Jax,

I agree with your logic on this one, as I would also carry 40% in a pony and not simply air. Emergency's do not happen often so you basically carry a pony bottle just to carry a pony so you might as well give it a second purpose; the basic nitrox cert allows for up to 40% and at least some of the courses touch on using higher % mixes in order to accelerate decompression, which I am assuming you are doing. So you are getting 2 uses out of your pony bottle.

Why would you carry 40%? What if you are diving deeper than the MOD of 40%? You dump the gas before each dive?

Why would the bottle have two uses? What is the second use besides bail out? If it is for decompression then it's not an emergency gas source, it's a deco bottle.

Even at the recreational limit of 130 you (or your out of air diver) will not be exposed to a high enough PPO for a long enough duration to lead to OXTOX. A PPO of 1.4 is extremely conservative as it is, and you will definitely be at or below a PPO of 1.4 within 1-2 minutes as you will be heading to the surface. OXTOX is cumulative and not instant at recreational depths on recreational mixes (<40%). I disagree with the flaming going on around you using 40%, a minute's exposure to a PPO of 2.0 will not likely kill you, but drowning definitely will.

Why not just use air and remove the risk associated with diving at a pp0 of 2? How do you know how long it will take before you start your ascent in an emergency?

Also I don't see flaming, a few people being narky about post counts but not about Jax's question.

 

[joe8mofo]

Why would you carry 40%? What if you are diving deeper than the MOD of 40%? You dump the gas before each dive?

Why would the bottle have two uses? What is the second use besides bail out? If it is for decompression then it's not an emergency gas source, it's a deco bottle.



Why not just use air and remove the risk associated with diving at a pp0 of 2? How do you know how long it will take before you start your ascent in an emergency?

Also I don't see flaming, a few people being narky about post counts but not about Jax's question.

If someone wanted to carry a bottle of 40% on every dive they do and switch to it at say 30 ft and breath it until they hit the surface simply to reduce their nitrogen load then great. Let's say for a moment that the primary use of this bottle is strictly to do that. Worse case scenario, if someone had to breath from the pony bottle due to an Out of Gas situation they would be at no great risk given that its 40% and they are heading towards the surface from depth. Again 40% and a ppo of 2.0 at max recreational depth is better than no gas if the OOA diver happened to grab the pony regulator.

If this was in the solo diving forum I would agree that it should be termed a bailout bottle with a lower MOD, but this is posted in the basic forum and the OP inferred he wasn't diving alone by how he posed the question. Why else would you have 40% in a pony unless you were using it to accelerate offgassing?

 

[Jeff Toorish]

You may want to rethink that. An open valve allows gas to escape. Depending on where you carry the bottle you might not realize that it is leaking gas. It is much easier to open a valve than it is to recapture lots gas.

You beat me to it.

Pressurize the tank then turn it off. There should be plenty of gas for a couple of breaths, giving you time to turn on the tank. If there is no air, then it leaked, and it might have all leaked if the tank was on.

Jeff

 

[lowviz]

I'd like to hear experienced thoughts on a scenario:

I'm diving with a pony that has 40% Nitrox. My primary tank will have anything from 30% - 36% Nitrox.

I'm approached by an OOG Diver. S/he grabs my pony reg and sucks desparately.

Do I leave him or her on it, grab the victim's BC and head for the surface?..........

Yep, that's a problem.

Why would you carry 40%?.............

I've been in exactly that same situation. The reason: 40% is all you get until you take Advanced Nitrox. One of my dive boats calls 40% "bull***t gas" because it causes more problems than it solves. My humble advice is to use air for now, then use 80 or 100% when you take advanced nitrox. The tables indirectly address this by saying accelerated washout is done with 50% or greater. When I realized that you don't get credit for accelerated washout with 40% I stopped slinging it and went to air. Advanced nitrox solves your dilemma: suck this and tox out...

 

[Kern]

What sort of a reduction in your N₂ loading do you get from breathing EAN40 at a safety stop on a no stop dive? How long does the safety stop have to be to make it worthwhile?

So they off gas a little more N₂, but as they don't have a deco obligation, was there anything to accelerate?

Seems like muddled thinking & complexity for its own sake to me.

 

[Sas]

If someone wanted to carry a bottle of 40% on every dive they do and switch to it at say 30 ft and breath it until they hit the surface simply to reduce their nitrogen load then great.

Then it is not a pony. Ponies are there for emergency use and need to be usable at your max depth.

Let's say for a moment that the primary use of this bottle is strictly to do that. Worse case scenario, if someone had to breath from the pony bottle due to an Out of Gas situation they would be at no great risk given that its 40% and they are heading towards the surface from depth. Again 40% and a ppo of 2.0 at max recreational depth is better than no gas if the OOA diver happened to grab the pony regulator.

Yes it is better than no gas, but even better would be air or something that has a lower pp02 level. Why would I risk oxtox when I am doing an NDL dive with no deco obligation to worry about being affected by switching to air for an ascent?

If this was in the solo diving forum I would agree that it should be termed a bailout bottle with a lower MOD, but this is posted in the basic forum and the OP inferred he wasn't diving alone by how he posed the question. Why else would you have 40% in a pony unless you were using it to accelerate offgassing?

The OP is a she and I would not agree with you even posting in the solo divers' forum. If I am using something as an emergency bailout bottle then I don't want it to have a pp02 of 2.0+ at my max depth. If you are carrying something to accelerate decompression then it is a deco bottle and not what this discussion is about.

 

[Dominantly]

You newbie's

People sometime confuse really low on air (the nice, could I have some of your air please?), with actually Out. I've had a few more than couple, and they were all ugly. Oddly also never from my buddy. My worst was someone that grabbed the reg from behind, and then first choked me, which quickly went to a surface bolt, where they knee -ed in the head, all the way to the surface.

I use a back mounted pony, and while I can easily open and close the valve, leave it on (but I have a wireless pressure transmitter on it)and the second stage is on my chest.

One thing I will never understand, is running out of air. Rule number one is "Don't ever run out of air underwater". Rule number two is "If you cannot do rule number one, then don't dive".

I have had and been with divers where equipment broke, but those don't seem to lead to the same sort of behavior.

People like these guys:
YouTube - Scuba Diving Accident Intervention Bahamas 12/04/08

 

[joe8mofo]

The OP is a she and I would not agree with you even posting in the solo divers' forum. If I am using something as an emergency bailout bottle then I don't want it to have a pp02 of 2.0+ at my max depth. If you are carrying something to accelerate decompression then it is a deco bottle and not what this discussion is about.

Jax,

I apologize for referring to you as a he, I only looked at your level of certification in your profile.

Saspotato,

Its a good thing I am already a member of the solo divers forum and that I can and will post there; so you can take your issues with my opinions elsewhere as they won't gain any ground here.
Simply due to the fact that you have more posts and more dives than I does not make you correct in any sense of the word.

You keep on saying its a bailout bottle, and what has been made ABUNDANTLY clear here is that there is no logical reason to carry 40% in a bailout bottle past it's MOD unless it is to serve purpose as a "deco bottle."

 

[joe8mofo]

DUTY CALLS
xkcd: Duty Calls

 

[Sas]

Its a good thing I am already a member of the solo divers forum and that I can and will post there; so you can take your issues with my opinions elsewhere as they won't gain any ground here.

Wha? You posting the same thing in the solo divers' forum does not mean I will think any differently of what you have said.

Simply due to the fact that you have more posts and more dives than I does not make you correct in any sense of the word.

I don't recall saying having more dives or posts makes one more correct about things.

However I still think you are making things overly complicated for no sensible reason. Please, if you think you are correct, post why you are correct and why I am not correct, don't just go and be snarky. Taking disagreement with your opinion personally is lame.

You keep on saying its a bailout bottle, and what has been made ABUNDANTLY clear here is that there is no logical reason to carry 40% in a bailout bottle past it's MOD unless it is to serve purpose as a "deco bottle."

Yes sounds about right. So what is your problem with what I have said?