Talk:Argox (scuba)

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[edit] Everybody with adequate breathing gas never has an "out of air experience"??

((Finally, provided that the diver carries adequate breathing gas, the need to resort to breathing suit inflation gas should never occur.))

You are joking, yes? There is an intermediate stage of diving, recognized by most dive agencies, between shallower sport diving depths (down to about 70 feet) where direct assent is a reasonable option in a failure of the primary system; and deeper dives which do not require helium but still don't require full doubles and a manifold. In that system, your pony is your friend if your buddy happens to be swimming ahead of you, and doesn't notice your problem. Even DIR has directions for rigging a pony (though they aren't the same as NAUI's), so don't tell me only scuba doofuses use them. I've used a bracket-mounted 40 cf cylinder (with separate air guage) for cold water diving many times, and been happy to have it. Stage mount if that offends.

Because argon can't be used (for long) below 60 feet doesn't mean it's worthless above 60 feet. Most people in trouble wish they could stay at 15 feet for a while on the emergency ascent, and argox is made for that.

A last point: Argox may be narcotic below 60 ft but narcosis doesn't hit you the first breath you take of the narcotic mix. At least 5 breaths are needed, and you can safety ascend quite a ways during that time. But it's a lot longer if you're merely blowing bubbles and praying (assuming your OOA emergency didn't involved choking in the first place and you have bubbles to blow, that is).

Finally, stop capitalizing nitrogen. Sbharris 08:08, 31 May 2006 (UTC)

Steve,

To be honest, it hadn't occured to be that argonox could be used as a combined pony and suit inflation bottle for single tank diving, because I've never seen anyone use argon unless they're diving trimix. While such a practice does make a bit more sense than sticking a 2nd stage on a small suit inflation bottle, I'd still consider it ridiculously dangerous. There'd only be a small improvement in warmth, if any improvement at all*, over using air inflation, and the risks incurred would be massive. At just 17m, 20% argox would have and EAD of 45m (see maths below), which is a huge narcotic load, and especially bad in an emergency situation. Given that (at least where I come from) pony bottles are usually used in the 30-40m range, the use of argox as a pony bottle gas seems pointless. I don't think I've ever seen anyone (except for training purposes) carry a pony on dives shallower than 17m.

Also, pony bottles aren't actually ever used in DIR. There certainly is a DIR method for rigging a side-slung bottle, but (in DIR) that's only used for decompression, stage and rebreather drive bottles, never ponies. The theory there is that if you think you need a pony, you actually need twins.

As for the EAD maths, argon is 2.3 times more narcotic than air according to the exotic diving gases page. I'm not sure what the "OW partition" you refered to is. From this, the relative narcotic factor of 20% argox can be calculated. Assuming oxygen is as narcotic as nitrogen, we get the following.

And that gives an EAD of 45m at 17m. If oxygen is considered non-narcotic, then 20% argox would have even more than the full 2.3 factor of argon.

From the current state of the article, I think the following things should be changed:

• Dedicated suit inflation bottles should be represented as being just as common (if not more so) than deco gas inflation.
• The mention of using argox as an emergency gas (in a pony bottle) for dives in the 30-45m range should be removed, given 20% argox's suicidal EAD of 72-102m in that range.
• Argox deco gas: "...not currently recommended [as a deco gas]" - add "and rarely, if ever, used".

What do you think?

Finally, I only capitalised nitrogen once, and that was due to carelessly cut-and-pasting from the title of the nitrogen narcosis article. ;-)

* Apparently some study found that in a blind trial, there was no difference in divers' skin temperatures whether using air inflation or argon inflation. I can try to find the details of it if you want.

-- David Scarlett^(Talk) 09:27, 31 May 2006 (UTC)

[edit] The MOD's of argox due to argon narcosis and (for high O2 mixes) due to O2 tox

If we use a more realistic air-narcosis MOD of 40 m (ppN2 of 3.9 atm) due to nitrogen, reflective of sport diving recommendations (and coincidentally just about where I myself begin to feel the onset of narcosis), then the MOD for argox 20% should be about 37 fsw (assuming the O2 has no narcotic effect, and argon is 2.3 times as narcotic as N2). I've changed the text to show that, allowing me to remove the bit about using an unrealistic or "outside limit" air MOD of 45 m, which apparently somebody was unhappy about.

Argox is interesting outside of a drysuit inflation gas which can be used as an emergency gas above 37 ft, allowing a reasonable decompression stop anywhere above 37 fsw, where otherwise a diver would have to make a straight no-stop ascent.

This second use would be as a theoretical deco gas at O2 concentrations somewhat higher than 20%. The reason is isobaric counterdiffusion, the theory that during decompression, each inert gas in a mix passes from alveoli into tissue (or the reverse) according to the absolute difference in that gases' partial pressures in each compartment. In such cases, it's theoretically useful to breath heliox as a bottom gas, loading compartments with helium, and then switch to sucessively heavier and heavier molecules in the inert fraction, on deco. In theory, this would let the helium escape from tissues faster due to having no helium to oppose it, while at the same time, other heavier gasses would not pass as much the "other way" (ie, the wrong way) into tissues from the deco mix. This, due to their heavier weights and thus slower diffusion. The use of such gases becomes possible in deco because although they are all more narcotic than helium, deco is done at successively shallower depths, allowing the use of more narcotic heavier species like nitrogen, but also (less narcotic) neon and (more narcotic) argon. Or course most deco now is done off trimix with 50% nitrox or something, and no need for anything fancier, but some impressively low depths have been reached by experimental divers using proprietary mixes of inert gases in deco, starting with hydrogen on the bottom, then moving to heliox, then neox, then nitrox, then argox, and finally nearly pure O2 near the surface (including a good long stretch of breathing pure O2 on the boat or shore, where it still has good effects but the dangers of seizure are far less).

Under such conditions, it's interesting to see what kinds of argox could be used for such purposes. Argon really isn't very expensive (the cost is essentially that of the tank rental) so argox could be used by gas blendors more than it now is. What mixes might be used?

Figuring a maximal ppN2 of 3.9 gives a maximal MOD argon partial pressure (ppAr) of 3.9/2.3 = 1.7 atm. I will leave it to the student to show that the argon MOD for air equivalent 40 m is given by:

Argon narcosis MOD depth = D_ar (fsw) = (33F + 23.1)/(1-F) where F is the fraction of oxygen, assuming the rest is argon. Plug in 0.2 for 20% argox and you get the 37 fsw used above.

Now, if your limit ppO2 on decompression is 1.5 atm (being conservative) it's easy to show that:

Oxygen toxicity MOD depth (fsw) = D_ox = 33[(1.5/F)-1] where again F is the fraction of oxygen. If this fraction is 1.0, then 16.5 ft is your max depth for deco on pure O2.

If you're using argox for deco, what is the mix fraction place where the two dangerous partial pressure curves for O2 and Ar cross, and as you go deeper, you will get into trouble sooner from oxygen MOD than from argon narcosis MOD? To find out, you can set the two different MOD's in the two equations above (one for argon, one for oxygen) equal to each other, to get one quadratic equation in one variable (F = fraction of oxygen). That's the fraction of oxygen above which your argox oxygen is limiting your MOD depth, not your argon narcosis MOD.

Again, I leave it to the student to work out from the quadratic equation, that this F (when you set the two equations equal) is 47% or so (actually, 46.875%). Any more oxygen % than this in your argox, and oxygen will limit your MOD before the argon narcosis goes. The depth also happens to be the maximum you can reach with any 2 component argon-oxygen mix (simple argox). It occurs at 47% oxygen and 53% argon, and the MOD where you've reached the limit for both components can be found from either MOD equation above, since both give the same MOD answer for this F: for example, MOD(O2) = 33 fsw [1.5/46.875)-1] = 72.6 or about 73 feet salt water (fsw).

Thus, deco with argox at shallower depths can in theory use a higher fraction of oxygen than 47% (accoding to what depth you want to start deco at), but (again) the MODs of those argox mixes in deco are limited by their oxygen, not their argon.

An even easier way to do this than solving the quadratic to get the max depth for the argox which is limited by both O2 and argon, is simply to note that the max ppO2 is 1.5 and the max ppAr is 1.7 atm (remember that comes from the 3.9 atm for N2/2.3 narcosis factor). Add these up, and you get a maximum of 1.7 + 1.5 atm = 3.2 atm total pressure which the mix will support safely, and this represents 1 atm pressure from air, and 2.2 atm of water pressure or 2.2*33 = 72.6 fsw. Of course, the same answer. Then, if you didn't know it, you could calculate the O2 fraction as 1.5 atm O2/3.2 atm total = 0.47 = 47%, again as advertized. So solving that nasty quadratic isn't really necessary-- just fun.

The 50% argox deco gas therefore looks quite reasonable. The fact that anything over 47% O2 with argox is limited by oxygen toxity, not argon narcosis, is of course true for the theoretical 50% O2 or even 80% O2 argox's which would preumably replace their 50% and 80% nitrox counterparts, for deco purposes. Simply put: you don't have to worry about the argon narcosis effects for 50% argox deco mixes, or any argox that has more O2 than 50%. The reason is the O2 will get you first on anything hotter than 50% O2. That's true of nitrox also.

All of this is OR, so limited by WP:NOR, so I've left most of it out of the article. But I've left footprints here to let anybody pursuing this, retrace my thinking with a minimum of pain. SBHarris 03:11, 21 June 2007 (UTC)

[edit] Suit inflation

The article states that technical divers use their deco cylinders to inflate their drysuits. Assuming Trimix is used, the suit should not be inflated using backgas because of the thermal properties of He. The most common way to inflate the drysuit is by use of a dedicated 6 or 14 cubic foot argon bottle. The suit is, as far as I am aware, never inflated using a decobottle since the regulator on a properly rigged deco bottle would not have the extra drysuit hose required. Not to mention the fact that each decobottle would then require an extra hose, this would result in a mess. As someone already said, when using Trimix, the suit is inflated by means of a small argon (not argox) bottle. This needs to be changed in the article. Abiermans (talk) 22:57, 8 May 2008 (UTC)

It's easier to simply have an octopus and an extra hose on a deco bottle than it is to carry an entire dedicated drysuit inflation bottle. Particularly when the average diver is likely to have several spare standard octos around, anyway. However-much a "mess" the latter is, a separate inflation bottle and hose is even more of a mess, and heavier. And I do know divers who rig their deco bottle with a standard octo and extra hose, for just that reason. You personally might not, but that's fine. We can put that some do, and some don't. SBHarris 00:29, 9 May 2008 (UTC)

I think the 'average' recreational diver wouldnt be using He based mixes and therefore have little need for argon inflation. However, a small argon bottle can be very neatly tucked away on a doubles setup. I'd send you picture of this to show how much more streamlined this would be as opposed to having a forest of hoses on deco bottles. I have been diving for a long time, I dive doubles pretty much exclusively as do most of my buddies, I just wanted to point out that I have yet to see anyone use a decobottle for drysuit inflation. Argox is not a breathing mix that I have seen used. It is just not a practical thing to do, also using 100% argon is a far better choice for suit inflation. It is kind of like using 80/20 instead of 100% O2 for decompression, it is just totally ineffective. But I think we might not really need to change the text since both options are mentioned. Cheers! Abiermans (talk) 18:15, 9 May 2008 (UTC)

You don't have a forest of hoses on deco bottles. You must have ONE extra hose on ONE of your deco bottles. 80/20 argox is easy to make if you don't care that it's only 2200 psi (you hot shot a bottle to 450 with O2, then fill the rest of the way with argon from a commercial H cylinder of argon-- it requires exactly the same inert gas CGA fitting as your He cylinder). In other words, you need a boat fillwhip with an inert CGA adapter, but if you use He at all, you already have one.

There is NO analogy betweeen 80/20 argox and 80/20 nitrox. 80/20 argox is an inflation gas that can also be breathed in an emergency down to surprisingly low depth (certainly down to any depth you're going to deco at). It is better than air or nitrox as a suit inflation gas, and if people had a way to breathe the gas in their suits it would be more common (in theory in a real emergency you could always move your inflator bottle line to your BC and breathe from it that way-- at least that saves you from having to dive with a bottle of unbreathable gas, even if you're not diving helium; in that case your suit inflation bottle becomes your secondary, and although these are frowned on like spare airs, they have their place in moderately deep dives.) The other possible future use for argox has been pointed out above: argon is cheap and with decent compressors, 50/50 argox may one day it may be the deco gas of choice, to be used at 50 fsw and above. It's slower than N2 to diffuse into tissues, but it lets the He out just as fast. In theory it could be used starting at 60 to 70 fsw (basically a bit over 3 atm), and going right up the depth at which you switch to pure O2 (15 fsw or so = 1.5 atm). That would rid you of deco nitrox entirely. I haven't included this, because no organization recommends it. The Navy looked at it, but not in the right way. So it's all OR. SBHarris 02:52, 12 May 2008 (UTC)

You can indeed have ONE of the decobottles fitted with a suit inflator hose. The problem with this setup is the fact that you can no longer hand this decobottle to someone else if they needed it without loosing your suit inflator. It also makes manageing that bottle unnecesarilly more complicated. And once again, while the article does state the two ways to inflate a suit, using a decobottle do to this is certainly not the common and recommended way to do it, regardless of what gas the bottle contains. What I meant to say by comparing 80/20 argox and 80/20 N2/O2 is the fact that both of these gasses are contrived and both are not ideal for their intended purposes. This sort of ties in with the whole 'pony bottle' debate. Having a bottle that is used to breath and inflate your suit for fear of losing gas somewhere is not the solution, proper airmanagement is the solution here. And, if this is such a great idea why is nobody using it? But of course we can agree to disagree on this.Abiermans (talk) 22:31, 14 May 2008 (UTC)

Well, proper air management is the answer to everything. Except when it isn't. Or you blow a gasket or your buddy does, or somebody panics or does something dumb. I merely suggest a way to make all the gas you take with you breathable. If you're in a situation where you're handing off one of your deco bottles to somebody else, you surely don't need a suit inflator hose anyway, since you're in trouble and either holding at depth, or ASCENDING. Drysuits work just fine with no hoses, so long as you go one-way up (that's what valves are for). At this point, perhaps you're going to give me some weird artificial OOA scenario in which you have to swim down in a tunnel or ship in order to get up, and my answer in that case is, that if you take the hose out of your BC and use it for just enough gas to get rid of a little emergency chest-squeeze of that sort, trimix back gas is not going to turn you into an instant popsickle. Having the extra breathable gas is still more important. In any case, none of this addresses the very important issue of what to put in your pony bottle if you're using a drysuit in a 100 foot dive in cold water, breathing air from a single standard steel sport tank of 100 or 120 cfu, as I often do (there are a lot of divable ships sited deliberately at 100 fsw). In that case, argox in a pony works very well. And beats hell out of the prospect of breathing from your BC or blowing bubbles and hoping you can make it to your buddy or the surface, if something goes wrong with a main gasket. SBHarris 23:27, 14 May 2008 (UTC)