Using argon tank as pony bottle

[phishphood]

Is it OK to use a former argon bottle as a pony tank? I have the chance to pick up a 13CF used argon bottle and wanted to make it my pony. Any thoughts? It needs a hydro and vis anyways.

 

[akdeepdiver]

yes as long as you empty the argon out and refill it with air. But with 13 CF all you have is basically a spare air tank.

 

[ajduplessis]

They are marked/painted (around here they are blue) as argon and could potential be filled as such, or by accident swapped with another with argon. These very remote possibilities have the potential to kill you.

Scuba cylinders MUST have the correct markings & colors to identify the intended use. This I believe is law in most if not all countries. I would therefor suggest getting it marked/painted to the standards for what you will use it for. This way you remove potential mistakes. No reputable fill station here will fill a argon marked bottle with air!!!!! You will have to do it yourself with transfill whip.

 

[rjack321]

Just peel off any argon labels, have it hydroed, visualed and filled with air. No special cleaning or anything like that required.

 

[uncfnp]

Good advice about the tanks itself but as to the size. Do you know your sac rate? For the average recreational diver, a 13 cf tank will probably be adequate to get you safely to the surface from about 100 feet or less, NDL, in an OOA emergency. But there's not much on your profile to go by...

 

[halocline]

13 cft is the equivalent of about 500 PSI in an AL80, so that's a sizable emergency reserve for OW, NDL diving. Personally I have some doubts about the safety factor of any small bail out bottle in recreational diving, but that's a whole different and contentious subject. Certainly if someone is diving in a way that more than 500 PSI in a full size tank is needed to get to the surface, a case could be made that it's pushing the envelope into technical diving.

Spare air is only 3 cft (that's for the "big" one!!) so the comment about a 13 cft bottle being the same as a spare air is not true. Spare air provides less than 1/4 of a 13 cft bottle.

 

[Wookie]

I use a 13, and have plenty of gas for an ascent from 130 with safety stop, and I'm 300# 50 year old fat guy. My wife uses a 9.

 

[Kharon]

I agree with Wookie. At my actual (resting in a chair) SAC (surface air consumption not respiratory minute volume) adjusted for depth (atm's) and dive factor (difficulty) [formulae available on request] I could get to the surface with a 3 minute safety stop from 130' at the recommended ascent rates. That's cutting it just a tad close for me but doable as long as nothing else pops up. I consider a 13 cf from 90' and shallower to be perfect for me. Deeper than that a 19 cf would make me more comfortable but I actually don't think I would bother unless one was easily available or I planned a lot of 130' dives. I'm not into wrecks so I tend to be a lot shallower than that. I've got a 27 cf Faber that I use for putzing around (snorkel till I find somewhere I want to hang for a while and then descend) so I guess I could set that up as a pony if I really wanted a larger redundant source.

 

[nimoh]

personally, for the extra preparation (reg setup, mounting), I don't think it's worth the effort for such little extra gas.

However, I don't think there is anything wrong with doing it, just a potential serious issue. In my area we have no special color for argon cylinders, and filling stations will not fill an argon bottle unless it is marked as such (i.e. a decal such as "argon - do not breathe". Removing this decal, would mean that it shouldn't be filled with argon. I use the word "shouldn't" since I would wonder about having some guy in the back room filling a bunch of argon bottles, and grabbing that one by mistake and filling it.

Perhaps it would be best to test it for oxygen content after every fill.

 

[phishphood]

Thanks for the input Nimoh. Everyone else, thank you for your thoughts but your discussion is getting far off topic from what I intended this thread to be. My question was on the conversion of the argon bottle to pony, not whether the size was sufficient for anything or not.