What to fill a pony bottle with?

[deadly_risk]

And why do you think you're going to skip a SS?

I don't. I don't use them at all, I assumed if you were using one something has gone wrong and if there was ever something happening that would get a diver to skip or forget the stop it would be something going wrong with your or your buddy's back gas requiring the use of the pony.

So, why bother?

No idea, that's why I ask.

Fill with air and you're done.
In the other hand, I would say your concept is right; EAN32 would be better for a recreational dive... My point is that a pony has so little gas that you would not benefit from that.

Ok cool.

I have never been below 50' so like water temps (I thought 70 was pretty warm until I jumped in...) I have no practical experience with deep(er) ascents, how much air would be used or any of the rest of it.

 

[DandyDon]

FYI: Spare Air, a true bail-out bottle, kind of an inside joke around here but dealers sell them with a smile, markets a 3 CF Nitrox model, which costs $60 more than the air model. It's not likely that a fill station is going to even think of attempting to partially fill a 3 CF tank with some Oxygen then top it off with Nitrox quality air to attempt an in-tank blend of Nitrox - especially for a tank that has to have the valve removed for plane travel!! Indeed the $250+ kit includes an adapter to fill the mini-tank from a larger, regular tank with already blended Nitrox. But get this...

You pay $60 more than for the Air 3 CF tank & kit only because it was Oxygen clean when it left the factory, but will not be after one plane flight;

You get nothing more for the $60 as you can do the same thing with the $190 kit;

Even if you put 40% Nitrox in the tiny little tank, what difference could it make in 3 CF for a rapid ascent; AND

Technically, you really should have it Oxygen cleaned after each day of flying...!​

Maybe the public asked for it, and the typical customer who buys their product might not know enough to know better, but - still, it just seems like a real insult to offer it. :silly:

​

 

[Jorgy]

On just about each dive when I carry my 19 CF pony I take some breaths at the safety stop just to pass the time and make sure everything is working, I do it with my eyes closed to practice deploying it, plus I pressurize and de-pressurize the system itself........

So I am always topping off the tank, seems that way anyway......

Unless you bank 32% then you will end up with something less and less over time.......

So why bother......and who wants to pay to O2 clean it?

Also, the Nitrox sticker is huge..........

Just my thoughts..............M

 

[james croft]

Easier than that is to not run out of gas during your dive.
Don't get me wrong, I have 4 ponies of various sixes from 6 cf to 30.
I use them when solo diving, but never used one because I dive rock bottom profiles and frequently watch my spg.

 

[Jorgy]

Not sure if you post was related to mine..........

But just to clarify, I have never run out of back gas and have never used to pony other than to check it and practice with it..........

When I say top off, that is after a long weekend of diving where due to pressurizing then depressurizing and some practice the bottle is down to 2700-2800 psi.

I just take a breath or two to check that all is OK..........not because I am out of gas

M

 

[DandyDon]

Not sure if you post was related to mine..........

But just to clarify, I have never run out of back gas and have never used to pony other than to check it and practice with it..........

When I say top off, that is after a long weekend of diving where due to pressurizing then depressurizing and some practice the bottle is down to 2700-2800 psi.

I just take a breath or two to check that all is OK..........not because I am out of gas

M

I don't think he was posting to you. Your skill drill makes good sense. SSs are certainly a good time to work on various ones. It sucks to need one in a hurry and not remember how. :blush:

 

[DA Aquamaster]

The MOD is 132 ft with a PO2 of 1.6 and that MOD is not going to cause oxtox over the short period you could be on it with a small pony. It used to be the normal MOD for 32% any way before agencies got even more conservative and backed off to a MOD of 1.4 for the working portion of the dive.

In fact, at 152 feet the PO2 would still only be 1.8 and although it is well above 1.4 or 1.6, the CNS toxicity issue is one of both time and PO2, so going on 32% at 150' for the minute or so it takes you to get to pass through 132' on ascent is most likely not going to cause a CNS hit.

Early British experiements with enriched O2 mixes during WWII involved divers at 50' on 100% O2 - a PO2 of 2.5 - and tox events were not normally encountered for 10 minutes or so at that depth. So in effect, the farther over 1.6 you get the less time you have at that depth before a CNS hit is likely to occur, but you will most likely not immediately tox at 1.7 or 1.8. It is not ideal, but it is a breathe what you have situation that is far better than drowning.

All that said, I agree the short duration of a small pony makes using nitrox somewhat pointless, and air keeps the logistics much simpler.

 

[Web Monkey]

Ponies don't have that much gas to be worrying about MOD and such.

They do if Oxygen Toxicity is on your list of things to avoid.

Terry

 

[DA Aquamaster]

I could put space aliens on my list of things to worry about but the stress and effort would be largely wasted as I am not likely to die from alien attack or experimentation. The same applies to a recreational diver with 32% in a pony -they'd have to go significantly below the recreational limit of 130' ft to tox on the contents of a 13 filled with 32%.

 

[rmc77]

They do if Oxygen Toxicity is on your list of things to avoid.

Terry

With the amount of gas you have in a pony, you could easily hit 1.8 PO2 with no issues... it's PO2 versus time that you need to look at, not only MOD.
I'm not saying you should plan to dive higher than 1.6 PO2, but if you do hit higher PO2 for any reason, it won't kill you instantly. That's all.
MOD is not a line that you cross and you're gone, it's an imaginary line that you should not cross to avoid shortening your O2 clock. The issue is that once you cross that line, your time limit will decline exponentially.
So, as I said, if you're in an emergency ascent you should not worry about the MOD of your pony... you'll be leaving that depth and way less than a minute. And even you stay at that depth, with the amount of gas you have in a pony, you'll be going out of gas (again!!) way before you start feeling any symptoms of O2 toxicity...