Couple questions on a pony bottle for bail out

[kwinter]

Hey Sonic04GT,

I dive Nitrox.
However, my ponies are filled with air.

What justification could you possibly have for this? The only acceptable reason I can imagine would be the first dive after flying to a destination with the empty pony that could only be filled with air immediately after arrival. Otherwise this makes no sense whatsoever.

The pony is for emergency use. That means you plan for the worst possible time. You are diving nitrox, presumably to extend your NDL. So you might very well be beyond the air NDL at the time that you need the pony. Now you grab your emergency supply and immediately go into a deco situation because you have switched to air. Of course you are also going to immediately ascend (if you can) so your deco obligation might clear on the way up. Unless, as you said, you managed to get yourself tangled in some line or something else prevents your ascent. But why risk putting yourself into a deco situation in the first place?

The gas in the pony doesn't get used in normal situations other than a breath or 2 to check the reg on each dive. It needs only an occasional top off. There is no reason for it to be filled with air. It should probably be the richest gas you carry, as long as it does not exceed your max pO2 at max depth. There is simply no justification for any nitrox diver to have a pony filled with air.


iPhone. iTypo. iApologize.

 

[dumpsterDiver]

What justification could you possibly have for this? The only acceptable reason I can imagine would be the first dive after flying to a destination with the empty pony that could only be filled with air immediately after arrival. Otherwise this makes no sense whatsoever.

The pony is for emergency use. That means you plan for the worst possible time. You are diving nitrox, presumably to extend your NDL. So you might very well be beyond the air NDL at the time that you need the pony. Now you grab your emergency supply and immediately go into a deco situation because you have switched to air. Of course you are also going to immediately ascend (if you can) so your deco obligation might clear on the way up. Unless, as you said, you managed to get yourself tangled in some line or something else prevents your ascent. But why risk putting yourself into a deco situation in the first place?

The gas in the pony doesn't get used in normal situations other than a breath or 2 to check the reg on each dive. It needs only an occasional top off. There is no reason for it to be filled with air. It should probably be the richest gas you carry, as long as it does not exceed your max pO2 at max depth. There is simply no justification for any nitrox diver to have a pony filled with air.


iPhone. iTypo. iApologize.

I generally use air. It is cheap, free ususally, fast... no mixing and SAFE.. there is no chance of getting the wrong mix from the dive shop and if you dive deep one day and shallow another, do you want to screw with dumping and refilling?

Also, I like to tell myself if I ever feel an oxygen hit coming on from nitrox, it would be better to switch to air in the pony and hit the inflator.

I admit, I will whip the pony fills off a nitrox tank if I have no choice, but I prefer air.

 

[markmud]

What justification could you possibly have for this? The only acceptable reason I can imagine would be the first dive after flying to a destination with the empty pony that could only be filled with air immediately after arrival. Otherwise this makes no sense whatsoever.

The pony is for emergency use. That means you plan for the worst possible time. You are diving nitrox, presumably to extend your NDL. So you might very well be beyond the air NDL at the time that you need the pony. Now you grab your emergency supply and immediately go into a deco situation because you have switched to air. Of course you are also going to immediately ascend (if you can) so your deco obligation might clear on the way up. Unless, as you said, you managed to get yourself tangled in some line or something else prevents your ascent. But why risk putting yourself into a deco situation in the first place?

The gas in the pony doesn't get used in normal situations other than a breath or 2 to check the reg on each dive. It needs only an occasional top off. There is no reason for it to be filled with air. It should probably be the richest gas you carry, as long as it does not exceed your max pO2 at max depth. There is simply no justification for any nitrox diver to have a pony filled with air.


iPhone. iTypo. iApologize.

Hey Kwinter,

Thanks for the question.

My pony rig has one job. Get me to the surface. I dive Nitrox to give me a bigger margin for error. I don't dive to the limit of NDL. I tend to be "dialed back one notch" from NDL.

Air is the best choice for me!

What if I load 36% in my ponies and I dive to 130 fsw---I can't use my pony if I need it in that case.

markm

 

[maniago]

I agree with Dump and mark (I'm not a complete jack_$$).

Air, air and only air in my ponies, for exactly the same reasons. I don't get nitrox for free, so matching for everydive is not cost effective; but I pump my own air, so I do get to play with the pony for training anytime and not feel like I'm incurring another cost hit. Seems a bit petty in the face of safety, but I feel the added training compensates for the risk in this area.

 

[kwinter]

You are all missing the point. The supposition is that we are talking about a recreational nitrox diver. No deco. Nothing deeper than 40m/132 ft. There is no diving you are going to do that you can't use 32% (at 1.6 max) or 28% (at 1.4 max). You pay for the pony fill one time. The bottle remains full unless needed for an emergency. Yes, a tank of air might get you to the surface. But why put yourself into a situation that is clearly sub-optimal? Let's examine the reasons you list for using air.

I generally use air. It is cheap, free usually, fast... no mixing and SAFE.

A single nitrox 28% or 32% fill on a pony bottle would be less than a couple of beers and last at least a year unless used. And if you don't think nitrox is SAFE, you shouldn't be using it, EVER!

There is no chance of getting the wrong mix from the dive shop

Use an analyzer, like you were taught. Or demand a refund from your nitrox course.

and if you dive deep one day and shallow another, do you want to screw with dumping and refilling?

As long as you stay within recreational limits, the one fill of either 28% (max pO2 1.4) or 32% (max pO2 1.6) will be breathable at any depth. No need to ever dump and refill.

Also, I like to tell myself if I ever feel an oxygen hit coming on from nitrox, it would be better to switch to air in the pony and hit the inflator.

WTF? You're worried about an OxTox hit at recreational depths within NDL for a max of 32%? Please ask for that refund ASAP. AFAIK there has never been a documented case of OxTox under those circumstances.

My pony rig has one job. Get me to the surface. I dive Nitrox to give me a bigger margin for error. I don't dive to the limit of NDL. I tend to be "dialed back one notch" from NDL.

Air is the best choice for me!

Then you should be diving air in your primary tank as well. There is absolutely no justification for saying nitrox is better in your main tank, but air is better in the pony. Even if you don't push close to NDL, you would finish the dive on nitrox if you didn't have whatever equipment problem caused you to go to your pony. But once you have that issue and grab the pony reg, you would rather be breathing a different gas? Preposterous.

What if I load 36% in my ponies. I am diving at 130 fsw---I can't use my pony if I need it in that case.

Then why would you have 36% in the pony, EVER? C'mon folks, use some logic and rational thought.

I agree with Dump and mark (I'm not a complete jack_$$). Air, air and only air in my ponies, for exactly the same reasons.

Just how complete a jack_$$ you are remains to be seen, since you are blindly agreeing with people whose arguments are nonsense.

I don't get nitrox for free, so matching for every dive is not cost effective; but I pump my own air, so I do get to play with the pony for training anytime and not feel like I'm incurring another cost hit. Seems a bit petty in the face of safety, but I feel the added training compensates for the risk in this area.

Once again, it is a one-time fill. You don't match anything for every dive. Once it is filled, it stays filled unless you need it or have a reg free flow, etc. It is there for you every dive. There is nothing wrong with having a pony with 28% even though you have air in your main tank because you are only diving to 20 feet today. But having the richest gas you can use at the max depth you can dive is always at least as good as air and usually better.

FYI, rebreather divers take bailout tanks with them in case of a problem. They are nothing but big (minimum 40 cf) pony bottles. They don't get used unless there actually is a problem. I probably top mine off every couple of years. We don't dump the gas and refill them with the "ideal" gas for the dive we are doing. We have several tanks with different mixes and take whatever we need without exceeding the MOD. Since a recreational diver with a pony would only have one emergency tank, it should be the richest gas that can be used at the maximum depth you are going to dive. If (by the book) you limit your diving to 40 meters/132 feet and you only feel safe with a max pO2 of 1.4, then fill your pony with 28% and be done with it. Maybe it will cost you $10. It will last until you have to pull the valve for your next flight.

I don't know how to explain it any clearer.

 

[JohnN]

I don't know how to explain it any clearer.

Good points, but you're overlooking the hassle of trying to get a PP Nitrox fill when you travel with a pony.

I've never had a problem getting fill with "just" air, but any sensible shop would insist on O2 cleaning the tank before they did a PP Nitrox fill (the valve was off, who knows what crawled in there and died ).

Nitrox adds time, hassle and money. Given the purpose of the pony is to get you immediately to the surface, I fail to see any advantage of Nitrox over air for that limited ascent time

 

[MrChen]

I was going to breath my pony to the surface on my last dive just to see what I'd end up with at the surface. Currently my pony is full of air and I was diving nitrox. It was at the end of my 2nd drift dive and I wasn't far off from my NDL. I had planned to breath it prior to the dive. As I yanked the reg out of the rubber bands and took a breath, my thoughts went to my NDL and I immediately went back to my reg on nitrox. Last thing I needed was a hit because I wanted to test my pony. I might get it filled with nitrox, maybe 32%. I have yet to go deeper than 95 ft and if I ever do plan to go deeper, then I'll get it adjusted. So there's some merit to getting a nitrox fill. And yes, my vis sticker is marked o2 clean.

 

[dumpsterDiver]

You are all missing the point. The supposition is that we are talking about a recreational nitrox diver. No deco. Nothing deeper than 40m/132 ft. There is no diving you are going to do that you can't use 32% (at 1.6 max) or 28% (at 1.4 max). You pay for the pony fill one time. The bottle remains full unless needed for an emergency. Yes, a tank of air might get you to the surface. But why put yourself into a situation that is clearly sub-optimal? Let's examine the reasons you list for using air.



A single nitrox 28% or 32% fill on a pony bottle would be less than a couple of beers and last at least a year unless used. And if you don't think nitrox is SAFE, you shouldn't be using it, EVER!



Use an analyzer, like you were taught. Or demand a refund from your nitrox course.



As long as you stay within recreational limits, the one fill of either 28% (max pO2 1.4) or 32% (max pO2 1.6) will be breathable at any depth. No need to ever dump and refill.



WTF? You're worried about an OxTox hit at recreational depths within NDL for a max of 32%? Please ask for that refund ASAP. AFAIK there has never been a documented case of OxTox under those circumstances.



Then you should be diving air in your primary tank as well. There is absolutely no justification for saying nitrox is better in your main tank, but air is better in the pony. Even if you don't push close to NDL, you would finish the dive on nitrox if you didn't have whatever equipment problem caused you to go to your pony. But once you have that issue and grab the pony reg, you would rather be breathing a different gas? Preposterous.



Then why would you have 36% in the pony, EVER? C'mon folks, use some logic and rational thought.



Just how complete a jack_$$ you are remains to be seen, since you are blindly agreeing with people whose arguments are nonsense.



Once again, it is a one-time fill. You don't match anything for every dive. Once it is filled, it stays filled unless you need it or have a reg free flow, etc. It is there for you every dive. There is nothing wrong with having a pony with 28% even though you have air in your main tank because you are only diving to 20 feet today. But having the richest gas you can use at the max depth you can dive is always at least as good as air and usually better.

FYI, rebreather divers take bailout tanks with them in case of a problem. They are nothing but big (minimum 40 cf) pony bottles. They don't get used unless there actually is a problem. I probably top mine off every couple of years. We don't dump the gas and refill them with the "ideal" gas for the dive we are doing. We have several tanks with different mixes and take whatever we need without exceeding the MOD. Since a recreational diver with a pony would only have one emergency tank, it should be the richest gas that can be used at the maximum depth you are going to dive. If (by the book) you limit your diving to 40 meters/132 feet and you only feel safe with a max pO2 of 1.4, then fill your pony with 28% and be done with it. Maybe it will cost you $10. It will last until you have to pull the valve for your next flight.

I don't know how to explain it any clearer.

do whatever you want... Somebody might find themsleves deeper on a wall than they want... I would rather have air. Filling a tank with PP blending DOES have some potential to get the wrong mix.. Also, a pony is checked and breathed from on every dive and some people even practice with them comming up. Probably a pony should be topped off once every few trips at least. the dive shop will slam 1000 psi of air in the bottle, for free and with no discussion.

Draining it completely and doing a PP blend and then checking it... Ain't gonna be free...

 

[scubadada]

My pony is filled with air, I can use it in any situation.

 

[markmud]

I was going to breath my pony to the surface on my last dive just to see what I'd end up with at the surface. Currently my pony is full of air and I was diving nitrox. It was at the end of my 2nd drift dive and I wasn't far off from my NDL. I had planned to breath it prior to the dive. As I yanked the reg out of the rubber bands and took a breath, my thoughts went to my NDL and I immediately went back to my reg on nitrox. Last thing I needed was a hit because I wanted to test my pony. I might get it filled with nitrox, maybe 32%. I have yet to go deeper than 95 ft and if I ever do plan to go deeper, then I'll get it adjusted. So there's some merit to getting a nitrox fill. And yes, my vis sticker is marked o2 clean.

Hey Mr. Chen,

You should fill your pony with Nitrox. It works for you.

markm