To shop owners or owners of spare air tanks

[Texasguy]

I have a 40cu pony. When I come to fill a 130cu, I ask them to top off my pony. Most stores have no problem as loss usually attributed to some regulator squeezes on the surface and a few test breaths underwater, 200 PSI max after some number of dives. However, I also have a whip, this would allow me to take my high pressure tank and leak some into my 3Kpsi pony. The whip is $100 but when you need one, it is priceless. If you need to "leak" some cubic feet for your spare air, I'd get the whip.

(you can also find one with yoke connectors if you require such)

https://www.divegearexpress.com/dgx-gas-transfill-hose-with-analog-gauge

 

[rhwestfall]

Not specifically addressing Spare Air (I won't go there), my LDS will bump/fill a pony with air/21% free. They like having safe divers around.....

 

[Bob DBF]

The big difference is that 1.6 cu ft is what would be available when you reach the surface, while the 1.7 or 3.0 Cu ft in the spare air is available when you go for that first breath after the OOA/LOA.

I would like to add that the 1.6 cuft is still available at the surface. The spare air is in addition, not instead of what is available in the tank later.

The only time a spare air might be better than a pony is when you try to pack it in your baggage.

In my case, the pony is too much of a PITA to deal with all the time, so I mostly dive with no redundancy rather than a little.

Originally Posted by scagrotto
And as far as how to get it filled, that last means that using 3000psi rental tank will leave you with only 2885 psi for your first dive. Just suck it up and shorten your dive by a couple of minutes. Of course if you figure the spare air is good enough as a safety device you can be back on the boat with 385 psi instead of 500.

If one goes OOA, I doubt it would make a difference what pressure they started at, or whether their dive was a couple minutes shorter. And the "back on the boat with 385 psi" comment just detracts from your reasoned arguments.


The problem is not the spare air, it is what it is; nor is it the advertising, it's implied I get a beautiful woman if I buy a certain type of car; the problem is a diver that won't crunch the numbers and objectively decide if the spare air is right for his dive plan. If a spare air is not right for your dive plan, don't use it. If you don't know why it is right for your dive plan and you take it because you think it will save your life, then you are a [-]moron[/-] gambler.



Bob
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That's my point, people, by and large, are not taught that diving can be deadly, they are taught how safe it is, and they are not equipped with the skills, taught and trained to the level required to be useful in an emergency.

 

[scagrotto]

the "back on the boat with 385 psi" comment just detracts from your reasoned arguments.

Are you sure it's not a reasoned, but subtle, argument about gas planning?

 

[wetb4igetinthewater]

I dive with a 30 cu ft pony that I purchased from the LDS where I used to get fills (before I became a DM at another shop). I find that over time, turning it on/off, purging the air remaining in the hose/2nd stage, it does lose some pressure. That LDS had no issues ever with topping it off. The manager said to me "Kosta, I've made plenty of money off you." I always felt treated well there, and hence they got a lot of business from me when I started out diving.

 

[Attreui]

Now that I have dove with it, and practiced with it a little. I have to disagree with some of the stuff said. I agree that it is not designed as a pony bottle. But I had no problem with it running out of air from recreational depths to a controlled ascent with a small safety stop. I tried several scenarios and while I obviously can only pretend to panic breathe, I tried to out breathe it and still could make it to the surface (uncomfortably). I hope to never need it and if I start doing more than 60-70 feet warm water reef dives I would reconsider it but for now don't see a downside.

The EAN version isn't for people who think they need nitrox spare air. It's so people who go travel diving on EAN can fill it from their tank and not have to worry about getting normal air to fill the spare air.

 

[decompression]

Now that I have dove with it, and practiced with it a little. I have to disagree with some of the stuff said. I agree that it is not designed as a pony bottle. But I had no problem with it running out of air from recreational depths to a controlled ascent with a small safety stop. I tried several scenarios and while I obviously can only pretend to panic breathe, I tried to out breathe it and still could make it to the surface (uncomfortably). I hope to never need it and if I start doing more than 60-70 feet warm water reef dives I would reconsider it but for now don't see a downside.

The EAN version isn't for people who think they need nitrox spare air. It's so people who go travel diving on EAN can fill it from their tank and not have to worry about getting normal air to fill the spare air.

That doesn't make sense....


Sent from my iPhone using Tapatalk

 

[drrich2]

Is there realistically any expected problem from putting nitrox from your main tank in a 'regular' Spare Air? From what I understand, you don't need an O2-clean tank for banked nitrox, but rather nitrox obtained via partial-pressure blending, where they put pure oxygen into your tank 1st. If you fill from your main (nitrox) tank, no pure oxygen.

Richard.

 

[KDAD]

I agree it doesn't make sense.

I agree that it is not designed as a pony bottle.

What is it designed as then?

But I had no problem with it running out of air from recreational depths to a controlled ascent with a small safety stop. I tried several scenarios and while I obviously can only pretend to panic breathe, I tried to out breathe it and still could make it to the surface

Sounds promising. :rolleyes

(uncomfortably). I hope to never need it if I start doing more than 60-70 feet warm water reef dives I would reconsider it but for now don't see a downside.

Again, what does this mean "uncomfortably "? Hasn't the whole argument against a spare air been that it doesn't have enough capacity for use below 60-70 ft? Finding situations where it might work only creates a false sense of security. The downside is that you may end up below 70 ft and run into a situation where you need it and then run low on your backup gas. That's uncomfortable.

 

[Attreui]

Is there realistically any expected problem from putting nitrox from your main tank in a 'regular' Spare Air? From what I understand, you don't need an O2-clean tank for banked nitrox, but rather nitrox obtained via partial-pressure blending, where they put pure oxygen into your tank 1st. If you fill from your main (nitrox) tank, no pure oxygen.

Richard.

That would be better for someone with a lot more experience to answer. I know that when we are EAN certified they drill in your head that you cannot put EAN into anything that isn't cleaned and rated for it. That was what several divemasters that I talked to answered when I asked that same question as to why you would need EAN in what is basically a CESA bottle. It made sense to me. When I go to the islands and rent a tank of EAN they are not going to fill the spare air with air or let me top it off one of their normal air tanks for free. Shrug. Maybe you are correct.

---------- Post added December 8th, 2015 at 07:18 PM ----------

I agree it doesn't make sense.



What is it designed as then?



Sounds promising. :rolleyes



Again, what does this mean "uncomfortably "? Hasn't the whole argument against a spare air been that it doesn't have enough capacity for use below 60-70 ft? Finding situations where it might work only creates a false sense of security. The downside is that you may end up below 70 ft and run into a situation where you need it and then run low on your backup gas. That's uncomfortable.

]

No the argument as far as I have seen is that they are "bottles of death". For a recreational diver, who is diving in the warm water on the shallower reefs this seems to be a useful item in case of an emergency to get you to the surface or to a safety stop depth where if you do empty the bottle can do a safe CESA. When I said uncomfortable, I mean that when I was basically deliberately hyperventilating to see if I could use it for this purpose, it did get tough to pull breath at the end of the safety stop in which case I could have done a CESA and been fine. Its never comfortable to feel your tank run dry whether you are in an emergency or not. I would not use it past 70-75 feet. I would carry my actual pony at that point if that was the plan. But the majority of what I wanted it for was 35-50 foot reef dives.