The smallest pony bottle (extra air source)

[hmb]

I googled a little, seems like these things are all around 4 CF or larger.
Is there anything smaller?
How long would usually 4 CF bottle lasts at the depth of 3-10 meters? 5 min?

TIA

 

[luckydays]

We tried one in a pool once at 10 feet deep and it got maybe 10 breaths on it. So what maybe 1 minute. IMHO it is one of the most useless devices and is not a good safety device. .

 

[newman_diver]

I wouldn't suggest anything smaller than a 30 for a redundant air supply.

 

[NorthWoodsDiver]

you can get something called a "spare air" in a 1.5 and a 3 cubic foot size. they are nifty little devices but IMO just a pool toy.

I own one still and have used if for inspecting a dock once in 8ft of water once, its hanging in my office on a shelf wasting away.

I wouldn't recommend anything smaller than a aluminum 40 unless you only dive to 60ft or so, in which case an ali 19 would work.

 

[luckydays]

Nifty device, sure but $200 pool toy is out of my league. I am way to new to be looking at pony's or other such gear so I know nothing about what size would be a good option for you but I can tell you that the spare air is not a good device. We used them in the navy as a emergency air source used to escape engineroom's in emergency situations. Would barely last a 20 second run out of the space. In the 10' pool it did not last a minute and certainly not that long at any sort of depth.

Waste of money and I would not even want one for free.

 

[redacted]

Try asking yourself what is the largest pony you can carry to and use at your various dive destinations. And why not go with that? If you drive to all of your destinations, why not use a 30 or 40. They are probably more gas than you could ever need to extract yourself safely from an emergency. I travel by air to many of my destinations. So, while I knew that a 19 was more than adequate for emergencies, I went with the 13 to make travel a bit easier. For me, it is quite sufficient to do a normal ascent from 100 ft. 130 ft would be a bit of a hurry. The smaller tanks will probably not let you do a normal ascent. But, if you must, they will give you some gas to work with as you conduct a CESA. Why be satisfied with that?

 

[dcs917]

I'd recommend a 30cf Pony as a redundant air source. You should also take a look at some of the topics on Gas Management to do a more precise calculation of capacity needed at depth based on your Surface Air Consumtion (SAC) rate.

 

[RonFrank]

A 4CF spare air/pony is useless unless you are diving 20 feet of water! That is 1/20th the size of an AL80. It *might* get you to the surface in a huge hurry, but that assumes it is full, and you are breathing normally. This is all highly dependent on SAC rate, but 4CF is not much air at all.

I have a 19CF pony. It would basically handle getting me to the surface at any rec depth in a safe manner. It is 25% of the air in an AL80. So the question becomes can you get to the surface from any depth safely on 25% of the air you would normally use on the entire dive? The answer for me was absolutely. Another way to view this is that if you normally start an ascent at 1000psi, and end up with 500psi, you use 1/6 of the air in an AL80 ascending, and the 19CF provides 1/4 or more air for the ascent than most normally use.

However keep in mind if something does go wrong, your SAC rate may increase.

Traveling with a 30~40CF tank is not really a good option with current airline policies.

A buddy of mine has a 13CF. He feels that is safe. It is approx 1/8 the size of an AL80, so IMO not quite enough for a good slow ascent, but certainly enough to get on to the surface with a reasonable ascent rate.

If you are thinking of getting one of these for emergencies on vacation, one must balance the size/weight/volume with travel restrictions.

You can sling an AL80 if that makes you comfortable! But I don't think that is necessary.

 

[bamamedic]

I googled a little, seems like these things are all around 4 CF or larger.
Is there anything smaller?
How long would usually 4 CF bottle lasts at the depth of 3-10 meters? 5 min?

TIA

Why is the size such a concern? Are you planning on taking it in checked luggage?

At a SAC rate of 1.0 (not unheard of in an emergency situation), a 4 c.f. bottle will last about 2 min at 30 feet (10 meters). That's not a lot of time to sort through an emergency that may come up and make a safe ascent. It's even less time if you decide to dive deeper than 10 meters.

To be honest, I hardly notice my AL40 anymore. It's slung by my left side, and it doesn't get in the way, doesn't affect my trim, and if I chose to use it as a pony bottle, it would provide more than enough air to get me safely to the surface from rec depths.

 

[redacted]

A 4CF spare air/pony is useless unless you are diving 20 feet of water! That is 1/40th the size of an AL80. .

New math?