Diving with 11lt aluminum tank + pony bottle

[Sbiriguda]

Hello,
especially for price and maintenance cost reasons I a considering to buy a second hand set of S80 aluminum 11lt tank + 7 lt pony bottle. I would use them for very simple dives, without going too deep and being cautious during the dive.
The S80 would be like this one (more or less)
Bombola s80 da sub o per carabina pcp in alluminio - Sports In vendita a Brescia

I kindly ask you if you think that this is a good idea or it is still better to stick to a different solution, like a steel 15lt tank. If you think S80+7L pony bottle is good, maybe you can give me some suggestions on how to buy pony bottles. If it's better to buy new or used is good, brand and product types, and how to check it before the purchase
Thanks

 

[chrisch]

7 litre is a lot of spare gas for just 11 litres back gas. Why do you want a bailout tank if you do simple dives and cautious? Are you planning solo diving? For a bailout tank you need enough gas to get you to the surface safely. The most common size for open water is 3 litre. A good buddy is a much better option, but that debate has been had many times.

As to new or secondhand that really depends on what is available. It is a long time since I lived in Italy but I remember that having the tank tested was not expensive there. If that is the case the secondhand could save you some money. Often though it is cheaper to buy new. 12 litre steel is probably most common in Europe.

There is some good information here - Bombole in acciaio o alluminio

 

[chrisch]

If you want good advice it is also perhaps worth talking to my friend Max he is not far from you.

Verona Sub - Iniziano i Corsi Sub a Verona

 

[Sbiriguda]

Thanks
Yes, I am also planning solo diving in very safe conditions and without taking useless risks with "dangerous" dives.
I have been recommended a retailer that seems to be reliable and sells new tanks for 210 EUR with 4 years warrantee
Centro Ricollaudo Bombole a Casale Monferrato
That sounds good 15lt steel tank
Anyway I am interested to pony bottles and S80 11lt aluminum tank. Aluminum perhaps requires less maintenance and I am interested in pony bottle also for other purposes
About your friend Max, I am close to Milano, it's about 2 hours from Verona, quite far though I might happen to go there and talk with him

 

[chrisch]

...Aluminum perhaps requires less maintenance and I am interested in pony bottle also for other purposes
About your friend Max, I am close to Milano, it's about 2 hours from Verona, quite far though I might happen to go there and talk with him

Aluminium is not any better than steel in my experience. Steel does not change buoyancy so much as the gas is used up.

We used to live in Cassina de Pecchi - I did my trimix training with Max. They do a nice Sunday dive in Garda. You could phone him if you want to know all about tanks and the costs in Italy - he is an honest person.

I don't know if it is still there - a long time ago there was a dive shop in Como that sold tanks. Also Pianeta Dive in Biassono. We had good experiences with both those shops.

We used to dive in Lago di Como - there are a few places you can park at the side of the lake, but not much to see. A bit north of Cernobbio I think is the nearest place to Milano.

 

[kelemvor]

For the tanks that I own, I prefer steel for primary. I do use aluminum for deco/stage/pony. It comes down to a couple things in my mind:
1. How much gas do you want/need?
2. What are the tank buoyancy characteristics?
3. What is the weight? Can you manage the tank on land for shore diving or on the boat?
4. Size. Is the tank way too big or small for your body?
5. Price

I also prefer low pressure tanks, because they can be overfilled by a willing fill station. I generally put a little over 140cuft of gas into my steel 108. Sorry for the imperial measurements there.

Usually (always? I'm not sure) steel tanks will be more negatively buoyant. In my opinion, that is a very good thing. When I dive with a steel 108 on my back, I don't need any weights at all in fresh water. Only a few pounds in salt.

Al80 (I think that's 11l?) is the most common tank in my part of the world. They are very cheap compared to steel, so shops use them, abuse them, and throw them out when they can't pass a hydro/vis. Aluminum definitely wins on point 5 (price).

When it comes to a pony tank, I went with a small 13cuft (S13S 1.9 liter) tank. It will be enough for my purposes, and is small enough that I can bring it on an airplane when I travel. That S050 (48.4cuft) tank is probably too big to take on an airplane if you travel without paying a big fee.

I think if I were considering something as large as an S050, I would probably just go ahead and sling a second s80 (11l) instead. Better yet, dive it as "doubles" backmount or sidemount. Where I live, S040 or S080 are the most common sizes used for a slung tank. I use an S040 for o2 accelerated decompression when required. The main drawback to doubles is that you'll need a different BCD (for sidemount) or additional hardware and maybe a different bcd (for backmount).

 

[chrisch]

...
I also prefer low pressure tanks, because they can be overfilled by a willing fill station. I generally put a little over 140cuft of gas into my steel 108. Sorry for the imperial measurements there....

You will not find anywhere in Europe that will overfill. Alu tanks tend to be 200bar (about 3000psi) and most European countries fill to 200 bar. The compressor or mix panel will cut off at 200 or you can have 300 bar if you have the correct DIN fitting and a 300bar tank.

Here in the UK we have 232 bar (I don't know why the difference). However if you take your tank to most other European countries you get a 200 bar fill.

Filling a tank beyond it's design pressure is a massive failure of basic safety regulations and anyone doing it would be sacked, if it were the dive shop owner they still would find themselves in very big trouble. Most customers also would be upset to find that their tank had been overfilled.

If you need more gas then buy a bigger tank, if you want a higher working pressure buy a tank that is rated for a higher pressure. I have no idea why this practice is acceptable in other parts of the world. High pressure gas is probably the most dangerous thing there is in scuba diving.

 

[Tribal]

Here in the UK we have 232 bar (I don't know why the difference). However if you take your tank to most other European countries you get a 200 bar fill.

Newer steel tanks are almost always 232 bar? Its the old ones that are 200bar.
In Belgium and the Netherlands they always fill them around 230bar. It’s aluminium that they don’t overfill.

 

[Sbiriguda]

When I get tanks from the divings in the Italy mostly I find 210 or 220 bars checked with the pressure gauge. So I would say they are 230 bar steel tanks not completely filled

 

[Searcaigh]

11L Aluminium (S80) and 4L (S30) is my usual configuration locally here in UAE and works well for me as:

1. I frequently dive solo and provides me with a redundant supply of gas
2. I don't use an octopus second stage on my primary regulator set up, so in the case of donation too an out of gas (OOG) diver I can hand everything over whilst ascending. My primary second stage is on a long hose.
3. I usually have it filled with EAN50 and use it as a deco gas on 30m dives occasionally.

The more you use a pony / stage it becomes second nature to carry it and using also becomes second nature. However I never use it to extend dives (i.e. breath from it for this purpose) and my deco dives are planned using EAN50.

My regular buddies know what's in the pony and are well experienced divers.

Personally if I had the choice I'd use a 10L or 12L steel, just to lose some weights when I dive dry.