S80 12 lt tank + 7 lt stage bottle for dives alone or with friends

[Sbiriguda]

I would like to buy a tank for some easy dives to do alone or with friends. Everything very safe and without taking risks.
The usual configuration for this sort of things would be a 15 liters steel tank which is about 250 euros including shipping here. I have been suggested an alternative solution. Aluminum S80 12 liters tank + 7 liters aluminum stage bottle. Aluminum should be lighter, requires little maintenance and it's a bit cheaper. S80 tanks are about 200 euros new and much less used. S80+stage bottle should be also quite safe

What do you think? Is that a good idea or I should stick to the usual 15 liters steel tank?
Thanks

 

[ATJ]

While aluminium tanks might seem lighter, they are more buoyant and so you need to carry more weight. If you look at the weights of the tanks and buoyancy you generally find the total weight is more for aluminium over steel.

I use a 12.2L steel with a 5 or 7L steel tank for redundancy.

 

[ATJ]

S80: S80 - High Pressure Aluminum Gas Cylinders | Composite Cylinders
Weight: 14.2kg
Buoyancy empty: 1.9kg

Faber 12.2L: Faber 232 bar Steel Cylinder Range and Specifications Faber Steel Cylinders - 232 bar - The Scuba Doctor Dive Shop
Weight: 12.9kg
Buoyancy empty: -0.75kg

i.e. total package with the Faber 12.2L (which holds more air anyway) will be around 4kg lighter.

 

[Sifossifoco]

Aluminum should be lighter

That's wrong. In fact Aluminium tanks need thicker walls than steel tanks, and end up weighting more.

 

[Sbiriguda]

Thanks I didn't notice that...
Interestingly, they both weight more and require more weight in the belt... Just the opposite of lightness. So i guess the only reason why some recommended aluminum tanks is that here they seem to be easier to find second hand and so usually they are cheaper. Maybe they also require less maintenance

 

[Sbiriguda]

Aluminum doesn't rust, i mean

 

[ATJ]

Aluminium still corrodes.

Here in Australia, tanks have to be inspected and hydrostatically tested every 12 months, steel or aluminium. If you never get water inside the tank, both steel and aluminium tanks will last for years. If you do get water in the tank, you can have problems with either type.

 

[Sifossifoco]

Exactly. Aluminium is a softer material that can be more easily damaged, but is less prone to corrosion. The fact that Aluminum tanks are cheaper and easier to maintain is the reason for their diffusion, especially around salt water.

 

[Sbiriguda]

Ok that makes sense. Here in Italy the new tanks must be inspected after 4 years when they are new and after 2 years after the first inspection. This applies both to aluminum and steel tanks. In my case I would not have an intensive usage (unlike a diving center, let me say) and I would use them mostly in fresh water since there are few spots in the seaside accessible from the beach in Liguria and most of them not comparable to the dives that can be accessibile from a diving center. So once the boat is paid It doesn't make much sense to use my own tank. In the lake instead I would use the tanks much more often. On the other hand I would have to bring them in the car trunk etc so maybe since steel Is harder It Is actually more impact resistant

 

[Sbiriguda]

As for the price, that would be the best advantage of aluminum, i am still not sure It Is really better. From my naive question you probably understood that i am not expert, so buying second hand could be a risk. Moreover, the price of used tanks Is lower but given the cost of servicing them and the fact that the first test lasts 4 years instead of 2 if they are brand new the advantage of buying used tanks Is actually reduced unless they are given away for a song...