15 liter tanks

[divezonescuba]

There has been some past discussion on 15 liter tanks versus AL100s. It has been inconclusive with some saying they are the same and some saying AL100 tanks at 3300 psi are actually 13.2 liters or so in volume.

I used these 15 liter tanks for a couple of rec dives in Dahab after our technical diving was over. It seemed to be somewhat subjectively lighter than than an AL100 from the few times I have used one of those.

My tanks were pressurized to 2900 not 3300, so I was wondering if I actually had much more as than an AL80 / 11.3 liter tank?

 

[grantctobin]

200bar*15L=3000Liters
207bar*11.3L=2340Liters

 

[DiveClimbRide]

Also
200bar*15L=3000 litres
224bar*13.2L=2,956.8 litres

More than an AL100 as well

 

[Angelo Farina]

Usually here in Europe people use 15 liters steel as the standard tank you find everywhere. Often they are equipped with two valves and two posts, so you can use two fully independent regs.
The standard pressure was usually 200 bar before year 2000. But lately you mostly find 232 bars. Which means 15x232=3480 liters: this is enough if you do not exceed 50m and limit the deco to less than 20 minutes, which is what most people here consider reasonable for rec diving.
Beyond this, better to go for a 10+10 liters at 232 bars.

 

[divezonescuba]

I suspect that they were not steel tanks. They were not painted and did not appear to be galvanized. They looked like aluminum.

They had flat bottoms with no boots. The valves were conventional single outlet DIN.

Are there flat bottom 15 liter steel tanks In Europe?

Are there true 15 liter AL tanks in Europe?

 

[Degenerate]

Usually here in Europe people use 15 liters steel as the standard tank you find everywhere. Often they are equipped with two valves and two posts, so you can use two fully independent regs.

15 liter steel tanks with double valves might be the standard tank around your neck of the woods, but it is absolutely not the "standard tank you find everywhere" in Europe, not even close.
Shame though, they are nice tanks.

Edit: Really had to edit this too, because you say that 50m dives with 20 minutes of deco is considered rec diving and it most definitely is not.
Diving to 50m with a deco obligation is in no way a recreational dive and I'm having a really hard time figuring out how you think that is a recreational dive.
That is without a doubt a technical dive and there is no way you can tell me it isn't.
Again, nobody considers this to be recreational diving, if you're racking up deco then you are well beyond the limits of recreational diving.

 

[DiveClimbRide]

I suspect that they were not steel tanks. They were not painted and did not appear to be galvanized. They looked like aluminum.

They had flat bottoms with no boots. The valves were conventional single outlet DIN.

Are there flat bottom 15 liter steel tanks In Europe?

Are there true 15 liter AL tanks in Europe?

Were they flat bottom or concave bottom?

 

[Angelo Farina]

15 liter steel tanks with double valves might be the standard tank around your neck of the woods, but it is absolutely not the "standard tank you find everywhere" in Europe, not even close.
Shame though, they are nice tanks.

Edit: Really had to edit this too, because you say that 50m dives with 20 minutes of deco is considered rec diving and it most definitely is not.
Diving to 50m with a deco obligation is in no way a recreational dive and I'm having a really hard time figuring out how you think that is a recreational dive.
That is without a doubt a technical dive and there is no way you can tell me it isn't.
Again, nobody considers this to be recreational diving, if you're racking up deco then you are well beyond the limits of recreational diving.

I had to be more specific. I was referring to countries such as Spain, France, Italy and Greece. And UK, of course..
Regarding the boundaries for rec diving, I was referring to the dominant no-profit organizations in these countries, not to commercial USA-based for-profit certification agencies, which have standards more limited in depth and deco practices.
More explicitly; I was referring to CMAS standards (but BSAC in UK is very similar). For a complete recreational diver holding a 3 stars recreational degree the max depth is a ppO2 of 1.4 bars, which means 56m in air.
And deco is allowed if the corresponding specialty course has been followed. Same for Nitrox, an additional specialty course is required
Here the official specifications: https://www.cmas.org/document?sessionId=&fileId=5392&language=1

 

[divezonescuba]

Were they flat bottom or concave bottom?

Flat Bottom.

 

[divezonescuba]

I am thinking that these 15 liter tanks were actually Luxfer AL100s. These are suppose to be 5 pounds lighter than Catalina AL100s which I am more familiar with. That could account for my impression that they were different than normal AL100s.

So, a Luxfer AL100 (actually 99.3), 3300 psi tank filled to 2900 has about 87.3 cubic feet of gas. Whereas a Luxfer AL80 has 77.4 when at 3000 psi.

A gain of 9.9 cf of gas is less than half the expected amount when looking at the common tank ratings of 100 and 80. Since, I finished most of the recreational dives with 1000 psi or more with the "15 liter" tank anyway, it does not really appear to justify the increase bulk of the "15 liter" tank.