Why are AL80 tanks often refered to as 12L tanks (rather than 10L?)
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Ryan Mcshane
Contributor
Ali 80 is 11.1L at 207bar. Its stamped on luxfer 80’s in the uk
OP
You should call them just "aluminium 80"s and if someone asks how much they would be in litres you can say that "they come from a weird country which is not using the metric system and where one can not simply calculate anything by the decimal system and all measurements taken are fractional and difficult to interpret without tables and calculator and extensive knowledge.... but if you really want to know how much the tank volume would be in the real world it is something close to 11.1 litres though NOT EXACTLY that because that would be considered high treason in that weird country which manufactures them"
hehehe
not sure how helpful this would be to a metric diver (c) just wanting to know if he roughly has the same amount of air available as he's used to or not
OP
Good to know - 11L it will be from now on then.
Wonder what our alu "15L" really are, I've got a feeling 13L might not sound as good as 15L, at least from a marketing point of view
OP
OP
My metric, steel 10L tanks will nominally have 3000 L of gas at rated pressure (300 bar).
(In reality, they will hold about 10% less due to compressibility showing itself at above 230 bar).
Light sarcasm aside, this is an example of the fact that when dealing with metric tanks, the water volume only tells half the story about the tank's capacity. You have to know the pressure rating as well, and that's normally either 200, 232 or 300 bar. Some years ago, I had two 15L tanks. One was rated for 200 bar, the other for 300 bar. That's a 50% (OK, 40% if we take compressibility into account) difference in capacity. I've sold both and have only 10L 300 bar tanks now, BTW.
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I think all classic Luxfer AL80 are 80 cubic feet / 2,300 L @ 3000 PSI / 210 bar ambient temp.
I just want people to know how much gas reserve they have compared to what they're used to having with steel tanks.
AL80s being the most popular rental aluminium tanks for warm water diving worldwide, this should be very common knowledge, but it's tricky somehow.
I'll stick to 11L for now and try to get people around me to stop refering to them as 12L tanks...
It would not be an overfill if the tank is rated for 230bar or more, it is just using fully the tank rated capacity
Yeah thats what I meant. We have steel 10 12 and 15s and Al60 (I think 60) that are 9.6, Al80 (11.1) and All100(13.6)
Easier to also call them (the aluminium ones) 10 12 and 15, and fill them to 230 insted of rated 207.
Another interesting point: I've only seen rental tanks being filled to 200 bars (plus usually around 10% just in case but still called 200bars ). My LDS can fill 300 but they do so very rarely (I guess for special tec dives - I don't do tec).
I think we Europeans try to keep things simple. Here are the choices: 10, 12 ,15 or 18lt at 200bar and if you are very lucky 300 bar.
PS: I only have about 150 dives in my hometown in Greece and around Indonesia so very limited experience but I have a feeling that these are the norm for warm water rec diving.
OP
So calling AL80 12L would come from a 30 bar overfill? 30 bar = one extra liter?
interesting
we aim for 200 on the boat, though the station overfills so that it's roughly back 200/210 bar a few hours later at ambient temp.
Anything higher is frowned upon as the valves start wearing down fast, leaking etc.
It’s only because in Europe you only see 10l, 12l and 15l for the common sizes.
I have never seen yet an AL80 because I have dived only in Europe (I am a newbie too so not seen too many people doing complicated dives)
So I imagine if you go to another country you’ll name it whatever you are used to.
I am pretty sure that most of people who never use litres will try to call the capacity whatever they are used to if they use steel tanks.
Just my 2bar psi ?
Also if you give me an AL80 and don’t tell me how many litres equivalent, I’ll have no clue what a cubic feet mean or represent as I have never used this unit in my life, I’ll have to convert in litres to make sense of it.
Same if you gave me psis instead of bars.
Edit: is the AL80 the same size than a steel12l ? That would make sense if the customers didn’t realise that there is no 12l and would intuitively think it must be a 12 because it is too big to be a 10l.
The 10l I have seen are fairly short so anything that is roughly the same height than a 12l, I would have probably made the same mistake and assume that it is a 12l
Here s a pic of steels if you want to compare:
Faber Steel Cylinder
(There are short and fatter 12l as well but most of people don’t use them)
I have never seen yet an AL80 because I have dived only in Europe (I am a newbie too so not seen too many people doing complicated dives)
So I imagine if you go to another country you’ll name it whatever you are used to.
I am pretty sure that most of people who never use litres will try to call the capacity whatever they are used to if they use steel tanks.
Just my 2
Also if you give me an AL80 and don’t tell me how many litres equivalent, I’ll have no clue what a cubic feet mean or represent as I have never used this unit in my life, I’ll have to convert in litres to make sense of it.
Same if you gave me psis instead of bars.
Edit: is the AL80 the same size than a steel12l ? That would make sense if the customers didn’t realise that there is no 12l and would intuitively think it must be a 12 because it is too big to be a 10l.
The 10l I have seen are fairly short so anything that is roughly the same height than a 12l, I would have probably made the same mistake and assume that it is a 12l
Here s a pic of steels if you want to compare:
Faber Steel Cylinder
(There are short and fatter 12l as well but most of people don’t use them)
