steel /aluminum mark on tank

[vicmac]

Hi, I m looking to buy a second hand steel 100 tank. There is one I have seen but the owner does not know what it is anyway I asked him to write down the markings on the neck. How do I tell if it is steel or aliminium, I tried to look it up and all I found out was for aliminum it will say al, and also some steels will say pst, for pressed steel tank. Can anyone give me more info please? Cheers!

 

[captain]

Hi, I m looking to buy a second hand steel 100 tank. There is one I have seen but the owner does not know what it is anyway I asked him to write down the markings on the neck. How do I tell if it is steel or aliminium, I tried to look it up and all I found out was for aliminum it will say al, and also some steels will say pst, for pressed steel tank. Can anyone give me more info please? Cheers!

If a magnet sticks to it it is steel, if it doesn't it's aluminum.
Aluminun tanks other than the very first old ones made when aluminum came into general use will be marked AL before the pressure rating, usually 3000 psi. Old ones will be stamped SP but you don't want to buy those any way.
Steel tanks will be stamped 3AA or E before the pressure rating but the E marked tanks will be high pressure tanks 3400 psi and above.

 

[knowone]

Ask the owner to write down the numbers for us too.

 

[spectrum]

If the bottom is flat you can pretty much count on it being aluminum, it fact that may be an absolute statement but I'm not positive.

 

[vicmac]

ok here s the info he s given me, though it seems he hasn't given all the markings, any way heres what I have 8A191, 0208302 and 2A181, 7A986

 

[ianr33]

If the bottom is flat you can pretty much count on it being aluminum, it fact that may be an absolute statement but I'm not positive.

Not quite true. Buddy of mine has some ancient Al90's with round bottoms.
Probably fair to say that 99.9999% of flat bottomed tanks are Al.

 

[vicmac]

Owner wrote...."K I dont see a tc on it...and a magnet DID stick to it!LOL. and it has a flat bottom."
Right Im really confused now! if a magnet sticks its steel....yes its steel then,...hold on it has a flat bottom!!????

 

[vicmac]

and it has a flat bottom."

Im wondering if they were just looking at the boot, and not at the tank??!! It was their dads tank, they dont know too much about scuba!

 

[spectrum]

Not quite true. Buddy of mine has some ancient Al90's with round bottoms.
Probably fair to say that 99.9999% of flat bottomed tanks are Al.

I kind of figured there may have been a few. Ii can live with 99.9999%

Pete

 

[ianr33]

Owner wrote...."K I dont see a tc on it...and a magnet DID stick to it!LOL. and it has a flat bottom."
Right Im really confused now! if a magnet sticks its steel....yes its steel then,...hold on it has a flat bottom!!????

Any chance they put the magnet on the valve rather than the tank itself?

Or maybe there was glue on the magnet