How to tell size of 3500 psi steel tanks?

[Grog]

Does anyone know of a reliable way to get the cylinder size of an older 3500 psi (Manufactured in 1981), either by measurements or serial numbers? Also, was it not (or is it still not) a requirement of the US DOT to have the manufacturer's name on the stamp, or do some manufacturers use symbols? There is one on it that looks like an "R".

 

[kwinter]

There should be an SP number (special permit) for hydro. That permit would certainly give the manufacturer. Most common was PST. You can find it on the DOT web site.

As for size, if it is about the height of an aluminum 80 or just a shade taller, it is most likely a HP120. I'll gladly take it off your hands. HP100s were shorter, about the height of a 63.

Neck size should be 7/8 and valve should be 300 bar DIN.

BTW, you should make sure the SP has been renewed and is current. If not, the tank can not be filled or inspected.

 

[bamafan]

Scuba Cylinder Specification Chart from Huron Scuba, Ann Arbor Michigan

This might help.

 

[spectrum]

In all likelihood it's PST cylinder. Look for either a stylized Pst or possibly an over lapping CL (Cochran Labs did early PST testing) as the symbol in the original hydro marking. The chart mentioned above is a good reference for height. 100 CF was a very common size for that product and many were branded out to the likes of US Divers and Genesis. Some were painted others had hot dipped galvanize finishes.

Also these cylinders will have the 7/8 thread neck, this is a machine thread and is SMALLER than the common 3/4 straight pipe thread seen on most cylinders.

3500 PSI Cylinders will be for DIN use only. I have 4 of them in the 100 CF size and they are dandy.

 

[Grog]

Thanks for all your input. I recently bought these and was told they were 120 and the size seemed right, I just wanted to confirm and couldn't find a size chart with 3500 psi cylinders in it, although I assumed the 3442 would be very close. After doing a bit more digging (after you folks giving me some direction). I found the permit (or exemption E9791) is good until 2015.

Thanks for the help.

 

[dfx]

Does anyone know of a reliable way to get the cylinder size of an older 3500 psi (Manufactured in 1981), either by measurements or serial numbers?

Fill the cylinder with water, measure how many cubic feet of water it holds, multiply by 238, voila