How to tell age of CO2 Tank? Or Just Toss it?

[volleybiggs]

A friend of mine had 20 oz CO2 tank. It had a leaky pin valve and was going to toss it. I told him those valves are $5 and to let me have it. Just wondering how I can tell how old the tank is and if it is worth replacing the valve if it is too old. Saw the Hydro testing number on one of the links mine says E1800 but I did not see that is a Hydro test number.

[The Pumper]

look at the part of the tank where it curves for the head of the bottle. There should be a date. There should be a number, then a triangle then another number.

[volleybiggs]

I meant to say this was a 9oz co2 tank not the 20oz. Does that matter as far as the date? There are no dates around the neck only on the bottom

[oldironmudder]

Size doesnt matter. ALL air cylinder tanks will have a date on them.

[volleybiggs]

I guess the date is on the tip of the bottom. 5(a small circle)1
Would that be May of 2001? Is there a date when they are no good?
I was reading on one of the links I found here where

Bottles 2 inches in diameter or less, and less than 2 feet long DO NOT have to be tested.
"The 2 and 2 rule."

http://www.hydrotester.com/when.htm

[DFSniper]

yeah, so if you dont have the "3AL" on the top, you should be good.

[Kenny_McCormic]

9oz never need hydro put a a squirt of oil on the pin valve and work the pin in and out for a few minutes, them go get it filled, that should fix the leak. NEVER DO THIS TO A HPA TANK IF YOU VALUE YOUR LIFE!!!