Question about hydro testing

[phenom]

Hey guys, I'm about to buy a used tank from somone, The person selling it said it was hydro tested in 2009 so its still good and so is the visual. The sticker will prove that the visual is okay ofcourse. All of a suddon I realized that I have never seen a hydro sticker on any tank, (but then again I am a new diver) I was told that hydrotesting is stamped on the inside of the tank from a friend, is that true? do some dive shops put them on the outside or just the inside?

thanks in advance for all the help!

 

[WeldonDowd]

They are stamped on the outside of the tank so they can be read easily. Look for it near the factory stamps right below the neck. It will be a month and year stamp. In the photo below it is the stamp where the paint is chipped off around it.

 

[g1138]

It should be stamped on the shoulder of the tank, on the outside.
Most shops will stamp it above or next to the original/last hydro date and mark it with a color.

 

[herman]

And what you are looking for is a 1 or 2 digit month/ hydroers stamp / 2 digit year stamp in the metal, a hydro is not a sticker. You should find something like 4@09 , meaning it was last hyrdoed in april 09 at the hydro facility who's hyrdo stamp is "@" . A unique facility stamp is issued to each hydro facility, it's somewhat of like a trade mark. The oldest one, which will be under the paint if the tank is painted is the manuf date and initial hydro, the rest are retest. While most stamp in order, some do move around the neck so it may take a little looking to find the latest one.