When does Hydro Officially expire?

[jokers]

I know that if you are using a DOT standard or ISO standard tank that you have to hydro test your tank every 5 years, the main difference is that if you are using a ISO standard you can hydro test your tank as many times as needed, where a DOT standard tank is finished after 15 years. I also know that when you look on the side of the tank it has a born on date and if it has been hydroed a "sticker" epoxied to the tank. What i am unsure of is when the tank expires is it the first of the month or the last of the month? For example if i have a tank with a born on date of 9/17 if i was going to a big game or tournament would they still fill it or since it expires on 9/22 would they refuse? I can see either side of the coin.
Is there anywhere in writing not a paintball stores site that i can go to either print the rule out or show someone?

[scottieb]

The month/year format lacks the day because it's the month that matters. The fifteenth month from the birth month signifies the end, ie fifteen Septembers from your 9/17 tank.

[Alexndl]

What I have heard from my local hydrotest shop here in Canada, hydro test is good until 5 years on the last day of the month stamped

For carbon fiber the max life is 15 years (the resin holding the fiber is not as strong over time)

For aluminum tank max life is as long as it pass the hydrotest every 5 years (I have seen scuba tank being still good after more than 15 years)

[DocsMachine]

Yep. It's like a car registration- If the tag says "SEP 22", it's good 'til midnight on the night of the 30th of September.

Doc.

[jokers]

Thank you all I appreciate the info