Hydro Testing is the way of testing a pressure vessel (like a paintball air tank or CO2 tank) to make sure its safe to continue using.  When you have your tank hydro tested, the tester (after removing the regulator or valve) fills the tank with high pressure water at a higher pressure than what your tank is rated to hold.  So if you have a Macdev 4500 Air Tank the tester fills it with water pressure which exceeds 4500 PSI.  The reason water is used during the test is because if the tank fails the test and leaks only a little trickle of water will leak out of the tank.  If a high pressure gas was used to test the tank, and the tank fails, the tank would more than likely explode.

If your tank passes the test, the interior of the tank is dried, the regulator or valve is reattached, and the tank is mailed back to you with a hydro test label permanently “epoxyed” to the tank.  If your tank fails the test, it has been rendered unsafe for use.  A large hole is drilled into the tank so it can not be filled and the tank is mailed back to you.

How often do I need to test my paintball air tank?  Well that depends on your tank itself.  All tanks manufactured and/or sold here in the US are certified buy the Department of Transportation (DOT).  Which means that every tank will have a DOT Number.  If you do a search online for your specific DOT number you will find the certificate information and about half way down the long government document you will find how often you are required to hydro test your tank and you will also find the lifespan of your tank (how many times it can be retested). Once you know how often your tank needs to be tested, simply check your tanks label or markings for the “Born on Date”.  The born on date will be a in the format of month/year.  So for August of 2006, it will read 08 06.  There may be some markings in-between month and year so you will have to use your head a little if the dates don’t jump out at you.  For more information on reading your tanks markings please click here.

Aluminum air tank or CO2 tanks have to be tested every 5 years and have a unlimited life span.  Steel tanks have to be tested every 3 years and have a 24 year life span.  Fiber  Wrapped and Carbon Fiber tanks have to be tested every 3 or 5 years (depending on the DOT number) and have a life span of 15 years.  Its important to note now that tanks which have less than a 2″ diameter and are less than 2 feet long do not need to be tested at all.  These tanks may also have no DOT markings on them, so don’t pull your hair out trying to find them.  Here is a pretty good list of paintball DOT numbers.