What is a visual eddy test?

There is some confusion between a SCUBA visual exam, a visual inspection,  and a visual eddy current test.  All tank filling personnel are required to conduct a visual inspection of the outside of the tank to make sure there is no visible damage that could compromise the integrity of the tank.  We’re looking for dents, dings, and gouges.  The cost of the visual inspection is including in the cost to fill.

A SCUBA visual exam is done on breathing air tanks periodically.  The tank is emptied, and the valve is removed so they can look inside the tank for any corrosion, mold, or debris that could have accumulated in the tank and get into your regulator or lungs.  Most SCUBA shops charge $10-$15 for a visual.  If you use your SCUBA tank for an airgun or paintball marker and never for breathing, you don’t need a periodic SCUBA visual exam.  We do a complete Visual exam at the time of hydro testing.

A visual eddy current test checks tanks for sustained load cracking around the valve.  We use a probe that has an electrical current and creates a magnetic field which can highlight cracks in the aluminum.  Cracks are bad for everyone.  Aluminum tanks need to have some elasticity so they can expand as they are filled.  A crack is a clear indication that the aluminum won’t expand at that point, and the crack will widen.  Aluminum tanks made prior to July 1990 could have been made with 6351 aluminum alloy.  Some manufacturers started switching over to 6061 aluminum alloy as early as 1988.  Most fill personnel require anything made prior to 7/90 to have a visual eddy inspection at the time of the hydro test.

It’s important here to note that a if a tank doesn’t pass a visual inspection or a visual eddy current test it can’t be filled.  But tanks that don’t pass a SCUBA visual inspection can usually just be cleaned out and filled up.  I personally think beverage tanks should get a yearly SCUBA style internal inspection.  With home kegerator systems becoming increasing popular there runs a risk of bacteria growing in the tank and tainting the beverages.  For example, if there is a leak in the airline causing the tank to empty while the keg is still pressurized, beverages can back fill into the tank and start growing bacteria at a rapid pace.  if you have a beverage cylinder and have seen fluid in the lines between the keg and the tank ask for an internal visual inspection.  If your lines aren’t transparent, think about changing out a section to one that is.

I hope this answers some questions and keeps some people safe.  Please feel free to contact us with any questions.


How do I know if my tank is out of date?

Every tank is labeled with the date of manufacture and your hydro testing schedule is based off of that.  Looking over your label you’ll see lots of information, but you really only need two or three things.  The date of manufacture, the last hydro test if applicable, and the PHMSA exemption number.

Paintball tank label
Example of a label

In the picture above the first line is the regulatory information for Canada’s testing standards.  The second line is the US exemption or now called the special permit number.  The “DOT” has been replaced with “SP” on more recent bottles.  The third line is the serial number.  The fourth line is the date of manufacture.  If there was a more recent hydro, it should be adjacent to the date of manufacture for ease of locating.

The date of manufacture is the month followed by a symbol or number and then the two digit year.  The date in the bottle above is May 2003.  Which puts the end of life date at the end of May 2018.  So as of this article being written this tank is best used as a windchime and can’t be tested or filled.  All fiber wrapped tanks have a fifteen year lifespan, but the solid aluminum paintball tanks can be tested until they fail.

To know how long your tank has between hydro tests, go to:  https://www.phmsa.dot.gov/approvals-and-permits/hazmat/special-permits-search  and enter in the E or SP number.  For example E 10945 as in the picture above.  There will be a paragraph labeled testing, and it will indicate how long the period between tests is.

If you have any questions, take a picture of your tank and email it to us at info@paintballhydro.com

Thanks for reading!  Nick.

How to judge the quality of a hydro-test facility

Daniel Hogan, one of founding partners has always stated that the end consumer doesn’t know the results of the quality of the hydro-test, they only see the stamp on the bottle.  That being said, it stands to reason that a company that doesn’t spend much time or effort to properly label your tank after testing may not have put much effort into testing it.  Here at paintball hydro we understand that paintball tanks are exposed to PEG (the fill of a paintball), sunlight, moisture, and generally being tossed into gear bags or rubbed on the ground.  To combat these issues, we make sure to overcoat our hydro labels with a solid coat of high grade epoxy to make sure they stay on.

We test the integrity of the threads on each bottle with a no-go gauge to ensure the threads are deep enough for the valve not to blow off.  Ninja paintball is the only other company that we know of that does this, probably because they know something about the bottles they sell.  Paintball players who fly frequently with their bottles take the valves on and off for the TSA should be especially concerned with this issue.  Most players only have their valve off every five years for testing, and it’s less of a concern.  Pro players who have had the valve removed and reinstalled several times usually sell off their old bottles and there are lots of used bottles out there.

Fiber wrapped bottles take time and patience to test properly.  We love this sport and we wouldn’t speed our way through a test because the fiber wrapped bottles take longer to test than a solid aluminum or steel tank.  We understand the consequences of a bottle failing out in the real world while someone is holding it.

Hydro tests cost about the same everywhere, so it makes sense to go with a company that you trust and who understands what paintball cylinders go through in their lifespan.  Check out their website, talk to someone who works there, and go with a company you trust.