Hydro testing, why do it? What is it? and Why bother?
article by Young Choi
If you have been around paintball long enough, sooner or later, you will hear the term the “Hydro test.” Basically the paintball cylinder that you have on your paintball marker needs to be retested for its serviceability every three to five years.
Department of Transportation (DOT) requires vessels (bottles) to be tested regularly and it is a good idea to do. I would hate to imagine having a full bottle failing on me inches from my chest cuz it was way past hydro.
I took a trip over to Hydrolab www.hydrotester.com and owner, Geoff Pentz, was kind enough to give me an over view on the testing process and patient as he answered all my questions. Geoff Pentz is an avid paintball player and dive shop owner. He saw a need for the services that his company offers. In the past, many testers treated the paintball vessels (due to the small size) with indifference and basically put customer service last for the paintballers in favor of the much larger and more profitable testing of larger tanks like scuba and bulk Co2 bottles.
It intrigues me that people will refuse to get their bottle hydro tested. Working at the local shop and field, I have turned away people due to out of hydro bottles. I’m amazed how many of them (the player) will say that another shop/field have filled their tanks recently even though their bottles hydro date has expired. So then they leave all upset with me, I’m looking like the bad guy while that other shop/field probably gained a customer for life cuz big meanie me won’t fill their expired tanks. Even though there is a slight chance of a bottle failing, it is still there. I don’t want to become a statistic, as I’m sure you wouldn’t either.
|HPA bottle purposely filled to burst|
First off, I get nervous filling my own tanks. I get even more nervous fill a stranger’s tank. I don’t know if their tanks were filled off of a system that maintains their filling system. I don’t know if their tanks were filled off of a system that ensures no moisture gets to the player’s bottle. A compressor system that is neglected and with poor moisture scrubbers/filters will allow moisture into the bottle causing rust and having a negative effect on the bottle’s structural integrity. I don’t know if their tanks were constantly flash filled super heating and weakening the structural integrity of the bottle. Too many variables to worry about, I’m confident with my air tanks, but can you say the same with yours? All I’m getting at is this; please get your tank tested once the date expires.
Ok, enough of my lecturing, let’s get on to how the hydro test is actually done. Due to DOT statutes, I was unable to actually see the process. However Mr Pentz was very helpful explaining the process. Before I get into the actual process, I have to give you a little class on what that label on the side of your bottle means.
|Now you know what it all means|
Every carbon fiber wrapped bottle has a label on the side. Every metallic bottle has the pertinent information stamped into it near the top of the bottle. If you look at the image to the right you will notice the DOT Number. The DOT Number is the number that is given to that certain bottle lot to make it easily identifiable by the DOT. To the right of the DOT Number is the Maximum Operating Pressure, in this instance it is 4500. So this particular bottle is capable of holding 4500 PSI. Below the DOT Number is the Canadian equivalent of the DOT Number and to the right of that is the pressure rating in BARs (each Bar is equivalent to 14.508 PSI, so 14.508 X 310 = 4497.48 PSI well it’s close enough to 4500 PSI).
Below that is the bottle manufacturer’s serial numbers.
Below the serial numbers is the Hydro Date (or Born on Date). This date denotes when the bottle was manufactured. Depending on the bottle (some need to be tested at the three mark and some at the five year mark) it usually needs to be tested three years after the Hydro Date. For the bottle in the image, this bottle would need to be hydro tested on December in 2007. Were the bottle a five year bottle, it would need to be hydro tested on December in 2009. Every fiber wrapped bottle has a maximum 15 year life span. In 2019 this bottle will have to be destroyed due to its life span being expired.
Next to the Hydro Date is the REE number. This number is important for the testers themselves. I’ll explain more on this number in a bit.
|Oversized dial to aide accurate readings|
The testing process has to be very precise due to the small size of the paintball bottles in use for paintballing purposes.
|HPA bottle is attached and prepped to dip|
In a nutshell, the paintball bottle is separated from its regulator. Hydrolab has every form of tool to properly remove any regulator that is out on the market. Surprisingly enough, or not, Hydrolab can also work on most any regulator that is used for paintball. The regulator-less bottle is visually inspected. The insides of the bottle will be checked out for any signs of debris or rust. The outer shell will then be inspected to ensure no obvious failures will occur. This is usually due to a violent impact where the carbon fiber wrapping can plainly be seen to be frayed. The regulator-less bottle is then attached to the upper portion of the machine as seen in this image. It is then lowered into the water vat in the lower portion of the machine.
|Lid comes down and makes a seal|
The upper portion lowers down so the bottle is completely submerged in the water in the vat and then makes a seal. Water is pumped into the vat and the water level is zeroed out to prepare for a reading. Water is pumped into the bottle being tested and the pressure inside the bottle will slowly be increased to 5000 PSI (for most 3000 PSI tanks) and 6500 PSI (for most 4500 PSI tanks). The water that is displaced from the bottle expansion can be read in CCs (Cubic Centimeters). Now this is where the REE number comes in. If the displaced amount of water from the vat exceeds the REE number (in CCs) the bottle fails. As a side note, the bottle is filled with water due to the fact that water does not compress like air does. Were a bottle to fail while testing, a violent explosion will not occur. Water will just exit out of the testing vat. Were a bottle to fail with compressed… well that could be “exciting.”
|Water is pumped into the bottle|
There are other particulars too; the air temperature must be maintained to a constant 75 degrees to get the most accurate reading for the small tanks used for paintball. A bottle must regain at least 5% of its original size within a certain time period. Different bottles will have slightly different figures used to for testing so it is important for the tester to have updated books with the DOT.
|Displacement of water must stay below REE to pass|
I have used Mr. Pentz’s company (and have referred everyone that asks for a hydro test) for all my hydro testing needs. Hydrolabs are very fast and I have often gotten bottles returned two days after shipping. I very much appreciate that a paintball enthusiast has made a niche in the paintball market. Before I was aware of Hydrolabs, I would often use a testing company that didn’t care all that much for the smaller bottles that we use for paintball. I have waited longer than three weeks from other testers and have had this huge Recertified label that covered half my bottle. Hydrolabs uses a small label that doesn’t interfere with the looks of our bottles.
|Difference in label sizes|
I would like to thank Geoff Pentz’s for his helpfulness and (most importantly) his patience. If you need your bottle tested, please do so and not neglect it.