Bottle facts

[Sidewinder]

Sidewinder,

"The Yellow" is the Yellow airgun forum and they have a classified sales forum too. Do be warned that if you go there, you might end up expanding your interest in this new hobby into other more expensive realms . . .

The reason that shops won't fill or test a CF tank past 15 years is that they are governed by the DOT regulations and can't do so. If you know somebody at one, you could probably get them to run a test on a tank and verbally tell you how it does, but if you are not friends with them and have a clear understanding of what you want done up front they will drill a hole in it straight out to cover themselves (that is what they do to failed or expired tanks).

Now, while no test facility is likely to be willing to do a hydro on a CF tank in its last year of life, I have heard that most will do it if there is at least a year left on the tank. That would give me a good bit of peace of mind and I intend to try that with mine before I get to that point.

Oh yeah, I've been there just didn't know it was called "yellow page"

About the bottles ... they are regulated by 49 CFR. Some thoughts about that..... The intent is to regulate the transportation of hazardous material including the containers in commerce. All such containers must bear a DOT number. If a private person has and uses compressed HP air that is not commerce and not commercial in nature. One may hold and compress air any way he wishes as a private person. The problem is that DOT number being marked on the bottle. Here is what part of the CFR says: "the law authorizes the Secretary to apply these regulations to persons who cause hazardous materials to be transported in commerce." Then (as usual) it takes it further by saying "The law also authorizes the Secretary to apply these regulations to persons who manufacture or maintain a packaging or a component of a packaging that is represented, marked, certified, or sold as qualified for use in the transportation of a hazardous material in commerce."

The DOT number on the bottle by being "marked" on it "represents" it as qualified for use of the transportation of hazardous material in commerce. Or in other words transporting air. ...... If the DOT number is removed then no one is claiming compliance for commercial purpose. It is now just a bottle belonging to a private citizen. Of course, this is just my theory and as bifurcated as the CFR's can be who knows? People at the fill places I do not expect to have a clue but just do things as told because "that's the way we have always done it" I know it would be like peeing up a rope to get someone monitored by any agency to understand this. For all these reasons I'd just rather do my own filling with something reasonable. I still would want a hydro test done whether or not anyone signed it off on an older bottle. That's just common sense.

Back in 2006 there was in the Federal Register a notice of rule making concerning SCBA, SCUBA and Oxygen bottles manufactured of Aluminum Alloy 6351-T6. Out of 3.7 million of these bottles Mfg. there was 13 cases of side load cracking (SLC) resulting in failure around the neck and shoulder of these bottles. At that time the Feds wanted to initially impose a 40 year service life on these bottles. After the comments period the agency relented and made this statement: " ‘After consideration of these comments, we agree our proposed 40- year service life for cylinders manufactured of aluminum alloy 6451–T6 and used in SCUBA, SCBA, carbon dioxide, and oxygen services is not warranted at this time."

To my knowledge, all bottle mfg's switched to 6061-T6 alloy which doesn't have SLC problems and life of the bottles can be ?"UP TO" 45 years. Now we are 10 years past all this and I can't find anyone who really knows "the rest of the story".

As I said, If I get a bottle made in the last 10-12 years I would not hesitate to fill and use it myself. Having said that. I would STILL like to do a hydro test every two (2) years because of the multiple cycles. In air gunning you are constantly filling and depleting the bottle. Each time is a cycle of sort regardless if you just cycle the bottle from 4,000 down to 3,000 there's still a degree of expansion and contraction and that results in fatigue of any metal over time. Every time you fill the bottle you are in effect pumping up a hand grenade. As Dirty Harry would say "Do ya feel luck ... Well, do ya?"

[Sidewinder]

Did find a letter from MSA the mfg of the bottle I have to a fire chief about his SCBA bottles. According the them the Steel 3AA bottle like the one I have are this way.... "Steel (3AA) and Aluminum (3AL) cylinders still have a 5-year hydrotest and unlimited shelf life as long as it passes the hydrotest and visual inspections.

Can't say that the DOT didn't royally screw this up as it pertains to carbon wrapped bottles. The wrote exemptions based on having bottles inspected every three years. They said they would revisit the issue in 12 years. That was in 1997. Then they said the bottles would have a shelf life of 15 years with only two inspections allowed at 5 years. As usual some writer (probably jr. lawyer) tried to word it the way he though was clearly. What occured was that all the FD's who bought new bottles say in 1998 had bottles inspected three years later. In this case it would have been 2001. The next inspection due in 2004 etc. It was around 2006 when the ruling came out of 15 years with two inspections allowed at 5 year intervals. Now all those bottles which by then had been inspected twice on the 3 year interval were 7 years old, been inspected twice and were rendered useless Per DOT after only 9 years of life. This is so typical. I'm finding all sorts of letters from confused FD chiefs and others trying to make sense of this mess. And it IS a mess IMO. It's little wonder that any economic progress can possibly be made by productive citizens in an environment such as this.

As far as I can determine, get a bottle, get a shoebox or something similar. Use your head, use quality fittings and pump to your heart's content. These bottles are likely good for 40 years in normal service and 20 in repeated filling. Steel bottles such as the 1982 3AA I have, enjoy an unlimited shelf life if passing a 5 year hydro test. This is the way I look at it and I'm sure others view it differently, but I think it works for me and I'm comfortable with it unless I hear or find other information that would make better sense.

By now I'm sure this is one dead horse but also sure it can stand a bit more beating. ..

[iride]

So when the tanks go bad they blow up like a bomb? Or do they just pop and blow a hole in them, I now have a great white tank that is one year old.
I plan to buy me a compressor, And then buy me one of the little Ninja like tanks to fill my gun a couple of times in the field....
I know buying used you never really know what the tank has been through, So is everyone saying I need to have it tested before using?
Maybe put it in the gun safe to air it up a few times?
How come my air gun tank does not need to be tested, I have my cheek resting on my Cricket's when I shoot them at 3,400 PSI .
Has anyone know of a tank to blow up??????
Mike

[maraudinglizard]

Mike,
They are like bombs going off, they will blow out windows, ceiling tiles, and walls. I have been in scuba shops where one has blown and what a mess. Luckily the tank they were filling was in a water tank for cooling when it blew but it still wiped out the shop and injured the employee. The tank had a current hydo and vis. You just never know what will happen with any of them. Being a certified cave diver, I have seen a practice that cavers use when filling their tanks, they double up the burst disk in the valve which in turn allows them to fill beyond the tank rating which will eventually cause tank failure. If you keep the tanks filled to the rating they will last a good while. Overfilling and "hot filling" (tanks that a filled to fast and not cooled properly in water tanks) are disasters waiting to happen.