I've had good luck checking with Airco, or Airproducts web published important information about these sorts of issues.

I will say that it has been a good long many years since I supplied "oxygen" to a Learjet, and about all I remember now is that it is very important not to ever get any oil, or use any on the fittings, as this may well create a poisonous gas, (Carbon Monoxide?)

Filled big DC 6 tires with nitrogen in cages.

I'll not go on about common sense, and whether or not this is an "academic" question, or you got some tanks and want to fill them.

Only reason I posted was to warn you not to get any oil on breathable "oxygen" tank fittings.

Thanks for the response. Got the question from a coworker who is always looking for ways to eliminate hazards from the workplace and fellow employees. Will check with Airco and AirProducts as suggested. thanks again.

Check the Federal OSHA standards, 29CFR1910, available at the OSHA web site, first. Yes they must be filled in a explosive containing apparatus. Go to most fire houses and they can show you how they fill there Self Contained Breathing Apparatus (SCBA) cylinders that they wear and use when in potentially hazardous atmospheres. One guy in my fire dept once wasn't using it and had a cylinder explode on him. It was so forcefull that the shards of the aluminum cylinder 1) took a scallop size chunk out of his leg, 2) put a substantial dent into one of the large cascade cylinders, 3) and another piece of it bounced off the wall, hit a fire truck, bounced off the wall again, bounced off the ceiling and finally broke a window in a fire engine three bays away! Ten years later he still has a ringing in his ears from the noise and air pressure wave.

The air source must also be tested either annually or semi-annully in a lab for purity and the results posted at the compressor or cascade system.

These are not things to be played with. The composite cylinders (fiber glass wrapped) that are now in use contain over 4,000psi. All cylinders must also be visually inspected and the results recorded each time they are refilled.

I was in the home medical oxygen business years ago and the "no oil" rule on 100% oxygen cylinders is absolutely correct. The oil does not create a toxic fume, rather, it increases the risk of fire dramatically...even spontaneous combustion under the right circumstances.

As an aside, I think 'Myth Busters' did an episode on this question of gas tanks exploding and creating shrapnel. Their results showed there would be a rupture of the tank with rapid release of the gas (and possible movement of the cylinder) but no explosion with flying shrapnel. They had to add C4 to get the tanks to go boom.

hey stubby,

I remember seeing parts of that episode, it always takes them forever to get to the part where something , "blowed up real Good".

But I wouldn't rely on their methods to to cover every possibility.

There was a segment where they were exploring the hazard of striking two hammer head faces together,( warning label on hammer warns against doing so , that it might shatter ). They tried everything THEY could think of and the result was no shattering, so they declared it a busted myth.

Well, I personally observed my boss use my hammer as a cats paw, to extract a nail from a piece of wood by striking it with his hammer. A jagged flake of steel the size of a nickel and razor sharp flew off , partially embedding itself in his upper arm, lots of bleeding. I think Mythbusters can be reckless and potentially encouraging dangerous behaviour by refuting manufacturers warming labels

If you go to the New Jersey Dept of Fire Safety web site there are 2 accident reports pertaining to air cylinder failures. Both were aluminum cylinders (a type which is in wide spread use today) which did not have any visual defects in them, the causes were metalurgical. The first one details how a fire fighter was refilling the cylinder and it catastrophically exploded with resultant shrapnel. The shrapnel damaged his hand so badly that it had to be amputated, took out his eyes (he is now blind), made him deaf and did other damage. The second one is the one that I mentioned in my previous post. I arrived within a minute after the second one occurred. I heard it while I was in my car one block away from the firehouse. I personally saw the destructive power and the shrapnel it created. Both of these happened within one year of each other about 8-10 years ago.

As for Myth Busters, that is drama TV and not scientific research.

C-4 is childs play compared to the destructive power of an explosive fragmenting compressed air cylinder.

Compressed air has much different properties than Oxygen. Oil in gauges and lines is only a nusaince with comp air, not the potentially explosive fuel in O2 apparatus.

During my days as a Navy frogman at EODMU-1 in Hawaii, our SCUBA cylinder refilling station consisted of an aluminum water tank, divided to hold the cylinders upright. This both helped to keep the cylinders cool while being filled to 3000psi, and would have soaked up considerable energy in the event of a catastrophic failure. Though I've never heard of any kind of dive cylinder failure.

Keep in mind that all pressure tanks are required to be hydrostatically tested on a periodic basis. During testing, the tank is pressurized to 150% of the working pressure and checked for expansion. Any tank that fails is so marked and cannot legally be pressurized ever again.

Furthermore, any damage that might cause a catastrophic failure is almost certain to be fairly obvious, and all tanks should be visually inspected before being hooked up for refilling.

I do admit that my experience was a very long time ago and may be somewhat out of date.

These days it's not recommended to fill breathing cylinders in a water filled container. Although you are correct in that it does keep the cylinder cool while filling, it also induces condensation inside the tank (which is not so good).

As for safety:- if you fill cylinder standing upright on the floor and it explodes, you will end up dead! If you fill cylinder standing upright in a water tank and it explodes, you will end up dead and wet!

I am not familiar with specific codes, however, I can give tips based on personal experience. Tanks must pass hydro and visual. Aluminum tanks can suffer metallurgical degradation if over heated. Overheating can be caused by direct sunlight, especially if tanks are coated with a high emissivity finish. Of course, one must use an oil free source of dry air. Dew point of fill air should be -40 degrees or lower. Make sure that compressor inlet is up-wind from driver (engine). I still like to fill tanks in water. It may not offer adequate protection in the event of an explosion, but it keeps tanks cooler. Fill tanks slowly to minimize temperature rise.

I believe you're right, if the air is dry as it should be then there wouldn't be any moisture.

I believe that if you understand the reason breathing air needs to be dry, you will never forget it and risk a fatal accident. The regulator reduces air pressure from tank pressure to your breathing pressure As air pressure is reduced, heat is released, and the gas gets colder. When the gas temperature goes below the dew point of the gas, liquid water condenses out of the gas. As the temperature goes below the frost point, the water freezes and clogs the regulator. This cuts off the air supply and can result in death. Now you not only understand that air must be dry, you also know why, and will never forget.

Hadn't thought about that aspect, makes sense. Water can sure be troublesome , similar effect, low-pressure+ water= carburetor icing, not good when flying.