O2 tank explosion

[Lobzilla]

As I've said several times, I'm not suggesting that this is what happened, but there *was* a fire and *must* have been something that caused it. My only point here is that depending on what was there, there doesn't necessarily need to be a spark or a flame that set it off....

The "thing" that causes chemical reactions to take place is called Activation Energy.

As Charles pointed out earlier, some alkali metals will ignite under normal environmental conditions (21% oxygen, moisture, standard temperature). However, if we sufficiently lower the energy provided by the surroundings through cooling the reactions will not take place. Furthermore, these compounds are not commonly stored in the typical garage and if they were, they would not exist in their original state for long.


FUEL-OXIDIZER-HEAT is what every fireman knows to be necessary for a fire (or combustion). Heat is one form of energy. A spark that ignites the combustible air/fuel mixture inside of an engine is another form. Even a flash from a strobe that will set off a sensitized mixture of Hydrogen and Oxygen is just energy.

It is well understood, and does not warrant speculation, when chemical reactions occur in general and under what specific conditions combustions take place (regardless of how many people on SB paid attention in Chemistry).

What needs an answer is the question whether:

1. a combustion occured INSIDE of the bottle that then subsequently ruptured
2. the cylinder ruptured due to mechanical stress and the escaping oxygen caused a fire outside
3. both events occured in the order listed

 

[ot1]

Yes but has she ever seen a 3000 psi aluminum welding tank?

Welding tanks are always steel, and they are quite heavy, meaning the walls have to be very thick.

 

[ot1]

The "thing" that causes chemical reactions to take place is called Activation Energy.

As Charles pointed out earlier, some alkali metals will ignite under normal environmental conditions (21% oxygen, moisture, standard temperature). However, if we sufficiently lower the energy provided by the surroundings through cooling the reactions will not take place. Furthermore, these compounds are not commonly stored in the typical garage and if they were, they would not exist in their original state for long.


FUEL-OXIDIZER-HEAT is what every fireman knows to be necessary for a fire (or combustion). Heat is one form of energy. A spark that ignites the combustible air/fuel mixture inside of an engine is another form. Even a flash from a strobe that will set off a sensitized mixture of Hydrogen and Oxygen is just energy.

It is well understood, and does not warrant speculation, when chemical reactions occur in general and under what specific conditions combustions take place (regardless of how many people on SB paid attention in Chemistry).

What needs an answer is the question whether:

1. a combustion occured INSIDE of the bottle that then subsequently ruptured
2. the cylinder ruptured due to mechanical stress and the escaping oxygen caused a fire outside
3. both events occured in the order listed

1. certain alloys can become brittle over time, including aluminum alloys.
2. aluminum burns very hot and is used in pyrotechnics(fireworks), and in thermite.
3. Oxygen can cause the aluminum alloys to age by oxidation.
4. obvious from the photo that there was an explosion inside the tank.
5. Conjecture, but the tank valve was probably bent upon impact after the explosion, not from impact with the floor. Shockwave on the inside of the tank blew out the oring the moment the valve was bent. It would be impossible to bend the valve that way unless the tank was not standing, but laying ontop of a bench or such and the impact was directly on the valve with the full weight of the tank on it at impact with the floor.
6. Conjecture, but if there was a nut or bolt laying on the floor that caused the tank to crack when it hit the floor by providing a fulcrum cleave, as walls of the tank are not very thick. A jet of oxygen erupting though a wall crack, likely caused the tank to explode, just from the friction of the jet on aluminum.
7. The hand was severed from the tank shrapnel.

8. oils on a concrete floor can combust when a stream of high pressure oxygen hit them.

9. Certain materials can spontaneously combust in the presence of pure oxygen, like perhaps the clothing on his back became saturated with oxygen, if not spontaenous, an already existing heat source cause them to ignite, since its likely not all the oxygen was consumed in the initial blast.


It would be wise not to store pure oxygen in an 22 yo aluminum cylinder.

 

[DandyDon]

Interesting post up to the last...

Furthermore I would not want to breathe oxygen stored in an aluminum cylinder to prevent possible induction of alzheimer's, via inhalation of aluminum oxide.

I believe that's more genetic. They found a village in Columbia with a cluster of early only Alzheimer's from the genetic clusters. Alzheimer cluster sparks dream of cure - CNN.com

But back to the explosion...

 

[mitsuguy]

My advice would be not to store pure oxygen in an aluminum cylinder, especially a 22 year old cylinder. Furthermore I would not want to breathe oxygen stored in an aluminum cylinder to prevent possible induction of alzheimer's, via inhalation of aluminum oxide.

If you truly believe this, then I suggest never riding on a dive boat or in an ambulance again and needing O2. I cannot recall seeing a portable steel O2 cylinder. All the DAN kits and similar that I've seen are aluminum cylinders, the portable O2 cylinders that (for lack of a better term off top of my head) old people drag around with them, the cylinders stored in ambulances, and I'm sure there may be some in hospitals as well that are aluminum, with the larger ones most likely being the big steel K bottles or similar...

 

[ot1]

If you truly believe this, then I suggest never riding on a dive boat or in an ambulance again and needing O2. I cannot recall seeing a portable steel O2 cylinder. All the DAN kits and similar that I've seen are aluminum cylinders, the portable O2 cylinders that (for lack of a better term off top of my head) old people drag around with them, the cylinders stored in ambulances, and I'm sure there may be some in hospitals as well that are aluminum, with the larger ones most likely being the big steel K bottles or similar...

You are right, I was over the top with my statement, I should have worded it more carefully. Age of the tank being a primany consideration, not the fact that it was aluminum, sorry.

The tank could be of 6351 alloy.

"Luxfer discontinued use of 6351 alloy in June 1988 and since that time has only manufactured scuba cylinders from Luxfer’s proprietary L6X® formula for 6061 aluminum alloy. Out of more than 40 million cylinders, no Luxfer cylinder made from L6X® (6061) alloy has ever exhibited a sustained-load crack (SLC)."

 

[John C. Ratliff]

Concerning the aluminum oxide, and the potential for breathing it, there is a device on everyone's regulator called a "sintered filter." There is another thread about these sintered filters, which describes them as potentially filtering down to 0.5 microns. If that is not enough for you, buy a used Dacor Olympic 400 or 800. These regulators have a second filter in the first stage advertised as follows:

Special double filtering system traps particles in the air down to ten millionths of an inch and prevents these impurities from contaminating the regulator.

Of course, this would also prevent these impurities from getting into the diver's lungs too. I have two of these regulators, and was very surprised to find it when I took the reg apart just a few weeks ago.

One other thing about aluminum oxide; it does not progress like rust in steel tanks. It forms a hard scale, and virtually stays where it is at. You probably won't see any aluminum oxide powder or flakes on the bottom of a twenty-year-old tank unless it has been highly abused.

SeaRat

 

[Scared Silly]

The tank could be of 6351 alloy.

Actually it has been confirmed that the cylinder was made from AL6351 mfg date 4-88.

 

[ot1]

I was looking at the one photo in this thread, which shows the Oring protruding. From the lone photo the valve appears to be in line with the tank body, on both axis, meaning it doesn't look bent. There is a gap at the point where the oring blew, but no other gap is evident. The neck appears swollen where the oring is blown out. I don't think the initial O2 escape was from the neck. I continue to believe a shockwave from within the tank, caused the oring to blow and create the swollen neck.

Are there more photos available of the tank from different angles to dispute this?


I have been searching for other photos of accidents with older tanks, and they all show rips through the valve stem threads. This lone photo is unique in that way that indicates that the neck portion of the tank had no fractures or unseen cracks.

I wonder if the eddy-current testing, tests the entire body of the tank not just the threaded area and neck? Does anyone know?

With the energy potential of 2 hand grenades, and the likely hood to cause serious injury if the tank suddenly blows, it doesn't seem there is a valid reason or worth the risk to have a tank with a 6351 alloy still in commission.

 

[05sportsman]

I was looking at the one photo in this thread, which shows the Oring protruding. From the lone photo the valve appears to be in line with the tank body, on both axis, meaning it doesn't look bent. There is a gap at the point where the oring blew, but no other gap is evident. The neck appears swollen where the oring is blown out. I don't think the initial O2 escape was from the neck. I continue to believe a shockwave from within the tank, caused the oring to blow and create the swollen neck.

Are there more photos available of the tank from different angles to dispute this?


I have been searching for other photos of accidents with older tanks, and they all show rips through the valve stem threads. This lone photo is unique in that way that indicates that the neck portion of the tank had no fractures or unseen cracks.

I wonder if the eddy-current testing, tests the entire body of the tank not just the threaded area and neck? Does anyone know?

With the energy potential of 2 hand grenades, and the likely hood to cause serious injury if the tank suddenly blows, it doesn't seem there is a valid reason or worth the risk to have a tank with a 6351 alloy still in commission.

As a matter of fact I do....Eddy current testing be it by Visual Eddy or one of the Visual Plus machines (I run a Visual Plus 3) is only on the threads itself. It has a threaded probe that you run down in the threads to the bottom and then it reads on the way out. The Luxfer tanks have relatively short threads but on some of the WK tanks the threads are so deep none of the manufacturers of these machines make a probe that goes to the bottom. From my standpoint it dosen't look like a SLC crack as the threads are intact.