THIS is why you hear warnings not to service oxygen equipment

[Munkul]

The heat was caused by the pressure rapid pressure release through the small opening. I don't think it was actual combustion that caused the heat.

Take a blow nozzle on your airline Squeeze the tip between finger & thumb & release the air. You will feel it heat up pretty quickly.

Incorrect. The rapid pressure release would have caused the internal temperature of the tank's contents to cool down significantly. Look at any high pressure tank when you use a high flowrate. It starts freezing.
The heat in this case was undoubtedly caused by the oxygen reacting with hydrocarbons and also the aluminium once it started to heat.

As for the blow nozzle and fingers, that's a dangerous practice . Never put pressurised liquids or gas next to your skin. If it heats up when you do it, it's friction that does it, not the air.

[Kelvin]

I have seen a few people who had bad leg injuries from motor vehicle crashes and such. Only had one that was in cardiac arrest when we arrived. She had both legs taken off above the knee when pinned between two cars. However, we saved her. A couple of tourniquets, an endotracheal tube, and a couple of large bore IVs running wide open, and she had a pulse by the time we got to the ED. In fact, that one sticks out in my mind because when we went to visit her in ICU a few days later, she was angry with us for not letting her die. We thought we would get a hero's welcome. Instead we were hated. Not the reaction I expected.

I would say my experience is that most bleeding injuries take a while to die. I have even seen patients with ruptured aortic aneurysms survive (none of my patients, but some peers of mine)

That's a pleasant surprise. Thanks for the reply. Only case I knew about was a race car driver who ruptured femoral and died...

[BaTu]

The Scariest thing about that story for me is,,, what that guy did would have occurred to me too!

I'm not sure that, if I was responsible for those cylinders and had to deal with one that had a valve that wouldn't open, the thought that it could be loosened, just enough, to start to bleed that it would be a good solution to the problem

Was there any significance to the "tool marks" the wrench left on the valve I wonder?

[bakodiver]

I work in the scuba industry as well as welding, and this type of accident has been studied ad nauseum. The thinking is that powdered aluminum oxide from oxidization is wedged in the threads, and the act of turning the threads causes enough friction and heat to ignite the oxide powder in the presence of pure oxygen. There is a well known video in which a diver drops an aluminum decompression cylinder from the trunk lip of his car to the road. The impact is enough to ignite the aluminum oxide powder and the tank explodes. I think that guy died, if i remember correctly. Non- operative valves should be drilled through with a fine drill and allowed to vent slowly.

[psacustomcreations]

I am with bakodiver on this.

I am a diver who maintains dive equipment and deals with O2 cleaning. Plus I cut apart about 100 to 150 steel and aluminium cylinders a year.

It is very common to see aluminum oxidation inside those cylinders.

I use a crescent wrench as well as an F wrench to remove valves. I have the exact same chain vise on my bench. Or I use a tristand vise. Granted 90 percent of the time I am just tossing the valve in the scrap pile so don't care what happens to it.

The type of wrench isn't the problem. Removing, cleaning and maintaining valves isn't the problem.

It was that the valve was stuck and he tried to brute force it off.



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[Kelvin]

...It is very common to see aluminum oxidation inside those cylinders...

Can't comment any more on this particular case, but I do know that aluminum powder mixed with an oxidizer makes one hell of a powerful kBOOM. It's what's used to make flash powder, the stuff that powers everything from firecrackers to M80s.

[G-ManBart]

In fact, that one sticks out in my mind because when we went to visit her in ICU a few days later, she was angry with us for not letting her die. We thought we would get a hero's welcome. Instead we were hated. Not the reaction I expected.

Wow. I guess people just process things differently and maybe she was just in a temporary angry phase and moved past it with time...at least hopefully for her.

[BluCllrPlt]

In fact, that one sticks out in my mind because when we went to visit her in ICU a few days later, she was angry with us for not letting her die. We thought we would get a hero's welcome. Instead we were hated. Not the reaction I expected.

Reminds me of Lt. Dan in Forrest Gump

[CAVEMANN]

Just remember, aluminum is combustible under the right circumstances. If there was aluminum flaking off from the inside of the cylinder, that could ignite.

I was filling a welding cylinder, I'm guessing steel because of the weight. The Ambo crews filled the E tanks and NEVER followed the proper order on the cascade system, the tanks can get very HOT as the pressure builds, uncomfortably HOT. The human body is also considered a hydrocarbon in the presence of pure oxygen.

[tadawson]

Wow. I guess people just process things differently and maybe she was just in a temporary angry phase and moved past it with time...at least hopefully for her.

Or (as sad as this sounds) it was a suicide attempt which was thwarted . . .

[Fast Leroy]

I work in the scuba industry as well as welding, and this type of accident has been studied ad nauseum. The thinking is that powdered aluminum oxide from oxidization is wedged in the threads, and the act of turning the threads causes enough friction and heat to ignite the oxide powder in the presence of pure oxygen. There is a well known video in which a diver drops an aluminum decompression cylinder from the trunk lip of his car to the road. The impact is enough to ignite the aluminum oxide powder and the tank explodes. I think that guy died, if i remember correctly. Non- operative valves should be drilled through with a fine drill and allowed to vent slowly.

I thought divers used compressed filtered air not compressed Oxygen?

[Louie1961]

Or (as sad as this sounds) it was a suicide attempt which was thwarted . . .

No not as suicide, just a stupid accident with lots of alcohol involved. The victim was the designated driver (and sober) and on the way back from a trip to the indian casino when her car stalled on the interstate. All her drunk friends got out and were running all over the highway. The victim was trying to round them up when another car came along and hit her, smashing her into the rear end of her own car and taking off both her legs. Sad really.

[bakodiver]

I thought divers used compressed filtered air not compressed Oxygen?

It was a decompression cylinder. Technical divers will use a bottom gas of either air or trimix, then use rich oxygen mixtures of 50% and 100% to decompress on the way up, at prescribed shallower depths. In layman's terms, it flushes the nitrogen out of their bodies by replacing it with oxygen, which is metabolized by the body. 100% oxygen deco cylinders are commonly aluminum 30 or 40 cubic foot cylinders, which is what exploded in the video of the guy dropping it from his car trunk.

[tadawson]

Rebreathers also use 100% O2 plus a separate diluent gas.

[Munkul]

It was a decompression cylinder. Technical divers will use a bottom gas of either air or trimix, then use rich oxygen mixtures of 50% and 100% to decompress on the way up, at prescribed shallower depths. In layman's terms, it flushes the nitrogen out of their bodies by replacing it with oxygen, which is metabolized by the body. 100% oxygen deco cylinders are commonly aluminum 30 or 40 cubic foot cylinders, which is what exploded in the video of the guy dropping it from his car trunk.

Username checks out.

[CAVEMANN]

The smelter where I worked used LOX to aid combustion in the FLASH FURNACE, it was trucked in & once we had a tractor-trailer transporting roll over & breach one of the tubes, the LOX was low pressure & leaked onto the asphalt where it absorbed, members of the Fire Dept monitored oxygen levels being emitted and kept that portion of the road blocked and direct traffic around it until it was deemed safe by the Chief and plant safety department.

[William McCormick]

In the old days I always had one of these as my key chain. When I was on duty I would stick it in my waist band almost they way you would carry a 45 pistol "Mexican" style: over the right hip with just the keys sticking out. I never lost it that way. The only difference is that back then they made these with a hexagonal cut out in the end of it (instead of just a plain circle). The large end of the wrench fit the packing nut on old style D and E cylinders. The skinny end was for opening the valve. EMT shears, O2 wrench, buck knife, CPR mask and and a 3 cell mag light were my standard EDC equipment when I was in uniform.

Attachment 1735041

Years ago I made these for the medical oxygen tank refilling house. So they could crack twenty bottles at a time. I used to cut them out of a solid block of 7075 T-8 hardened material. Then I could only get T-7 hardened stuff and it was just not the same. The idea was if you dropped them they wouldn’t spark.





Sincerely,

William McCormick

[William McCormick]

Can't comment any more on this particular case, but I do know that aluminum powder mixed with an oxidizer makes one hell of a powerful kBOOM. It's what's used to make flash powder, the stuff that powers everything from firecrackers to M80s.

If a tiny copper capillarity tube that can absorb twice the heat of aluminum will heat so hot that you cannot touch it while filling under 2,000 psi I suspect that when he cracked that thread, the pressure shot into the tank side of the thread and then was slowed by the still partially sealing tapper thread and that heated the aluminum threads hot enough to totally fail.

Sincerely,

William McCormick

[CAVEMANN]

If a tiny copper capillarity tube that can absorb twice the heat of aluminum will heat so hot that you cannot touch it while filling under 2,000 psi I suspect that when he cracked that thread, the pressure shot into the tank side of the thread and then was slowed by the still partially sealing tapper thread and that heated the aluminum threads hot enough to totally fail.

Sincerely,

William McCormick

I doubt the size of tube had anything to do with it, the tank basically became a diesel engine on the compression stroke & maybe on steroids & an unknown fuel, when yoou introduce 2000 PSI or more into a cylinder quickly it WILL GET HOT, very hot, very quickly. When filling SCBA tanks at the fire department we cooled the tanks with water and sometimes icewater & that was just compressed breathing air.

[William McCormick]

I doubt the size of tube had anything to do with it, the tank basically became a diesel engine on the compression stroke & maybe on steroids & an unknown fuel, when yoou introduce 2000 PSI or more into a cylinder quickly it WILL GET HOT, very hot, very quickly. When filling SCBA tanks at the fire department we cooled the tanks with water and sometimes icewater & that was just compressed breathing air.

To me the loosening of the threads, seems like a small capillary tube and if that heats in under a second as you crack the first tank, which the fellow stated was its duty to reduce the heat in the tank being filled, then perhaps as the air raced around the loosest part of the thread and then ran into the tighter part of the thread and compressed the air there, it may have dumped all its heat right there.

Sincerely,

William McCormick

[CAVEMANN]

To me the loosening of the threads, seems like a small capillary tube and if that heats in under a second as you crack the first tank, which the fellow stated was its duty to reduce the heat in the tank being filled, then perhaps as the air raced around the loosest part of the thread and then ran into the tighter part of the thread and compressed the air there, it may have dumped all its heat right there.

Sincerely,

William McCormick

Who knows.

[Jax]

I once had a large medical oxygen cylinder. A co-worker made art objects from decomissioned cpmpressed gas cylinders. I asked and he gave me some valves from oxygen cylinders. The ONLY REASON I never proceeded to remove valve from the med cylinder and replace it was because there were no threads for a safty cap. After reading this I'm convinced it's true that higher powers must be watching over fools. Note to self "If you don't understand how it work's,leave it alone".

[2strokeforever]

Under 2000 psi oxygen almost any metal will light up at very low temperature...

Steel, Stainless steel, aluminum, you name it, it will burn.

The friction of lossening threads would be all it takes to get the aluminum started.