O2 cylinder exploding

What is the chemistry behind this?

http://www.youtube.com/watch?v=9lw_fhNAIQc


--

Boris Mohar



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Boris Mohar wrote:

Maybe there was some oil or dust in the valve that ignited when the fast stream of O2 was released. Randy
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Grease will explode if subjected to 2,000-psi oxygen. A dab will do.
Joe Gwinn
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I was first inclined to think, "No... that was just a loose cylinder" until I saw the evidence of fire and the ruptured tank.
This was probably caused by friction: Some folks have surmised there may have been oil or grease in the valve. That's not likely, even if the guy was dumb enough to squirt some PB or Liquid Wrench on the valve. It probably would not have gotten past the thread seals. It MIGHT have gotten exposed to O2 if he had the valve loose enough. They didn't say anything about the application of a rust-breaker oil, though, and I think they would have, if that had been the case.
However, a tightly installed pipe thread engages metal-to-metal, even with sealant present. Wrenching a threaded component apart always causes extreme friction until the taper relieves the fit. Some metal would have been abraded away as a fine powder, along with the generation of enough highly localized heat to initiate combustion.
Once the fire started, it was self-sustaining. Then the O2 pressure (likely above 2500psi to start with) rose high enough from the addition of heat and combustion products to rupture the tank.
That slide show is definitely not breakfast fare.
LLoyd
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Total agreement with Lloyd. That is why it is emperative to have the vessel empty before disassembly.
Bob Swinney

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Lloyd E. Sponenburgh wrote:

At 2000 psi is the generation of heat even a requirement for a small shaving/dust particle of steel to combust?
Dave
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At STP, most metals become pyrophoric at sizes smaller than about 1000 mesh (around 0.5 micron).
I don't have the tables on it, but I'd guess that pure pressurized O2 would lower that to more like 300 mesh.
Such small particles are the normal result of friction between threads.
That said, there WOULD be very high localized heating, so the two together are almost a "gimme".
LLoyd
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Lloyd E. Sponenburgh wrote:

A belt-and-suspenders approach to blowing your own poor ass up-
Dave
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I am never going to feel as comfortable around the welding tanks again. Yikes!
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snipped-for-privacy@lycos.com wrote:

Imagine cutting into a big one with a disc grinder or a torch...
D
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snipped-for-privacy@lycos.com wrote:

At least Argon shouldn't be able to do that.
Pete C.
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And if the tank was empty - there would not have been the massive oxidizer ready for fire. Drain down the tank and fill with water.
Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member http://lufkinced.com /
Pete C. wrote:

-
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But Martin, that's the whole thesis of this accident review... He COULDN'T drain down the tank. The valve was either frozen or broken -- so he intended to just loosen the fitting, and let the tank drain that way.
And that's a big mistake.
In the Navy, if a tank top was damaged in any way whatsoever, the whole tank got AXED in our guillotine "tank disposer-of-er". Cam Rahn Bay got its share of empty tanks with no valves...
Now, the military is a lot more cavalier about throwing away money than a civvy company would be, but in this case, they should have a policy in place to waste a little to save a lot.
LLoyd
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True, it wont burn but there is still an awful lot of energy stored in it just as Pressure X Volume . If the tank ruptures it still has plenty of destruction available to do you in.
Tom


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Tom Miller wrote:

Yes, but the procedure the guy who blew his arm off was trying would likely have worked without incident.
Pete C.
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snipped-for-privacy@lycos.com wrote:

Why?
I'd bet that hey have killed or injured far fewer people than, say, light fixture falling off ceilings.
Don't grease them, dont try moving them about without the cover over the valve, don't do stupid shit like trying to remove valves while they are under pressure. You'll be fine.
Figure out the explosive energy potential in the gas tank of your car, if you need some perspective. Then you can try to find a nice couch to hide under while you try to stay safe.
Cheers Trevor Jones
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I have to agree on that.

I know that. Now I wonder the next time I turn on the valve at work if the guy that set the tank followed all of the above precautions.
What if some clueless idiot put grease or oil on threads not knowing better and I'm the first to crack the valve?

It is pretty fair. Just bought 5# of black powder as part of a group buy. Got it for 11.00 a pound. It still is in the trunk of my car. I bet my little Saturn might have a chance to get close to its namesake if a fire broke out.

My couch isn't that sturdy and I've gained a few pounds. Have you kicked your dog today or did he bite you?
Wes S
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Five pounds of BP will lift an 120 lb. fireworks shell approximately 1000' high (out of a fairly close-fitting mortar).
SFX guys use two to five pounds with a "pole cannon" to roll cars at speed.
Five pounds would definitely blow all the windows and the trunk lid. It would probably also "alter" the basic body shape by inflating it. But I doubt it would disintegrate the vehicle. The ensuing fire would, though.
LLoyd
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On Wed, 01 Nov 2006 15:44:54 GMT, "Lloyd E. Sponenburgh"

I had a tech working for me who spent $3000 ordering ammo components over lunch about a week before Y2K. He had 140# of smokeless sitting in his living room. He moved on to another job not long after.
I got my all time favorite quote from him: "I believe the best value for your entertainment dollar is gasoline." That was said with a completely straight face. This was when I lived in Texas, not Michigan.
Pete Keillor
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On Wed, 01 Nov 2006 19:28:07 -0500, Pete Keillor

Hummmm...he had me beat. Though not by much.

You mean its NOT?
Damn....
Gunner
Rule #35 "That which does not kill you, has made a huge tactical error"
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