O2 tank explosion

[charlesml3]

Charles, I disagree. Perhaps you should have had a more qualified Chem professor. Oxidation can occur very rapidly and with enough heat to ignite "certain mixtures" of chemicals, making them spontaneously combust or detonate. No flame, no spark, no red hot poker required.

Was making this personal really necessary? That aside, there is nothing in someone's garage that meets this requirement. It takes VERY specific chemicals under very controlled circumstances to make this happen.

Charles, if it was that "Oxygen and oil can not cause a fire", please direct yourself to the nearest fire department and convince them.

I don't need to. Oxygen an Oil alone cannot cause a fire. There positively MUST be some source of heat to raise the oil to it's combustion point. As a perfect example, let's consider any space shuttle launch you see on TV. The shuttle's main tank contains liquid Hydrogen and liquid O2. Surely we can all agree that this is about as perfect a mixture as it gets for a fire. During the launch a HUGE stream of hot sparks are blasted across the engine cones. These are clearly visible in the footage. They have to be there to ignite the mixture. This is physics and chemistry, not opinion.

Charles, you should be aware that certain synthetics, polar fleece, nylons, even cotton will support rapid combustion when saturated in O2.

Of course they will. Almost anything will burn under pure O2. What's the source of ignition?

-Charles

 

[charlesml3]

I don't know if you have read any of my previous posts, but, do you think it possible that the valve getting spun in an O2 rich environment, friction of the valve threads against the tank neck threads, coupled with high pressure O2 rushing around the threads could have caused a fire? Perhaps a small amount of contamination in the thread area, possibly even the wrong type of thread lubricant?

I don't see how this could be possible. The problem is the huge amount of pressure on the valve from the contained gas. Put a valve on hand-tight and fill the tank. That "3000 pounds per square inch" is putting about 3000 pounds of pressure on the valve and creating an enormous amount of friction between the valve and tank threads. I know I can't get my pony valve to loosen a bit until the tank is completely empty.

We can only speculate still, but the only thing that makes sense so far is some kind of catastrophic tank failure due to the impact.

-Charles

 

[DwayneJ]

I don't see how this could be possible. The problem is the huge amount of pressure on the valve from the contained gas.

We can only speculate still, but the only thing that makes sense so far is some kind of catastrophic tank failure due to the impact.

-Charles

How do you even know how full the tank was? Let the on scene professionals do their analysis.

Dwayne

 

[charlesml3]

How do you even know how full the tank was? Let the on scene professionals do their analysis.

Well if it was pretty much empty then all of these arguments about O2 reactions are rather pointless, aren't they?

And I fail to see how my discussion of these points is in any way preventing "the on scene professionals [from doing] their analysis."

-Charles

 

[John C. Ratliff]

Agreed. I didn't mean to suggest that they had to be independent. That said, there has to be some source of heat to raise the fuel to it's ignition point...

Concerning the Mythbusters episode, I'll have to look that up. But there is a concept of Lower Explosive Limit (LEL) and Upper Explosive Limit (UEL) for any gaseous hydrocardon or material. The LEL is the lower limit below which the vapor will not ignite, as there is not enough fuel to burn. The LEL is the limit above which there is too much fuel and not enoughoxygen in the mixture to have

We're starting to confuse two different things here. "Explosion" vs. "Burn." The lit cigarette dropped into the toilet of gasoline doesn't set it on fire because the cigarette burns at a temperature below the ignition point of the fuel. True enough, if the environment was 100% O2 plus the fuel, it's possible that the tobacco/paper mix could have reacted quickly enough to hit the ignition point of the gasoline. Hella unlikely scenario, but I suppose it's possible...
-Charles

Charles,

Gasoline is classified as a "Class IB Flammable Liquid: Fl.P. below 73°F and BP at or above 100°F" (-45 degrees F). If what you say is true, then you could not possibly burn yourself with a cigarette. Ever heard of "cigarette burns"?

Now, concerning the need for an ignition source, take a look at these recommendations from Fluor concerning mixing oil and oxygen in a welding unit.

I believe that there is a reason for changing out all the O-rings and ensuring that no incompatibile grease is in a scuba rig to be used with nitrox.

SeaRat

 

[charlesml3]

Gasoline is classified as a "Class IB Flammable Liquid: Fl.P. below 73°F and BP at or above 100°F" (-45 degrees F). If what you say is true, then you could not possibly burn yourself with a cigarette. Ever heard of "cigarette burns"?

Of course I have. I also know that the temperature at which your skin will burn is LOWER than the ignition point of gasoline. I looked for the Mythbusters episode which clearly demonstrated this but it isn't online. There are several other videos on Youtube that bust this myth.

I never ceases to amaze me how pervasive the Hollywood nonsense effects have become. I guess we all repeatedly view the scene where the bad guy pours gasoline over the hero's car and then throws a lit cigarette at it and the car explodes into flame. Great effect, but total crap.

It seems that in this thread, many of the posters believe that a "room full of O2" will also explode. Maybe like the scene in the movie where the bad guy rips the stove away from the wall opening a city gas pipe and shortly thereafter, the entire house is blown into tiny pieces. There are really two problems here. One, O2 doesn't explode. Two, city gas will not produce an explosion of this magnitude. Yes, the city cooking gas IS quite explosive, but it will not blow the entire house into tiny pieces. It'll overpressure and shatter windows windows but that's about it. Again, Mythbusters has videos where they tried to replicate the Hollywood outcome without success. The Hollywood effects artists cheat it because a city gas explosion in a house just isn't all that dramatic.

-Charles

 

[Belmont]

...city gas will not produce an explosion of this magnitude. Yes, the city cooking gas IS quite explosive, but it will not blow the entire house into tiny pieces. It'll overpressure and shatter windows windows but that's about it. Again, Mythbusters has videos where they tried to replicate the Hollywood outcome without success. The Hollywood effects artists cheat it because a city gas explosion in a house just isn't all that dramatic.-Charles

I have to correct you on this.

I was witness to a house explosion caused by methane gas.

The house explode in front of my eyes. I can still see it, the whole front of the house collapsing in the street and the lighter material flying in the air. One person died in that explosion.

A few years later another house blew up near where I live. One woman who was in the shower was found sitting in the middle of the street with only bruises. Part of the roof ended up a thousand feet away.

In 1965, in Montreal, there was a gas explosion in an three story building, 28 persons died. The building looked like the one in the Oklahoma City bombing.

See the picture here (the text is in French) Une explosion au gaz naturel tue 28 personnes - L

 

[DwayneJ]

Again, Mythbusters has videos where they tried to replicate the Hollywood outcome without success.

-Charles

Ahhh Mythbusters again! When under graduate and post graduate degrees in materials science are boring, take too long to complete, or leave questions to be answered, Mythbusters to the rescue.

Dwayne

 

[John C. Ratliff]

Of course I have. I also know that the temperature at which your skin will burn is LOWER than the ignition point of gasoline. I looked for the Mythbusters episode which clearly demonstrated this but it isn't online. There are several other videos on Youtube that bust this myth.

I never ceases to amaze me how pervasive the Hollywood nonsense effects have become. I guess we all repeatedly view the scene where the bad guy pours gasoline over the hero's car and then throws a lit cigarette at it and the car explodes into flame. Great effect, but total crap.

It seems that in this thread, many of the posters believe that a "room full of O2" will also explode. Maybe like the scene in the movie where the bad guy rips the stove away from the wall opening a city gas pipe and shortly thereafter, the entire house is blown into tiny pieces. There are really two problems here. One, O2 doesn't explode. Two, city gas will not produce an explosion of this magnitude. Yes, the city cooking gas IS quite explosive, but it will not blow the entire house into tiny pieces. It'll overpressure and shatter windows windows but that's about it. Again, Mythbusters has videos where they tried to replicate the Hollywood outcome without success. The Hollywood effects artists cheat it because a city gas explosion in a house just isn't all that dramatic.

-Charles

Charles, please watch some of the CSB link Also, there are numerous cases of oxygen cylinder explosions. This is one I remember from some time ago.

By the way, the flash point (Fl. P) for gasoline is minus 45 degrees F (minus 42.8 degrees C).

SeaRat

 

[05sportsman]

I also agree with this, that the tank ruptured, but from undetected cracks, and it came apart violently, and that a fire ensued do to the O2.

Charles, what alloy of tank did Mythbusters use? I'm guessing they used was post 1990. Mythbuster needs to test with pre '88 tank made of AL6351 and that was heavily used. A rifle shot may not produce the same type of ringing in a tank as when it struct concrete, which is another possibility. Ringing which could hamonically propagate a crack. Kinda like the Liberty Bell's destruction. The tank's boot would keep the most of the tank off the concrete, which would prevent immediate dampening, and allow the ringing to propagate from the shoulder where it first impacted.

I really don't want to argue further about what could have or could not have started the fire, the result was tragic. I have an '86 tank which I just retired upon news of this accident.

The tank just passed hydro less than 6 months before the accident (Shows 6/10 hydro on video). If a hydro shop is using correctly calibrated equipment and knows what they are looking for on the visual inspection a tank that is going to rupture will NOT even make it into the test jacket. Not to mention the required eddy current testing that the tank must have passed to have a current hydro.

But on a side note, while testing the other day I had an AL80 1973 USD. Visual Plus 3 pointed out 4 cracks longer than 2 threads and 1 that was 4 threads. Not to mention when I went to pick it up from the dive shop I had to drain the air out myself. Made me think twice!