O2 tank explosion

[mitsuguy]

It's the explosion here that I really can't understand. All we can do here is speculate until more details come forward.

-Charles

I believe the explosion was most likely the tank itself, not an explosion as in fireball explosion...

Ignition source of the fire may have simply been the heat of friction itself as O2 was squeezed through a small space...

 

[John C. Ratliff]

Incorrect. There are three things required to support combustion:

1) Fuel
2) Oxygen
3) Ignition source

In the presence of 100% O2, damn near anything will suffice as a fuel.

In this particular case, we have both a fire and an explosion and precious few details as to which came first and how it happened. If the tank fell and cracked the valve then we have a free flow of 100% O2 in an enclosed space with plenty of fuel sources. Next we need a source of ignition. Someone suggested the pilot light on the water heater. That's plausible, but it seems unlikely.

O2 doesn't burn. It supports combustion. It's the fuel that burns. If the O2 reached the water heater, it's just going to make the LP in the water heater burn more efficiently. It's not going to "ignite the O2 and blow up the garage."

It's the explosion here that I really can't understand. All we can do here is speculate until more details come forward.

-Charles

Charles,

Not quite right.

OXYGEN or OXYGEN, LIQUID (7782-41-7) Heat of water will vigorously vaporize liquid oxygen. A strong oxidizer. Reacts violently with reducing agents, combustibles, organic and easily oxidizable materials; contact may cause fire and explosions. The low temperature may cause brittleness on contact with some materials.
Hohanish, Richard P., and Stanley A. Green, Rapid Guide to Chemical Incompatibilities, Van Nostrand Reinhold, 1997, page 625

OXY5840 CAS #: 7782-44-7, OXYGEN
...Hazard Overviews
Compressed Gas...
Health: Stored as a cmopressed gas in cylinders. Eye and skin contact may cause frostbite. Inhalation of pure oxygen can cause dizziness and caugh above 1 atm.

Fire: Noncombustible. However, it is a strong oxidizer capable of igniting combustibles. Remove cylinder from fire area as high temperatures may cause it to rupture.

Reactivity: Stable, when kept isolated as a compressed gas in cylinders or as a cold liquid in vented, insulated containers. Hazardous polymerizations cannot occur. Avoid: combustible materials (wood; paper; oil; grease); heat; ignition sources. Incompatible with: phosphine; hydrazine; hydrogen sulfide; acetaldehyde; acetylene; acetone; secondary-alcohols (2-propanol; 2-butanol); aluminum; alkali metals (lithium; cesium; potassium; rubidium; sodium); ammonia; carbon tetrachloride; chlorinated hydrocarbons; benzene; carbon disulfide; halocarbons (1,1,1-trichloroethane; trichloroethylene); hydrocarbons (1,1-diphenylethylene; gasoline; cyclohexane; ethylene; cumene; p-xylene; buten-3-yne); metals; metal hydrides (sodium hydride; uranium hydride; lithium hydride; potassium hydride; rubidium hydride; cesium hydride; mangnesium hydride; methane; polymers (foam rubber; neoprene; Teflon)...
"OXY5840 CAS #: 7782-44-7, OXYGEN" in Genium's Handbook of Safety, Health, and Environmental Data for common hazardous substances, Volume 2, H-Z, Genium Publishing Corporation, One Genium Plaza, Schenectady, N.Y. 12304-4690, McGraw-Hill, 1999, page 2681.

From these sources, it is apparent that contact with any of the incompatible materials listed above can cause either fire and/or explosions, irrespective of an ignition source. This reminds me of how close we came when an aircrewmember was found sitting on an inflatable air mattress which he had filled from the oxygen line inside a HC-130 Hercules aircraft, leaning up against the JP-4 internal tanks (for air-to-air refueling of helicopters), smoking a cigarette!

SeaRat

 

[sharksdelight]

Hey folks,
Just to fill you in. Still don't know what their insurance situation is but, please, if you have anything you can spare to help them please either send it to me or on their Paypal donation site. I was told that there were some complications with the donation site but I am not sure what they were or if it has been solved. Since Ricks sole business was Nautilus Productions they certainly do not have any income coming in. At any rate, it looks like a very, very long recovery process and probably months before Rick will be out of the hospital.
Rick's wife Cindy, who was also injured in the explosion is having a tough time of it as you can imagine but greatly appreciates all the support both Rick and Cindy are receiving. Like I said from the beginning, you couldn't find nicer people. And that's all the news I have for now.
Steve

 

[05sportsman]

I hate to hear that, We are keeping them in our thoughts and prayers. Thanks for the update.

 

[Diver0001]

In this particular case, we have both a fire and an explosion and precious few details as to which came first and how it happened. If the tank fell and cracked the valve then we have a free flow of 100% O2 in an enclosed space with plenty of fuel sources. Next we need a source of ignition. Someone suggested the pilot light on the water heater. That's plausible, but it seems unlikely.

I'm not a chemist but I don't believe that a spark or a flame is always necessary to ignite combustion in an oxygen rich environment.

Oxygen is much more powerful oxidizer than most people realize and some substances will ignite in contact with 100% oxygen at room temperature.... For example pyrophoric metals like phosphorus and some other metals like titanium when contaminated by a catalyst and exposed to even mildly elevated ppr02 due to compression. Even common things you might find in a garage will combust at room temperature without a "spark" under the right conditions. Things like compost, rags contaminated with linseed oil or even a pile of coal will do it. All of this without a source of external ignition.... or put another way, the temperature needed to cause ignition is room temperature or below in some cases.

I obviously don't know if anything like this actually *caused* the fire, I'm just saying it's theoretically possible.

As for my reaction. First and foremost my thoughts go out to Rick and his wife. I'm a little shocked, to be honest, that something like this could happen so easily. Especially the fact that the fire got inside the tank and caused it to explode. That's really a shocker. I wouldn't have thought that was possible. :shocked2: Knowing this, I for one will be giving a lot more thought to how to deal with deco tanks in the future.

R..

 

[Bob DBF]

Charles,
From these sources, it is apparent that contact with any of the incompatible materials listed above can cause either fire and/or explosions, irrespective of an ignition source.
SeaRat

"ignition source" does not have to be an independent element. The heat produced from the chemical reaction of O2 oxidizing the incompatible materials becomes the ignition source and then the material becomes the fuel as well. Once the fire is started in an O2 environment everyone comes to the party very quickly. The difference between a fire and an explosion is the speed of the burn.

Bob

 

[charlesml3]

From these sources, it is apparent that contact with any of the incompatible materials listed above can cause either fire and/or explosions, irrespective of an ignition source.

You're misinterpreting this. Nothing in this description supports the conclusion that several people here seem to be reaching : "In the presence of 100% O2 something in the garage spontaneously ignited." True enough there are some alkali metals that will but they'll also react with the O2 found in plain, old air. Highly unlikely he had these materials lying around because they can't be left "lying around." They have to be kept in a jar of oil or other substance to keep them from reacting with air.

I'm not a chemist but I don't believe that a spark or a flame is always necessary to ignite combustion in an oxygen rich environment.

Yes, actually it is. There absolutely HAS to be some source of ignition. Be it a spark, flame, heat due to friction, SOMETHING. There has to be something there to raise the temperature of the fuel to it's ignition point (which varies depending on the fuel).

There's a great episode of Mythbusters that illustrates this point. They pour some gasoline into a small container and drop a lit cigarette into it. We've seen this in all kinds of movies where the gasoline erupts into flame.... except in real life it doesn't. The cigarette burns at a temperature below the ignition point of gasoline. Therefore, no fire.

-Charles

 

[pjones]

You're misinterpreting this. Nothing in this description supports the conclusion that several people here seem to be reaching : "In the presence of 100% O2 something in the garage spontaneously ignited." True enough there are some alkali metals that will but they'll also react with the O2 found in plain, old air. Highly unlikely he had these materials lying around because they can't be left "lying around." They have to be kept in a jar of oil or other substance to keep them from reacting with air.



Yes, actually it is. There absolutely HAS to be some source of ignition. Be it a spark, flame, heat due to friction, SOMETHING. There has to be something there to raise the temperature of the fuel to it's ignition point (which varies depending on the fuel).

The accelerated oxidation of a high level of O2 creates heat in the chemical reaction itself. The accumulation of heat at a grater rate than it is capable of dissipating it is the source of heat that causes the ignition. It does not require an outside source to provide ignition as it does it by itself.

There's a great episode of Mythbusters that illustrates this point. They pour some gasoline into a small container and drop a lit cigarette into it. We've seen this in all kinds of movies where the gasoline erupts into flame.... except in real life it doesn't. The cigarette burns at a temperature below the ignition point of gasoline. Therefore, no fire.

They did not do that experiment in an elevated O2 environment so It doesn't really apply here. That experiment could have drastically different results if it were preformed in a high O2 environment.

 

[John C. Ratliff]

You're misinterpreting this. Nothing in this description supports the conclusion that several people here seem to be reaching : "In the presence of 100% O2 something in the garage spontaneously ignited." True enough there are some alkali metals that will but they'll also react with the O2 found in plain, old air. Highly unlikely he had these materials lying around because they can't be left "lying around." They have to be kept in a jar of oil or other substance to keep them from reacting with air.



Yes, actually it is. There absolutely HAS to be some source of ignition. Be it a spark, flame, heat due to friction, SOMETHING. There has to be something there to raise the temperature of the fuel to it's ignition point (which varies depending on the fuel).

There's a great episode of Mythbusters that illustrates this point. They pour some gasoline into a small container and drop a lit cigarette into it. We've seen this in all kinds of movies where the gasoline erupts into flame.... except in real life it doesn't. The cigarette burns at a temperature below the ignition point of gasoline. Therefore, no fire.

-Charles

Charles,

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 burning. Therefore, when the cigarette is dropped into the gasoline, the mixture is above the UEL, and no burning occurs. If you look at the NIOSH Pocket Guide for Chemical Hazards and look up "gasoline" you will see that you can only have an explosion of the gasoline vapors when the mixture is between 1.4% (LEL) and 7.6% (UEL) in air. But the Flash Point of Gasoline is -45 degrees F. So it will give off vapors enough at any temperature above this to have an ignitable mixture. It is not that the cigarette is below the ignition point, which it is not. It's that the mixture is such that combustion is not supported; it has to be in that "flammable range" of 1.4% to 7.6% mixed in air.

Now, concerning oxygen, the sources I had above specifically state that it does not need an ignition source with these incompatible chemicals to produce either fire or explosion. What gives? I think the heat of the reaction is vigorous enough to provide the third leg, which is not a spark necessarily, but heat. Now, lets say that there was some toluene on the surface near where a 100% oxygen leak occurred. If we look up toluene in the NIOSH Pocket Guide, we get a flammable range of between of between 1.1% and 7.1% in air. If we look further down the page, for incompatibilities, we see "Incompatibilities & Reactivities--Strong oxidizers." Oxygen is a very strong oxidizer. Toluene, I think even in a very small quantity, could react with the oxygen and produce a fire/explosion.

Perhaps the most famous oxygen fire was that which occurred with Apollo 1, which cost astronauts Lt. Colonel Virgil I. Grissom, USAF. Lt. Colonel Edward H. White, II, U.S.N. Lt. Commander Roger B. Chaffee their lives. Here is Wikipedia's writeup of the cause:

Cause

Since the CM was designed to endure outward pressure in the vacuum of space, the plugs-out test had been run with the cabin pressure at over 16 psi, almost 2 psi above the ambient sea level pressure at Launch Complex 34 and near the upper limits of measuring devices in the spacecraft. This represented over 5 times the oxygen density carried within the Mercury and Gemini spacecraft while in spaceflight (which was only 3 psi but equal to the partial pressure of oxygen at sea level and thus very breathable). Following a worldwide survey of artificial oxygen-rich environments, it was found that rarely if ever had a 100% oxygen environment been created and maintained at such a high pressure, in which materials not normally considered highly flammable can burst into flame. The investigation also found much substandard wiring and plumbing in the craft. Hence, the fire was at first believed to have been caused by a spark somewhere in the over 25 km (16 mi) of wiring threaded throughout the command module.

The review board noted a silver-plated copper wire running through an environmental control unit near the center couch had become stripped of its Teflon insulation and abraded by repeated opening and closing of a small access door. This weak point in the wiring also ran near a junction in an ethylene glycol/water cooling line which was known to be prone to leaks. The electrolysis of ethylene glycol solution with the silver anode was a notable hazard which could cause a violent exothermic reaction, igniting the ethylene glycol mixture in the CM's corrosive test atmosphere of pure, high-pressure oxygen.[18][19]

The panel cited how the NASA crew systems department had installed 34 square feet (3.2 m2) of fuzzy Velcro throughout the spacecraft, almost like carpeting. This Velcro was found to be explosive in a high-pressure 100% oxygen environment. Up to 70 pounds of other non-metallic flammable materials had crept into the design. Buzz Aldrin in Men From Earth states that the three astronauts complained that they wanted the flammable material removed, and that there was to be no flammable material in the spacecraft; the flammable material was removed, but was replaced prior to delivery to Cape Kennedy.

In 1968 a team of MIT physicists went to Cape Kennedy and performed a static discharge test in the CM-103 command module while it was being prepared for the launch of Apollo 8. With an electroscope, they measured the approximate energy of static discharges caused by a test crew dressed in nylon flight pressure suits and reclining on the nylon flight seats. The MIT investigators found sufficient energy for ignition discharged repeatedly when crew-members shifted in their seats and then touched the spacecraft's aluminum panels.

However, the ignition source for the Apollo 1 fire was never officially determined.[16]

It is interesting also to note as a diver that the pure oxygen atmosphere of Apollo I was there to counter the potential for decompression sickness of the astronauts.

SeaRat

 

[Diver0001]

...snip...

There's a great episode of Mythbusters that illustrates this point. They pour some gasoline into a small container and drop a lit cigarette into it. We've seen this in all kinds of movies where the gasoline erupts into flame.... except in real life it doesn't. The cigarette burns at a temperature below the ignition point of gasoline. Therefore, no fire.

-Charles

Charles, I'm most definitely not the most knowledgeable person on this board but it should be clear to everyone that basing ones knowledge of physics and chemistry on what one sees on Mythbusters doesn't necessarily paint the whole picture. I like the program too and I think those guys are great but there is more to this than meets the eye. I guess I wasn't able to explain it well enough before so let me try again.

Let's start with a concrete example. Titanium. Titanium is a pure element that can spontaneously combust (burst into flames) in an environment containing the following conditions:

1) pure titanium
2) pure oxygen
3) a catalyst like certain oils
4) a certain amount of over-pressure increasing the pprO2 to something like 24 bar (350psi)

Under these conditions, titanium will "spontaneously combust". That means it will burst into flames even when nobody "lights it". Why? Because of the oxidation. Oxidation causes heat and in some cases, like described above, the oxidation creates so much *intrinsic* heat that the related chemical reactions are self-propagating.

As related to the accident, I guess one could theorize that if the deco bottle in question had a titanium dust cap that had some contaminant on it and that the pressure of the gas escaping from the bottle once the neck seal had been broken caused a local environment around the dust-cap in excess of 350 psi (which isn't that strange considering that the pressure inside of the tank could have had an environment with maybe 10x that...) that the dust-cap could ... no.... *would* have burst into flames without anyone lighting a proverbial match. Once again, I have no idea of whether or not this happened... but I'm saying that something *like* this is theoretically possible regardless of what Mythbusters says about gasoline.

And that is only one example. If one were to think it through (and had a more extensive understanding of chemistry and metallurgy than I do) then there are many chemical compounds and elements that may have been present in a typical garage that could, in theory, create similar conditions for spontaneous combustion in a high-oxygen environment.

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....

Some things will simply burst into flames at room temperature if there is enough O2 and the right conditions available..... that's a simple fact.

R..