"Pure oxygen is flammable." True or false?

[Guest]

In the book Welding by Don Geary the author states on page 7, "Pure oxygen is flammable." I disagree.

The way I understand it, oxygen is required for oxidation but oxygen is not a fuel. The higher the concentration of available oxygen the faster an item will oxidize. For example, a lighted cigarette can flare up into a flame in the presence of a high concentration of oxygen.

If oxygen is flammable why won't the oxygen from an oxygen tank in an oxyacetylene outfit ignite?

The reason I'm asking is that I've read and heard this statement so often that I'm beginning to doubt myself.

Thanks,
Dan

[Forrest Addy]

You are correct. Geary's statement is false.

Oxygen is one third of the fuel, oxy, heat source triad that initiates conmbustion. Take away one and there is no combustion. Oxygen is not a fuel. It's an oxidizer which if present in larger concentration results in more vigorous combustion. Oxidizers include halogen gasses like chlorine, sulfur, and other elenents that accept valence electrons with a consequent release of chemical energy. I think. It's been 45 years since HS chemistry.

So, oxygen is not a fuel. It's an oxidizer. What's his name either has his facts wrong or is guilty of a dumb blurt. Geary needs to bring out the hazards of working with oxygen but without committing technical solecisms.

I like what's printed on the oxy cylinder label: "Caution!! Oxygen vigorously accellerates combustion." This is true. I once saw a safety film in HS on fire hazards. In one demo a plain cotton tich hospital mattress was saturated with oxygen and ignited on a firing range. It went up like a pound of black powder poured out on the ground.

And yes, my buddies had to try it with a pissy old crib mattress and a dad's welding oxy. It worked as advertized. What the nmovie didn't mention was how hard it is to extinguish blazing mattress fragments and dispose of the evidence before the Fire Departnent arrived.

[This message has been edited by Forrest Addy (edited 01-06-2006).]

[japcas]

I have a welding book at home but I can't remember the title of it at the moment where the author states that you can cut with an oxy acetylene cutting torch even after cutting off the acetylene. He says that you start the cut as normal and then shut off the acetylene while keeping the torch moving into the cut. He says as long as the torch keeps moving the oxygen will continue to cut the metal. I have never tried this with my torch at home.

[pgmrdan]

I tried this and it works. It's tricky but once the steel hits the kindling point and you hit the cutting torch lever you can shut off the acetylene and watch the steel continue to burn.

Richar Finch talks about this in Welder's Handbook.

Another book (the one with the gray cover) talks about a lance being used to apply only oxygen to an initially heated piece of steel. It talks about piercing steel several feet thick using this method. The lance is a consumable hollow metal tube that can be several feet long and only delivers oxygen.

[Rustystud]

Forest Andy:

I read the first post then read yours you did a A1 job. I thought about the first post and how I would answer it. You read my mind almost 100%. It was scary we must have had the same science teacher in another life.
I commend you for being so thorough with your post.
Rustystud

[Norman Atkinson]

This is chemistry which dates back to the Pholgiston theory and Joseph Priestly in 1774.

What you have read is something as old as the debunked belief. Forrest Addy is perfectly correct- but this is first year Chemistry stuff. If you ain't got to this level, you should choose to leave the damned stuff alone. Other instances of just how dangerous Oxy is all too true.

Again, with steel- iron red hot, the introduction of pure oxygen from a torch is simply creating an iron oxide from the parent metal- and a gap or cut where it fell in sparks in your ear or in your neck!
It's called reducing- although you might think otherwise from the bad language- which is a by-product.

Really, you should go back to or re-learn the basics in chemistry or physics- before venturing into second level stuff such as welding.

Norman

Evan's jet powered human post illustrates the oxygen chemistry. Hydrogen Peroxide is
water H2 O but with an atom of oxygen hanging on to make it H2 O2. In simple terms, it is the stuff to clean wounds or teeth or dirty clothes. It frees the atom off with surprising results. The rest of the gubbins quiets down to water or steam again!
Thank , you Evan, for your help in Distance Chemistry lessons.


[This message has been edited by NORMAN ATKINSON (edited 01-06-2006).]

[sch]

Norman: I think the jet was a 'real jet',
a miniature turbine engine fueled with kerosene and air breathing with no added oxydizers. H202 devices are usually rocket engines, not jet engines and use essentially pure H2O2 or with only a few % of water.
Steve

[Norman Atkinson]

Wasser "real jet"?
I came from an era of Lorin and Babst and athodyds. Goblin engines, Meteors with re-heats, V1's with Shmitt Argos engines and V2's from the Verner Braun stable before he was defected. Miss Braun was piloting, pilotless V1's and we were using rockets on jet aircraft.
Then of course we were introducing water and glycol into Merlins and Griffon Spitfires which were fired up by Coffman cartridges which were strictly rockets.

And then I was almost 20!

My mistook! Got a City and Guilds in Welding.That I do remember.

N

[Dawai]

Oxygen will make everything burn, including you. Just ask the apollo astronauts. A unshielded switch ignited the blaze.

When you prep chemical lines for oxygen service you swab them out with a full-evaporating cleaner, the least dab of oil and you can have a blaze. It lowers the self ignition point that low. Oil the regulators on your oxy-actylene bottles and have the same results.

Oxygen is one essential part of the flaming process. Perhaps why it was included as flammable. It takes both to burn, even steel at the right temperature. It takes a oxidizer and a fuel to burn.

[Norman Atkinson]

David,
Exactly! I am guilty of hogging the post and it was time to give others a chance to add their contributions.
As each post appears, each bears out earlier warnings.
Cheers and thanks, Mate

N


[This message has been edited by NORMAN ATKINSON (edited 01-06-2006).]

[Boomer]

While in vocatioal school I was about to use the acetelene torch. A friend near by had a cigarette so I asked him for a light and he held out his smoke. I turned the acetelene on and held the torch to it. Just then another student said "that won't work" I then turned on the oxygen and POOF! Made an instant believer.
Had fuel, had heat, added oxygen, got fire.

Solecism....betcha don't get to use that word every day.

H2O2 aka T-Stoff?

[Dawai]

Now Magnesuim: Some bright young man from NORTH GEORGIA, I won't admit who..

Took a whole shovel full of magnesuim shavings and put them into a campfire at the lake. GOD, it was so bright My shadow was on the trees hundreds of yards away, Since the people on the highway about 100 yards away were having trouble and stopping, The magnesuim was shoveled up and put into the bay, muddy water.

Mucho to everyones surprise it self-oxidizes and burns underwater once ignited. You could see it under the muddy water burning brightly.

Now, imagine if I had added aluminum and iron filings to the mix? a meltdown of the shovel..

[Wirecutter]

To add to what's been said - no O2 is not flammable by itself, but it's presence can get almost anything to burn, and fast.

Somewhere out there, there's a video of a guy in an asbestos suit with a flask of LOX at the end of a 15' pole. He pours it on a hot BBQ grill in the middle of a bright sunny day, and the white-hot meltdown of the grill washes out the entire scene in bright white. It's pretty impressive, albeit crazy.

I've also heard that a charcoal briquette soaked in LOX has the explosive power of a stick of dynamite.

This all goes to why I'm reluctant to have an OA welding setup at my home.

-M

[Weston Bye]

I remember a picture of a mildly burned Navy pilot - his lips were dry so he applied Chapstick to his lips while suiting up for a flight. Ignited when he put on his oxygen mask. 1st & 2nd degree burns to lips, nose & cheeks under the mask.

Wes

[Evan]

The hydrogen peroxide as used in the Bell jet pack doesn't burn either. It undergoes an exothermic reaction when promoted by a catalyst such as platinum. The reaction releases the binding energy of the extra oxygen atom and goes: 2xH2O2>O2+2H2O.

The end result is water in the form of superheated steam and free oxygen.