Looking at a NASA pic, I see a tank marked, “Liquid Oxygen No Smoking.” I think, “Yeah, duh.” But then I wonder, when the Liquid O does explode, what is it combusting with? When gasoline or hydrogen tanks explode, the contents are oxidizing with the O in the surrounding air. Is the O in the tank O1 and is oxidizing with itself to form O2? Is there simply enough stuff in standard air to fuel the O when it’s in such plentiful supply?
The danger is not about the tank exploding. The danger is that if there’s any significant leak, the surrounding environment might end up with a concentration of gaseous O2 that’s substantially higher than normal atmospheric concentration. Any fire that happens in an oxygen-rich environment is going to be extremely vigorous, and some things may even spontaneously oxidize.
Here’s a demo of what can happen to a fire in an O2-rich atmosphere.
If you go over the youtube channel for The King Of Random, he plays around with liquid O2. Pouring it on things like a piece of carpet or a potato chip and lighting them on fire. They’ll burn much better, as you’d expect, with the liquid 02.
So, sure, o2 isn’t flammable on it’s own, but if it leaks and your flicked cigarette lands in a little pile of leaves, you could end up with a much bigger problem than you typically would.
I don’t think one would ignite by itself but it would mix with anything on the ground including the dirt itself and then it just takes a spark. If it was a BLEVE due to being overheated (boiling liquid expanding vapor explosion) it would scatter over a wide area. We used LOX a lot at work and I have seen films of it burning like furious hell at the end of a stainless steel pipe. In that case it is consuming the steel pipe itself but that is because it was under very high pressure to begin with, not just a non pressurized tank dumping the contents. There are charts showing the relationship between pressure and various materials and damn near everything burns above 3000 psi. All it takes is a little energy, like opening a valve too quickly and allowing the LOX to accelerate and hit a 90 degree bend too abruptly.
If you were smoking a cigarette and walked into a high oxygen area the ciggy would become a flare. I have helped transport drums of high proof hydrogen peroxide. They would leave the drum cap slightly open to avoid any pressure buildup. It it sloshed a bit when on the towmotor each drop would [poof] as it hit the asphalt.
Dennis
Russian cosmonaut-in-training Valentin Bondarenko learned the very hard way what can burn – himself included – in a high-oxygen atmosphere in March 1961:
Uncovering Soviet Disasters Chapter 10: Dead Cosmonauts, James Oberg, Random House, New York, 1988.
(This part starts about 19 paragraphs down the page. Subsequent paragraphs describe the aftermath in gruesome detail.)
O2 doesn’t need to be at high pressure burn metal.
An oxyacetylene torch is a torch that’s fed acetylene gas from one tank as a fuel, and pure O2 gas from another tank as the oxidizer. to cut steel plate, you heat the steel with the torch until you’ve melted a hole through it, and the edges of the hole are molten and glowing red hot. Then you squeeze another lever on the torch that greatly increases the O2 flow rate. This is when you can really start to make progress with your cut: that extra O2 oxidizes the steel, releasing far more heat and enabling a much faster cut than you could get if you continued using the torch without all that extra O2 coming out.
Then there’s also the thermic lance. This is basically a steel pipe filled with steel and aluminum filler rods. You light the end of the tube with an oxyacetylene torch, and then you blow pure O2 through the pipe. Now you’ve got a torch that can burn through pretty much anything.
Derek Lowe, author of the well appreciated “Things I Won’t Work With” series of essays, also wrote a few “How Not To Do It” essays.
Here’s a delightful little [del]tale[/del] [del]anecdote[/del] data point: How Not to Do It: Liquid Oxygen Cylinders
TL;DR: Very reminiscent of the Rocket Car story, two guys who think they know what they’re doing scavenge a damaged O tank and try to make it work, with highly exothermic results. The weird part of this story is they, and a whole bunch of other people, somehow didn’t get blown to smithereens! But their pick-up truck sure did! Picture included :eek:
I’ve read that book. Yuri Gagarin sat death-watch for the poor guy.
IIRC, once you start cutting, you can shut off the gas and the steel will continue to burn away with just the oxygen.
There are pre-heat nozzles that stay on durning the cut.
Three NASA astronauts died due to an explosion in an oxygen-rich atmosphere.
An oxygen-rich atmosphere can result in an explosion with very little provocation. I’m pretty sure that even a static electric discharge can set it off.
If anything can burn, it will with LOX. In plants where we make it by the tons, it will explode the asphalt road if spilled. Lines (pipes) in oxygen service need to extra extra clean : even the slightest amount of dirt and grease can set off an explosion. Commonly used lubricants or gaskets or seals have to special (no rubber or graphite).
Sometimes workers will work around oxygen vents, leave the plant and light up a cigarette outside only to have their clothes (and themselves) catch fire because clothing absorbs oxygen. Lots of burns happen all the time with scuba divers and even with patients with oxygen enrichment at homes.
This is an old video from the armed forces but it is very relevant THE MAN FROM LOX LIQUID OXYGEN SAFETY & HANDLING PROCEDURES 81840 - YouTube
Why SCUBA divers? The vast majority of recreational divers have ordinary atmospheric air in their tanks. For the deep divers using Trimix, the blending from pure O2 bottles (along with helium and nitrogen) is done at a facility that produces the Trimix - and the tank they end up with has an O2 percentage that’s equal to or lower than atmospheric.
Everything you say is correct and maybe I am paranoid but anything to do with concentrated oxygen worries me.
Take this diver for example:
“ Former WRAL News photographer Rick Allen had pulled into his garage on Jan. 3 when an oxygen tank used for diving toppled over and exploded. He suffered burns over 20 percent of his body, and his arm was blown off.”
Pure O2 bottles can be used as part of an accelerated decompression protocol. The terminal decompression stop is done at around 5-7 meters, and breathing highly oxygen enriched air/pure O2 helps offgas nitrogen faster. I’d be delighted to quickly find a dive table that says it though.
Obviously, this is a technique for advanced divers, technical divers only. Pure O2 is poisonous at somewhere around 1.5 atmospheres partial pressure. Doesn’t take much additional seawater to reach that pressure.
Are rebreathers enriched in O2? Or do they supply a more or less atmospheric mix? I guess it depends on the rebreathing rig (thinking of guys like the late David Shaw)
For that case, I wonder if it was the specific gas so much as the fact it was a falling compressed gas bottle? Which have a stupendous amount of force behind them, should they topple and shear off the valve stack.
In the Apollo 1 case the astronauts died from smoke inhalation and any burns suffered were post mortem. There was no explosion inside the cabin. The linked article does not contain the word “explosion”.
The fire inside the cabin caused a rapid buildup of pressure which ruptured it. This sounded like a muffled explosion to some nearby but it was not an explosion in the normal sense.
An oxygen-enriched environment can definitely cause rapid, almost explosive burning of combustable materials. In this video, engineering students immersed and saturated various items with LOX while igniting them. In no case was there an actual explosion but a LOX-saturated carpet exhibited what might be called explosive burning.
That would cause damage and injury, but not start a fire.
Would a diver keep a tank of pure oxygen around?
To add on to Joey P 's post, in addition to common failures of compressed gas bottles, there are unique causes, failure modes and impacts for oxygen bottles:
Causes : A little amount of grease or even metal particles or shavings left inside the bottle during refilling. Duck tape or electrical tape pieces or sometimes even the wrong gasket or o-rings.
Failure modes : If you have metal dust in the cylinder and the cylinder falls, it may create a spark inside the cylinder and combustion starts inside the cylinder. Look at this investigation where the fire happened inside the cylinder. Often diving cylinders are made of aluminum which itself burns readily in oxygen.
Impacts : We are all carbon based lifeforms. Its quite different to have fuel burning on our skin versus our skin burning as fuel. And everything that can burn will readily burn in pure oxygen. Even wet things.