Sciencemadness Discussion Board

Shooting oxygen tank shows fire and no fuel ??

metalresearcher - 13-12-2021 at 10:32

No, I would never do such experiments, despite I like fire and light...

But then these guys (at 14:11) shoot successfully the 200bar oxygen tank, a bright flame appears and the steel melts and make a perfect circular hole in its wall all within a single second.
But a flame ?
Where is the fuel ?
Oxygen does not burn in itself ?

https://youtu.be/lAdAtaUfGPk?t=855

Twospoons - 13-12-2021 at 11:24

The steel is the fuel. The bullet impact will inject hot steel fragments into the pure 200bar O2 atmosphere - ignition of the steel is no surprise.

Shooting a 200bar O2 tank is a spectacularly dumb thing to do.

[Edited on 13-12-2021 by Twospoons]

Johnny Cappone - 13-12-2021 at 16:55

Quote: Originally posted by metalresearcher  
No, I would never do such experiments, despite I like fire and light...

But then these guys (at 14:11) shoot successfully the 200bar oxygen tank, a bright flame appears and the steel melts and make a perfect circular hole in its wall all within a single second.
But a flame ?
Where is the fuel ?
Oxygen does not burn in itself ?

https://youtu.be/lAdAtaUfGPk?t=855




@Twospoons is right.
When sufficiently heated and exposed to an intense or high pressure flow of pure oxygen, the iron/steel will burn violently. The bullet's impact provides the initial heat needed to ignite the metal. In fact, almost all common metals when heated sufficiently will burn to powder oxide in the presence of a stream of pure oxygen. Unfortunately, some engineers overlooked this fact when designing the diesel engines and their fuel intake/mixing systems for some of the first submarines in the last century. Having cylinders of pressurized pure oxygen on board to power internal combustion engines seemed like a great idea until you found out otherwise. Poor sailors.

By the way, there is an extremely cool tool based on this concept (burning metal in a stream of pressurized oxygen), it's called a "thermal lance". It is capable of cutting large sections of steel using only the heat generated by burning the metal in pure oxygen. I would love to have one of these!

https://en.m.wikipedia.org/wiki/Thermal_lance

https://youtu.be/JI5whCBV0bk


Fire Lance

MadHatter - 14-12-2021 at 12:18

That's what a former roommate of mine called it. He
was a locksmith. He said they use a hollow tube of
magnesium with oxygen flowing through it.

Triflic Acid - 15-12-2021 at 07:35

aka thermal lance. These have been proposed for cutting into solid steel vaults. You take a rod of steel and melt the tip. then pass oxygen through the rod. Wait for the fun to begin :D

yobbo II - 15-12-2021 at 11:48


You can make a thermal lance quite easily. A pipe full of steel wires. See UTUBE.

It would take a mighty powerful gun to penetrate a O2 300bar gas cylinder.

I once knew of some dudes who had nothing to do and had a suppy of big (full) oxygen cylinders beside a lake. They would open the cylinder with a wrench (as you do when going to use the cylinder). The noise must have been LARGE. They would then toss the cylinder into the lake where it would take off like a torpedo. Some where never seen again. Some disappeared for some seconds and then reemerged like a missile from the bowles of the lake...
Them were the days.............

Yob

Triflic Acid - 15-12-2021 at 11:51

they should have packed the cylinders with magnesium shavings, then ran far far away. The explosion that would create :)

metalresearcher - 15-12-2021 at 13:20

Quote: Originally posted by Triflic Acid  
they should have packed the cylinders with magnesium shavings, then ran far far away. The explosion that would create :)

Or put a bag of thermite under the bottom of the cylinder and then poke a sparkler in the bag, light it and run FAST ! You get a nice missile !

Twospoons - 15-12-2021 at 13:56

Quote: Originally posted by yobbo II  


It would take a mighty powerful gun to penetrate a O2 300bar gas cylinder.

Yob


He used an .50 cal APIT (armor piercing incendiary tracer) round in a Barrett. This is a gun designed as an anti-material weapon. One application is shooting engines to disable vehicles.

[Edited on 15-12-2021 by Twospoons]

Fulmen - 16-12-2021 at 01:43

Quote: Originally posted by yobbo II  

It would take a mighty powerful gun to penetrate a O2 300bar gas cylinder.


Not really, I'm pretty sure a standard 762 Nato will do the job.

RogueRose - 20-12-2021 at 07:01

I've seen a few video's of people making their own thermal lances using a variety of different metal tubing & portable bottles of O2 (the red Bernzomatic bottles). The most common tubing I've seen used is steel brake lines. To light the torch a simple vinyl hose is used to connect the tank & tube and a small bit of very fine steel wool is inserted into the end of the pipe and lit (looks like even a normal lighter will work here!) quickly followed by turning on the gas as the wool slowly burns up. When the gas starts flowing, the end of the tube instantly ignites.

I'd be very interested in which types of metal give the hottest flame as I think it would be interesting to try different types of stainless steel, copper, brass, titanium & aluminum tubing. I also think it would be interesting to put a piece of wire down the tube to give it more metal to burn.

I would like to try this and find out which metals give the hottest flame, but at the temperatures these things produce, I have no idea how to accurately calculate the flame temp. If anyone has any ideas, please let me know as I might try this test out over the Christmas break.


On a side note, about the small O2 tanks, here is some info about them.
The small bottles state they have 1.4 oz of O2 & it seems that 1 mole of O2 has a volume of 22.4 liters, so this bottle should have ~27.8L of O2 (or it could be double that, I'm not sure if the 1 mole @ 22.4L is 16g of O or 32g of O). I'm not sure how long this will last & the prices are pretty steep for such a small amount as I've seen them as high as $20/bottle, though I've seen them advertised for 1/2 that but they are often not in stock or shipping is very expensive.

yobbo II - 21-12-2021 at 16:40


Some sort of system like this will measure temperatures if you can find an affordable one.

Yob

Colleen Ortiz - 26-1-2022 at 03:13

Hello, this looks like a cool experiment. Oxygen is not combustible. It has the ability to make an existing fire burn hotter, quicker, and/or longer while remaining completely non-flammable. Most significant calibers, I'm prepared to wager, might cause a tank to leak. At high pressure, oxygen becomes a liquid, thus it doesn't require as large a tank as, for instance, compressed nitrogen (nitrogen requires much higher pressures to liquify). Because the gas cannot be ignited, oxygen tanks cannot explode if the gas is ignited. Oxygen is an oxidizer rather than a fuel. The burning of other fuels will be aided by oxygen. If you lit a match in a stream of oxygen flowing from an open tank, the match would quickly burn out, but the oxygen would not explode. The reason oxygen tanks burst during a fire is that the heat causes the pressure in the tank to rise faster than it can be vented. It also weakens the metal making it unable to hold the pressure. As the pressure vents, the oxygen also intensifies the fire making more heat.
The iron/steel will burn fiercely when suitably heated and subjected to a strong or high-pressure flow of pure oxygen. The initial heat required to ignite the metal is provided by the bullet's impact. In reality, in the presence of a stream of pure oxygen, practically all common metals will burn to powder oxide when heated sufficiently. Unfortunately, while developing the diesel engines and associated fuel intake/mixing systems for some of the earliest submarines of the past century, some engineers neglected this aspect. Having pressurized pure oxygen cylinders on board to fuel internal combustion engines looked like a good idea until you realized it wasn't.

Fantasma4500 - 14-2-2022 at 17:42

im 99% sure they coated the inside in plastic
that fireball was not from what.. 5 grammes of steel, no way. having torched my way through 300 millimeters of steel, spent weeks looking into pools of boiling steel- no way.
if we first up imagine the sharp bullet impacting, it wont in a brisant manner turn the steel into dust, it will rather pierce it like a knife, seperating it
however- they might be hardened. theyre typically made of manganese steel- 20%? its known that you must not combine oil with highpressure oxygen- but plastic and high pressure oxygen?
could it be maybe the lead itself caused the explosion? anyone that has watched apache footage would at first suppose theyre using explosive rounds
of what ive found- they dont, the lead simply travels great distances where it ends up basically molten and on impact downright explodes

maybe if oxygen bottles are hardened i would buy into the steel dust explosion theory, coming to think of it, having worked at scrapyard, a warm memory hits me about 6 months ago they accidentally threw an oxygen bottle into a 5 ton metal shear mounted on a machine, the shockwave was well felt 50 metres away, but very little smoke, as for safety protocol with such accidents we have to recover and identify the sinful materials
it seemed to be just barely 10mm thickness, opened up- but not shattered, the material had from the pressing/explosion warped. the inside was a dull grey, and it had a very slight hardened feel to it, so theyre not super hardened

now- i think of yet one more thing, someone mentioned hes using armor piercing? that could be tungsten carbide
tungsten isnt super good with oxygen and high temperature, what are the odds that the tungsten penetrated the front and then exploded on the inside in the pressurized oxygen atmosphere?

just by chance i looked at 11:45 in the video, theres an up close slow motion. this one seems to be quite well hardened and you can see the steel burning up
he does mention in the .50 before shooting, that its a tracer round
the slow motion does also show black smoke, which seems to wear off after the first bit, this could be Fe3O4 which forms at high temperature, the hole is very perfectly round, the back side isnt as fine, supposedly the bullet tumbled after impact and had it burn unevenly

so to cap off, it simply penetrated the tank, and the entrance/exit holes turned into torches
it wasnt about the bullet itself
it wasnt about the hardening of the steel tanks, or alloy
it wasnt an combustible inside the tanks or outside

from first look it did look like it was a lot more instantaneous, and not very much torch like
impressive that the impact had enough heat to kickstart the burning of the steel, that has to be about 800*C, maybe extra pressure helps getting it going a bit lower.