oxygen/acetylene mixture

[NoltaiR]

Its been a while since I last posted here because I screwed something up in my browser when trying to remove the pop-ups that wouldn't allow me to log in correctly here. Anyways I have been using the elite/UK forum (and yes, I am from the USA.. I just like the way those people think) and here was my latest posting there (note that when I post there I always have to think in metric so if I have any figures in this post then they will be in metric units):

--------start of eliteforum post by noltair------

I read somewhere on either this forum or the main forum that someone had filled bags
with a oxygen/acetylene mixture then set it off with a firecracker.. I have been searching
for that topic for the past 25 minutes now and I have finally given up so I guess I will just
start a new topic.

Anyways I usually have a hard time getting a hold of any sort of explosive (I mean it's
been hell just trying to attain the materials to make a good rocket propellant!!); however,
my father is a welder by profession and he keeps large tanks of oxygen and acetylene in
our garage and are connected to a welding torch. The person who had the original posted
idea used it in bags.. I however went a step further by filling a medium sized
balloon--which slightly compresses the gas--with the common ratio of oxygen to acetylene
that I use when I weld (I don't know this ratio in number amounts).

I had never tried using an oxidized gas as an explosive before so I was uncertain what the
results would be. I did not want to tape a fuse on it as I have read in places before because
I just don't trust my improvised fuses on something that I have never tried before. So I set
the balloon (which was slightly smaller than a soccerball) on the corner of a sheet of large
newspaper and I lit the opposite corner on fire and stood back about 15 feet (like a moron
I did this all within my CLOSED garage because I didn't expect much of a result). It took
a few seconds for the fire to make its way to the balloon and then it detonated (and I do
believe this could be considered a detonation--could it possibly be considered a primary
explosive???). The report was awesome even though the balloon wasn't very large. The
metal walls of the garage shook and if there would have been a bigger balloon used then
the windows would never have made it. My ears were ringing for about a minute..
needless to say the balloon had been vaporized. Just then my dad (who had been in our
house which is about 15 meters from our garage) came running out asking what had gone
off--he has always been quite displeased with my liking of anything that explodes--to
which I replied was nothing more than a homemade firecracker...

It is time for me to get some sleep but I am going do some more experiments in the days
to come on the oxygen/acetylene mixture which I will post the results as they come up.

---end of eliteforum post by noltair---

If you have any suggestions on how I can make this formulation any better then please do so. Also I have made about 10 video tapes of an episode of 'scitrek' from discovery channel called 'explosive situations'--and yes, the commercials have been taken out--. If you would like a copy then please notify me.. I expect no payment for this; HOWEVER, if you do *happen to have* some leftover chemicals (specifically KNO3, KClO3, KClO4, german mesh Al) that you want to get rid of this would be most greatly treasured!

[da man]

Acetylene can be made by reacting calcium carbide (also called calcium dicarbide) with water.

(Thank you for stating an irrelevant fact. The question isn't "How to make acetylene" since he has cylinders of it already. The question is how to make the explosion more powerful. NBK2000)

[ January 08, 2002: Message edited by: nbk2000 ]</p>

[Arkangel]

Used to fill upside down paper cups with this mixture on a bench and then set them off, even did a cardboard milk carton of the stuff, which when it exploded, bruised my leg with a couple of bits of cardboard shrapnel.

I assume he gets the mixture right by setting a good flame on the oxyacetylene torch then knocking the flame out on a hard surface. You then have a nozzle emitting an explosive gas. You can then either put it in some kind of rigid container like the milk carton, or perhaps a balloon like he describes. If the mixture is set right, there would not be much you could do to increase the power of explosion, other than increase the volume of gas being used. The 2 ways of doing this would be having a bigger container, or having some kind of pressure vessel.

First is easy, the second much less so. I thought about having a small compressor (like the cigarette lighter operated jobs for your car), doing it, and pushing the air into a car tyre or something like that. Imagine what would happen if you pumped your average tyre up to 30psi with that mix. Ignition could be via a vehicle spark plug system on a tube connected to the tyre valve. That part is easy, the bit that scares the shit out of me is the idea of some kind of reciprocating compressor that gets warm anyway, has all sorts of organic lubricants in the pistons etc. The ideal way would be some form of non friction compressor like a bellows, but how close to it you'd want to be, Hmmmmmm, not very if you ask me.

[mrloud]

Instead of putting it in a container under pressure you could just confine it and ignite it. We all know how much noise a Coke bottle makes when bursting due to the pressure from subliming dry ice. Perhaps a PET bottle full of the gas would be worth trying. In a field. Along way from people.
Speaking of dry ice: put some dry ice pellets in a baloon. Tie knot in baloon. Drop baloon into 2L Coke bottle. Fill bottle the rest of the way up with oxy/acetylene. Wait for the dry ice to sublime and inflate the baloon thus compressing the oxy/acetylene. Once you are satisfied that there is lots of pressure in the bottle, ignite it.

The only problem is, I really dont know how much explosive force the gasses generate when ignited. I know it is loud and will pop a cardboard box; but the energy released could be due to a sudden and rapid rise in temperature causing a small but fast expansion. Consequently, very little motive force will be imparted. Effective explosives work on the basis that a rapid change in chemical structure results in a byproduct taking up vastly more volume than the original substance. Somehow I don't think oxygen and actylene fit into this definition of an effective explosive.

I think some experimentation is in order. :)

[Anthony]

The easiest way to pressurise a container with oxygen/acetylene would be use the pressure from the bottles it is stored in. You probably get 50-100psi at the torch?

Buy a surplus weather ballon, they're about 12ft in diameter...

IIRC acetylene/air mixtures can detonate, DV around 3000m/s.

[Arkangel]

Well that's true to a point, but you what concerned me was that to get the right mixture you generally have to set a flame and knock it out, leaving the gas mix flowing. The Oxy is stored in the bottle at a much higher pressure than the acetylene, so if you put the nozzle into a gradually pressurising container, the back pressure might affect both regulators differently, and therefore the mixture. Seperate compression of the mix was a more accurate method, but I like the principle around the subliming dry ice. I'm sure you could make some form of frictionless diaphragm compressor that would work reasonable well.

I'm not sure how you could covertly move around with a weather balloon, but if you got one it would be fun to put in an old car with a delay fuse :D (cackles evilly)

[ January 08, 2002: Message edited by: Arkangel ]</p>

[NoltaiR]

So far what I have gathered from your replies is that the only way to make the explosion bigger is to add more to use more at one time (whether compressed or not). The compression idea sounds like it is better (which leads me to believe that my mixture is a LE because it requires oxidation and there is no critical mass that it must reach... anyways that is my assumption) although I do not know how I will be able to detonate it while still pressurized.

I made another charge this morning and used it within a mortar to shoot off a commercial pyrotechnics artillery shell (with the lift charge removed) which it shot like a bullet--much better than the regular BP lifting charges.

I do not make a flame and then knock it out as some of you have assumed (I expect that doing this would damage the torch tip); rather I have much experience with welding and I know how much to open the valves even without actually lighting it.

Current Experiments Underway:
*I am going to tie a rock (as a weight) to the balloon and put a small charge of BP (covered in tape) on the balloon and connect a waterproof fuse to the charge. In hopes that I can pull this off without getting the charge wet, I am going to test this 'balloon charge' out underwater

*I am going to place a small ziplock bag of gasoline on the balloon and then light my balloon the 'customary way' (I put the balloon on one end of a sheet of paper and light the opposite side)... I would like to see if the charge is powerful enough to particleize (probably not a word) the gas and then set it off. If this works then I can sufficiently have a large incendiary/explosive which would cost relatively nothing for me to construct.

*I don't know where I can get a weather balloon but I know a party place that sells 6 ft balloons for 'party favors'. I am not sure how I am going to light this thing as I figure there is too much risk in doing my 'customary' ignition that I have described before. If I could get calls from neighbors complaining about the small balloon (1 ft diameter) explosion.. I almost fear the results of this supersized bomb.. If I somehow do attain a weather balloon, I will be sure to video record it or at least take many pictures..

[ January 08, 2002: Message edited by: NoltaiR ]</p>

[Arkangel]

Unfortunately, there's nothing magic about it, the only way to make this more powerful is by getting the mixture perfect(your way or mine, doesn't really matter as long as you don't damage your kit, which as yet I haven't) and then by increasing the amount of gas available for the explosion.

One way to initiate it whilst pressurised could be to use something like an HT spark, perhaps from a car sparkplug mounted in the pressure vessel (easy enough if you have the welding and engineering skills) and a mini ignition system rigged up just for the job.

Otherwise, if you have seen firetrace fire extinguishers, they are an extinguisher bottle filled with CO2 or whatever, and a long thin plastic pressure hose (1mm internally) leading off. When a fire burns through the pipe the extinguishant is released at that exact point, hopefully where the fire is. With a system like that, you just need to burn through the pipe somewhere and you'll do the trick.

[vulture]

Acetylene can detonate in two ways:
-as FAE, vol% 1,5 -82% in air where an oxidation occurs 2 C2H2 + 5 O2 -> 4 CO2 + 2 H2O

- if pure acetylene will detonate if pressurized by simply decomposing: C2H2-> 2C + H2
after this the carbon and hydrogen could be oxidized resulting in a second explosion :D

[Arkangel]

Whhich explains why the 2 bottles in an oxyacetylene set are at quite different pressures I guess. Don't they have a liquid or something in the acetylene bottle that it is dissolved in or something? I know they are heavy as fuck, even when you have run out of gas

[vulture]

Yes, the bottle contains kieselgur (same thing used in dynamite to stabilize NG) which has been soaked in aceton, the acetylene dissolves in this. Otherwise the bottles would just explode during filling.
BTW, the critical pressure is 6,24MPa

[PYREX]

A good alternative for weatherballoons are waste bags. The fact that wastebags can not be pressurized is neglegible if you consider that balloons of such a size only contain a pressure of several milibars.
I once filled a 10l bag with acetylene/air(!), it was heard over 1km. Imagine a 200l bag... ...with O₂ :eek:

[NoltaiR]

In doing my oxygen/acetlyene mixture experiments I have the following results:

Experiment: Put a 12" diameter balloon underwater (tied down by string and bricks) and ignited (to see if this mixture in a balloon could be used as a depth charge).
Results: No real power as a depth charge because (being that this is a gas mixture) all pressure was directed towards the surface of the water rather than make a shockwave around it. No continued experimentation on this idea will continue.

Experiment: put a bowl of gasoline on top of a 12" balloon and ignited--testing to see if the gas would particlize and ignite
Results: the gasoline was blown into the air but the explosion of the balloon was consentrated in the shape of the original balloon and none of the gasoline ignited. Continued experimentation on this may result if I discover a way to ignite the gasoline.. give me some suggestions!

Experiment: More volume, more explosion? A 24 inch diameter 'punching balloon' was ignited
Results: Report was approximately equal to (maybe even less) than my usual 12" balloons.. only difference was the fireball was obviously larger being that it takes the shape to the original balloon. I believe the reason to this has just been previously answered by another person who stated that the more volume, the less the pressure. Continuation on this experiment will go forth if I can find a balloon of a much stronger rubber that can be large and yet extremely pressurized.. my torch is currently rated at 81-87psi.

------My conclusions/suggestions-------
as a propellant, this mixture seems to be much more powerful than your everyday smokeless powder which leads me to believe that a cheap way to reload cartridges in the future could be simply by refilling gas. As an explosive, this mixture leaves no residue (that I can see) as most all other HE and LE do after use; therefore this could make this mixture the pride of a criminal being that it leaves no real evidence other than whatever its casing was.

[ January 10, 2002: Message edited by: NoltaiR ]</p>

[NoltaiR]

hmmm... no one replied to my last post.. did my ideas stump them or did the other 'forumites' (as nbk calls them) think my ideas of using an explosive gas to replace ammunition propellants too rediculous to comment on? :rolleyes:


haha well anyways the past few days I have been using my balloon charges for the noise only (I admit that I tend to get caught up in simply having fun than doing real experimentation).. but now I have a new idea to put forth:
In the atomic bomb, a nuclear shell/case is used filled with a HE that will (upon detonation) cause the nuclear core to reach critical mass and release its energy. Would it be so illogical of a thought to use this idea with my 'balloon charges'? What I mean is, if I put some sort of HE within the balloon (when deflated) and then fill it with oxygen/acetelyne, could I skip the stop of having to use a blasting cap? The reason I am saying this is because someone has posted that the mixture detonates rather than deflagrates (they said 3000m/s although that sounds a bit outrageous to me). Does anybody think that the explosion of the balloon (upon ignition) would make a powerful enough shockwave to replace a bcap???

I tried my mixture within an old intertube (with a electrical rocket ignitor rubber cemented into part of the tube) and set it off. The explosion was still not much louder than my balloon charges (I am starting to think the reason is possibly because the bigger the volume, the lower the pitch of the explosion) however I was 30 ft away from it and I felt shockwave quite noticably as it blew across my body.. I mean it didn't knock me over or anything but it was definitly noticable.

[nbk2000]

Here's an idea for you:

Rather than using ballons, use a polymeric soap solution to make a dense bubble foam from the gas mix.

2% PVA, dibromide soap, glycerine, water.

Details are found in a popular mechanics or science article during the mid to late '60's. The bubbles would last for hours or days.

It's solid enough that you can cut a big chunk of it off with cardboard and carry it around.

Interesting possibilities, that.

Big blob of foam next to victims doorway.

"What the fuck is this?"

Rod laser pulse onto small patch of carbon dust on foam, instant incandecense, BOOM!

Traces: Soap and carbon soot. Bomb techs confused as hell, no idea what the fuck it was. Victim killed by blast, but no explosives found.

Hydrogen and oxygen floats as a big layer of foam in doorway overhead. Lightbulb broken out to reveal naked filament, immersed in foam.

Victim walks in, flips on switch, BLAM!

Foam layer underneath victims car. .22 tracer skip fired through foam when victim is at car door. Big explosion, possible gas fire, the usual.

With foam to hold a flammable gas in place, the possiblities really present themselves. And the forensic guys will be shaking their heads as to how this "cloud of gas" was able to exist long enough to be hazardous.

:D

BTW: It's another Newbie No-No to say "Why hasn't anyone replied to my topic?".

Sounds like whining, and we really hate whiners here.

[ January 13, 2002: Message edited by: nbk2000 ]</p>

[mongo blongo]

I like that idea! :)
But what is dibromide soap? Is that just normal soap?

[nbk2000]

It's soap that uses bromine instead of hydroxide (lye) as the sopanification agent for the fat. I believe it's used as some sort of medical sterilizing soap. Don't ask me where you can buy it 'cause I have no idea.

You'd probably have to make it. Good news though is that it doesn't take a lot to make the foam.

[NoltaiR]

I think I understand your idea but the mixture just isn't powerful enough to do any real damage in any form that doesn't involve including something for schrapnel (unless you just wanted to try to burn the person).

Anyways I have another idea (and yes, I know that many of these ideas sound a bit rediculous that I have mentioned.. but then again creativity is the fuel of invention :cool:

The idea is making a weak (but cheap) version of a det cord.. you could simply fill a waterhose with the mixture
(any desired length.. just as long as it is capped up at one end when filling and then when your done cap both ends.. maybe a commercial rocket ignitor cemented into the side of the hose)
When ready to use, simply uncap one end and put it into the HE..
The more compressed you make it, the more powerful the final explosion will be.

---conclusions---
I already see flaws in this experiment but give your suggestions and maybe I can work this idea out

[nbk2000]

If you have a large enough volume of gas exploding, then there's no need for a fragmentation kill mechanism. Concussive blast alone will do it. It's especially effective in a confined space.


And it leaves no physical evidence behind to be traced back like metal fragments would.

[mark]

Or maybee, not killing and maiming people may lead to no evidence? Just a thought.

[Phoenix]

would it be more powerful if you take butan instead of acetylen?? it has a larger density and so will create more energy by volume??
i know acetylen is itself exothermic but the density of butan is a lot of higher
i once made 4 L of butan ox was really good but i havent compared it to acetylen ox
does anyone of you know ??
or maybe even take a gas with oxygen that has a biger density then O2
NO2 or something

[A_W]

Just be careful with those acetylene/O2 mixes! My grandfather (who is a professional welder), told me about some guys filling a small plastic bag with acetylene/O2, and dropped it from a building. The bag hit a car, exploded, and the guys had to pay for the damage done to the car. This must mean that acetylene/O2 mixes are quite sensitive to friction/shock. <img border="0" title="" alt="[Eek!]" src="eek.gif" />

[kingspaz]

or static discharge from the bag.

[mark]

Their also quite sensitive to murphys law. The baloon poped right as I ignited my lighter. Took the hair right off my arm, glad their wasnt any oxygen inside or the arm would be gone.

<small>[ April 25, 2002, 07:13 PM: Message edited by: mark ]</small>

[Project IGI]

Too bad on your accident, hope it doesn't happen again.

[xoo1246]

Bubble the gas through water if you want to avoid static electicity discharges.

[A_W]

mark- How long had the baloon been lying around with the acetylene? After some time, oxygen will be absorbed trough the baloon wall, and the explotion will get much louder. This is a common chemistry demonstration: The lecturer has two baloons. One is recently filled (with hydrogen though), and one has been lying around (not sure how long) Both are ignited, and one is much more powerful than the other.

[vulture]

You can't just compare this with your experiment, the balloons used in the experiment weren't oxygen balanced and likely contained too much hydrogen. The acetylene balloon had already pure oxygen mixed in, so it's likely that absorbing oxygen would only make the explosion less powerful.
Also, if more oxygen comes into the balloon, some acetylen will escape from the balloon, otherwise the pressure would rise by itself.

[mark]

My baloon was freshly filled. It went straight from the bottle to the fuse, as I dont believe in waiting. This could have happened to any gas, and the moral of the story is not to make powerful devices out of cheap korean baloons.

[Jager]

My grandfather used to make oxygen/acetylene explosives. He would fill black industrial size trash bags with the mixture, and set them off with a long piece of masking tape, if you wanted more security that the tape would not go out you can coat the sticky part in blackpowder. I forgot the ratio he used but he found one that worked the best.

[mark]

You could probobly use leather punching bag balls or basketballs as containers.

[EP]

So far only one person has mentioned using anything other than thin, flexible plastic (either bags or balloons). Has anyone compared a 2L or similar plastic bottle with a balloon/bag of comparable volume? Seems like the extra confinement would create a larger bang/more powerful explosion.

It's already been said, but be careful with this stuff! I think static is a much bigger risk with this compared to other things like BP. I read a year or so about a welder on the 4th of July filling plastic bags with acetylene and one went of very close, killing him.

When filling in the field, it would be difficult to bubble through water, what about giving the filler and the balloon/whatever a quick mist of laundry anti-static spray? It may even be flammable! :)

<small>[ April 28, 2002, 07:35 PM: Message edited by: EP ]</small>

[NoltaiR]

A coke bottle would prove much more powerful than any trash bag due to the fact that oxygen/acetylene functions as a deflagrating explosive that builds power due to the amount of confinement given as well as a bottle holding more pressure than a balloon or bag would.

A basketball would also be a good thing to try because unlike a cokebottle, you can completely flatten it and then fill it up (so it would be acetylene and O2 rather than acetylene, O2, and air).

[grimreaper]

first you solder 2 thin but long wires (as long as possible) at least 10 metres, to a 21 watt 12 v bulb (automobile type) , this you dangle in your 5 gall plastic drum ) you then fix a 110/220v plug on the other end , then you put an equally long piece of 1/4 " nylon pneumatic tube (rubber air line also works ) in the bag or container with a stone or large nut taped on the end , then about 2" of water in the bottom along with about 1/2 cup of washin up liquid

retire behind your shield (old mattress )

light up the welding torch, get the mix neutral, snuff the flame, now put the nozzle in the end of the tube , keep an eye on the container , when the bubbles / foam start to come out of the neck shut down the torch , close the cylinder valves , store the bottles away , no hurry

you sure nobodys around ? ok plug it in , if you done this indoors you probably dead allready , if outdoors, once your ears stop ringing start thinking up real good excuses coz the police gona come callin real soon

the tubing whips like a bastard and the extension lead you used instead of thin wire will likely have been ripped from the wall , as for the plastic drum hope the original owner didnt need it because the only parts you will find are the really thick bottom and neck parts

this could likely be modified for plastic bags , remember , washing up liquid water, bubbles = no static, no big rush
REMEMBER
LONG TUBES , LONG WIRES , MATTRESS , EXCUSES

[fused]

I saw a picture of a car, where someone had a balloon filled with acetylene gas in the backseat.

Apparently he was going to be tailgating at a football game and wanted to give some of the guys a show.. big mistake.

Well the whole roof of the car was dented upwards a good 10" and it blew all the windows out completely. Also the man and his wife who the car belonged to suffered burst eardrums and some other shit.. I can't remember. Apparently the culprit was static electricity. Yeah he also went to prison for like 5 years.. what a bunch of shit.

Also I read somewhere of someone who was trying to get the best bang for the buck with acetylene and he had sprayed anti-static spray into a 5gal bucket to coat the insides and lid, then filled it with acetylene. He must have used an electric det (I sure as hell would). He claims it made a very big boom and completely ripped the bucket up. It seems fairly easy.. not so sure about the safety aspects though. I'd check into the anti-static spray for sure.. might be handy in other projects as well.

[Meawoppl]

I would not have though it so dangerous. I guess there is a reason that I keep those tanks outside.

Here is the link:
http://www.boingboing.net/2006/02/23/acetylene_filled_bal.html

They all survived, just hurt their eardrums and picked up some glass. I am guessing there was O2 in that balloon as well. It probably from the sister tank on the welding torch. Plain old C2H2 is harder to light than propane in my experience, and I don't think that it would have caused such a powerful blast.

I know everyone here has lit H2 balloons . . . pop!

[Bert]

It's dangerous allright. In 30 + years of pyro, this and Armstrong's mix are the only things to send me to an ER. I advise you not to mess with it.

[Bluebanshee]

I used to mess around with oxy acetylene mixes, one really fun thing that we came up with was to take a party popper (small plastic party pyrotechnic that makes a small bang and fires streamers out on the pull of a string) and dismantle it to the point where you just have the pyrotechnic wrap in a small stub of plastic, then take a plastic drink bottle cap, drill a hole in it and glue the party popper stub into it.

Fill a large plastic drink bottle (preferably the 3 litre ones) with the oxy acetylene mix and screw on the modified cap. tie a longer length of string to the party popper.

You then have a device capable of being ignited by a string pull, i.e you can use the string as a trip wire, or manually pull it yourself. this device is very loud and will scare the living daylights out of anyone who trips it, its fairly harmless though. Incidentally, the string pull mechanism can be used to set off all kind of other pyros also.

Oh and I wouldnt even think about compressing the oxy acetylene mix into any kind of container, i think its almost certain to spontaneously ignite from the pressure alone, even without an ignition source. The gas mix itself has a fairly high energy output per unit mass, however, being a gas theres v little mass per unit volume, and as such you will never get a very high velocity and pressure of detonation.

About the best thing you can do with it from a fun point of view, is to fill a large container (say around 30-40 litres) and explode it. it will set car alarms off a few hundred metres away and make the neighbours think that world war 3 has begun. :)

[FireBomb]

While I have never experimented with oxy acetylene mixtures but I have had some close calls with it before.

Here about 2 years ago I was cutting some steel for a bracket and while cutting I hear a small popping sound about as loud as a small fire cracker but I didn't think anything about it and continued cutting.

The next I heard an even louder pop about as loud as a 22lr and out of the corner of my eye to my horror I saw my acetylene tank hop up into the air about 3 inches.

Needless to say I almost crapped my pants and immediately turned off the gas and took my tank outside and checked for leaks with soap and water and found a small hairline crack at the base of the tank.


Here several years back about 10 or so a welder was cutting up some old underground tanks he purchased to sell for scrap.

They turned out to be used for gasoline storage from an old gas station and he being an idiot didn't purge the tanks with inert gas before starting to cut them.

Needless to say they were picking up pieces of him up in a wheat field almost 1/2 a mile away.

While that was not an acetylene related explosion it showed to me the extreme dangers of fuel air mixtures.

I have always wondered the effectiveness of an Oxy acetylene based weapon would be.

That brings to mind the movie "Underworld Evolution" while not a great movie it did have an interesting explosive weapon in it.

A small device about the size of a hockey puck that when activated released a compressed flammable gas and then after it had mixed with the air several seconds later it initiated a spark igniting it.

This has always intrigued me as someone could fabricate a device small enough to be portable containing two tanks one oxygen and another acetylene.

This device would then be transported to an enclosed area and a timer set then once the timer goes off the tanks valves open releasing the gas to be mixed and after several seconds or minutes ignite the gases.

[Unsunghero]

Well talking to NBK here on his polymeric soap bubble idea, me and some friends had had a little bit to drink one night (all great or terrible stories begin with that line). So anyways we found a bottle of bubbles..I had the idea to blow the bubbles up with the torch and light them, but the problem with this is that you can't pressurize the gas, I think that would be exceedingly difficult. You would have to have a really, really big bubble for that..then again I think a 20x20 bubble of acetylene would be a GREAT last conscious image sort of thing.

Well, I think the problem with that device would be the other gasses in the air. The nitrogen etc. you can't light a oxy-acetylene torch from very far heh. It would have to disperse the gasses FAST to actually work. Even then I think it would be a pretty unreliable way to clear a room.

Honestly i don't see this working, you would have to instantly not only disperse most of the tank, but it would have to be dispersed as far as you want the fiery inferno to extend.

I would think something like a tank with a electronic sparker/detonator or something rigged on the top of it would work. It would be exceedingly simple, it doesn't take much to set off acetylene, open the tank, throw it, hit a button, a spark from the wires, boom.

Another thing I just thought about, why the oxygen? The reason for oxygen in the torch is to intensify the acetylene to melt metal. While this works great when you want a pile of molten "crap" I don't honestly see the need for the oxygen to intensify the flame, acetylene burns really hot 900 °C (1652°F) according to wiki (didn't see it anywhere else for pure acetylene). Have you ever seen what pure acetylene fire does to flesh? It's not pretty, pretty sure pure acetylene would fuck you up pretty fast. Besides if the tank blows, you get shrapnel, this would work well for anti-personnel scenarios.

Another thought:
If you used oxygen with it you could possibly make something like a gaseous thermite bomb. If you could rig it right I think with the right mix of oxygen/acetylene (not to mention quiet a bit of it) blow a hole in something with an HE, and burn through it. Lemme sketch a little design out for it. This would obviously need some tweaking but you get the idea, it would blow the weak point in the tank etc. out and the oxy/acetylene mixture would follow the lane of least resistance. If you compressed enough for a 20-30 second burn you would have a decent sized hole. Slip a gun barrel in for an assassination, throw in your tear gas, get line of site, etc. This is the ONLY reason i could think of you needing the oxygen.

http://img395.imageshack.us/img395/8430/idrawgoodfc8.png

Sorry for the terrible picture quality..I think I had a few good suggestions though.
Um, for some reason image shack isn't working but I just noticed I forgot the oxygen, and I forgot to mention if someone DID try this I know acetylene tanks have some kind of liquid, but I can't remember for the life of me what.

[FireBomb]

I forgot to mention if someone DID try this I know acetylene tanks have some kind of liquid, but I can't remember for the life of me what.


The cylinders are packed with various porous materials (e.g. kapok fibre, diatomaceous earth, or, formerly, asbestos), then filled about half way with acetone. The acetylene dissolves into the acetone. This method is necessary because above 207 kPa (30 lbf/in²) (absolute pressure) acetylene is unstable and may explode. There is about 1700 kPa (250 lbf/in²) of pressure in the tank when full

Straight from Wikipedia got to love it.

Another Idea I thought up last night was to initiate a mixture of Oxy/acetylene under moderate pressure.

Someone could use a small high pressure tank like the ones used for paintball using compressed air.

These tanks range from pressure ranges of 3500 psi to 5500 psi and are used instead of Co2. They provide more constant pressure and the players don't have to worry about liquid Co2 freezing the O-rings in there guns or pressure drops do to temperature.

Any way the tanks are moderately priced and decent sizes ranging from 50 ci to 120 ci.

[nbk2000]

Please do compress a mixture of acetylene and oxygen in a steel pressure bottle.

Please let us know when you'll be doing it so we can watch the news. :)

[megalomania]

There is no "may" about acetylene decomposing. It breaks down into pure carbon at the slightest hint of pressurization. At high pressure it will explode without oxygen, and with oxygen the explosion will just be bigger. I too would love to see you try... Please send video of the experiment, lifeflight rescue, post reconstructive surgery, and trial to one of the FTP's.

[Unsunghero]

Again I ask, why do you need oxygen in this mixture to torch someone? I've personally never seen an acetylene tank go up, but I've seen small amounts of acetylene go off, and it's enough to detonate into a fierce fireball. One time when I was working with an oxy/acetylene torch I had just turned it on (just acetylene) and I accidentally brushed my hand with the flame. It burned through my glove and left blisters in about a second and a half (didn't notice it for a bit because through the gloves you don't feel heat much).

[Rbick]

Look back a few posts, they talk about "pure Acetylene flame" and how it can "fuck" you up. I've never worked with Oxy/Acetylene torches before, but it makes sense... Perhaps the decomposition of pure Acetylene (C2H2) is enough to cause a noticeable flame? This of course would just be broken down into 2 Carbon atoms and H2 (Hydrogen gas). But if bonded with Oxygen, making Carbon Dioxide and Water, the heat generated would be far greater due to the energy created by formation of both CO2 and H2O is quite high. Just be glad you only had the Acetylene on when you burned yourself ;)

Or maybe if you had introduced a spark, that could have been enough energy to begin a reaction bonding the Oxygen from the air with the Acetylene coming from the torch?

Sorry if this is off topic, but previous posts talk about assassinations and hockey pucks filled with Acetylene... Too far out of my league here :rolleyes:

[Unsunghero]

Yes, a spark is certainly enough to instigate a reaction, thus why we use a "sparker" to light it. Basically just a piece of metal brushing a piece of flint is used to light it.

I am very lucky I only had the acetylene on, that's why I don't turn on my oxygen 'til I'm pointing at the steel.

The decomposition causes more than a "noticeable" flame, it creates an extremely bright, hot inferno. When you add oxygen it goes more into a blue flame that is MUCH brighter and MUCH hotter, basically to punch through a piece of metal you add a high-pressure blast of oxygen (when you hit the lever).

Thinking about it, it does give off some tiny carbon particles, might be applicable in the ionization of gasses thread.

Maybe you could have 2 tanks, with a hose connecting the 2, each tank would be a regulator so they wouldn't mix 'til it's time. In the middle of the hose would be emission media, so basically you hit the valve/regulator/etc wait about 10 seconds, it emits your favorite mix (70/30 or 66/34) you ignite it and the flashback detonates the acetylene, which will get at least a little into the oxygen tank detonating that. So basically it would be like having a primary and a booster, oxygen being you're booster.

A method of guaranteeing the flashback is kind of unknown to me, but a suggestion would be open the hose to the acetylene and not the oxygen. You could just have a regulator on the oxygen, when you turned it on it would mix with the acetylene and I'm pretty sure it would go back into the acetylene bottle (which would be at 1-2PSI tops).

[nbk2000]

For anyone actually suicidal enough to try it, one of those lovely jihadi videos on making oxy-acetylene gas bombs out of propane canisters:

http://www.megaupload.com/?d=5C0M4KI5

It does pack a wallop.

Apparently the ratios are 25%/75%, though I don't know which is O2 and which is Acetylene.

[Rbick]

HA that video is hilarious. I don't know where you find this stuff nbk, but it is entertaining. Something tells me that these people really don't care how suicidal it is, as long as it works... And if they die while attempting it, thats ok, because it was for the JIHAD!

[barrydbryson]

My father was also a welder by trade. His wonderfully explosive gasses began disappearing unexpectedly when I turned 14 or so. C2H2 was my first explosive to play with; and I can attest to the "rubber dust" from thoroughly shattered balloons. A 6X18" acetylene cannon soon followed; but it made entirely too much noise, often bringing the county police. (They wanted to fire it; so after 4 or 5 rounds they were laughing hysterically and jumping with joy!)

But, to increase the fun factor of this July 4th salute, I suggest that you compress a stoichiometric mixture of C2H2 and O2 to about 5 atmospheres inside a 2-liter soda bottle. I've carefully monitored the rupture pressure of these containers; and it's about 95 psig. So maybe it would hold the explosive mixture at 75 psia. I plan to lathe turn a rugged metal "Coke" bottle cap and install a coaxial electric spark igniter within. Such a permanent "boom machine" would require only legal chemicals; electricity, and a good supply of pop bottles.

I'm wondering now what kind of adiabatic flame temperature would result from such an explosion. It's been almost 40 years since I took engineering thermo (twice!); but if we knew the temp. at state 2 we could probably whip out the peak pressure and calculate its attenuation with distance. I know the gas in the atmospheric 6X18" gun has about the heating value of 10 grams of TNT; and it sounds like it! I'll dust off Faries's big blue book and study up on the subject; but I welcome anyone to chime in with information; personal experiences, etc.

Acetylene guns have been a fascination of mine since I moved into rice country 25 years ago and heard their anti-bird music. Hurry retirement! I want to play again; and I've still got one good eardrum.

Here are some fresh dull pencil figures on the true "pop" bottle experiment:

gas volume: 122 cubic inches
initial gas pressure: 90 psia
total mass of reactants: 0.0648 lbs (29 grams)
heating value of reactants: 611 BTU
adiabatic flame temp: about 3700 deg. R
surface pressure: about 1130 psia on an spherical equivalent container (3.076inch radius)

These numbers were arrived at by relating heats of formation of the reactants to the heating value of the acetylene. P and T values are from gas tables by matching the enthalpy of the reactants.

BTW, the notorious "Coke" thread appears to be 1.088"X8 threads/inch. 'gotta get that cap made!
BB

[Bert]

You know and understand why compressing acetylene gas beyone 15 psi or so is a bad idea, of course?

The most professional gun shot, cannon and mortar simulators I have seen made for military training use Oxygen and gaseous propane. None compress the charge beyond atmospheric pressure after mixing. http://www.orlandospfx.com/battlefield.html

[Yafmot]

Hey, guys, there's another name for an OA device. It's called a Thermobaric Weapon! I've had some dealings with the nice people at Indian Head, which is DOD's preeminent lab for energetic materials. (Don't bother to call them; they're pretty closed-mouthed about this shit.)

One of their publicly known concoctions involves Ethylene Oxide & #2 Diesel. (Don't fuck around with EO: it's way toxic and will take the hide right off you.) It's sprayed, abruptly, into a fine cloud of mist, and then set off with a high temperature deflagratory agent, typically just M-80 mix with a little bit of Zirconium in it. They also work with quite a few metallic aerosols which I can't talk about except to say that it's akin to "Dragon's Breath."

One of the tests that I saw was on a calm day. There was a tower about 20 feet tall with the device on top. Old cars and anthropomorphic dummies were arranged around it at various distances. A few freshly euthanized animals, mostly goats, were among the test targets.

At the end of the countdown, a cloud of vapor about 30 ft. in diameter quickly emanated from the top of the tower, immediately followed by the ejection of the metallic flame into the cloud, which was almost simultaneous with the detonation of the vapor. (I was watching from a bunker, 300M away, with a spotter scope.)

WOW!!! The thermal and overpressure effects of that thing were just unbelieveable! The closer vehicles were knocked to flaming pieces, the ones at mediun range (about 150 ft.) were sent flying, the farthest ones had all the glass knocked out, the closer dummies were pretty well pulverized, with the more distant ones twisted and dismembered. The whole range had the stench of charred "goat squeezin's," and a goat's horn was found stuck in a car door.

It's no wonder these fuckers are known as the "poor man's nuke."

If you keep thinking the way you are, you're just going to stink up the place with "Eu-de Michelin." You don't need to pressurize it in a tire. Or a tank. Or a pop bottle or anything else. You might, however, want to try a different Oxidizer. Here's why...

Oxygen has a very strong affinity for just about any other element, or even itself, for that matter. O2 has to be thermally dissociated to atomic Oxygen before it combines with anything (except when forming Ozone), and that's why it's not used by racers in their engines; by the time it starts to work on the fuel, the piston is already well past TDC, so you just wind up increasing heating without doing nearly the work the mixture should be theoretically capable of. It is, however, capable of cooking pistons, rings, exhaust valves & seats, plus glazing Graphitic Carbon onto everything in sight.

On the other hand, Nitrous Oxide (N2O) works very nicely in engines for the same reason Nitrogen forms the basis for so many explosives. Nitogen is thought of as "inert," or nearly so, because it doesn't like to grab onto much of anything. That's why nitrated explosives are generally unstable; the Nitrogen wants to dump whatever is attatched to it, and let the molocule revert to its more basic constituents. In an engine, even though the N2O has only about 33%, by weight, of Oxygen, it dumps the O with much less energy input, meaning that much more of the charge is put to work in the arc of maximum mechanical advantage, generally between 40 deg. after TDC and 40 BDC.

In a thermobaric application, N2O works much better for the above reasons plus one other. In an engine, under normal operation, the atmospheric oxygen (about 20%) is reacted with the Hydrocarbon fuel, providing an intense, instantaneous blast of heat, and the Nitrogen (about 80%) becomes the working fluid, expanding violently upon heating.

So, I think if you put flowmeters on both the Oxygen and Acetylene lines, take readings based on your ideal flame, switch Oxidizer tanks and use a little over three times the flow of N2O as for O2, squirt it in a big bag, and set it off with a directionalized charge of flash (remotely!), you will come up with a very brizant detonation with a huge thermal component and a truly devastating overpressure. Hell, I'd almost bet money on this one.

Just make sure you use some Looooong fuckin' wires!

[Charles Owlen Picket]

I don't remember the numbers and such.....I'm just searching my memory for this but wasn't the Daisy Cutter (something like the BLU92) first designed as a "dry" FAE device and was "re-designed" in a similar manner??? One of those new "big bad bastards" are designed in a similar fashion, I believe...

[Yafmot]

How'd my post get knocked off? I just wrote a long winded dissertation on why N2O would work better than O2 in a thermobaric device. I also gave a pretty detailed description of a test I saw, replete with trashed cars and splattered goats.

Oh, well, try about 3x the amount of Nitrous oxide as you would O2, and set it off remotely. VERY remotely.

Whoops! Now it's back.

Anyway, Charles, The "Daisy Cutter" was just a big-ass bucket of Comp-B with a nose on one end and some fins on the other. It was yanked out the back door of a C-130 or C-141 by a parachute & made instant LZs in the jungle. It was purported to kill the worms in the ground 400 feet from the epicenter of the blast.

[Charles Owlen Picket]

My question at this point would be.... how much does a Thermobaric type weapon cost? Aside from effect overall, is it more efficient or presents more of a cost savings?

[-=HeX=-]

Yafmot: NO2 would work great. You are onto something, but would explosive rupturing of the cans not be better than gaesous mixing? And IIRC A THERMOBARIC weapon is cheaper for the damage dealt.

btw, what size would a acetylene FAE bomb have to be for a 10 metre blast radius of shock and flame, or is that a dumb question. And how does the 7gram hexamine and 7gram HMTD thermobaric explosive work. The video makes it appear to be impact ignited...

[Yafmot]

Charles, to answer your question first, when they say "Poor Man's Nuke," they mean DIRT po'. Thermobaric devices, themselves, are just shit-cheap. #2 Diesel, for the amount of latent energy, is practically free. (For max. thermal effect, I would recommend JET-A, JP-4 or JP-8 if you can get it. I used to get JP-7 from a friend of mine who worked on SR-71s at Beale AFB, but they don't make it any more). Ethylene Oxide is inexpensive in bulk, but the handling/environmental/sequestration costs would eat your average private individual alive. Hence my recommendation for N2O, which can be had at any decent race shop.
With the air launched thermobarics they've been trying to stick in caves (with great success, I might add), the lion's share of the cost is wrapped up in the delivery system, which shoots the cash outlay right up there, especially if you add in the cost of the launch platform (F-16, F15, FA-18, A-10 etc).

HeX, first off, I distinctly said N2O, that's NITROUS OXIDE, LAUGHING GAS!!! If you get a whiff of it, you might get a little dizzy. If you get a REALLY good whiff of it, your ears will ring, you may laugh uncontrollably, and you might well hallucinate.

If you get a good whiff of NitrIC Oxide, NO2, you will get an irritation not unlike being teargassed. After an hour or so, the irritation will subside, and you'll probably just go about your business. The next day, you'll wake up feeling fine, except for maybe a headache, but as the day progresses, you'll feel shorter of breath. This is because the N2O that deposited iself onto your mucous membranes is, thanks to the water in your linings and a little body heat, converting into HNO3 and, by extension, converting your lungs into decomposed mush. Not to worry. The outcome is assured; you'll be dead by dinnertime.

And yes. cost per amount of damage is a good way to determine the cost effectiveness of an explosive device. I think they call it "Bang for the Buck."

As to the size of device for a 10 meter radius, with the proper stoichiometry a large trash bag, properly ignited, would likely knock the shit out of anyone within a 30 foot radius (in the open). Want more thermal effect? Go a little fuel rich. Overpressure? Go a little lean. Want to go bigger? Any dry cleaning supply outfit would probably have the plastic bags used to line industrial laundry carts. These fuckers are HUGE. We once used one to contain a bunch of Hydrogen-filled rubbers we charged off a good ol' NaOH, Al and H2O reaction. We made a couple of dozen of the H balloons, plus about a half dozen of some filled with OA. The thing had tons of lift, so we stuck about five feet of visco on it (meticulously straightened), with about 18 in. going into the big bag and taped to one of the OA-filled condoms. We lit the fuse, let it go, and the thing climbed like a fart in the bathtub, straight up, to at least 1,000 feet (it was dark, so it was hard to tell the exact altitude). And then....

BAM!..bomp..BAMBABAM..bomp bombadathump..BABAM.. thumpadabump..BAM! The thing looked like the goddamned Hindenburg, slowly sagging, with pieces descending slowly in flames, while the lighter pieces that got caught in the Hydrogen flames shot rapidly upward. The "copperchopper" was soon about, and had apparently reported a possible midair, and there were several calls to local TV and Radio stations reporting UFOs. This added immensely to both our amusement and fear factor.

Whoops! Getting sidetracked here. Suffice it to say that if you're going to play with Thermobarics, GIVE YOURSELF PLENTY OF ROOM UNLESS YOU DON'T LIKE OPEN CASKET FUNERALS!!!.

I have not seen or heard of the Hexamine-HMTD device you mentioned, but if you could get a det off a puff of Hexamine dust, you probably wouldn't need to use HMTD or any other primary to set it off. Just a well-directed charge of flash, like an open-ended M-80.

JUST BE CAREFUL!!! This stuff is no joke.

[-=HeX=-]

Sorry for my nitric/Nitrous confusion, I know the difference, it was a typo.

Thanks for the info about the size of the device, as it is very important to a job I must do. Clearing out a chav infestation. I intend to set it off 20 meters away and make them run.

The HMTD and hexamine thermo charge has quite got my attention at the moment so I am going to look into it.

Cool story about the huge air bomb, tons of lift you say? I would have attached a 50 kilo ANFO Charge with a 2 kilo ETN Booster to it with 10 feet of visco. It would have edetonated at a high altitude. Heh, but that is just me. How much did it cost?

[Yafmot]

Cost? Aw, Hell, I'm not sure, exactly. We're talking about close to 30 years ago. Let's see, there was the big laudry cart liner. My friend worked at a dry cleaning supply, and he used them to save LOTS of aluminum cans. They came on rolls so big & heavy that they were best moved about with a hand truck. I have no idea what they'd cost now, but I do remember they were made by Mobil Chemical. I think they were just plain old Polyethylene.

As for the rest, it just involved a jar of Lye from the supermarket, a roll of aluminum foil, and some tap water. In those days, two liter Coke bottles were made of glass, with a rather large neck on them. We'd throw in some loosely wadded balls of foil, a couple tablespoons of Lye, and about a half quart of water. An ice bath was a definite necessity for a couple of reasons. One, a runaway reaction could break the bottle, and we'd have a nasty mess on our hands. Two, an overly vigorous reaction would boil the water, leaving condensation in the condom, weighing it down.

So, let's see. A couple of boxes of rubbers, a jar of Lye, a roll of Al foil, some ice, and youre going to have to figure out something else for the vessels, maybe a cheap wine jug or three. We ran multiple shots in multiple bottles, otherwise we'd have been up all night generating enough H2 to fly all of that OA. What's that? About 10 bucks? Of course, you'll have to figure out where to get a plastic bag that big, just to bundle it all up in, and you'll have to get your hand on an OA rig, to fill the real bangers. (The baloons with pure H2 just make kind of a thump. The OA baloons go off pretty violently, provided you've got the stoichiometry correct.

When I said "tons" of lift, I didn't mean it literally. When we were at launch weight, with all the different gas bags in place and everything taped that needed to be (with 4 H2 balloons to every one OA balloon), we had maybe 5-10 lbs. of excess lift, which was needed for a decent climb rate.

As far as finding some of those big laundry cart liners, might I suggest a hospital housekeeping department, or perhaps a uniform shop, the kind that rotates various coveralls and the like for shops they have contracts with; a bit like a diaper service, which also might be a place to check.

And, as always, be way careful with this stuff. If even one of those rubbers full of OA goes off in close proximity, you'll be scorched meat. Hydrogen has, pound for pound, the highest caloric content of any combustible fuel. The reason Acetylene is used for welding is the incredible heat it generates when oxidized. This is due to the fact that all of the molecular bonds are triple bonds, which release a huge amount of thermal energy when broken. If that whole thing goes off in your face, it won't leave much more than a greasy spot, so again, HeX, BE CAREFUL!!!. Don't fully assemble it until right before launch. Don't let your visco curl up on you. Stupid little shit like that gets you hurt. Try to think of everything and then some.

And don't forget to keep us apprised of any progress. Maybe some video.

Thanks.

P.S. What the Fuck's a chav?