Explosive flour - Archive File

[megalomania]

sealsix6
Frequent Poster
Posts: 154
From: NYC,NYC,USA
Registered: NOV 2000
posted 05-07-2001 07:59 PM
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Ok I was looking around on www.howstuffworks.com and I came across something that you guys may seem intrested in. Flour when spaced out far enough (1 or 2 grams of dust per cubic foot) can become explosive. You can read the article on it at http://www.howstuffworks.com/question150.htm they have some pretty intresting articles.


PYRO500
Moderator
Posts: 1465
From: somewhere in florida
Registered: SEP 2000
posted 05-07-2001 08:40 PM
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it is possible to ignite a cloud of flour but unless it is in a closed area it will be crapy, this kind of thing happens on accidents sometimes, the incidents are called grain elevator explosions


Agent Blak
Frequent Poster
Posts: 766
From: Sk. Canada
Registered: SEP 2000
posted 05-08-2001 12:51 AM
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Coal Dust/Methane in a mine shaft supposedly goes at like 6x the speed of sound(330m/sec roughly?). This was said on tlc. Chem teach did a demo with mushroom spores(Dry) in closed it was awsome.
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A wise man once said:
"...There Will Be No
Stand Off At High Noon
... Shoot'em In The Back
And, Shoot'em In The Dark"

Agent Blak-------OUT!!



SATANIC
Frequent Poster
Posts: 237
From: australia
Registered: SEP 2000
posted 05-08-2001 01:41 AM
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basically the larger the surface area, the quicker it burns right? so the huge surface area of the flour with air inbetween will burn relatively easily. The same can be said of the dispersion of FAE's


blackadder
Frequent Poster
Posts: 313
From: London
Registered: DEC 2000
posted 05-08-2001 02:53 PM
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I was talking to anthony about this, and he said that he got his spudgun and filled the barrel up with flour, and shot it into a camping stove flame thing.
I just tried it, I was using a 1metre long 40mm wide barrel on my spudgun, filled with flour, and I had a mini-bonfire at the back of my garden, and you know the rest. Bloody hell, you try it, for me it created a bloody fucking ENOURMOUS flame!!!!! A massive yellow cloud of fire, about the size of a van/truck. After you could get the smell of burning flour.



Anthony
Moderator
Posts: 2306
From: England
Registered: SEP 2000
posted 05-08-2001 04:01 PM
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I had best results with corn flour but it does surprise people
Agent Blak, 300m/s is rougly mach 1 (assumbing 1000fps = mach 1).

I'm not *sure* but I think flour is actually detonatable



BoB-
Frequent Poster
Posts: 679
From:
Registered: SEP 2000
posted 05-08-2001 07:55 PM
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Theres a breif mention of this in the "Initiator for dust explosions" section of the IMH, it claims that five pound charge initiated by the device will destroy a 2,000 cubic feet enclosure.
Gasoline works better

[Desmikes]

I am pretty sure that speed of sound IS 330 mps (varies w/t of course) so six times that will be about 2000 mps and as far as I know even military FAE's can't do that. I think its like 1800 max. I don't think that it's possible for a cloud formed by natural means (perhaps excluding mines) to be big enough to go from deflagration to detonation anyway. FAE's are always detonated with a secondary charge otherwise they will just burn.
Substitutig sulfur for flour gives much better results and it is even more fun when you mix in some AP (makes it ignite much easier) hwver I'm yet to successfully detonate any FAE in open air, it usually just burns. Has anybody had more luck with it than I?
I gotta find some POS shed that I could do some gasoline experiments in. I did some calculations and figured that you need close to 5 liters of gasoline per 10 cubic meters.

[Imperial]

Does anyone know approximately what power of flame would be needed to ignite flower? Like just a small spark or a relatively hot flame?

It sounds like a good idea for a display or practical joke, but it may be dangerous if it burns too hot. I have heard of using cornflower for special effects, etc. but I have never tried it. If it burns out quickly and doesn't release too much energy, then I think it may be good to try for experimentation's sake. If it burns at too hot a temperature, though, it may not be such a good idea. Same with ignition temperature. It needs to be reasonable.

As for the dust notion, if something is suspended in air as dust, and contains something which has a lot of chemical potential energy like carbohydrate or petrol, etc. then it is going to cause a much larger fireball than if it was just lying around and it is going to be a lot easier to ignite. The reason for this is that when it is suspended in air, it is surrounded by oxygen which is required for combustion, and a lot more surface area is in direct contact with oxygen than when it isn't suspended. This makes for a faster, hotter, and easier to trigger reaction. It is also the reason that Molotov Cocktails (the petrol, etc evaporates inside the bottle) and aerosol flamethrowers work so well.

[Arthis]

I need to correct you on a few points.

First, the principle of Molotov cocktails is to put fire to something (a car, a building, what you want) by spreading some fuel (even better is a bit gelified) on it. The bottle makes this incendiary device easy to handle. As petroleum burns well, when the bottle is broken it comes partially in contact with the flame that makes the whole liquid burns. Nothing to be compared with FAEs.
You're right about aerosols.

You're on a pyro forum, so telling us there is no way making too hot fireballs is quite funny. If you're too scared to make explosives then don't. We don't care. Anyway, whatever the temperature may be when burning, without precautions you can be burnt. You won't stand either 800 or 1200 °C.

Corn flour is not really used in pyrotechnics, it's dextrin, which is obtained by cooking the flour, that is used.

Flour is not easily flamable. As told by desmikes, even sulfur works better with a little AP. A small mix of AP and flour should give you a nice fireball, even if AP alone too. A relatively hot flame is needed to lit the flour, as it's no really a fuel.

But for that you need to make AP, what you don't seem to be ready to. It may work with a firecracker, but that's not sure. In case you can use a little fuel to make an ignition flame. Not on all the flour otherwise it won't spread in the air to make a fireball, flour particles will agglomerate and it will be fucked.

[yt2095]

apparently dried milk powder gives impressive results also (probably the hydrolysed fat content being a fuel in its own right)

I remember watching some sort of documentary many years ago, where 2 identical pianos were set in a feild. one had a small stick of dynamite only in it, and the other had the same charge with a bag of milk powder around it.
the 1`st piano was a mess after detonation but the second one was match sticks! i remember thinking no way! but they did other demos with other powders and different setups and it was YES WAY!
I`m wondering if a small PC fan and a battery with a hopper/funnel to feed flour into the fan to airiate the flour to fill large areas, or down a pipe for displays? certainly a cheap way to make large fire balls, without having to mess with volatile liquids.

[Imperial]

Of course I am not scared to make too hot explosives, I just need to know how hot they are so I can take the necessary precautions :D. In my experience, I have known many who have experimented with things like the Anarchist's Crapbook and been seriously injured. I don't want that to happen to me, so I intend to take precautions.

I have tried AP before, and I find it to be reasonably fun and reliable. I have never mixed it with flour, though.

If flour isn't too explosive and is hard to ignite, I can see little use in it other than something to spread a flame/fireball.

What I am thinking is having a primary device surrounded by a sack of flour, such that when the primary device ignites (something slightly explosive), it will spray flour everywhere which will set alight from the primary device. May make a nice fireball (adding AP will make it better probably).

Of course, you could encase the dust in some sort of gel to make it adhere to things while it burns, but that would defeat the purpose of an FAE entirely.
Sorry about the Molotov Cocktail confusion; I thought that that was part of the reason it had such a huge flash when the bottle broke. What Arthis said is a lot more logical, though, since petroleum does burn very quickly.

[Arthis]

A fireball is a fireball, experinment with small quantities. Once you're scared, then you want to use a whole sack.
Try with 5gm AP, and 15 gm flour around it. You see how it's powerful, the risks, etc., then you can do it on a larger scale. (though the interest is pretty limited)

[Ropik]

One accinedt happened few years ago about 2 kilometers from my house. I thought that it is fallout, armageddon, something similar or even worse. It was earth and eardrums shattering explosion with deep tone like airbomb. Next day I went to the mill. Errr... to the crater. There wasn't any evidence that there was any building. Only big(I say big, some 25 meters wide) hole was left. From this time i believe that FAEs are extremely powerful.

[Caesar]

a few days ago i took an empty paper towel role and divided it into sections. I filled it 40% with pyrodex and 60% with flour. i put alluminum foil all over it. it flashed and got flour everywhere, but no explosion, and not even a cloud of flour, just a big area of flour. it was shot out of it more like debris than anything. any suggestions? the only thing i could think of was to make it tighter which i think i will do this weekend.

[Bert]

I filled it 40% with pyrodex and 60% with flour.

What effect were you hoping to achieve, besides scattering flour around the area?

If you were hoping for a fuel/air explosion, the explosive dust would have to be dispersed in appropriate concentration BEFORE the ignition source came into contact with it.

If you wanted a fireball effect ("cremora" fireball), try using a larger ammount in a container with an open top and lifting it with black powder. Ample directions for achieving this effect are available to you if you search-

Pyrodex is not a terribly useful material for pyrotechnics. It was designed to do the work of BP only in the higher backpressure environment of muzzle loading weapons, it burns too slowly in most of the lower pressure pyrotechnic applications. I won't even use the stuff in my BP guns, it's very hard to prevent corrosion when using it. If you can't buy BP, learn to make it, it's a good entry level project. Looking at your posts so far, you should concentrate on the basics and read a lot...

[MightyQuinn®]

Better yet....

Take little 1lb bags of flour out to the 150 yard mark at your local range. Proceed to fire a .50 caliber Inceniary Blue-Tip round at the bag and watch it go....

It bursts in to a rather impressive fireball and will impress your friends. Somewhere I have a video of this effect. You would think we are shooting at gasoline.

Who said flour was boring? :D

[ChocBruceMousse]

[QUOTE=Imperial]Does anyone know approximately what power of flame would be needed to ignite flower? Like just a small spark or a relatively hot flame?

It shouldn't take a very large spark to ignite this...flour grinding mills have long been known to explode. There are several cases in the past 50 years which are pretty easy to find out about. Here is an example.

http://www.chemeng.ed.ac.uk/~emju49/SP2001/webpage/intro/intro.html

This is a very obvious page, you guys already know all the qualifiers for this type of explosion.

[Bert]

My understanding of industrial dust explosions is that they are often 2 stage affairs- A small initial explosion or some other kind of shock or vibration event gets all the dust stuck to the rafters, walls and etc. shook off into the air, and then an explosion takes place with this material. A candle flame is plenty to get the proper flour/air mix going, I've seen it done deliberately. The kind of dust cloud that will sustain an explosion isn't present normaly in a space occupied by people, you couldn't breathe or see in it.

[CommonScientist]

You guys should go visit my thread in the Demolition forum, about the Dust Initiator setup, and what you need, etc.

Im assuming the only thing your going to get if you put a 10g AP cap in a bag of flour is a big white mess in your blast area, right?

[Bugger]

As well as an explosively combustible powder, the other requirement for an industrial dust explosion is an adequate supply of an oxidant. So, in the case of flour, it would be most likely to occur when very finely ground, and very loosely packed. It would also to be very dry.

While excessive heat, or a hot spark from machinery, can initiate such a flour explosion, another strong possibility IMO is static electricity discharges, resulting from friction between flour particles, and between the flour particles and handling machinery or cointainers. This is most likely when the flour is being moved; it would be especially likely if pneumatic conveying is used, with a cyclone used to separate out the flour at the end of the ducting.

Bugger.

[FUTI]

It's old stories and it happend often in the old times in the mills. Maybe that's why people in my country often belive that mills are haunted with vampires and monsters :D If I find the movie that is make for high scool demonstration for higher surface higher reaction rate story kind a story (you guess right it's with flour) I will post it.
Well the aerosol explosives are very bad stuff. Mines are one of the places that it usually happens (coal dust or methane doesn't matter). It is in use by armies now. They claim they use it for de-mining minefields as the blast produce enough pressure to activate all mines in it, but we all know that weapons can be used in number of ways (no bad weapons just bad people). More important it is silent campain going outthere for its use as non-destructive substitute for nuclear weapons as it can leave infrastructure intact and kill only enemy personal (hell why not chemical weapons?). I remember the article that states...500kg bomb of "conventional" army explosive fired at wall behind which is a tank hiden destroy the wall, but bomb same size and mass with aerosol explosive make no damage to wall but destroy tank. It suck all oxygen (that kill people) in a second (in very huge area) producing two shock waves. One with lowering the pressure durring explosion blast spreading and oxygen uptake(that destroy tank pulling the hull out of it) and the second when the atmosferic pressure restores back (that kill those that survived somehow the first one). I believe that injuries made are not of destructive type but more like those that divers are exposed on rapid pressure change. Old generation of this explosive use ethylen-oxyde (something carcinogenic that you would not want to came by but...) and time fuse. I can find from place to place info that Russiens made little progress there making a self detonating kind (spreads to a rigth concentration and say ka-boom)...I would like to know how :confused: (waaait don't shot!) :D I mean don't shoot me for not having notting relliable to back the last info!

[FUTI]

Here is the link to a descriptive experiment which can give you a hint what is going on in that flour explosions.
http://chemlearn.chem.indiana.edu/demos/13-7%20Surface%20Area%20and%20Reaction%20Rate.htm
I can't find now the movie about that experiment I saw once but...I'll look for it again.