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Author: Subject: Understanding detonation alittle better
IgnorantlyIntelligent
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[*] posted on 19-1-2004 at 16:10
Understanding detonation alittle better


I was wondering if there is a difference between putting presure on something or having an actual detonator. Take AN/Soy for instance, it can be detonated with only 2g of AP(Ive heard on E&W). 2g of AP doesnt have any more force than a hard blow from a hammer on an anvil so does that mean that a blow from a hammer on the AN/Soy would be the same? Does the fact that there is an actual "wave" when using a detonator matter? The reason I am wondering is because I have tried detonating AN based explosives using an anvil and a sledge hammer with no success. This doesnt make me very confident that my detonator/booster will work.(50g of lead syphnate)
Any info would be great.




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[*] posted on 20-1-2004 at 04:49


As I understand it, a detonation wave (as provided by a detonator) is produced when a substance burns faster than the speed of sound. This det wave then passes through the secondary HE. As it does so it 'busts open' the molecules of the secondary HE. Those busted molecules immediately recombine into gaseous products (CO<sub>2</sub>, N<sub>2</sub> etc) and in doing so help to propogate the det wave. Whacking something with a hammer doesn't create a supersonic shockwave and so won't cause any secondary HE's to explode. Primaries, however, can be shocked into detonating and providing the supersonic shock wave needed.

Basically, your hammer blow isn't providing anywhere near the short, sharp shock needed to detonate secondaries.

Feel free to correct me though, I am no expert.
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[*] posted on 20-1-2004 at 05:58


I use Lead Styphnate in my detonators and it is in a steel detonater container(plumbing pipe w/caps) My detonaters are huge(about 50g of LS/NC) and play the role of the booster aswell. Does having a steel container hinder that shockwave apon detonation? If the steel only bursts out one side and it detonates the ANFO on that side, will the wave from the ANFO detonate the rest of the ANFO or will i have an incomplete det? The 2lbs of ANFO will be burried under dirt to the brim of the bucket.



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[*] posted on 20-1-2004 at 06:35


iirc you want to have the walls of the detonator as thin as you can get. Your primary should be able to undergo DDT (deflagration to detonation transition) with minimal confinement. Drinking straws are good, apparently.
That way you don't get the issue of 'side detonation' or any of that. I would imagine, though, that the shock wave will set off most of your AN mix but I can't be sure. You want maximum confinement of the main charge rather than of the det.

All of the above is gleaned from reading rather than experience so don't just take my word for it. I have never, and this is actually true, made dets or played with any AN mixtures so I don't claim to be an authority.
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tom haggen
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[*] posted on 20-1-2004 at 21:26


Durning the detonation of a high explosive the molecules break apart at a microscopic level. You can not break a molecule apart with a hammer. Your handle is goofy man.


[Edited on 21-1-2004 by tom haggen]




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thumbdown.gif posted on 21-1-2004 at 02:06


Hmmm... ...so why, in almost every article about high explosive compounds I meet there's information how heavy a load at what height has to fall on it to detonate it?
You cannot break A molecule apart with a hammer, but you can break MOLECULES apart with a hammer. The shock just rips them apart.
Sorry, YOUR handle is goofy.
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[*] posted on 21-1-2004 at 04:05


Depends upon whch HE you are referring to.
Some will go with a 2kg weight from just a few inches whereas others require a significantly higher drop.

I saw a programme on BBC2 last week where they dropped an anvil onto half a kg of TNT from about 20 metres...and it just turned to dust. No explosion or anything. They also put a half kg of TNT into a fire...it just burned.

A hammer will provide enough shock for some HE but not all. Stuff like AN (which iirc is the most insensitive HE around) or TNT just isn't going to go up when you bash it (but something like NG almost certainly would). And why would you want it to? Can you imagine a demo team ready to blow a building - they get the 'all clear' and a team of guys go into the building with sledgehammers and start whacking all the charges... lol.
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[*] posted on 21-1-2004 at 09:33


In sensitive HE the blow of a hammer just initiates the collision of individual molcules
causing them to break apart? The hammer doesn't actually break them apart, so part of what I said was true.

You half to admit ingnorantlyintelligent is a goofy handle.




[Edited on 21-1-2004 by tom haggen]




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[*] posted on 21-1-2004 at 14:18


I've always understood that the crystal structure shattered under force/pressure causing whatever compound you may have to detonate.

Might you have a reference to back up what you're saying? Molecules are always bumping into each other(unless at absolute zero) so do they just bump harder or faster?

And no I don't "half" to admit it is a goofy handle.
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[*] posted on 21-1-2004 at 16:02


I'm afraid I can't cite a source, but I'm pretty sure that it has now been established that detonation is a thermal process, i. e. the detonation wave compresses and therefore heats the material which then burns normally. I think that the early work was dome at one of the US national labs. All I could find with a brief web search was that detonation waves in PBX-type materials propagate primarily by compression heating at discontinuities in the material, causing "hot spots" that initiate the burning behind the detonation front.
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[*] posted on 22-1-2004 at 06:15


Well if it detonates from compression, and the heat produced by the compression, then why does a sledge hammer not work like a detonater?
What I'm asking is, is there any none physical step in a detonation. By that I mean what things other than compression(impact), and the heat caused by compression, detonate an HE. Is there an unseen chemical proccess undergoing? Like free atoms slaming into and bonding with the HE, or something like that?




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[*] posted on 22-1-2004 at 06:54


Dets generate millions of pounds per square inch of pressure very quickly and in an extremely localised area. A sledgehammer will not get anywhere near that and the pressure it does generate will be spread over a wider area. Well, that's my theory anyway.

I think we may need Philou, or another extremely knowledgeable and experienced person, to shed a little more light here.
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[*] posted on 23-1-2004 at 06:02


Well I'm convinced a sledge hammer doesn't create enough pressure or heat and certainly not as much as a booster charge.
The main reason I made this thread was because I have recently been trying(in my dreams of course) to detonate different AN based mixtures. ANFO, AN/WAX, AN/Soy, AN,Acetone. None of these detonated fromt he hammer. I only had a chance to test ANFO and AN/Acetone with actual dets.
I guess I'll just have to get(make) some ammonia dynamite for my big ANFO charges.
Goofy handle........so you've used my sledge hammer? :)
thanks everyone




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