Sciencemadness Discussion Board - Is it the same ?

Is it the same ?

underground - 26-10-2013 at 11:49

As the title says, are the two following set ups the same or not ? Is there any possibility that the 2nd one did not actually fully detonated or something like that ?

[Edited on 26-10-2013 by underground]

Fantasma4500 - 26-10-2013 at 15:16

yes it is..

i would however say keep the primary out of the main charge, and keep the booster in it, or run the primary INTO the booster as a core, that would be a sure win..

you want the booster to have as large surface contact and the shortest to the entire charge as possible, if you are unsure of that it will work

also it would depend on if the initiation is just dumped loosely into, the more brisant the initiation is, the more sure you want to be of it being in full contact with the target charge

underground - 27-10-2013 at 08:48

Quote: Originally posted by Antiswat

yes it is..

i would however say keep the primary out of the main charge, and keep the booster in it, or run the primary INTO the booster as a core, that would be a sure win..

you want the booster to have as large surface contact and the shortest to the entire charge as possible, if you are unsure of that it will work

also it would depend on if the initiation is just dumped loosely into, the more brisant the initiation is, the more sure you want to be of it being in full contact with the target charge

So i guess the best initiation it should be the following one correct ?

franklyn - 27-10-2013 at 12:29

Don't be stingy with your primary and maximize all possible contact interface with all explosive componenets of the train. Point initiation radiates out in a sphere from the initiator. It blows back as well as forward and to all sides. Strong containment and tamping is better than explosive surface exposed to air. This geometry assures best results for high order detonation.

[Edited on 27-10-2013 by franklyn]

underground - 27-10-2013 at 12:55

So for a greater amount of main explosive you are going to use more amount of booster, that is correct ?

For example, to initiate a 100gr of TNT i guess 2g of RDX as a booster should be OK, but for 5kgr of TNT i guess you are going to need more than 2gr of booster

Quote: Originally posted by franklyn

Point initiation radiates out in a sphere from the initiator. It blows back as well as forward and to all sides.

Sorry about that but i can not understand you, unfortunately my English are not my mother tongue

Fantasma4500 - 27-10-2013 at 13:16

hes saying that it basically forms in a pretty neat circle, depending on brisance ofcourse and shape of the charge
this is how shaped charges work, at least the monroe effect, the circle clashes towards itself and forms a forward going beam of concentrated energy

anyways, make the charge less long and wider, so that you will have a decent ball shape, if not then perhaps use a longer booster.. but yes to have it inside the booster is the absolutely best idea

stuff like ETN you wouldnt need a booster for as its a booster explosive itself, im more than very sure that if you are able to set off 1g of it, a charge of 2kg would go off aswell with same initiation energy

Microtek - 28-10-2013 at 04:39

This setup ignores the acceleration of the shockwave generated by a detonating substance. The initiating power of a detonator is greater at the end of it than by the sides (even without a dimple in the end). This matters if you are working with relatively small amounts of primary and/or booster.

underground - 31-10-2013 at 14:02

So i guess that the best shape that you can do to achieve as possible full detonation of your explosive as possible must be lke to photo below, correct ?

Dany - 31-10-2013 at 19:23

Quote: Originally posted by underground

As the title says, are the two following set ups the same or not ? Is there any possibility that the 2nd one did not actually fully detonated or something like that ?

[Edited on 26-10-2013 by underground]

your question is very general, however it depend on the explosive that the charge is made of. If the explosive used is very insensitive there is a chance that none of the explosive fully detonate or even detonate. I will consider that the 2 configurations are cylinders. The first configuration is short, this mean there is a chance that the accelerating detonation wave is not able to reach full speed as predicted by calculation of D_cj @ that crystal density. If you detonate the detonator there is some distance (run up distance) to achieve full detonation speed so if the explosive charge is insensitive and too short (configuration 1) it is likely that full detonation speed will not be achieved. For the second configuration if we consider also that it is a cylinder, you notice that it has small diameter so here also if the explosive is insensitive the detonation velocity will suffer or the charge may not detonate at all. all explosive have critical diameter d_cr when they are packed as cylinders. This d_cr can range from few millimeter (PETN based explosive LX-16 has a critical diameter between 0.318-0.365 mm @ 1.7g/cm³, see https://e-reports-ext.llnl.gov/pdf/585792.pdf) or few meter like coal or dust explosions. In conclusion, if the charge are made of sensitive explosive the 2 configurations are indistinguishable and they will detonate @ full speed (sensitive explosive have small run up distance). however, if the explosives are insensitive like ANFO yes the shape become very important. Other factor are also important when talking about d_cr which are crystal density, confinement, particle size, temperature...

Dany.

underground - 31-10-2013 at 21:56

Thank you Dany, Very interesting...
To update that, in conclusion, it should not be a very big problem about the shape of easy detonated explosives, like ETN,RDX,NG,NG but it should be with explosives like ANFO ANAL that are difficult to detonate.
So, to continue with, the two basic parameters that we have to watch out when we are going to detonate some insensitive explosives are a) the critical diameter and b) the necessary distance it needs to achieve the primary/booster full speed of their detonation wave.
I guess different boosters and quantities has a variation of distance between them.
So Dany, if you was able to detonate 300gr of ANFO (yes small quantity) with some ETN as a booster, how your shape/set up would going to be to achieve as necessary as possible full detonation of ANFO ? How the ideal shape should must be ?

[Edited on 1-11-2013 by underground]

Dany - 31-10-2013 at 22:35

Of course the nature and quantity of booster will influence the run up distance.

There is no ideal shape for ANFO detonation, but suffice to say that 300 g of ANFO confined in heavy, thick steel tube is a good choice for this explosive. The heavy confinement assure that the expansion or rarefaction wave created at the interface of the cylindrical charge due to expansion will be delayed from arriving to the center of the charge. So the expansion wave will not interact with the detonation wave and reduce it's speed. however you should not confine ANFO to theoretical maximum density (TMD) because ANFO belong to the class of non-ideal explosive where the detonation velocity D_cj first increase with density and @ certain density the D_cj drop again. So there is an optimum density for achieving the maximum D_cj which is not necessarily the TMD. Another explosive composition that exhibit the same properties of ANFO is NH₄ClO₄/aluminium. for more information on critical diameter and other interesting detonation physics read this important report for Dr. Donna PRICE:

http://www.google.fr/url?sa=t&rct=j&q=&esrc=s&am...

Finally, i do not recommend you to handle explosive in this big quantity (yes 300 gr is huge for amateur!). even ANFO is insensitive but a little mistake with the detonator or the booster may become your last mistake. Working with explosive is like dancing with the devil if you are not an expert. In the laboratory energetic materials are produced on milligram scale behind a safety shield and wearing a Kevlar gloves. gram quantity are produced only after all safety test are made such as impact test, electrostatic discharge test (ESD) and friction test.

Dany.

Ral123 - 31-10-2013 at 23:07

And don't forget that explosives are very toxic. What you do today may effect your health after 20 years.

underground - 31-10-2013 at 23:20

Quote: Originally posted by Ral123

And don't forget that explosives are very toxic. What you do today may effect your health after 20 years.

I am not doing nothing right now, i just want to learn...

Quote: Originally posted by Dany

Of course the nature and quantity of booster will influence the run up distance.

There is no ideal shape for ANFO detonation, but suffice to say that 300 g of ANFO confined in heavy, thick steel tube is a good choice for this explosive. The heavy confinement assure that the expansion or rarefaction wave created at the interface of the cylindrical charge due to expansion will be delayed from arriving to the center of the charge. So the expansion wave will not interact with the detonation wave and reduce it's speed. however you should not confine ANFO to theoretical maximum density (TMD) because ANFO belong to the class of non-ideal explosive where the detonation velocity D_cj first increase with density and @ certain density the D_cj drop again. So there is an optimum density for achieving the maximum D_cj which is not necessarily the TMD. Another explosive composition that exhibit the same properties of ANFO is NH₄ClO₄/aluminium. for more information on critical diameter and other interesting detonation physics read this important report for Dr. Donna PRICE:

http://www.google.fr/url?sa=t&rct=j&q=&esrc=s&am...

Finally, i do not recommend you to handle explosive in this big quantity (yes 300 gr is huge for amateur!). even ANFO is insensitive but a little mistake with the detonator or the booster may become your last mistake. Working with explosive is like dancing with the devil if you are not an expert. In the laboratory energetic materials are produced on milligram scale behind a safety shield and wearing a Kevlar gloves. gram quantity are produced only after all safety test are made such as impact test, electrostatic discharge test (ESD) and friction test.

Dany.

Thanks Dany!!

Really useful !!

[Edited on 1-11-2013 by underground]