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careysub
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[*] posted on 9-9-2016 at 08:31


Quote: Originally posted by Tricka90  
When handling high explosives, especially primaries, what precautions do you take in terms of maintaining a safe distance between your hands and the energetic material, particularly when conducting dangerous procedures (testing, cap filling, etc...)? How do you evaluate the minimum safe distance for a given power and quantity of an explosive?
In his writings, Ledgar gives the following rule:

Quote:

"10 centimeters per 1 gram TNT equivalent, 50 meters minimum safe distance per 500 grams TNT equivalent"

Do you agree with that?
If the statement is correct my hand wouldn't get any permanent damage if 1 gram of let's say Silver Acetylide Double Salt detonates at a 10 cm distance, because SADS it's way less powerful than TNT (of course I'm supposing it's not confined in any dangerous material such as glass). It looks like a very tiny distance to me, what do you think about it?

Furthermore how would the rule applies to explosives with higher VOD than TNT such as ETN? I don't think there's a linear relationship between VOD and minimum safe distance because pressure of the shock wave grows exponentially with VOD.

The subject is complicated so I'm just looking for a general rule of thumb. How do you organize in order to estimate and keep the proper distances when dealing with EMs?
As for me I made all kinds of different tools (spatulas, pliers, spoons) which are long and made of wood (to reduce the risk of electrostatic discharge). They allow me to always maintain a gap of 10 cm at least between my hand and SADS, which is the primary I've been experimenting with. I always use them when dealing with relevant quantities of dry SADS (above 100 mg).
I still don't know how am I going to approach the handling of the more powerful (and still relatively sensitive) ETN.


p.s.
I know lots of EM enthusiasts tend to handle sensitive primaries with bare hand (as it can be seen even on YouTube). Maybe I'm too cautious but I prefer to always work as safe as I can.

[Edited on 9-9-2016 by Tricka90]


A good rule of thumb is that is it is in Ledgar it is probably wrong.

Safe distances actually scale with the cube of the explosives weight, certainly for larger charges (see Army FM 3-34), page 6-7:
https://info.publicintelligence.net/USArmy-Explosives.pdf
although it uses a catch-all 300 meter safe distance for "27 lbs or less" which is obviously extremely conservative for small charges, but still the cube rule is physically sound.

The table is generated from the formula:
D(ft) = 300 * W(lb)^(1/3)

If you used this for very small amounts you would get 300 ft for 1 lb, and 39 feet for one gram.

According to Shimizu the safety distance formula used in Japan is:
D(m) = K * W^(1/3) where K is a constant varying from 2.4 for black powder to 3.0 for high explosives (i.e. the difference is small from one EM to the next).
He does not say what unit W is in, but it would appear to be grams which is what he uses elsewhere in the chapter.

From this it would give the safe distance of 3 meters for one gram, not Ledgar's 10 cm.

The limiting factor in the Army calculations anyway is hearing injury. Incidentally, I hope you having a handgun fired one meter away, with a charge of about 0.3 grams is hazardous to unprotected hearing, even one shot. Good hearing protection will reduce the distance hazard (but only for you, who are wearing it).

Clearly it is very difficult to manipulate an explosive at the gram level from 3 meters away.

But this underscores the most important point - if you are handling EM materials for all practical purposes there is no safe distance. You are working entirely in the danger zone. Safety lies in making sure the stuff you handle NEVER explodes.

That said, direct physical contact with any sort of sensitive material is strictly verboten. Manipulation systems made of paper, cardboard, cloth, soft rubber (but be wary of static electricity with most any polymer) that keep hands away from the material is essential.

[Edited on 9-9-2016 by careysub]
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[*] posted on 9-9-2016 at 08:44


Quote: Originally posted by XeonTheMGPony  
it is all math work, here is the pdf. Rule of thumb the further you are or the more stuff to absorb the energy the better.

when pressing caps I use dry towels wrapped around the press to absorb the shock wave and to dampen any shrapnel produced, cotton is a good acoustic absorber.


Comment about this file - the lowest blast injury level given is
"0.35 kg/cm2. Minimal distance of possible rupture of tympanic membranes."
It is important to realize that membrane rupture is the maximally severe form of hearing injury - hearing loss injury starts at much lower pressure levels.

Plugging 0.001 kg (one gram) and one meter into the Sadowsky formula gives an overpressure of 0.118 kg/cm2, far more than enough to break a window (0.05 kg/cm3 given as the level for this), and certainly hazardous to hearing.
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[*] posted on 9-9-2016 at 10:06


Somewhat differing from the main topic, where would something like nitrogen-tri-iodide fall in this equation?

It's obviously never going to get to much more than a few grams (I'm bad at estimating things) but how brisant might a novelty like that be compared to, say, flash or blackpowder? I'm under the impression the usual demonstration amounts are too small to do much and that it's a rather wimpy explosive anyway, but I figured I'd ask since I can't find too much on its VOD or such.




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[*] posted on 9-9-2016 at 12:09


Quote: Originally posted by James Ikanov  
Somewhat differing from the main topic, where would something like nitrogen-tri-iodide fall in this equation?

It's obviously never going to get to much more than a few grams (I'm bad at estimating things) but how brisant might a novelty like that be compared to, say, flash or blackpowder? I'm under the impression the usual demonstration amounts are too small to do much and that it's a rather wimpy explosive anyway, but I figured I'd ask since I can't find too much on its VOD or such.


A few grams is excessive for a first attempt. Try 0.5 grams.

The Royal Society of Chemistry has a safe demonstration procedure:

http://www.rsc.org/Education/EiC/issues/2010May/ExhibitionCh...

A key point with this substance - after it is prepared, it is not sensitive as long as it is still wet. It must be laid out for demonstration detonation, and decontamination at once, and never disturbed again until exploded and decontaminated.

Rewetting it to render it insensitive again is an unreliable procedure.

If we use Wikipedia's decomposition energy for complete decomposition:
2 NI3 (s) → N2 (g) + 3 I2 (g) (−290 kJ/mol)
it is about 1/6 as energetic as TNT, and one of the weakest explosives known.


[Edited on 9-9-2016 by careysub]

[Edited on 9-9-2016 by careysub]
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[*] posted on 9-9-2016 at 14:21


Thank you everybody for all the replys.
The formulas and documents you posted are very useful, the problem is they don't seem applicable to small quantities of primary explosives:
Quote:

From this it would give the safe distance of 3 meters for one gram

I'm not expert but we all can agree for such distance to be extremely conservative (unless the explosive is confined in a material which can unleash dangerous fragments when exploding).
Quote:

if you are handling EM materials for all practical purposes there is no safe distance. You are working entirely in the danger zone. Safety lies in making sure the stuff you handle NEVER explodes.

Well, I agree with you, but I think in some cases one can withstand a detonation without getting hurt if there's a proper gap between the explosive and his hand. In such cases a safe minimum distance does exist and is also very important. For example when handling less than 100mg SADS in order to manufacture a blasting cap no permanent damage to the hands would occur if a gap of a few tens of centimeters exists. Otherwise the damage could be serious, so I say it would be reasonable to evaluate and respect a safe minimum distance in those cases. At least that's what I feel fair to say considering my very short practical experience on the subject, so it's possible I'm wrong.
Also I can't completely rely on the fact that doing all things properly means no detonation will ever occur. I think I can't be 100% sure so I'm always prepared for an explosion.
As for the hearing protection I think it would be very stupid to lose the hearing because of unespected detonation, considering that having ear plugs always on is easy, cheap and doesn't hinder one's ability to handle the substance (as it does maintaining a safe distance, which is often unfeasible).

[Edited on 10-9-2016 by Tricka90]
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[*] posted on 9-9-2016 at 15:07


Is there a quick way to distinguish acetic anhydride from acetic acid or from a mixture of both the anhydride and acid?
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[*] posted on 10-9-2016 at 14:09


Quote: Originally posted by stoichiometric_steve  
Is there a quick way to distinguish acetic anhydride from acetic acid or from a mixture of both the anhydride and acid?

Metallic zinc will set H2 gas free with acetic acid owing to available proton.Acetic anhydride should remain inert towards the naked metal.
For the mix maybe density or boiling point may be of some use.




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[*] posted on 10-9-2016 at 14:23


Acetic acid is miscible with water. Acetic anhydride is not (but does react with it). You could add a drop of the unknown to a small amount of cold water, and see if it's homogeneous. The zinc idea is also good, and you could probably use other metals too.

[Edited on 9-10-2016 by Metacelsus]




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[*] posted on 13-9-2016 at 03:45
RDX plasticiser


I made a small batch of RDX by the E process. Now I've been reading about the additional stuff you put in it to make it plastic, and tbh I'm not really in the mood to get hold of all that stuff. So I was wondering, would it be possible to use something as simple as xanthan gum or dextring or something alike?
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[*] posted on 13-9-2016 at 05:05


Oil or wax does the trick. Try making a dummy compound with sugar, salt or whatever inert you have that matches the particle size and see what you think. A few (perhaps 5) percent of wax should phlegmatize the RDX, it won't be plastic but well suited for pressed charges. 10% heavy oil should produce a putty-like plastic. Not as nice as PIB-based compounds but it will work just fine.



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[*] posted on 13-9-2016 at 08:16


What exactly is this "heavy oil" you refer to?

Serious question, google just gives me some real generic stuff. Is it a motor oil, some sort of specific brand or something?




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[*] posted on 13-9-2016 at 08:19


Any thick oil. Motor oil works, but my favorite is chain saw lubrication. You could also try grease.



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[*] posted on 13-9-2016 at 14:04
ETN or Picric Acid as my first secondary synthesis?


After gaining some experience with the manufacture of primaries I'm going to try and make my first secondary. I finally decided to either make ETN or Picric Acid since I have all the ingredients available. What of them would you suggest to a beginner? ETN seems easier to make, but it's also an extremely sensitive secondary. On the other hand Picric Acid synthesis is a bit harder and it's also toxic but his sensitivity is very low.
So what do you think is the right choice to start experimenting with secondaries?

[Edited on 13-9-2016 by Tricka90]
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[*] posted on 13-9-2016 at 17:17


Picric acid is definitely harder and will make dangerous fumes. It is also a hot nitration and gas several steps. Not really a beginners synthesis. I would do ETN or even Nitrocellulose first to get a feel do how a nitration goes. My two cents.



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[*] posted on 13-9-2016 at 17:22


Quote: Originally posted by NeonPulse  
Picric acid is definitely harder and will make dangerous fumes. It is also a hot nitration and gas several steps. Not really a beginners synthesis. I would do ETN or even Nitrocellulose first to get a feel do how a nitration goes. My two cents.


I found the Bodine procedure for picric acid straightforward and reliable - did it outside and was careful about the fumes. (I just wanted a little for an amine isolation reagent.)

[Edited on 14-9-2016 by careysub]
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[*] posted on 13-9-2016 at 19:04


Quote: Originally posted by careysub  
Quote: Originally posted by NeonPulse  
Picric acid is definitely harder and will make dangerous fumes. It is also a hot nitration and gas several steps. Not really a beginners synthesis. I would do ETN or even Nitrocellulose first to get a feel do how a nitration goes. My two cents.


I found the Bodine procedure for picric acid straightforward and reliable - did it outside and was careful about the fumes. (I just wanted a little for an amine isolation reagent.)

[Edited on 14-9-2016 by careysub]


Nice! I did it recently also. So far I've been storing it dry in a glass jar with a plastic cap, how do you all store your's? Is the water necessary?




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[*] posted on 14-9-2016 at 00:20


Quote: Originally posted by Gemlingur  
I made a small batch of RDX by the E process. Now I've been reading about the additional stuff you put in it to make it plastic, and tbh I'm not really in the mood to get hold of all that stuff. So I was wondering, would it be possible to use something as simple as xanthan gum or dextring or something alike?


Tested it out with salt instead of RDX, about a seventh of total volume was xanthan, it started out as a very moldable kind of a thick, fibrous ice cream, but when left to dry it started depositing either xanthan or salt at the edges, and wouldn't join itself when folded. Next test will be with varying amounts of xanthan, and then some petroleum jelly to see how that changes things. Making xanthan gum first and then trying to knead the salt in proved unsuccessful.
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[*] posted on 14-9-2016 at 03:10


When you're will be in the mood, go to the electro store and buy self-vulcanizing tape. All those things are 3: gasoline, oil and tape.
https://www.youtube.com/watch?v=CBK-NR4suEE
This tape = end of worry with plastification anything.
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[*] posted on 14-9-2016 at 06:20


Is there any way of quantifying the 'strength' of a solvent? And if so, what are some of the strongest?
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[*] posted on 14-9-2016 at 18:27


Quote: Originally posted by Maker  
Is there any way of quantifying the 'strength' of a solvent? And if so, what are some of the strongest?


You would need to be more specific as to your material of interest. What do you want to dissolve? And why?




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[*] posted on 15-9-2016 at 09:23


Quote: Originally posted by Bert  
Quote: Originally posted by Maker  
Is there any way of quantifying the 'strength' of a solvent? And if so, what are some of the strongest?


You would need to be more specific as to your material of interest. What do you want to dissolve? And why?

I didn't have a specific material in mind, just a general wondering.
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[*] posted on 15-9-2016 at 13:59


Quote: Originally posted by Tricka90  
After gaining some experience with the manufacture of primaries I'm going to try and make my first secondary. I finally decided to either make ETN or Picric Acid since I have all the ingredients available. What of them would you suggest to a beginner? ETN seems easier to make, but it's also an extremely sensitive secondary. On the other hand Picric Acid synthesis is a bit harder and it's also toxic but his sensitivity is very low.
So what do you think is the right choice to start experimenting with secondaries?

[Edited on 13-9-2016 by Tricka90]


I don't find the synthesis of Picric Acid from ASA that difficult, but if you don't wanna deal with high temperatures and still want to make a nitrophenol, try with trinitrophloroglucinol if phloroglucinol is available for you. Synthesis is perfomed at 0ºC and yields are good (look at Studies on 2,4,6-trinitrophloroglucinol (TNPG)⎯A novel flash sensitizer).

[Edited on 15-9-2016 by kratomiter]
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[*] posted on 15-9-2016 at 17:47


I would say also the synthesis of TNP is not really that hard, but for experienced people. It's not really a beginners one and although Rosco bodine's picric acid procedure is detailed enough so even a layman can get it, if you have zero experience with synthesis of energetics I wouldn't do this as the first one. ETN is easier to make and more powerful it is also less dangerous with only nitric vapour to worry about rather than copious amounts of potentially deadly fumes and hot acid.



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[*] posted on 15-9-2016 at 22:15


ETN first, IMHO. I did personally make trinitrophenol before ETN, as Axt on the old E&W forum had not yet directed the amateur chemistry community towards the newly available erythritol feed stock & original patent information when I first got the interest to perform such operatuons- also nitroglycerin and nitrocellulose as a highschool kid, long before the advent of "windows" and the general public venturing out onto the WWW.



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[*] posted on 21-9-2016 at 11:27


Somewhere in the energetic materials forum, there is attached to a post a blasting cap diagram (patent drawing?) that details a cap with a small, pyrotechnicaly driven flyer with electric ignition which strikes a secondary explosive, rather than using a HV discharge or a standard primary. As far as I can recall, the propellant for the flyer was nitrocellulose-

I had downloaded this to my old iphone, but do not seem to have saved it to my desktop- and that phone is now dead.

Ring a bell with anyone?

Related question- What is the highest "flyer" velocity that you know of anyone achieving with a deflagreting solid propellant system, rather than driven by a detonation. Ideally without needing something, (expensive, non disposable!) like a taper bore, or other complex, heavy metal fabrication?

[Edited on 21-9-2016 by Bert]




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