Sciencemadness Discussion Board - The amount of primary needed

The amount of primary needed

Gargamel - 18-11-2013 at 05:10

Hi,

do you guys by chance have some numbers on how much primary the industry usually uses to initiate the output charges of typical detonators?

An often quoted amount seems to be 300mg of LA.

However, apparently some people seem to have used as little as 200mg Ag-acetylide/nitrate double salt - directly on AN, without any booster:
http://www.youtube.com/watch?v=fh9UC6dai34

I find it very hard to tell if a blasting cap reached the maximum possible brisance. I don't have the equipment to actually measure the speed, I can only judge witness plate dents wich is usually a little vague.
I can distinguish total failures from "somehow went high order", but I cannot further narrow this down...

My favourite primary at the moment is Ag-Acetylide/nitrate, in combination with an ETN output charge.

How much primary would you use in this case?

golfpro - 18-11-2013 at 07:14

250mg pressed

NeonPulse - 18-11-2013 at 16:42

For etn caps I use 250mg SA/ds also but have used as little as 150mg with the same results. I would go for more to be sure though.

golfpro - 18-11-2013 at 16:43

Don't use that amount with a cap using RDX as the base charge though. SADS is weaker than LA or MF.

NeonPulse - 18-11-2013 at 18:13

For etn caps I use 250mg SA/ds also but have used as little as 150mg with the same results. I would go for more to be sure though.

testimento - 5-1-2014 at 08:42

Will ETN go off with flash powder initiated with electricity or will it need actual primary like TATP etc? I was planning to use few grams of casted ETN on bottom of a cap with a gram or two of flash with wire installed.

Turner - 5-1-2014 at 09:02

Definitely not. ETN may be initiated w/ FP by using some creative way, but definitely not when it is cast.

Vpatent357 - 18-8-2014 at 08:20

Getting back to the video, Silver acetylide initialization
Do you think he has reached a full detonation?

Currently i don't have secondary like PETN, ETN

but I have SADS,
250mg is enough for detonation of small charges like 2x activated ANNMAL?

I think the dual AN activation can make ANNMAL sensitive as a secondary nitrate esters

[Edited on 18-8-2014 by Vpatent357]

NeonPulse - 18-8-2014 at 16:43

Looks to be a complete detonation to me judging by the deformation of the rebar and the size of the leftover concrete there. I wouldn't put money on a 250mg SADS detonator initiating it every time though. Although the Al addition will help sensitivity its not a guarantee.Perhaps if you have access to bullets or shotgun shellsyou could use the propellant from them to fashion a small booster since you don't have other nitrate esters. A nice double base powder should work fine.A booster like that should make the charges much more reliable to fire. A good detonator is key. As the old saying goes, the harder you hit it the harder it hits back.

Vpatent357 - 19-8-2014 at 03:06

I slowly began to guide me to a possible synthesis of PETN

Although I'm not really confident with a small sense of fear ..

I currently own 60% HNO3 + 96% H2SO4 and I think I can get 98% quality PE
I saw this: PETN Synthesis with Acids Mix

Do you think a synthesis with mixed acids is wise? or should I invest myself in a distillation of HNO3

markx - 20-8-2014 at 03:53

Quote: Originally posted by Vpatent357

I slowly began to guide me to a possible synthesis of PETN

Investing in a HNO3 distillation unit is always wise...if you can spare the funds and time then definately do it

Albeit for PETN the mixed acid method, in my personal experience, seems to work quite excellent. PE is one of the most easily nitrated polyols out there....but it also seems that it is one of the most prone ones to runaways too. So always keep that in mind and be prepared for it, when conducting a synthesis.

As for the amount of primary....250mg of SADS for nitrate esters like ETN or PETN is overkill of the year. It will work with confidence, but is just wasteful of a valuable primary material from my point of view.

Hence I conducted a series of experiments to determine the optimum amount of SADS for ETN/PETN:

The base charge for all units was 0,3g PETN from mixed acid synthesis, recristallised from acetone, "hand pressed" into foil tube with a few mg of loose ester on top of the base. Primary was the designated amount of SADS on a separate pyrotechnic delay. The units were assembled with the primary part prior to use.
As one can see from the pictures, the initiation of base charge occurred reliably upwards from 20mg of SADS. The only charge that failed to detonate was the one with 12mg primary. For my purposes a 40mg SADS charge has worked very reliably on nitrate esters and also nitramine bases, I see no need to work with more. But since conditions may vary, I suggest to take this information as a rough guidance for the order of magnitude. Every particular design has its own optimum, but that is for everyone to work out on their own.

Vpatent357 - 20-8-2014 at 16:55

Very useful test,
I think 100mg SADS + 700mg PETN per cap is enough for most uses.

Quote: Originally posted by markx

What recipe or personal notes you follow for the synthesis of PETN,
I've heard ETN is more forgiving on the synthesis, have you ever had a runaway with PETN and may there be an explosion?

markx - 20-8-2014 at 23:28

Quote: Originally posted by Vpatent357

Very useful test,
I think 100mg SADS + 700mg PETN per cap is enough for most uses.
What recipe or personal notes you follow for the synthesis of PETN,
I've heard ETN is more forgiving on the synthesis, have you ever had a runaway with PETN and may there be an explosion?

100/700mg combo will definately be good for most uses....also for removing a substantial number of digits from your hand. Always keep that aspect in mind. I personally have not used more than 60mg on the primary part, but more will not harm reliability if you have enough silver around.
As for ETN, I find it performs every bit as good as PETN in the base charge....in fact I actually prefer ETN as it is much more easily compacted due to its flake form cristals and the platelets stick together making a sturdy mass that is not prone to crumbling. Only downside of ETN is its relatively low melting point, but I doubt that one would want to subject their contraptions to temperatures upward of 60C.
As for runaways....never happened with ETN (does not mean that one can go about carelessly adding huge amounts of polyol and not controlling temperature), happened plentyfully with PETN synthesis. The main factors to turn attention to with PE mixed acid nitration are:
a) temperature control
b) dilution of nitration mixture due to the reaction and the resulting oxydation of product, leading to a fast runaway at the end of the reaction. So do not try to squeeze the last out of your acid mix by adding a quantitative amount of PE, leave a bit of overhead.
c) long maceration times after the addition of PE are unneccesary and also seem to provoke a runaway. Every time I tried to macerate past 15min a runaway started to gather speed with exceptional fortitude and independent of reaction temperature, so 10min is plenty. PE is easily nitrated due to its branched structure and the resulting lack of steric hindrance.
d) PE precursor needs to be of high purity, paint industry grades are usually no good for energetic purposes.

And yes, an explosion can result from a violent runaway, hence always have a quenching bath ready and use small amounts. If a runaway has already started (flask spewing brown NOx fumes over the top) it usually gets out of hand, do not try to save the reaction, save yourself by quickly leaving the premises. Any equipment or reagents can be easily replaced, but the damage that can result to a person nearby may be irreversible.

As a guidance for synthesis procedure, one can use the following:
4,5g 98% purity sulfuric acid
4,5g 65% purity nitric acid
1g PE
Expected reasonable yield is 2g of PETN

Correct the reagent amounts for your respectable concentrations and search the site for further reference....the methods and procedures have been covered in past topics.

ETN

Laboratory of Liptakov - 1-10-2014 at 12:30

I also use ETN. Perfectly pressed. The flakes are like wax. Melting temperature 60C it is no problem in amateur practice. On the Sahara yes. Gobi Desert as well.
LL

HafizAmari - 1-11-2014 at 17:28

Quote: Originally posted by testimento

Will ETN go off with flash powder initiated with electricity or will it need actual primary like TATP etc? I was planning to use few grams of casted ETN on bottom of a cap with a gram or two of flash with wire installed.

I can not attest as to how reliable it is, but FP can initiate ETN. I have only done it a few times, because I can get comercial caps easily now

.

I used 900mg of ETN and 1500MG of FP. It worked perfectly fine. The ETN was melt cast as a base charge. The confinememt was an alluminum arrow shaft. I sealed the bottom of the tube with silver solder.

[Edited on 2-11-2014 by HafizAmari]

Gargamel - 2-11-2014 at 03:30

Quote:

I have only done it a few times, because I can get comercial caps easily now

No wonder.
I should join the Snackbarian Army too

LL, what kind of recrystalisation process do you use to get best density and handling properties? I found larger crystals are better, but the needles also dont handle to well.

Is there a way to get large crystals that are more squarish or something like table salt or sugar?

[Edited on 2-11-2014 by Gargamel]

NeonPulse - 3-11-2014 at 14:48

Rosco bodine's reverse re-crystallization works very well for this and PETN. You basically add ice and water slowly to the hot solvent. It does take a bit of practice to get right but the result is very good. The crystals form nicely into small dense free flowing product perfect for loading and plasticizing. I have used this method and its a good way to the desired properties. Take a look. Its in the RDX VS PETN thread I think.