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#21 ronmoper76

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Posted 16 March 2021 - 08:03 AM

i also have a book that talks ALOTt about detonating flash,with and without blasting caps...IM HUMBLY ASKING THE SAME THING? 



#22 ronmoper76

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Posted 16 March 2021 - 08:19 AM

 
The Significant factor here is that 23% of the incidents RESULTED IN SOME
FORM OF AN EXPLOSION, since pyrotechnic compositions are not normally
considered to be explosive in nature." [Emphasis added.] Of interest were the
TNT equivalence (Hi Explosive equivalence) tests. Of the six compositions used
for producing sound two were tested for TNT Equivalence with the following
results: Air Blast Simulator Mixture, as used in the M74A1 and M74 Simulator.
[Aluminum flake 9%, Black Powder 91%] TNT Equivalence was found to be
45%. Detonation Simulator Mixture, use: the infamous M80. [************] TNT
equivalence 80%. It should be noted that; "The M80 fire cracker mixture is no
longer manufactured but is reported along with the test data BECAUSE OF
SEVERAL CATASTROPHIC ACCIDENTS THAT HAVE OCCURRED." [Emphasis
added.]
 
"Critical Height" and "Critical Diameter" were also measured. "In the critical
height test the "Critical height to explosion data are reported as the greatest
material height in a given container diameter which did not result in transition
from burning to an" explosion.
 
Critical diameter tests the sample material using C4 as an explosive donor, to
determine the minimum diameter required to induce a explosive reaction.
 
The critical Diameter for the M80 composition was found to be 0.01 meters [4
inches!!!]. and the Critical Height was measured as being 3.96cm. [1.5 inches!!!]
[Fools rush in where angles fear to tread.]Of the photoflash mixtures tested, TNT
Equivalence of: 30-36-50% were measured. And even closer to homer a Yellow
Star Mixture [Magnesium 18%, Barium Nitrate 17%, Strontium Nitrate 16%,
Potassium Perchlorate 17%, Sodium Oxalate 17%, and HCB 12%] when tested:
 
"indicated that this mix would detonate and an explosive equivalence (as
compared to TNT) was greater then 50% in a contained vessel ***" This mixture
was also found to be sensitive to friction and impact.
 
Propagation Rates In Thermally Ignited Pyrotechnic Compositions. Richard W.
Collett, Tech Report ARLCD-TR-77049, August 1978, NTIS ADA060809.
 
"Work was performed to determine the propagation rates in loose, granular
confined pyrotechnic compositions when initiated thermally. Representative
materials included flash, igniter and flare compositions."All compositions were
tested confined in steel pipe 48" long by 2"id. both ends of which were sealed
with heavy end caps. An igniter pack placed in the bottom of the column was
used for thermal ignition.Conclusions: "All of the compositions tested developed
fast reactions which could cause explosions and be extremely hazardous ***.
The reactions are therefore all classed as detonative." [Emphasis added.]
 
Of the four basic compositions tested, PFP-555 [Aluminum 15u 40.0%, Barium
nitrate 140u 30.0%, and Potassium perchlorate 20u 30.0%] "can develop either
a low-velocity or high-velocity detonation when thermally ignited. Test 1- 920
meters/sec. Test 2-546 meters/sec."
 
Explosive Power of Pyrotechnic Compositions. 1.M. Jenkins, Et. All, 19th
Explosives Safety Seminar, Calif. 1980 Page 77 &ff.
 
"Various pyrotechnic compositions were assessed in three experiments:
 
1-To measure and assess the explosive power from various initiating stimuli.
 
2-To measure the explosive power expressed in terms of the equivalent mass of
TNT per unit mass.
 
3-The likelihood and effect of sympathetic initiation in a practical storage
situation."
 
Three initiating stimuli were used: 1/fuzehead 2/electric detonator, and 3/a
detonator boosted with a tetryl pellet. The composition being placed in a paper
mache pot, with the initiator being placed at the geometric center of the charge
mass.
 
Composition #11: Photoflash [40/60 Aluminum/Potassium Percolate] when
ignited by source number three, resulted in an "equivalent mass approximation
kg. TNT per unit mass" of 0.42. More rigorous testing using piezo-electric
pressure transducers to measure air blast and other experiments using foil
gauges raised the TNT equivalence to 50%.
 
TNT Equivalencies of Black Powder. Volume 1: Management Summary and
Technical Discussion, H.S. Napadensk and J.J. Swatosh Jr., lTIRJ6265-3,
Sept. 1972, NTIS ADA-044444. 69 pages + vii.
 
"Black powder charges ranging in weight from 8 to 150 pounds were evaluated
under different levels of confinement. The TNT equivalence for the final product
were found to range between zero to 43% for impulse and zero to 24% for
pressure, depending upon the level of confinement, the weight of explosive and
booster, and the distance form the explosion."
 
The generally quoted figure for the detonation velocity of BP is 400 meters/sec.
However A.F. Belyaev and RKh. Kurbangalina; Russ. J. Phys.Chem. 38:309-
310,1964, as quoted in the LLNL Explosives Handbook, URCL-52997, provide
the following figures Density g/cm3 appx. 0.7, det velocity appx. 1.3 km/cm3,
1.35 km/sec.
 
Hazards Testing of Ammonium Perchlorate. F.L. McIntyre, et al, 58 pages. NTIS
ADA-114966
 
A series of hazard classification tests were conducted on ammonium


#23 tenneyguy

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Posted 14 June 2021 - 06:27 PM

Different decomposition pathways.  There are several common examples that will burn if lit with a flame.  Some compositions however are capable of a DDT, which despite a common misconception, is not shorthand for detonation.  It stands for deflagration detonation transition.  The materials that are capable of a sustained stable deflagration need to be initiated with a shockwave.  This starts off a chain reaction of a different pathway that usually will release more energy, and be self-sustaining.  This is just postulation, but I suspect some of the reactions needed to induce a detonation are pressure dependent. 

 

I believe your last sentence is right on the money. For example, detonable smokeless powder is "burned" in small arms ammunition, among others, WITHOUT detonation, which CAN occur, and does cause devastating results. Typical burn rate vs pressure curves for smokeless show a peak pressure following which pressure begins to drop. This illustrates it's use as a propellant for projectiles (bullets). Such curves are based on increasing volume behind the projectile and increasing velocity of it, thus halting burn rate increase,in order to illustrate the PEAK pressure reached as it applies to the particular application. 

 

In the event the burning commences in a rigidly confined volume, the burning rate will increase exponentially very quickly, possibly until "something gives". Thus the use of smokeless powder as propellant depends on the burning rate never reaching that "point of no return" pressure. If it does, ruptured barrels, damaged gun mechanisms, and possible injury result.

 

It may be said then that smokeless powder MAY detonate under certain conditions whereas black powder will not.


Edited by tenneyguy, 14 June 2021 - 06:29 PM.


#24 tenneyguy

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Posted 14 June 2021 - 06:36 PM

From a quick look round on the web, there appears to be a lot of disagreement and confusion about what constitutes detonation. The guy who wrote the Wikipedia entries seems to be particularly confused. For me, it's only detonation if it propagates by the shock wave first, with the chemical reaction following. Any reaction that propagates only chemically is deflagration. Flash powder self-confines, but it doesn't detonate. It propagates chemically, by fire. It does go pretty fast, though, something in the order of 2000 ft/sec. That's less than any true high explosive, but it's comparable. I think TNT goes around 6000 ft/sec.

 

TNT detonation rate = 23,000 feet per second, very fast. 10 times the speed of a common rifle bullet.



#25 FlaMtnBkr

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Posted 12 September 2021 - 12:39 PM

On the topic of smokeless powder, double base smokeless is not only NC but nitroglycerin as well. I believe Bullseye has the most NG @ 40% if I remember correctly, which isn't a negligible amount. And obviously burns instead of detonates based on the very few shattered barrels and/or receivers. And of those few I think most are linked to material imperfections, excessive age and/or use, or an obstructed barrel and not because of an 'earth shattering boom' aka detonation.

I'm far from an expert but it's been my understanding that a detonation happens when a shockwave travels thru the material at sufficient speed/energy that molecular bonds are broken releasing a tremendous amount of energy almost simultaneously. And no heat, flame, or oxygen is required as with burning, and many times there are no visible flames. This is why Tannerite detonates because the bullet is traveling fast enough to impart enough energy to start the bond breaking. When it burns there is heat/flame and oxygen and the material/fuel heats and destructively oxidizes like a normal fire which lacks the necessary energy to break the molecular bonds that releases the explosive energy.

In something like flash powder the particles are very small with lots of surface area so burns fast like a small piece of tissue paper vs a log. And it also has its own oxygen supply and isn't slowed down by having to use what's in the air which is consumed and takes time for more to move in and replace the supply. Without the limits a very fast burn results, releasing lots of energy in a small instant. Metals also burn hot and higher temperatures result in higher pressure which increases how fast it burns which is also why containment can be important to allow greater pressure. And in some cases the chemicals involved can burn fast and hot enough to release enough energy to start breaking those energetic molecular bonds which adds more energy and it turns into a detonation thru the rest of the material, which is the deflagration detonation transition (DDT - where deflagration means burns really really fast).

At least this is my layman understanding of it all...

#26 Bourbon

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Posted 14 September 2021 - 10:27 AM

That is exactly the way I take it also.

 

I can say without doubt, you can take almost all of the above and detonate it with the right package and cap.. Double base "like Bullseye" is extremely impressive with a good cap. Kidd you not!






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