EXPLOSIVES
Title:
Date: 10/18/89
Time: 10:02 pm
Explosive File I
In the Beginning…..
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——————————————————————————– So, you want to
learn about some explosives, eh sonny? Well, you have come to the right place. Starting with this
file, a series begins that will try to bring that world of demolitions and fun ( ha ha ) a little
closer to you. This serier, ingeniously dubbed the "Explosive Files" will go through the
many types of explosives around. In addition, a few sidetracks will be made on the way in the areas
of fireworks or whatever seems appropriate. As you delve through what is contained in the files, you
may find some helpful information, you may not. But have fun reading them anyway.
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* The author and the management takes no *
* responsibility whatever for any
of the *
* information presented from hereon in any *
* of the Explosive Files. There
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If you haven’t figured this one out yet,
this file is formatted for 80 columns. And the rest of the files are the same way. So, using a quote
I saw once on a file on a board, " Use your damn printers people !!! "
And
now on with the show.
EXPLOSIVES
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To start learning about explosives, you have
got to start at the begining. I plan to be as thorough as possible, but I may forget things every
now and then. The files should still be complete though. So now to start at the beginning……
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An explosive is a substance that, under the influence of heat, shock, or some other
agency, undergoes a chemical reaction that causes it to decompose or break up quickly with more or
less violence ( whew ). Explosives fly to pieces because the materials composing them react in such
a way that solids or liquids are suddenly converted into gases, which tend to expand and rapidly
fill a larger volume of space. Heat is also developed and acts as a catalyst (something that changes
the speed of the reaction in some way. In this case it speeds it up. ). The noise associated with an
explosion is caused by air waves. An explosion is an intensified combustion also.
The history
of explosives is too long for one file, but certain events are covered in individual files. For
instance, gunpowder’s history is in the gunpowder file.
Lets narrow the scope a little here
and get a little introduction into explosives. How they are classified is a good thing to know, so
here it is.
There are basically 3 different types of explosives existing. All explosives fall
into one of these categories somewhere. What follows is a listing of each of these categories with a
brief description and some examples.
I. Propellants
Propellants, or
low explosives, are combustible materials, containing within themselves all oxygen needed for their
combustion. They burn themselves out but do not explode, and function by producing gas which
explodes.
Examples are Black powder and smokeless powder.
II.
Primary Explosives
Primary Explosives, or initiators as they are sometimes called,
explode or detonate when they are heated or subjected to shock. They do not burn and sometimes they
do not even contain the elements necessary for combustion. The materials themselves explode, and the
explosion results whether they are confined or not. Their brisance, or the shock which they produce
when they explode, differs considerably in different explosives, as does their sensitivity to heat
and the amount of heat they give off.
Examples : Mercury Fulminate, Lead Azide,
Fulminating Gold, the mixture of Red Phosphorus with Potassium Chlorate, Copper Acetylide, Nitrogen
Sulfide, and Tetracene.
III. High Explosives
High Explosives
detonate under the influence of the shock of the explosion of a suitable primary explosive. They do
not function by burning. Most of them can be ignited by a flame though and in a small amount
generally burn tranquilly and can be extinguished easily. If heated to a high temperature by
external heat or by their own combustion, they will sometimes explode. They are generally more
brisant and powerful than primary explosives. They exert a mechanical effect on whatever is near
them when they explode, whether they are confined or not.
Examples : Dynamite,
Trinitrotoluene, Tetryl, Picric Acid, Nitrocellulose, Nitroglycerin, Liqiud Oxygen mixed with wood
pulp, fuming Nitric Acid mixed with Nitrobenzene, Ammonium Nitrate , Ammonium Perchlorate, and
Nitroguanidine.
So Now you have taken the first step toward your explosive
education. The next file will be on igniters and will be important for detonating stuff. See ya
then.
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Your introductory description of explosives is so full of shit I hardly know where to begin. By way of background, I have been professionally involved in ordnance design since my high school days (early ’70s) and was trained by the best, starting with the former head of fuels formulation at Aerojet Solid Propulsion Company.
I have worked with ARDEC, Naval Surface Warfare Center, Air Force Research Laboratory Weapons Directorate, McDonnell Douglas Helicopter (now Boeing) Advanced Armament Division (since absorbed by ATK), SACO Defense, Talley Defense, Aerojet Propulsion Co, Rocketdyne, Southwest Research Institute Ballistics Lab and Naval Sea Systems Command. Need I go on?
Let’s see if I can straighten a few things out, in the order they were mentioned. First, there are TWO major classes of explosives, not three. They are…
Low Explosives.
These may include Propellants, but they’re all DEFLAGRATORY explosives. Black powder is the oldest and most familiar. It is nearly impossible to get it to truly “detonate,” i.e. develop a supersonic overpressure wave. (”Air waves?” Gimme’ a break!) Deflagration is a rapid burning (Oxidation) reaction. It generally requires a fuel, such as an organic substance or a finely divided metal, and an Oxidizer, such as a Nitrate, Chlorate or Perchlorate, although there are others. In fact, several comps don’t carry any Oxygen at all, perhaps the best known being a Zinc/Sulfur propellant (although the impetus and therefore the specific impulse are rather weak).
Perhaps the best known, outside of Blackpowder, is a flash comp known as M-80 mix (70/30 KClO4/dark Aluminum). (That’s the official arsenal designation. M-100, M-1,000 and the rest are all bullshit. The actual designation is “Composition-Pyrotechnic-M-80.” using the above formula.)
Deflagration can best be described as the rapid oxidation/combustion of two or more elements into another product by rapid reorganization of constituent materials, resulting in an equally rapid energy release, usually heat and gaseous expansion.
When contained in a vessel such as a heavy walled, paper tube, suffucient pressure accumulates to burst it in such a manner that it develops an overpressure wave which can be loosely described as an “explosion.” If the force released is sufficient to create an overpressure with enough shock and gaseous expansion, work can be accomplished. Before the advent of Nitroglycerin and other high explosives, this is how blasting operations were accomplished, such as mining and road building. They would drill holes in the geologic structures to be disrupted, light a fuse that was placed in the charge and run like hell.
And of course, this deflagatory reaction created sufficient pressure to propel a projectile out of a tube with enough force to push a small pellet of lead into an opposing combatant, or a stone, Iron ball or explosive vessel into a castle wall, a ship’s hull or a formation of troops.
In the late 19th century, Alfred Nobel discovered that cellulose fibers could be subjected to a mixed acid Nitration to produce a substance (Nitrocellulose) which could propel a projectile with much more force than blackpowder. This so-called “smokeless” propellant was capable of acheiving much higher velocities than the ancient, nitrate-based propellants that people used to kill each other with for all of those hundreds of years. Nowadays, propellants may include Nitroglycerine , as both a plasticizer and inhibitor(believe it or not) to keep the NC from detonating under pressure. Ethyl Centralite may also be employed for this purpose. Nitroguanidine may also be employed, primarily as a bulking agent, and doeesn’t add much to the kinetic impetus, but does “fluff” the charge for ease of ignition, and does at least “carry its own weight” as far as power. In recent years, Nitramines (think RDX) and Nitric Esters (think PETN & HMX) have added substantially to velocity (& hence KE), but at the expense of bore erosion problems.
High Explosives.
This is a different animal entirely. Instead of a fuel and an Oxidizer rearranging themselves, the reaction is based on the ability of Nitrogen to combine (but only barely) with other elements in a tenuous fashion which makes the resulting molecules hang together until they are somehow jarred apart.
High explosives are rated according to comparison with TNT (Trinitrotoluene) in terms of expansion, brisance (primarily measured as Velocity of Detonation, or VOD), and reactive pressure, sesiitivity to shock, friction and heating on a percentage basis. For instance, PETN (Pentaerythritol Tetranitrate) has an overall energy release of 160% of TNT, and Nitroglycerine about 120. There are other parameters as well, such as Oxygen balance when blending with other compounds. For instance, PETN has a negative OB (-8%), and Ammonium Nitrate a positive one. So when the two are mixed in the correct proportions and properly detonated, they compliment each other, and some of the brizance (shattering effect) of the PETN is combined with the “heave” (gaseous expansion & therefore work)of the AN is combined.
Primary Explosives.
Unless you really know what you’re doing, these are nothing to mess with. Especially Organic Peroxides. Some are super easy to make, but that doesn’t mean that just anybody can go fucking around with this stuff.
Silver Fulminate was the original initiator compound for NG/Dynamite, but it’s so sensitive that it has been relegated to cigarette loads, throwdown “poppers” and the like. Soon after, it was found that Mercury, subjected to the same Nitration process, would produce an initiator (Mercury Fulminate)that was as powerful as the Silver-based compound, but much less sensitive, making it safer to handle.
Still, the Hg-based primary had its problems. Today, the standard layout is Lead Azide, which is much less sensitive than its predecessors, and delivers sufficient force to shoot most Gelatin Dynamites. ANFO, however, is still so insensitive, and so commonly used, that a booster between the primary & secondary charges is required. This usually takes the form of a small amount of PETN, RDX or HMX. With Primaries, the main concern is not just the VOD, but the pressure developed. However, Detonation velocity is still important, and PETN (7,800 MPS), RDX (8,400) and HMX (9,000) will certainly take care of that. For large charges, seperate boosters are used which are significantly larger than the caps themselves, sometimes weighing several pounds. Also, nowadays the primary is dispensed with entirely, and an “exploding bridgewire” consisting of a small diameter wire or strip of foil, usually gold,is subjected to a quick(400usec), high energy(800vdc @400-600ma) burst of electricity, which actually vaporizes with sufficient force to initiate a booster charge, usually a Nitric Ester or Nitramine.
I won’t even go into military explosives, since some of the things I’ve worked with aren’t the kind of stuff I can talk about, and I don’t want to slip & lose my security clearance.
Like my dear, departed Dad used to tell me: “Keep your mouth shut when youre full of shit.” You should do the same.