Post by Bob WeaverWhat is the exact definition of a "high explosive"? Is flash powder
(potassium perchlorate based composition) considered a "high
explosive"?
Thanks
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The ATF is the government equivalent of the Queen of Spades .... words mean what I say
they mean!
In the rest of the world-
EXPLOSIVES
A SYNOPTIC AND CRITICAL TREATMENT OF THE LITERATURE OF THE SUBJECT
AS GATHERED FROM VARIOUS SOURCES BY DR. H. BRUNSWIG
TRANSLATED AND ANNOTATED BY CHARLES E. MUNROE, PH.D., LL.D. AND ALTON L. KIBLER, M.S., PH.D.
George Washington University
PIRST EDITION 1912
NEW YORK JOHN WILEY & SONS, INC.
LONDON: CHAPMAN & HALL, LIMITED
EXPLOSIVES
PART 1.
CHAPTER 1.
GENERAL BEHAVIOR OF EXPLOSIVE SYSTEMS.***
CONDITIONS GOVERNING EXPLOSIVE REACTIONS.
[*** Literature: M. Berthelot, Foree mat. exp., 18M. E. Sarrau, Theorie des explosifs,
1895. E. Cohen, Studien zur chemischen Dynamik, 1896. J. van't Hoff, Vor. theor. phys.
Chem., 1898-1900. P. Duhem, Thermodynamique et Chimi , 1902, J. W. Mellor, Chem.
Stat. Dyn., 1904. R. Pictet, Zur mechanischen Theorie des Explosivstoffe, 1902. J. P.
Wisser, The Phenomena and Theories of Explosion (without date). V. Jüptner, Expstoff.
Verbren, 1906. W. Nernst, Theo. Chem., 8; 1907.]
1. Among the many phenomena which may accompany an explosion, such as
detonation, flame and the shattering of near-by objects, the most important is a sudden
rise of pressure in the immediate region of the explosive. Freezing water, steam at high
tension and highly compressed gases, when expanding suddenly, can produce certain
phenomena similar to those produced by explosions, but in each of the former cases
there occurs, at the moment of transformation, a sudden fall from an original high
pressure, while in the case of explosive substances there is a sudden rise in
pressure.
2. Explosive reactions, such as are produced by explosive gaseous mixtures or
explosives ordinarily so-called are always accompanied by a chemical transformation,
which, being accelerated by the heat developed and by other causes, Proceeds with
greater or less velocity. Chemical reactions which do not give rise to increased pressure
because no gaseous decomposition products are set free, exhibit no explosive
phenomena. Therefore, thermite, the well-known intimate mixture of a metallic oxide, or
other oxygen carrier, with finely divided aluminum, which on being ignited undergoes
rapid combustion, but furnishes solid or liquid reaction products only, does not belong
to the list of explosives.
3. From the Practical as well as the theoretical standpoint facts arise which make it
difficult to form an exact conception of an explosive and to fix the conditions which must
obtain in order that a given substance may be designated as an explosive. Many
Phenomena indicate that an explosive is in general to be considered as an instabe
system which undergoes intramolecular transformation within an almost infinitely small
period of time. [W. Nernst, Theo. Chem., 672; 190?] This Conception is based essen-
tially upon observations of gaseous mixtures and other homogeneous systems where
practically no energy is wasted, but rather where the mere presence of an accelerating,
and apparently a nonparticipating agent, is sufficient to cause an explosive
transformation.
This conception meets with difficulties so soon as it is applied to a heterogeneous
systems where the contact surfaces of the component part's are very small and. in
certain cases absent. It is true that this, difficulty can theoretically be partly overcome by
the hypothesis of a mutual reaction of the components in the form of vapor, even in the
case of such difficultly volatile components as potassium nitrate or cellulose. Opposed
to this view, however, is the fact that systems which at ordinary temperatures are
supposed to react extremely slowly often give rise at these temperatures to reactions
entirely different from those which take place explosively at higher temperatures, so far
at least, as has been determined experimentally. [Vide sections 23 and 25.]
Explosives have also been defined as substances whose atomic groups are in unstable
equilibrium. According to this conception we might compare them to a cone standing on
its apex. [H. Ost, Lehrbuch der chemischen Technologie, 1907, Abschnitt
Explosivestoffe.] Again it has been conceived that there is a condition of atomic tension
[A. v. Baeyer, Ber., 18, 2278; 1885.] which, like a suddenly released spring, can
perform work. Such attempts at explanation are applicable only to homogeneous
systems. They cannot, without effort, be applied to the technically important types of
explosives having as a base heterogeneous mixtures composed, in part, at least, of
stable substances.
4. A better comprehension of the meaning of the term "explosive substance" maybe
had by determining what conditions are necessary to bring about an explosive reaction.
Although in practice these conditions have proved to be exceedingly variable yet in the
case of every explosion the following conditions, at least, must obtain:
(a) The reaction liberates heat and is therefore essentially. exothermal.
(b) The transformation is one of complete decomposition and hence the explosive
system presents extreme sensitiveness.
(c) The decomposition is definitely of such character as to render an explosion so
possible that it may be caused by any suitable initial impulse or shock.
The explosive reaction is necessarily connected with these three conditions and in
varying degrees which are determined by the nature of the particular explosive system
under consideration. Many substances, such as fulminates, nitrogen halides and nitric
esters, which in their explosive decomposition develop-heat, are also characterized by
extreme sensitiveness, and on this account are to be placed in the first class Of
explosive substances. A second class includes those compounds or mixtures that are
also capable of undergoing marked exothermal decomposition, but are less sensitive
and therefore demand an especially strong initial impulse to cause them to explode. It is
quite easy to understand why substances such as ammonium nitrate, picric acid,
potassium chlorate and others have, until quite recently, been considered nonexplosive.
Finally, we note that systems possessing an explosive potentiality, but which are
capable of several different transformations, frequently seem to prefer that
transformation which results in an explosion. This fact might easily suggest the j
erroneous idea that the direction which a chemical transformation takes generally
coincides with that in which the reaction evolves the most heat. [M. Berthelot, Mech.
Chim., 1878.]
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Martin Meyer
Explosives: An Introduction to Their Chemistry, Production, and Analysis
1943
CHAPTER 2
The Nature of Explosives
Explosion. Explosion is a familar phenomenon which we identify as a sudden event
which is accompanied by a loud noise or report, more or less flame, and the shattering
of nearby material into fragments which are hurled away from the explosion center at
high velocities. An explosive is probably most easily defined, with substantially equal
accuracy, as a material which under some circumstances will behave explosively as
just stated, as in any other way. The list of accompanying phenomena can be made
somewhat longer and they can be more carefully analyzed with respect to their
characteristics, but the definition is perhaps more meaningful than any other that could
be made at this point.
The definition is very broad and might include many things not now regarded as
explosives because the conditions under which they behave explosively have not yet
been called to our attention. Ammonium nitrate, NH4NO3, which is rather difficult to
explode, has for precisely that reason come to be regarded as an explosive only in
recent years. The definition is also practically valuable because any material which can
behave in the way described under easily producible or common circumstances
possesses elements of danger for those in its presence. Legal classification of
explosive materials and rules for their manufacture, handling, and storage are based
upon such considerations.
The essential requirements for explosion are, then: (1) a chemical material intrinsically
possessing the capacity for a certain behavior, and (2) conditions which initiate such
behavior. The necessary conditions usually mean a suitable impulse of some kind.
Hundreds of chemical materials which meet these two requirements are known; and
doubtless many are still unknown. In those unknown cases, it may be questioned that
the order of magnitude of their effects could greatly differ from those now known.
Among the chemical substance and classes of substances which are designated as
explosives may b included: many simple nitrogen compounds such as nitrogen iodide
(NI3), nitrogen chloride (NCl3), nitrogen sulphide (N2S3), cyanogen (C2N2), and
chlorazide (CIN3); hydrazoic acid and its salts, especialy of copper, silver, and lead;
similarly for fulminic acid, hydrocyanic acid, thiocyanic acid, oxalic acid, picric acid,
styphnic acid, and othe acids falling into other chemical groups mentioned here; some
hydrides as phosphine (PH3), stibine (SbH3), and acetylene (C2H2), a well as
acetylides such as copper acetylide (CU2C2) and phosphides chlorates and other
haloxy salts and compounds; permanganates many other oxidizing agents such as
hydrogen peroxide (171202); nitrate esters; nitro compounds in both the aliphatic and
the aromatic series; diazonium compounds; many organometallic compounds; some
ozonides; and in general any mixture of an easily oxidizable substance with a good
oxidizing agent.
The familiar impulses which initiate explosive reaction are the application of some
kind of energy, typically heat or mechanical shock. Of all the accompanying
phenomena, the m6st significant is the sudden rise in pressure which persists until the
reaction is complete; the magnitude of this pressure rise is associated with the amount
of heat evolved by the explosive reaction.
Other Definitions of Explosives. An explosive has also been defined as "a
substance which, when subjected to heat, friction, percussion, or other suitable
initial impulse, undergoes a very rapid chemical transformation, forming other
substances, mainly or entirely gaseous, which at the moment of their formation
tended to occupy a volume very much greater than that of the original substance."'
In general we might say that an explosive is any material which will undergo a rapid
change accompanied by a large increase in volume. This increase in volume
accounts for the pressure, and the heat liberated still further increases [U. S. A., TM
4-205 (1940), Coast Artillery Ammunition, p. 5.] the volume of gases formed,
usually in a ratio of more than 1,000 to 1. The force produced by the volume
increase, plus the explosion wave resulting from the rapid compression of the
surrounding medium immediately followed by a rarefaction, account for many of the
practical phenomena.
Practically useful explosives, for the most part, are solid initially and change partly or
entirely into gases as the result of explosion. Important exceptions are the explosive
gas mixtures which furnish power in internal-combustion engines. Single-gas explosives
are known, such as chlorine dioxide (C102), chlorazide (ClN3), acetylene (C2H2), and
others listed before. Liquid explosives include nitroglycerine and many liquid nitrate
esters and nitro compounds. The reactions involved are usually over-all. exothermic;
and the liberated heat raises the generated gases to a higher temperature, thus greatly
increasing their volume and contributing largely to the total force of the explosion.
Berthelot [Berthelot, sur la force de la poudre et des matières explosives.] gives eight
chemical classes of explosive materials. Of these, for our purposes, the most
important are: (1) explosive inorganic compounds such as azides and fulminates; (2)
explosive organic compounds such as nitroglycerine and trinitrotoluene; (3) mixtures
of oxidizable and oxidizing substances which yield gases on reaction, such as
gunpowder, phosphorus and chlorates, sugar and chlorates or perchlorates. He
classifies explosives also by physical state-solid, liquid or gas.
For purposes of controlling by law the manufacturing, handling, storage, and
transportation, a familiar explosives classification is: (1) low or propellent explosives;
[LE] (2) high explosives, also known as brisant explosives; [HE] (3) initiators; (4)
pyrotechnic mixtures (which strictly are not explosives ordinarily, although they require
care in handling and storage) used for producing smokes and smoke screens, flares,
and as incendiary materials. Gunpowder and smokeless powder are examples of
propellants, T.N.T. and nitroglycerine of high explosives, and fulminates of initiators.
Quantitatively the first two are the important classes.
But the latter classification is based largely on behavior under relatively fixed
conditions. It offers no sharp distinction related to chemical composition, and the
behavior is dependent upon a variety of factors. The principal differences inherent in
the classification are: (1) rate of explosion, which for some hundreds of pounds of
material may be as long as a quarter of a second for a low explosive and practically
instantaneous for a high explosive, and (2) sensitivity. But smokeless powder, which is
classified as a propellant, is chiefly nitrocellulose, which when detonated is a high
explosive; and nitroglycerine, which is classified as a high explosive and is indeed a
very sensitive material, merely burns without detonation when ignited by a small flame
under proper conditions. The original problem of making nitrocellulose available as a
propellant was that of reducing its velocity of explosion to a smaller value.
The explosion of a high explosive is characterized as "detonation." Its high velocity of
explosion, as compared with a low explosive, produces a shattering effect which is
qualitatively different, and makes it unsuitable for driving a projectile. The effect is
sometimes compared to a blow as opposed to a push. the rate at which the explosive
reaction travels through a high explosive depends on several factors and may vary from
1,000 to 10,000 meters per second. It is the shattering effect which earns the name
brisant explosive, and makes it suitable for some purposes-as- for some types of
blasting, initiators, boosters, and bursting charges. Initiators are essentially sensitive
high explosives, while the low explosive is useful as a propellent charge for projectiles,
although gunpowder, while still important, has since 1888 been largely displaced as a
practical propellant.
Experiment. This work should be done behind a barricade!
[snip]
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Definition
Explosives are solid or liquid*) substances, alone or mixed with one another, which are
in a metastable state and are capable, for this reason, of undergoing a rapid chemical
reaction without the participation of external reactants such as atmospheric oxygen.
The reaction can be initiated by mechanical means (impact, friction), by the action of
heat (sparks, open flame, red-hot or white-hot objects), or by detonating shock (Blasting
Cap with or without a booster charge). The resistance of the metastable state to heat is
known as Stability. The ease with which the chemical reaction can be initiated is known
as sensitivity.
The reaction products are predominantly gaseous. The propagation rate from the
initiation site outwards through the explosive material may be much slower than the
velocity of sound ( Deflagration--- Gunpowder) or may be supersonic (Detonation).
Explosives are solid, liquid, or gelatinous substances or mixtures of individual
substances, which have been manufactured for blasting or propulsion purposes. For
their effectiveness: Strength; Burning Rate; Brisance.
Materials which are not intended to be used for blasting or shooting may also be
explosive. They include, for example, organic peroxide catalysts, gas-liberating agents
employed in the modern manufacture of plastic materials and plastic foams, certain
kinds of insecticides etc. Table 12 gives a synoptical view over the whole field of
explosive materials.
*** Of course, gases and gaseous mixtures can also be explosive. Explosive mixtures
are often generated spontaneously (leaks in gas pipes; solvent tanks; firedamp in coal
minning).
Rudolf Meyer
Explosives 3rd ed 1987
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TM 9-1910
4. Definitions
(1) An explosion, a violent bursting or expansion as the result of great pressure, may be
caused by an explosive or the sudden release of pressure, as in the disruption of a
steam boiler. An explosive produces an explosion by virtue of the very rapid,
self-propagating transformation of the material into more stable substances; always with
the liberation of heat and almost always with the formation of gas.
(2) An explosive may be a chemical compound such as TNT or,, nitroglycerin, a mixture
of compounds, such as TNT and ammonium nitrate comprising amatol, or a mixture of
one or more compounds and one or more elements such as potassium nitrate, sulfur,
and carbon comprising black powder.
(3)An explosive may be solid, liquid, or gaseous. TNT and nitroglycerin are examples of
solid and liquid explosives, respectively. A mixture of 2 volumes of gaseous hydrogen
and I volume of gaseous oxygen, when confined, is an example of a gaseous
explosive. Military explosives are chiefly solids or mixtures so formulated as to be solid
at, normal temperature of use.
(4) The characteristic effect of explosives generally is the result of the great pressure
produced when a solid or liquid is suddenly converted into a much larger volume of gas
and the effective volume of this gas is greatly increased by the expansive effect of the
heat liberated simultaneously. A few explosives, such as cuprous acetylide, do not form
gases
CU2C2--->2 Cu+2C
because the heat liberated is not sufficient to gasify the products. In such cases, the
explosive effect is due to the rapidity of liberation of heat and its expansive effect on
the, adjacent air. A mixture of 2 volumes of hydrogen and 1 volume of oxygen, on
reaction, yields only 1 volume of gaseous water, but the heat liberated makes the
effective volume of the gaseous water much greater and pressure is produced
suddenly.
(5) While military explosives produce gases only, and this is necessary for maximum
explosive effect, a few yield solid as well as gessoes products of explosion. On
explosion, black powder yields solid potassium carbonate and sulfate as well as gases.
(6) The rates of transformation of explosives have been found vary greatly. One group,
which includes smokeless and black powders, undergoes autocombustion at rates that.
vary from a few centimeters per minute to approximately 4 meters per second. These
are known as "low explosives. A second group, which includes TNT and nitroglycerin,
been found to undergo detonation at rates from 1,000 to 8,500 meters per second.
Such materials are know., "high explosives." Low explosives undergo oxidation actions
or decomposition, elements or compounds being converted directly into other elements
and compounds, as in black powder and smokeless powder-
3C+S+4KNO3--->2N2+K2CO3+K2SO4+2C2+1/2O2
C24H30N10O40 -->5N2+10H+5H2O+11CO2+13CO
High explosives undergo much more rapid decomposition nitroglycerin-
2C3H5N309 --> 6C+10H+6N+180-->3N2+5H20+6CO2+1/202
Some high explosives, such as nitrocellulose, can be ca by physical conditioning to be
capable of functioning as a low explosive when ignited. Although the mechanisms,
rates of explosion of the two groups differ greatly, human sensory perception cannot
always distinguish between actions.
(7) From the foregoing, it will be recognized that an explosive is characterized by a
self-propagating reaction or decomposition with the liberation of heat and the
development of, local pressure effect. An explosive, therefore, may be defined as a
material that can undergo very rapid self-propagating decomposition with, the formation
of more stable materials, the liberation of heat, and the development of a sudden
pressure effect through the action of the heat on produced or adjacent gases. It will be
noted definition is applicable to the material in an atomic bomb which undergoes
nuclear fission.
--
donald j haarmann
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An explosion may be defined as a loud noise
accompanied by the sudden going away of
things from the places where they were before.
- Joseph Needham