Explosive

An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An explosive charge is a measured quantity of explosive material, which may be composed of a single ingredient or a combination of two or more.

The potential energy stored in an explosive material may, for example, be

Explosive materials may be categorized by the speed at which they expand. Materials that detonate (the front of the chemical reaction moves faster through the material than the speed of sound) are said to be "high explosives" and materials that deflagrate are said to be "low explosives". Explosives may also be categorized by their sensitivity. Sensitive materials that can be initiated by a relatively small amount of heat or pressure are primary explosives and materials that are relatively insensitive are secondary or tertiary explosives.

A wide variety of chemicals can explode; a smaller number are manufactured specifically for the purpose of being used as explosives. The remainder are too dangerous, sensitive, toxic, expensive, unstable, or prone to decomposition or degradation over short time spans.

In contrast, some materials are merely combustible or flammable if they burn without exploding.

The distinction, however, is not razor-sharp. Certain materials—dusts, powders, gases, or volatile organic liquids—may be simply combustible or flammable under ordinary conditions, but become explosive in specific situations or forms, such as dispersed airborne clouds, or confinement or sudden release.

Demonstration of the explosive properties of three different explosives. Each explosive is set on a solid marble base and is initiated by a glowing wooden stick.

History

At its root, the history of chemical explosives lies in the history of gunpowder.[1][2] During the Tang Dynasty in the 9th century, Taoist Chinese alchemists were eagerly trying to find the elixir of immortality.[3] In the process, they stumbled upon the explosive invention of gunpowder made from coal, saltpeter, and sulfur in 1044. Gunpowder was the first form of chemical explosives and by 1161, the Chinese were using explosives for the first time in warfare.[4][5][6] The Chinese would incorporate explosives fired from bamboo or bronze tubes known as bamboo fire crackers. The Chinese also used inserted rats from inside the bamboo fire crackers to fire toward the enemy, creating great psychological ramifications—scaring enemy soldiers away and causing cavalry units to go wild.[7]

Though early thermal weapons, such as Greek fire, have existed since ancient times, the first widely used explosive in warfare and mining was black powder, invented in 9th century in China by Song Chinese alchemists. This material was sensitive to water, and it produced copious amounts of dark smoke. The first useful explosive stronger than black powder was nitroglycerin, developed in 1847. Since nitroglycerin is a liquid and highly unstable, it was replaced by nitrocellulose, trinitrotoluene (TNT) in 1863, smokeless powder, dynamite in 1867 and gelignite (the latter two being sophisticated stabilized preparations of nitroglycerin rather than chemical alternatives, both invented by Alfred Nobel). World War I saw the adoption of TNT in artillery shells. World War II saw an extensive use of new explosives (see List of explosives used during World War II). In turn, these have largely been replaced by more powerful explosives such as C-4 and PETN. However, C-4 and PETN react with metal and catch fire easily, yet unlike TNT, C-4 and PETN are waterproof and malleable.[8]

Applications

A video on safety precautions at blast sites

Commercial

A video describing how to safely handle explosives in mines.

The largest commercial application of explosives is mining. Whether the mine is on the surface or is buried underground, the detonation or deflagration of either a high or low explosive in a confined space can be used to liberate a fairly specific sub-volume of a brittle material in a much larger volume of the same or similar material. The mining industry tends to use nitrate-based explosives such as emulsions of fuel oil and ammonium nitrate solutions, mixtures of ammonium nitrate prills (fertilizer pellets) and fuel oil (ANFO) and gelatinous suspensions or slurries of ammonium nitrate and combustible fuels.

In Materials Science and Engineering, explosives are used in cladding (explosion welding). A thin plate of some material is placed atop a thick layer of a different material, both layers typically of metal. Atop the thin layer is placed an explosive. At one end of the layer of explosive, the explosion is initiated. The two metallic layers are forced together at high speed and with great force. The explosion spreads from the initiation site throughout the explosive. Ideally, this produces a metallurgical bond between the two layers.

As the length of time the shock wave spends at any point is small, we can see mixing of the two metals and their surface chemistries, through some fraction of the depth, and they tend to be mixed in some way. It is possible that some fraction of the surface material from either layer eventually gets ejected when the end of material is reached. Hence, the mass of the now "welded" bilayer, may be less than the sum of the masses of the two initial layers.

There are applications where a shock wave, and electrostatics, can result in high velocity projectiles.

Safety

Types

Chemical

GHS-pictogram-explos
The international pictogram for explosive substances

An explosion is a type of spontaneous chemical reaction that, once initiated, is driven by both a large exothermic change (great release of heat) and a large positive entropy change (great quantities of gases are released) in going from reactants to products, thereby constituting a thermodynamically favorable process in addition to one that propagates very rapidly. Thus, explosives are substances that contain a large amount of energy stored in chemical bonds. The energetic stability of the gaseous products and hence their generation comes from the formation of strongly bonded species like carbon monoxide, carbon dioxide, and (di)nitrogen, which contain strong double and triple bonds having bond strengths of nearly 1 MJ/mole. Consequently, most commercial explosives are organic compounds containing -NO2, -ONO2 and -NHNO2 groups that, when detonated, release gases like the aforementioned (e.g., nitroglycerin, TNT, HMX, PETN, nitrocellulose).[9]

An explosive is classified as a low or high explosive according to its rate of combustion: low explosives burn rapidly (or deflagrate), while high explosives detonate. While these definitions are distinct, the problem of precisely measuring rapid decomposition makes practical classification of explosives difficult.

Traditional explosives mechanics is based on the shock-sensitive rapid oxidation of carbon and hydrogen to carbon dioxide, carbon monoxide and water in the form of steam. Nitrates typically provide the required oxygen to burn the carbon and hydrogen fuel. High explosives tend to have the oxygen, carbon and hydrogen contained in one organic molecule, and less sensitive explosives like ANFO are combinations of fuel (carbon and hydrogen fuel oil) and ammonium nitrate. A sensitizer such as powdered aluminum may be added to an explosive to increase the energy of the detonation. Once detonated, the nitrogen portion of the explosive formulation emerges as nitrogen gas and toxic nitric oxides.

Decomposition

The chemical decomposition of an explosive may take years, days, hours, or a fraction of a second. The slower processes of decomposition take place in storage and are of interest only from a stability standpoint. Of more interest are the other two rapid forms besides decomposition: deflagration and detonation.

Deflagration

In deflagration, decomposition of the explosive material is propagated by a flame front which moves slowly through the explosive material at speeds less than the speed of sound within the substance (usually below 1000 m/s) [10] in contrast to detonation, which occurs at speeds greater than the speed of sound. Deflagration is a characteristic of low explosive material.

Detonation

This term is used to describe an explosive phenomenon whereby the decomposition is propagated by an explosive shock wave traversing the explosive material at speeds greater than the speed of sound within the substance.[11] The shock front is capable of passing through the high explosive material at supersonic speeds, typically thousands of metres per second.

Exotic

In addition to chemical explosives, there are a number of more exotic explosive materials, and exotic methods of causing explosions. Examples include nuclear explosives, and abruptly heating a substance to a plasma state with a high-intensity laser or electric arc.

Laser- and arc-heating are used in laser detonators, exploding-bridgewire detonators, and exploding foil initiators, where a shock wave and then detonation in conventional chemical explosive material is created by laser- or electric-arc heating. Laser and electric energy are not currently used in practice to generate most of the required energy, but only to initiate reactions.

Properties of explosive materials

To determine the suitability of an explosive substance for a particular use, its physical properties must first be known. The usefulness of an explosive can only be appreciated when the properties and the factors affecting them are fully understood. Some of the more important characteristics are listed below:

Sensitivity

Sensitivity refers to the ease with which an explosive can be ignited or detonated, i.e., the amount and intensity of shock, friction, or heat that is required. When the term sensitivity is used, care must be taken to clarify what kind of sensitivity is under discussion. The relative sensitivity of a given explosive to impact may vary greatly from its sensitivity to friction or heat. Some of the test methods used to determine sensitivity relate to:

  • Impact – Sensitivity is expressed in terms of the distance through which a standard weight must be dropped onto the material to cause it to explode.
  • Friction – Sensitivity is expressed in terms of the amount of pressure applied to the material in order to create enough friction to cause a reaction.
  • Heat – Sensitivity is expressed in terms of the temperature at which decomposition of the material occurs.

Specific explosives (usually but not always highly sensitive on one or more of the three above axes) may be idiosyncratically sensitive to such factors as pressure drop, acceleration, the presence of sharp edges or rough surfaces, incompatible materials, or even—in rare cases—nuclear or electromagnetic radiation. These factors present special hazards that may rule out any practical utility.

Sensitivity is an important consideration in selecting an explosive for a particular purpose. The explosive in an armor-piercing projectile must be relatively insensitive, or the shock of impact would cause it to detonate before it penetrated to the point desired. The explosive lenses around nuclear charges are also designed to be highly insensitive, to minimize the risk of accidental detonation.

Sensitivity to initiation

The index of the capacity of an explosive to be initiated into detonation in a sustained manner. It is defined by the power of the detonator which is certain to prime the explosive to a sustained and continuous detonation. Reference is made to the Sellier-Bellot scale that consists of a series of 10 detonators, from n. 1 to n. 10, each of which corresponds to an increasing charge weight. In practice, most of the explosives on the market today are sensitive to an n. 8 detonator, where the charge corresponds to 2 grams of mercury fulminate.

Velocity of detonation

The velocity with which the reaction process propagates in the mass of the explosive. Most commercial mining explosives have detonation velocities ranging from 1800 m/s to 8000 m/s. Today, velocity of detonation can be measured with accuracy. Together with density it is an important element influencing the yield of the energy transmitted for both atmospheric over-pressure and ground acceleration. By definition, a "low explosive", such as black powder, or smokeless gunpowder has a burn rate of 171–631 m/s.[12] In contrast, a "high explosive", whether a primary, such as detonating cord, or a secondary, such as TNT or C-4 has a significantly higher burn rate.[13]

Stability

Stability is the ability of an explosive to be stored without deterioration.

The following factors affect the stability of an explosive:

  • Chemical constitution. In the strictest technical sense, the word "stability" is a thermodynamic term referring to the energy of a substance relative to a reference state or to some other substance. However, in the context of explosives, stability commonly refers to ease of detonation, which is concerned with kinetics (i.e., rate of decomposition). It is perhaps best, then, to differentiate between the terms thermodynamically stable and kinetically stable by referring to the former as "inert." Contrarily, a kinetically unstable substance is said to be "labile." It is generally recognized that certain groups like nitro (–NO2), nitrate (–ONO2), and azide (–N3), are intrinsically labile. Kinetically, there exists a low activation barrier to the decomposition reaction. Consequently, these compounds exhibit high sensitivity to flame or mechanical shock. The chemical bonding in these compounds is characterized as predominantly covalent and thus they are not thermodynamically stabilized by a high ionic-lattice energy. Furthermore, they generally have positive enthalpies of formation and there is little mechanistic hindrance to internal molecular rearrangement to yield the more thermodynamically stable (more strongly bonded) decomposition products. For example, in lead azide, Pb(N3)2, the nitrogen atoms are already bonded to one another, so decomposition into Pb and N2[1] is relatively easy.
  • Temperature of storage. The rate of decomposition of explosives increases at higher temperatures. All standard military explosives may be considered to have a high degree of stability at temperatures from –10 to +35 °C, but each has a high temperature at which its rate of decomposition rapidly accelerates and stability is reduced. As a rule of thumb, most explosives become dangerously unstable at temperatures above 70 °C.
  • Exposure to sunlight. When exposed to the ultraviolet rays of sunlight, many explosive compounds containing nitrogen groups rapidly decompose, affecting their stability.
  • Electrical discharge. Electrostatic or spark sensitivity to initiation is common in a number of explosives. Static or other electrical discharge may be sufficient to cause a reaction, even detonation, under some circumstances. As a result, safe handling of explosives and pyrotechnics usually requires proper electrical grounding of the operator.

Power, performance, and strength

The term power or performance as applied to an explosive refers to its ability to do work. In practice it is defined as the explosive's ability to accomplish what is intended in the way of energy delivery (i.e., fragment projection, air blast, high-velocity jet, underwater shock and bubble energy, etc.). Explosive power or performance is evaluated by a tailored series of tests to assess the material for its intended use. Of the tests listed below, cylinder expansion and air-blast tests are common to most testing programs, and the others support specific applications.

  • Cylinder expansion test. A standard amount of explosive is loaded into a long hollow cylinder, usually of copper, and detonated at one end. Data is collected concerning the rate of radial expansion of the cylinder and the maximum cylinder wall velocity. This also establishes the Gurney energy or 2E.
  • Cylinder fragmentation. A standard steel cylinder is loaded with explosive and detonated in a sawdust pit. The fragments are collected and the size distribution analyzed.
  • Detonation pressure (Chapman–Jouguet condition). Detonation pressure data derived from measurements of shock waves transmitted into water by the detonation of cylindrical explosive charges of a standard size.
  • Determination of critical diameter. This test establishes the minimum physical size a charge of a specific explosive must be to sustain its own detonation wave. The procedure involves the detonation of a series of charges of different diameters until difficulty in detonation wave propagation is observed.
  • Massive-diameter detonation velocity. Detonation velocity is dependent on loading density (c), charge diameter, and grain size. The hydrodynamic theory of detonation used in predicting explosive phenomena does not include the diameter of the charge, and therefore a detonation velocity, for a massive diameter. This procedure requires the firing of a series of charges of the same density and physical structure, but different diameters, and the extrapolation of the resulting detonation velocities to predict the detonation velocity of a charge of a massive diameter.
  • Pressure versus scaled distance. A charge of a specific size is detonated and its pressure effects measured at a standard distance. The values obtained are compared with those for TNT.
  • Impulse versus scaled distance. A charge of a specific size is detonated and its impulse (the area under the pressure-time curve) measured as a function of distance. The results are tabulated and expressed as TNT equivalents.
  • Relative bubble energy (RBE). A 5 to 50 kg charge is detonated in water and piezoelectric gauges measure peak pressure, time constant, impulse, and energy.
The RBE may be defined as Kx 3
RBE = Ks
where K = the bubble expansion period for an experimental (x) or a standard (s) charge.

Brisance

In addition to strength, explosives display a second characteristic, which is their shattering effect or brisance (from the French meaning to "break"), which is distinguished and separate from their total work capacity. This characteristic is of practical importance in determining the effectiveness of an explosion in fragmenting shells, bomb casings, grenades, and the like. The rapidity with which an explosive reaches its peak pressure (power) is a measure of its brisance. Brisance values are primarily employed in France and Russia.

The sand crush test is commonly employed to determine the relative brisance in comparison to TNT. No test is capable of directly comparing the explosive properties of two or more compounds; it is important to examine the data from several such tests (sand crush, trauzl, and so forth) in order to gauge relative brisance. True values for comparison require field experiments.

Density

Density of loading refers to the mass of an explosive per unit volume. Several methods of loading are available, including pellet loading, cast loading, and press loading, the choice being determined by the characteristics of the explosive. Dependent upon the method employed, an average density of the loaded charge can be obtained that is within 80–99% of the theoretical maximum density of the explosive. High load density can reduce sensitivity by making the mass more resistant to internal friction. However, if density is increased to the extent that individual crystals are crushed, the explosive may become more sensitive. Increased load density also permits the use of more explosive, thereby increasing the power of the warhead. It is possible to compress an explosive beyond a point of sensitivity, known also as dead-pressing, in which the material is no longer capable of being reliably initiated, if at all.

Volatility

Volatility is the readiness with which a substance vaporizes. Excessive volatility often results in the development of pressure within rounds of ammunition and separation of mixtures into their constituents. Volatility affects the chemical composition of the explosive such that a marked reduction in stability may occur, which results in an increase in the danger of handling.

Hygroscopicity and water resistance

The introduction of water into an explosive is highly undesirable since it reduces the sensitivity, strength, and velocity of detonation of the explosive. Hygroscopicity is a measure of a material's moisture-absorbing tendencies. Moisture affects explosives adversely by acting as an inert material that absorbs heat when vaporized, and by acting as a solvent medium that can cause undesired chemical reactions. Sensitivity, strength, and velocity of detonation are reduced by inert materials that reduce the continuity of the explosive mass. When the moisture content evaporates during detonation, cooling occurs, which reduces the temperature of reaction. Stability is also affected by the presence of moisture since moisture promotes decomposition of the explosive and, in addition, causes corrosion of the explosive's metal container.

Explosives considerably differ from one another as to their behavior in the presence of water. Gelatin dynamites containing nitroglycerine have a degree of water resistance. Explosives based on ammonium nitrate have little or no water resistance as ammonium nitrate is highly soluble in water and is hygroscopic.

Toxicity

Many explosives are toxic to some extent. Manufacturing inputs can also be organic compounds or hazardous materials that require special handing due to risks (such as carcinogens). The decomposition products, residual solids, or gases of some explosives can be toxic, whereas others are harmless, such as carbon dioxide and water.

Examples of harmful by-products are:

  • Heavy metals, such as lead, mercury, and barium from primers (observed in high-volume firing ranges)
  • Nitric oxides from TNT
  • Perchlorates when used in large quantities

"Green explosives" seek to reduce environment and health impacts. An example of such is the lead-free primary explosive copper(I) 5-nitrotetrazolate, an alternative to lead azide.[14] One variety of a green explosive is CDP explosives, whose synthesis does not involve any toxic ingredients, consumes carbon dioxide while detonating and does not release any nitric oxides into the atmosphere when used.

Explosive train

Explosive material may be incorporated in the explosive train of a device or system. An example is a pyrotechnic lead igniting a booster, which causes the main charge to detonate.

Volume of products of explosion

The most widely used explosives are condensed liquids or solids converted to gaseous products by explosive chemical reactions and the energy released by those reactions. The gaseous products of complete reaction are typically carbon dioxide, steam, and nitrogen.[15] Gaseous volumes computed by the ideal gas law tend to be too large at high pressures characteristic of explosions.[16] Ultimate volume expansion may be estimated at three orders of magnitude, or one liter per gram of explosive. Explosives with an oxygen deficit will generate soot or gases like carbon monoxide and hydrogen, which may react with surrounding materials such as atmospheric oxygen.[15] Attempts to obtain more precise volume estimates must consider the possibility of such side reactions, condensation of steam, and aqueous solubility of gases like carbon dioxide.[17]

By comparison, CDP detonation is based on the rapid reduction of carbon dioxide to carbon with the abundant release of energy. Rather than produce typical waste gases like carbon dioxide, carbon monoxide, nitrogen and nitric oxides, CDP is different. Instead, the highly energetic reduction of carbon dioxide to carbon vaporizes and pressurizes excess dry ice at the wave front, which is the only gas released from the detonation. The velocity of detonation for CDP formulations can therefore be customized by adjusting the weight percentage of reducing agent and dry ice. CDP detonations produce a large amount of solid materials that can have great commercial value as an abrasive:

Example – CDP Detonation Reaction with Magnesium: XCO2 + 2Mg → 2MgO + C + (X-1)CO2

The products of detonation in this example are magnesium oxide, carbon in various phases including diamond, and vaporized excess carbon dioxide that was not consumed by the amount of magnesium in the explosive formulation.[18]

Oxygen balance (OB% or Ω)

Oxygen balance is an expression that is used to indicate the degree to which an explosive can be oxidized. If an explosive molecule contains just enough oxygen to convert all of its carbon to carbon dioxide, all of its hydrogen to water, and all of its metal to metal oxide with no excess, the molecule is said to have a zero oxygen balance. The molecule is said to have a positive oxygen balance if it contains more oxygen than is needed and a negative oxygen balance if it contains less oxygen than is needed.[19] The sensitivity, strength, and brisance of an explosive are all somewhat dependent upon oxygen balance and tend to approach their maxima as oxygen balance approaches zero.

Oxygen balance applies to traditional explosives mechanics with the assumption that carbon is oxidized to carbon monoxide and carbon dioxide during detonation. In what seems like a paradox to an explosives expert, Cold Detonation Physics uses carbon in its most highly oxidized state as the source of oxygen in the form of carbon dioxide. Oxygen balance, therefore, either does not apply to a CDP formulation or must be calculated without including the carbon in the carbon dioxide.[18]

Chemical composition

A chemical explosive may consist of either a chemically pure compound, such as nitroglycerin, or a mixture of a fuel and an oxidizer, such as black powder or grain dust and air.

Chemically pure compounds

Some chemical compounds are unstable in that, when shocked, they react, possibly to the point of detonation. Each molecule of the compound dissociates into two or more new molecules (generally gases) with the release of energy.

  • Nitroglycerin: A highly unstable and sensitive liquid
  • Acetone peroxide: A very unstable white organic peroxide
  • TNT: Yellow insensitive crystals that can be melted and cast without detonation
  • Cellulose nitrate: A nitrated polymer which can be a high or low explosive depending on nitration level and conditions
  • RDX, PETN, HMX: Very powerful explosives which can be used pure or in plastic explosives

The above compositions may describe most of the explosive material, but a practical explosive will often include small percentages of other substances. For example, dynamite is a mixture of highly sensitive nitroglycerin with sawdust, powdered silica, or most commonly diatomaceous earth, which act as stabilizers. Plastics and polymers may be added to bind powders of explosive compounds; waxes may be incorporated to make them safer to handle; aluminium powder may be introduced to increase total energy and blast effects. Explosive compounds are also often "alloyed": HMX or RDX powders may be mixed (typically by melt-casting) with TNT to form Octol or Cyclotol.

Mixture of oxidizer and fuel

An oxidizer is a pure substance (molecule) that in a chemical reaction can contribute some atoms of one or more oxidizing elements, in which the fuel component of the explosive burns. On the simplest level, the oxidizer may itself be an oxidizing element, such as gaseous or liquid oxygen.

Availability and cost

The availability and cost of explosives are determined by the availability of the raw materials and the cost, complexity, and safety of the manufacturing operations.

Classification of explosive materials

By sensitivity

Primary explosive

A primary explosive is an explosive that is extremely sensitive to stimuli such as impact, friction, heat, static electricity, or electromagnetic radiation. Some primary explosives are also known as contact explosives. A relatively small amount of energy is required for initiation. As a very general rule, primary explosives are considered to be those compounds that are more sensitive than PETN. As a practical measure, primary explosives are sufficiently sensitive that they can be reliably initiated with a blow from a hammer; however, PETN can also usually be initiated in this manner, so this is only a very broad guideline. Additionally, several compounds, such as nitrogen triiodide, are so sensitive that they cannot even be handled without detonating. Nitrogen triiodide is so sensitive that it can be reliably detonated by exposure to alpha radiation; it is the only explosive for which this is true.

Primary explosives are often used in detonators or to trigger larger charges of less sensitive secondary explosives. Primary explosives are commonly used in blasting caps and percussion caps to translate a physical shock signal. In other situations, different signals such as electrical or physical shock, or, in the case of laser detonation systems, light, are used to initiate an action, i.e., an explosion. A small quantity, usually milligrams, is sufficient to initiate a larger charge of explosive that is usually safer to handle.

Examples of primary high explosives are:

Secondary explosive

A secondary explosive is less sensitive than a primary explosive and requires substantially more energy to be initiated. Because they are less sensitive, they are usable in a wider variety of applications and are safer to handle and store. Secondary explosives are used in larger quantities in an explosive train and are usually initiated by a smaller quantity of a primary explosive.

Examples of secondary explosives include TNT and RDX.

Tertiary explosive

Tertiary explosives, also called blasting agents, are so insensitive to shock that they cannot be reliably detonated by practical quantities of primary explosive, and instead require an intermediate explosive booster of secondary explosive. These are often used for safety and the typically lower costs of material and handling. The largest consumers are large-scale mining and construction operations.

Most tertiaries include a fuel and an oxidizer. ANFO can be a tertiary explosive if its reaction rate is slow.

By velocity

Low explosives

Low explosives are compounds where the rate of decomposition proceeds through the material at less than the speed of sound. The decomposition is propagated by a flame front (deflagration) which travels much more slowly through the explosive material than a shock wave of a high explosive. Under normal conditions, low explosives undergo deflagration at rates that vary from a few centimetres per second to approximately 400 metres per second. It is possible for them to deflagrate very quickly, producing an effect similar to a detonation. This can happen under higher pressure or temperature, which usually occurs when ignited in a confined space.

A low explosive is usually a mixture of a combustible substance and an oxidant that decomposes rapidly (deflagration); however, they burn more slowly than a high explosive, which has an extremely fast burn rate.

Low explosives are normally employed as propellants. Included in this group are petroleum products such as propane and gasoline, gunpowder (including smokeless powder), and light pyrotechnics, such as flares and fireworks, but can replace high explosives in certain applications, see gas pressure blasting.

High explosives

High explosives (HE) are explosive materials that detonate, meaning that the explosive shock front passes through the material at a supersonic speed. High explosives detonate with explosive velocity ranging from 3 to 9 km/s. For instance, TNT has a detonation (burn) rate of approximately 5.8 km/s (19,000 feet per second), detonating cord of 6.7 km/s (22,000 feet per second), and C-4 about 8.5 km/s (29,000 feet per second). They are normally employed in mining, demolition, and military applications. They can be divided into two explosives classes differentiated by sensitivity: primary explosive and secondary explosive. The term high explosive is in contrast with the term low explosive, which explodes (deflagrates) at a lower rate.

Countless high-explosive compounds are chemically possible, but commercially and militarily important ones have included NG, TNT, TNX, RDX, HMX, PETN, TATB, and HNS.

By composition

Priming composition

Priming compositions are primary explosives mixed with other compositions to control (lessen) the sensitivity of the mixture to the desired property.

For example, primary explosives are so sensitive that they need to be stored and shipped in a wet state to prevent accidental initiation.

By physical form

Explosives are often characterized by the physical form that the explosives are produced or used in. These use forms are commonly categorized as:[23]

Shipping label classifications

Shipping labels and tags may include both United Nations and national markings.

United Nations markings include numbered Hazard Class and Division (HC/D) codes and alphabetic Compatibility Group codes. Though the two are related, they are separate and distinct. Any Compatibility Group designator can be assigned to any Hazard Class and Division. An example of this hybrid marking would be a consumer firework, which is labeled as 1.4G or 1.4S.

Examples of national markings would include United States Department of Transportation (U.S. DOT) codes.

United Nations Organization (UNO) Hazard Class and Division (HC/D)

Dangclass1
Explosives warning sign

The Hazard Class and Division (HC/D) is a numeric designator within a hazard class indicating the character, predominance of associated hazards, and potential for causing personnel casualties and property damage. It is an internationally accepted system that communicates using the minimum amount of markings the primary hazard associated with a substance.[24]

Listed below are the Divisions for Class 1 (Explosives):

  • 1.1 Mass Detonation Hazard. With HC/D 1.1, it is expected that if one item in a container or pallet inadvertently detonates, the explosion will sympathetically detonate the surrounding items. The explosion could propagate to all or the majority of the items stored together, causing a mass detonation. There will also be fragments from the item's casing and/or structures in the blast area.
  • 1.2 Non-mass explosion, fragment-producing. HC/D 1.2 is further divided into three subdivisions, HC/D 1.2.1, 1.2.2 and 1.2.3, to account for the magnitude of the effects of an explosion.
  • 1.3 Mass fire, minor blast or fragment hazard. Propellants and many pyrotechnic items fall into this category. If one item in a package or stack initiates, it will usually propagate to the other items, creating a mass fire.
  • 1.4 Moderate fire, no blast or fragment. HC/D 1.4 items are listed in the table as explosives with no significant hazard. Most small arms ammunition (including loaded weapons) and some pyrotechnic items fall into this category. If the energetic material in these items inadvertently initiates, most of the energy and fragments will be contained within the storage structure or the item containers themselves.
  • 1.5 mass detonation hazard, very insensitive.
  • 1.6 detonation hazard without mass detonation hazard, extremely insensitive.

To see an entire UNO Table, browse Paragraphs 3-8 and 3-9 of NAVSEA OP 5, Vol. 1, Chapter 3.

Class 1 Compatibility Group

Compatibility Group codes are used to indicate storage compatibility for HC/D Class 1 (explosive) materials. Letters are used to designate 13 compatibility groups as follows.

  • A: Primary explosive substance (1.1A).
  • B: An article containing a primary explosive substance and not containing two or more effective protective features. Some articles, such as detonator assemblies for blasting and primers, cap-type, are included. (1.1B, 1.2B, 1.4B).
  • C: Propellant explosive substance or other deflagrating explosive substance or article containing such explosive substance (1.1C, 1.2C, 1.3C, 1.4C). These are bulk propellants, propelling charges, and devices containing propellants with or without means of ignition. Examples include single-based propellant, double-based propellant, triple-based propellant, and composite propellants, solid propellant rocket motors and ammunition with inert projectiles.
  • D: Secondary detonating explosive substance or black powder or article containing a secondary detonating explosive substance, in each case without means of initiation and without a propelling charge, or article containing a primary explosive substance and containing two or more effective protective features. (1.1D, 1.2D, 1.4D, 1.5D).
  • E: Article containing a secondary detonating explosive substance without means of initiation, with a propelling charge (other than one containing flammable liquid, gel or hypergolic liquid) (1.1E, 1.2E, 1.4E).
  • F containing a secondary detonating explosive substance with its means of initiation, with a propelling charge (other than one containing flammable liquid, gel or hypergolic liquid) or without a propelling charge (1.1F, 1.2F, 1.3F, 1.4F).
  • G: Pyrotechnic substance or article containing a pyrotechnic substance, or article containing both an explosive substance and an illuminating, incendiary, tear-producing or smoke-producing substance (other than a water-activated article or one containing white phosphorus, phosphide or flammable liquid or gel or hypergolic liquid) (1.1G, 1.2G, 1.3G, 1.4G). Examples include Flares, signals, incendiary or illuminating ammunition and other smoke and tear producing devices.
  • H: Article containing both an explosive substance and white phosphorus (1.2H, 1.3H). These articles will spontaneously combust when exposed to the atmosphere.
  • J: Article containing both an explosive substance and flammable liquid or gel (1.1J, 1.2J, 1.3J). This excludes liquids or gels which are spontaneously flammable when exposed to water or the atmosphere, which belong in group H. Examples include liquid or gel filled incendiary ammunition, fuel-air explosive (FAE) devices, and flammable liquid fueled missiles.
  • K: Article containing both an explosive substance and a toxic chemical agent (1.2K, 1.3K)
  • L Explosive substance or article containing an explosive substance and presenting a special risk (e.g., due to water-activation or presence of hypergolic liquids, phosphides, or pyrophoric substances) needing isolation of each type (1.1L, 1.2L, 1.3L). Damaged or suspect ammunition of any group belongs in this group.
  • N: Articles containing only extremely insensitive detonating substances (1.6N).
  • S: Substance or article so packed or designed that any hazardous effects arising from accidental functioning are limited to the extent that they do not significantly hinder or prohibit fire fighting or other emergency response efforts in the immediate vicinity of the package (1.4S).

Regulation

The legality of possessing or using explosives varies by jurisdiction. Various countries around the world have enacted explosives law and require licenses to manufacture, distribute, store, use, possess explosives or ingredients.

Netherlands

In the Netherlands, the civil and commercial use of explosives is covered under the Wet explosieven voor civiel gebruik (explosives for civil use Act), in accordance with EU directive nr. 93/15/EEG[25] (Dutch). The illegal use of explosives is covered under the Wet Wapens en Munitie (Weapons and Munition Act)[26] (Dutch).

UK

The new Explosives Regulations 2014 (ER 2014)[27] came into force on 1 October 2014 and defines "explosive" as:

"a)any explosive article or explosive substance which would —

(i)if packaged for transport, be classified in accordance with the United Nations Recommendations as falling within Class 1; or

(ii)be classified in accordance with the United Nations Recommendations as —

(aa)being unduly sensitive or so reactive as to be subject to spontaneous reaction and accordingly too dangerous to transport, and

(bb)falling within Class 1; or

(b)a desensitised explosive,

but it does not include an explosive substance produced as part of a manufacturing process which thereafter reprocesses it in order to produce a substance or preparation which is not an explosive substance"[27]

"Anyone who wishes to acquire and or keep relevant explosives needs to contact their local police explosives liaison officer.  All explosives are relevant explosives apart from those listed under Schedule 2 of Explosives Regulations 2014."[28]

United States

During World War I, numerous laws were created to regulate war related industries and increase security within the United States. In 1917, the 65th United States Congress created many laws, including the Espionage Act of 1917 and Explosives Act of 1917.

The Explosives Act of 1917 (session 1, chapter 83, 40 Stat. 385) was signed on 6 October 1917 and went into effect on 16 November 1917. The legal summary is "An Act to prohibit the manufacture, distribution, storage, use, and possession in time of war of explosives, providing regulations for the safe manufacture, distribution, storage, use, and possession of the same, and for other purposes". This was the first federal regulation of licensing explosives purchases. The act was deactivated after World War I ended.[29]

After the United States entered World War II, the Explosives Act of 1917 was reactivated. In 1947, the act was deactivated by President Truman.[30]

The Organized Crime Control Act of 1970 (Pub.L. 91–452) transferred many explosives regulations to the Bureau of Alcohol, Tobacco and Firearms (ATF) of the Department of Treasury. The bill became effective in 1971.[31]

Currently, regulations are governed by Title 18 of the United States Code and Title 27 of the Code of Federal Regulations:

  • "Importation, Manufacture, Distribution and Storage of Explosive Materials" (18 U.S.C. Chapter 40).[32]
  • "Commerce in Explosives" (27 C.F.R. Chapter II, Part 555).[33]

State laws

List of explosives

Compounds

Acetylides

Fulminates

Nitro

Nitrates

Amines

Peroxides

Oxides

Unsorted

Mixtures

Elements and isotopes

See also

References

  1. ^ Sastri, M.N. (2004). Weapons of Mass Destruction. APH Publishing Corporation. p. 1. ISBN 978-81-7648-742-9.
  2. ^ Singh, Kirpal (2010). Chemistry in Daily Life. Prentice-Hall. p. 68. ISBN 978-81-203-4617-8.
  3. ^ Sigurðsson, Albert (17 January 2017). "China's explosive history of gunpowder and fireworks". GBTimes. Archived from the original on 1 December 2017.
  4. ^ Pomeranz, Ken; Wong, Bin. "China and Europe, 1500–2000 and Beyond: What is Modern?" (PDF). 2004: Columbia University Press. Archived (PDF) from the original on 13 December 2016.
  5. ^ Kerr, Gordon (2013). A Short History of China. No Exit Press. ISBN 978-1-84243-968-5.
  6. ^ Takacs, Sarolta Anna; Cline, Eric H. (2008). The Ancient World. Routledge. p. 544.
  7. ^ Back, Fiona (2011). Australian History Series: The ancient world. p. 55. ISBN 978-1-86397-826-2.
  8. ^ Ankony, Robert C., Lurps: A Ranger's Diary of Tet, Khe Sanh, A Shau, and Quang Tri, revised ed., Rowman & Littlefield Publishing Group, Lanham, MD (2009), p.73.
  9. ^ W.W. Porterfield, Inorganic Chemistry: A Unified Approach, 2nd ed., Academic Press, Inc., San Diego, pp. 479–480 (1993).
  10. ^ "Archived copy". Archived from the original on 6 February 2017. Retrieved 5 February 2017.CS1 maint: archived copy as title (link) |2.1 Deflagration |Retrieved 05 February 2017
  11. ^ "Archived copy". Archived from the original on 6 February 2017. Retrieved 5 February 2017.CS1 maint: archived copy as title (link) |2.2 Detonation |Retrieved 05 February 2017
  12. ^ Krehl, Peter O.K. (24 September 2008). History of Shock Waves, Explosions and Impact: A Chronological and Biographical Reference. Springer Science & Business Media. p. 106. ISBN 978-3-540-30421-0. Archived from the original on 24 December 2017.
  13. ^ Krehl, Peter O.K. (2008). History of Shock Waves, Explosions and Impact: A Chronological and Biographical Reference. Springer Science & Business Media. p. 1970. ISBN 978-3-540-30421-0.
  14. ^ "Green explosive is a friend of the Earth". New Scientist. 27 March 2006. Archived from the original on 12 November 2014. Retrieved 12 November 2014.
  15. ^ a b Zel'dovich, Yakov; Kompaneets, A.S. (1960). Theory of Detonation. Academic Press. pp. 208–210.
  16. ^ Hougen, Olaf A.; Watson, Kenneth; Ragatz, Roland (1954). Chemical Process Principles. John Wiley & Sons. pp. 66–67.
  17. ^ Anderson, H.V. (1955). Chemical Calculations. McGraw-Hill. p. 206.
  18. ^ a b c Office, Government of Canada, Industry Canada, Office of the Deputy Minister, Canadian Intellectual Property (15 June 2015). "Canadian Patent Database / Base de données sur les brevets canadiens". brevets-patents.ic.gc.ca. Archived from the original on 18 October 2016. Retrieved 17 October 2016.
  19. ^ Meyer, Rudolf; Josef Köhler; Axel Homburg (2007). Explosives, 6th Ed. Wiley VCH. ISBN 978-3-527-31656-4.
  20. ^ https://blogs.sciencemag.org/pipeline/archives/2019/08/15/cant-stop-the-nitro-groups
  21. ^ Sam Barros. "PowerLabs Lead Picrate Synthesis". Archived from the original on 22 May 2016.
  22. ^ Robert Matyáš, Jiří Pachman. Primary Explosives. Springer-Verlag Berlin Heidelberg, 2013. pp. 331
  23. ^ Cooper, Paul W. (1996). "Chapter 4: Use forms of explosives". Explosives Engineering. Wiley-VCH. pp. 51–66. ISBN 978-0-471-18636-6.
  24. ^ Table 12-4. – United Nations Organization Hazard Classes Archived 5 June 2010 at the Wayback Machine. Tpub.com. Retrieved on 2010-02-11.
  25. ^ "wetten.nl – Wet- en regelgeving – Wet explosieven voor civiel gebruik – BWBR0006803". Archived from the original on 25 December 2013.
  26. ^ "wetten.nl – Wet- en regelgeving – Wet wapens en munitie – BWBR0008804". Archived from the original on 25 December 2013.
  27. ^ a b "The Explosives Regulations 2014". www.legislation.gov.uk. Retrieved 16 February 2019. UKOpenGovernmentLicence.svg This article contains quotations from this source, which is available under the Open Government Licence v3.0 Archived 12 February 2019 at the Wayback Machine. © Crown copyright.
  28. ^ "HSE Explosives - Licensing". www.hse.gov.uk. Archived from the original on 21 April 2019. Retrieved 16 February 2019.
  29. ^ "1913–1919". Archived from the original on 1 February 2016.
  30. ^ "1940–1949". Archived from the original on 4 March 2016.
  31. ^ "1970–1979". Archived from the original on 17 November 2015.
  32. ^ "Federal Explosives Laws" (PDF). U.S. Department of Justice, Bureau of Alcohol, Tobacco, Firearms and Explosives. Archived (PDF) from the original on 6 March 2016. Retrieved 1 February 2016.
  33. ^ "Regulations for Alcohol, Tobacco, Firearms and Explosives | Bureau of Alcohol, Tobacco, Firearms and Explosives". Archived from the original on 15 December 2014. Retrieved 13 December 2014. ATF Regulations
  34. ^ "ACASLogin". Archived from the original on 8 December 2014.
  35. ^ "Document – Folio Infobase". Archived from the original on 20 December 2014.
  36. ^ Special provisions relating to black powder Archived 5 June 2010 at the Wayback Machine

Further reading

U.S. Government
  • Explosives and Demolitions FM 5-250; U.S. Department of the Army; 274 pp.; 1992.
  • Military Explosives TM 9-1300-214; U.S. Department of the Army; 355 pp.; 1984.
  • Explosives and Blasting Procedures Manual; U.S. Department of Interior; 128 pp.; 1982.
  • Safety and Performance Tests for Qualification of Explosives; Commander, Naval Ordnance Systems Command; NAVORD OD 44811. Washington, DC: GPO, 1972.
  • Weapons Systems Fundamentals; Commander, Naval Ordnance Systems Command. NAVORD OP 3000, vol. 2, 1st rev. Washington, DC: GPO, 1971.
  • Elements of Armament Engineering – Part One; Army Research Office. Washington, D.C.: U.S. Army Materiel Command, 1964.
  • Hazardous Materials Transportation Plaecards; USDOT.
Institute of Makers of Explosives
Other Historical

External links

Ammonium nitrate

Ammonium nitrate is a chemical compound, the nitrate salt of the ammonium cation. It has the chemical formula NH4NO3, simplified to N2H4O3. It is a white crystal solid and is highly soluble in water. It is predominantly used in agriculture as a high-nitrogen fertilizer. Its other major use is as a component of explosive mixtures used in mining, quarrying, and civil construction. It is the major constituent of ANFO, a popular industrial explosive which accounts for 80% of explosives used in North America; similar formulations have been used in improvised explosive devices. Many countries are phasing out its use in consumer applications due to concerns over its potential for misuse.

Armor-piercing shell

An armor-piercing shell, AP for short, is a type of ammunition designed to penetrate armor. From the 1860s to 1950s, a major application of armor-piercing projectiles was to defeat the thick armor carried on many warships. From the 1920s onwards, armor-piercing weapons were required for anti-tank missions. AP rounds smaller than 20 mm are typically known as "armor-piercing ammunition", and are intended for lightly-armored targets such as body armor, bulletproof glass and light armored vehicles. The classic AP shell is now seldom used in naval warfare, as modern warships have little or no armor protection, and newer technologies have displaced the classic AP design in the anti-tank role.

An armor-piercing shell must withstand the shock of punching through armor plating. Shells designed for this purpose have a greatly strengthened body with a specially hardened and shaped nose. One common addition to later AP shells is the use of a softer ring or cap of metal on the nose known as a penetrating cap, which both lowers the initial shock of impact to prevent the rigid shell from shattering, as well as aiding the contact between the target armor and the nose of the penetrator to prevent the shell from bouncing off in glancing shots. Ideally, these caps have a blunt profile, which led to the use of a thin aerodynamic cap to improve long-range ballistics. AP shells may contain little or no explosive, in this case known as a "bursting charge". Some smaller-caliber AP shells have an inert filling or incendiary charge in place of the bursting charge.

As tank armor improved during World War II, AP designs were introduced that used a smaller penetrating body within a larger shell. These lightweight shells fired at very high muzzle velocity and retained that speed and the associated penetrating power over longer distances. In modern designs the penetrator no longer looks like a classic artillery shell design, but is instead a long rod of dense material like tungsten or depleted uranium (DU) that further improves the terminal ballistics. Whether these designs are considered to be AP rounds depends on the definition and may be included or excluded from reference to reference.

Bomb

A bomb is an explosive weapon that uses the exothermic reaction of an explosive material to provide an extremely sudden and violent release of energy. Detonations inflict damage principally through ground- and atmosphere-transmitted mechanical stress, the impact and penetration of pressure-driven projectiles, pressure damage, and explosion-generated effects. Bombs have been utilized since the 11th century starting in East Asia.The term bomb is not usually applied to explosive devices used for civilian purposes such as construction or mining, although the people using the devices may sometimes refer to them as a "bomb". The military use of the term "bomb", or more specifically aerial bomb action, typically refers to airdropped, unpowered explosive weapons most commonly used by air forces and naval aviation. Other military explosive weapons not classified as "bombs" include shells, depth charges (used in water), or land mines. In unconventional warfare, other names can refer to a range of offensive weaponry. For instance, in recent Middle Eastern conflicts, homemade bombs called "improvised explosive devices" (IEDs) have been employed by insurgent fighters to great effectiveness.

The word comes from the Latin bombus, which in turn comes from the Greek βόμβος (bombos), an onomatopoetic term meaning "booming", "buzzing".

Bomb disposal

Bomb disposal is an explosives engineering profession using the process by which hazardous explosive devices are rendered safe. Bomb disposal is an all-encompassing term to describe the separate, but interrelated functions in the military fields of explosive ordnance disposal (EOD) and improvised explosive device disposal (IEDD), and the public safety roles of public safety bomb disposal (PSBD) and the bomb squad.

C-4 (explosive)

C-4 or Composition C-4 is a common variety of the plastic explosive family known as Composition C. A similar British plastic explosive, based on RDX but with different plasticizer than Composition C-4, is known as PE-4 (Plastic Explosive No. 4). C-4 is composed of explosives, plastic binder, plasticizer to make it malleable, and usually a marker or odorizing taggant chemical.

C-4 has a texture similar to modelling clay and can be molded into any desired shape. C-4 is metastable and can be exploded only by the shock wave from a detonator or blasting cap.

Car bomb

A car bomb, lorry bomb, or truck bomb, also known as a vehicle-borne improvised explosive device (VBIED), is an improvised explosive device placed inside a car or other vehicle and then detonated.

Car bombs can be roughly divided into two main categories; those used primarily to kill the occupants of the vehicle (often as an assassination); and those used as a means to kill, injure or damage people and buildings outside the vehicle. The latter type may be either parked (the vehicle disguising the bomb and allowing the bomber to get away), or the vehicle might be used to deliver the bomb (often as part of a suicide bombing).

It is commonly used as a weapon of terrorism or guerrilla warfare to kill people near the blast site or to damage buildings or other property. Car bombs act as their own delivery mechanisms and can carry a relatively large amount of explosives without attracting suspicion; in larger vehicles and trucks, weights of around 7,000 pounds (3,200 kg) or more have been used, for example, in the Oklahoma City bombing. Car bombs are activated in a variety of ways, including opening the vehicle's doors, starting the engine, depressing the accelerator or brake pedals or simply lighting a fuse or setting a timing device. The gasoline in the vehicle's fuel tank may make the explosion of the bomb more powerful by dispersing and igniting the fuel.

Centennial Olympic Park bombing

The Centennial Olympic Park bombing was a domestic terrorist pipe bombing attack on the Centennial Olympic Park in Atlanta, Georgia, on July 27 during the 1996 Summer Olympics. The blast directly killed 1 person and injured 111 others; another person later died of a heart attack. It was the first of four bombings committed by Eric Rudolph. Security guard Richard Jewell discovered the bomb before detonation and cleared most of the spectators out of the park. Rudolph, a carpenter and handyman, had detonated three pipe bombs inside a U.S. military ALICE Pack.

After the bombings, Jewell was initially investigated as a suspect by the Federal Bureau of Investigation and the news media falsely focused on him aggressively as the presumed culprit. However, in October 1996, Jewell was cleared of suspicion when the FBI declared that he was no longer a person of interest. Following three more bombings in 1997, Rudolph was identified by the FBI as the suspect. In 2003, Rudolph was arrested and tried before being convicted two years later. Rudolph was sentenced to life imprisonment without parole for his crimes.

Diarrhea

Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin with loss of the normal stretchiness of the skin and irritable behaviour. This can progress to decreased urination, loss of skin color, a fast heart rate, and a decrease in responsiveness as it becomes more severe. Loose but non-watery stools in babies who are exclusively breastfed, however, are normal.The most common cause is an infection of the intestines due to either a virus, bacteria, or parasite—a condition also known as gastroenteritis. These infections are often acquired from food or water that has been contaminated by feces, or directly from another person who is infected. The three types of diarrhea are: short duration watery diarrhea, short duration bloody diarrhea, and persistent diarrhea (lasting more than two weeks, which can be either watery or bloody). The short duration watery diarrhea may be due to cholera, although this is rare in the developed world. If blood is present, it is also known as dysentery. A number of non-infectious causes can result in diarrhea. These include lactose intolerance, irritable bowel syndrome, non-celiac gluten sensitivity, celiac disease, inflammatory bowel disease such as ulcerative colitis, hyperthyroidism, bile acid diarrhea, and a number of medications. In most cases, stool cultures to confirm the exact cause are not required.Diarrhea can be prevented by improved sanitation, clean drinking water, and hand washing with soap. Breastfeeding for at least six months and vaccination against rotavirus is also recommended. Oral rehydration solution (ORS)—clean water with modest amounts of salts and sugar—is the treatment of choice. Zinc tablets are also recommended. These treatments have been estimated to have saved 50 million children in the past 25 years. When people have diarrhea it is recommended that they continue to eat healthy food and babies continue to be breastfed. If commercial ORS are not available, homemade solutions may be used. In those with severe dehydration, intravenous fluids may be required. Most cases; however, can be managed well with fluids by mouth. Antibiotics, while rarely used, may be recommended in a few cases such as those who have bloody diarrhea and a high fever, those with severe diarrhea following travelling, and those who grow specific bacteria or parasites in their stool. Loperamide may help decrease the number of bowel movements but is not recommended in those with severe disease.About 1.7 to 5 billion cases of diarrhea occur per year. It is most common in developing countries, where young children get diarrhea on average three times a year. Total deaths from diarrhea are estimated at 1.26 million in 2013—down from 2.58 million in 1990. In 2012, it was the second most common cause of deaths in children younger than five (0.76 million or 11%). Frequent episodes of diarrhea are also a common cause of malnutrition and the most common cause in those younger than five years of age. Other long term problems that can result include stunted growth and poor intellectual development.

Dynamite

Dynamite is an explosive made of nitroglycerin, sorbents (such as powdered shells or clay) and stabilizers. It was invented by the Swedish chemist and engineer Alfred Nobel in Geesthacht and patented in 1867. It rapidly gained wide-scale use as a more powerful alternative to black powder.

Today, dynamite is mainly used in the mining, quarrying, construction, and demolition industries. Dynamite is still the product of choice for trenching applications, and as a cost-effective alternative to cast boosters. Dynamite is occasionally used as an initiator or booster for AN and ANFO explosive charges.

Explosion

An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. Supersonic explosions created by high explosives are known as detonations and travel via supersonic shock waves. Subsonic explosions are created by low explosives through a slower burning process known as deflagration.

Explosive ordnance disposal (United States Navy)

United States Navy Explosive Ordnance Disposal technicians render safe all types of ordnance, including improvised, chemical, biological, and nuclear. They perform land and underwater location, identification, render-safe, and recovery (or disposal) of foreign and domestic ordnance. They conduct demolition of hazardous munitions, pyrotechnics, and retrograde explosives using detonation and burning techniques. They forward deploy and fully integrate with the various Combatant Commanders, Special Operations Forces (SOF), and various warfare units within the Navy, Marine Corps, Air Force and Army. They are also called upon to support military and civilian law enforcement agencies, as well as the Secret Service.

EOD Technicians' missions take them to all environments, and every climate, in every part of the world. They have many assets available to arrive to their mission, from open- and closed-circuit scuba and surface supplied diving rigs, to parachute insertion from fixed-wing aircraft and fast-rope, abseil, and Special Patrol Insertion/Extraction (SPIE) from rotary aircraft, to small boats and tracked vehicles.

High-explosive anti-tank warhead

A high-explosive anti-tank (HEAT) warhead is a type of shaped charge explosive that uses the Munroe effect to penetrate thick tank armor. The warhead functions by having the explosive charge collapse a metal liner inside the warhead into a high-velocity superplastic jet. This superplastic jet is capable of penetrating armor steel to a depth of seven or more times the diameter of the charge (charge diameters, CD) but is usually used to immobilize or destroy tanks. Due to the way they work, they do not have to be fired as fast as an armor piercing shell, allowing less recoil. Contrary to a widespread misconception (possibly resulting from the acronym HEAT), the jet does not melt its way through armor, as its effect is purely kinetic in nature. The HEAT warhead has become less effective against tanks and other armored vehicles due to the use of composite armor, explosive-reactive armor, and active protection systems which destroy the HEAT warhead before it hits the tank. Even though HEAT rounds are less effective against the heavy armor found on 2010s main battle tanks, HEAT warheads remain a threat against less-armored parts of a main battle tank (e.g., rear, top) and against lighter armored vehicles or unarmored vehicles and helicopters.

Improvised explosive device

An improvised explosive device (IED) is a bomb constructed and deployed in ways other than in conventional military action. It may be constructed of conventional military explosives, such as an artillery shell, attached to a detonating mechanism. IEDs are commonly used as roadside bombs.

IEDs are generally seen in heavy terrorist actions or in asymmetric unconventional warfare by insurgent guerrillas or commando forces in a theatre of operations. In the second Iraq War, IEDs were used extensively against US-led invasion forces and by the end of 2007 they had become responsible for approximately 63% of coalition deaths in Iraq. They are also used in Afghanistan by insurgent groups, and have caused over 66% of coalition casualties in the 2001–present Afghanistan War.IEDs were also used extensively by cadres of the rebel Tamil Tiger (LTTE) organisation against military targets in Sri Lanka.IEDs are being used by the terrorists of Balochistan Liberation Army (BLA), Balochistan Liberation Front (BLF), Baloch Republican Army (BRA) and Baloch Republican Guards (BRG) to destroy vehicles of Pakistani forces in Balochistan. They have been used since the fifth rise of insurgency in Balochistan from 2000 until now.

Nitroglycerin

Nitroglycerin (NG), also known as nitroglycerine, trinitroglycerin (TNG), nitro, glyceryl trinitrate (GTN), or 1,2,3-trinitroxypropane, is a dense, colorless, oily, explosive liquid most commonly produced by nitrating glycerol with white fuming nitric acid under conditions appropriate to the formation of the nitric acid ester. Chemically, the substance is an organic nitrate compound rather than a nitro compound, yet the traditional name is often retained. Invented in 1847, nitroglycerin has been used as an active ingredient in the manufacture of explosives, mostly dynamite, and as such it is employed in the construction, demolition, and mining industries. Since the 1880s, it has been used by the military as an active ingredient, and a gelatinizer for nitrocellulose, in some solid propellants, such as cordite and ballistite.

Nitroglycerin is a major component in double-based smokeless gunpowders used by reloaders. Combined with nitrocellulose, hundreds of powder combinations are used by rifle, pistol, and shotgun reloaders.

In medicine for over 130 years, nitroglycerin has been used as a potent vasodilator (dilation of the vascular system) to treat heart conditions, such as angina pectoris and chronic heart failure. Though it was previously known that these beneficial effects are due to nitroglycerin being converted to nitric oxide, a potent venodilator, the enzyme for this conversion was not discovered to be mitochondrial aldehyde dehydrogenase (ALDH2) until 2002. Nitroglycerin is available in sublingual tablets, sprays, ointments, and patches.

Plastic explosive

Plastic explosive is a soft and hand-moldable solid form of explosive material. Within the field of explosives engineering, plastic explosives are also known as putty explosives.Plastic explosives are especially suited for explosive demolition. Common plastic explosives include Semtex and C-4. The first discovered plastic explosive was gelignite in 1875, invented by Alfred Nobel.

Shell (projectile)

A shell is a payload-carrying projectile that, as opposed to shot, contains an explosive or other filling, though modern usage sometimes includes large solid projectiles properly termed shot. Solid shot may contain a pyrotechnic compound if a tracer or spotting charge is used. Originally, it was called a "bombshell", but "shell" has come to be unambiguous in a military context.

All explosive- and incendiary-filled projectiles, particularly for mortars, were originally called grenades, derived from the pomegranate, so called because the many-seeded fruit suggested the powder-filled, fragmenting bomb, or from the similarity of shape. Words cognate with grenade are still used for an artillery or mortar projectile in some European languages.Shells are usually large-caliber projectiles fired by artillery, combat vehicles (including tanks), and warships.

Shells usually have the shape of a cylinder topped by an ogive-shaped nose for good aerodynamic performance, possibly with a tapering base (boat-tail), but some specialized types are quite different.

TNT

Trinitrotoluene (; TNT), or more specifically 2,4,6-trinitrotoluene, is a chemical compound with the formula C6H2(NO2)3CH3. This yellow solid is sometimes used as a reagent in chemical synthesis, but it is best known as an explosive material with convenient handling properties. The explosive yield of TNT is considered to be the standard measure of bombs and the power of explosives. In chemistry, TNT is used to generate charge transfer salts.

Thermobaric weapon

A thermobaric weapon, aerosol bomb, or vacuum bomb, is a type of explosive that uses oxygen from the surrounding air to generate a high-temperature explosion, and in practice the blast wave typically produced by such a weapon is of a significantly longer duration than that produced by a conventional condensed explosive. The fuel-air explosive (FAE) is one of the best-known types of thermobaric weapons.

Most conventional explosives consist of a fuel-oxidizer premix (gunpowder, for example, contains 25% fuel and 75% oxidizer), whereas thermobaric weapons are almost 100% fuel, so thermobaric weapons are significantly more energetic than conventional condensed explosives of equal weight. Their reliance on atmospheric oxygen makes them unsuitable for use underwater, at high altitude, and in adverse weather. They are, however, considerably more destructive when used against field fortifications such as foxholes, tunnels, bunkers, and caves—partly due to the sustained blast wave and partly by consuming the oxygen inside.

There are many different types of thermobaric weapons that can be fitted to hand-held launchers.

Uncontrolled decompression

Uncontrolled decompression is an unplanned drop in the pressure of a sealed system, such as an aircraft cabin or hyperbaric chamber, and typically results from human error, material fatigue, engineering failure, or impact, causing a pressure vessel to vent into its lower-pressure surroundings or fail to pressurize at all.

Such decompression may be classed as Explosive, Rapid, or Slow:

Explosive decompression (ED) is violent, the decompression being too fast for air to safely escape from the lungs.

Rapid decompression, while still fast, is slow enough to allow the lungs to vent.

Slow or gradual decompression occurs so slowly that it may not be sensed before hypoxia sets in.

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