The concept and types of explosions and explosives. General characteristics of explosions and their damaging factors Explosion brief definition

Explosion - A quick physical or physicochemical process passing with significant emission release in a small amount in a short period of time and leading to shock, vibration and thermal impacts on the environment due to the high-speed expansion of the explosion products.

Delable explosion - energy release in the volume of the clouds of combustible gaseous mixtures and aerosols in the propagation of an exothermic chemical reaction with a subsonic speed.

Detonation explosion - an explosion in which the ignition of the subsequent layers of explosive occurs as a result of compression and heating by a shock wave characterized by the fact that the shock wave and the zone of the chemical reaction is inextricably each other with a constant supersonic speed.

The chemical explosion of non-confused substances from burning is characterized by the fact that the burning occurs when the combustible mixture is formed in the process of burning itself. : 36.

The explosion products are usually gases with high pressure and temperature, which, expanding, can make mechanical work and cause the destruction of other objects. In the explosion products, in addition to gases, solid highly dispersed particles may be contained. The destructive effect of the explosion is caused by high pressure and the formation of a shock wave. The effect of the explosion can be enhanced by cumulative effects.

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  By the origin of the separated energy distinguish the following types of explosions:

  • Chemical explosions of explosives - due to the energy of chemical bonds of the starting materials.
  • Explosions of tanks under pressure (gas cylinders, steam boilers, pipelines) - due to the energy of compressed gas or superheated liquid. To them, in particular, belong:
    • Explosion of expanding boobing liquid vapors (bleve).
    • Explosions when discharged pressure in superheated liquids.
    • The explosions when mixing two liquids, the temperature of one of which is much higher than the boiling point of the other.
  • Nuclear explosions - due to energy released in nuclear reactions.
  • Electric explosions (for example, under the thunderstorm).
  • Volcanic explosions.
  • Explosions in the collision of cosmic bodies, for example, when the meteorites fall on the surface of the planet.
  • Explosions caused by gravitational collapse (explosions of supernovae and others).

  Chemical explosions

  There is no one about what kind of chemical processes should be considered an explosion, there is no explosion. This is due to the fact that high-speed processes can proceed in the form of detonation or delagration (slow burning). Detonation differs from burning in that the chemical reactions and the process of energy is released to form the shock wave in the reacting substance, and the involvement of new portions of the explosive in the chemical reaction occurs at the front of the shock wave, and not by heat conduction and diffusion, as with slow burning. The difference in energy transmission mechanisms and substances affect the rate of processes and on the results of their environmental action, but in practice the most different combinations of these processes are observed and combustion transitions to detonation and back. In this regard, usually the chemical explosions include various rapid processes without refining their character.

  There is a more hard approach to determine the chemical explosion as exclusively detonation. From this condition, it is necessary that with a chemical explosion, accompanied by a redox reaction (combustion), the combustible substance and the oxidizing agent must be mixed, otherwise the reaction rate will be limited to the speed of the oxidizing agent process, and this process, as a rule, has a diffusion character. For example, natural gas slowly burns in burners of home kitchen stoves, because oxygen slowly falls into the burning area by diffusion by diffusion. However, if mixing gas with air, it will explode from a small spark - a volume explosion. There are very few examples of chemical explosions that do not have its own cause oxidation / recovery, for example, the reaction of fine oxide phosphorus (V) with water, but it can be considered as a steam blast.

  Individual explosives, as a rule, contain oxygen as part of its own molecules. These are metastable substances that are capable of stored or less for a long time under normal conditions. However, when initiating an explosion is initiated, sufficient energy is transmitted for spontaneous propagation of the wave of combustion or detonation, exciting the entire mass of the substance. Nitroglycerin, trinitrotrololol and other substances have such properties.

  Explosion - This is a very rapid change in the chemical (physical) state of the explosive, accompanied by the release of a large amount of heat and the formation of a large amount of gases, creating a shock wave capable of creating destruction by its pressure.

  Explosive substances (explosives)- Special groups of substances capable of explosive transformations as a result of external influences.
  Distinguish explosions :

  1. Physical- Eased energy is the internal energy of compressed or liquefied gas (liquefied steam). The power of the explosion depends on the internal pressure. The resulting destruction can be caused by a shock wave of expanding gas or fragments of a burst tank (example: the destruction of compressed gas tanks, steam boilers, as well as powerful electrical discharges)

  2. Chemical - an explosion caused by a rapid exothermic chemical reaction occurring to the formation of strongly compressed gaseous or vapor products. An example can serve An explosion of a smoke powder, in which a fast chemical reaction occurs between the associate, coal and sulfur, accompanied by excretion, a significant amount of heat. Formed gaseous products heated due to the heat of the reaction to high temperature, they have high pressure and, expanding, produce mechanical work.

  3.Atomic explosions. Right-flowing nuclear and whether thermonuclear reactions (fission reactions or nuclear core reactions), under which a very large amount of heat is released. Reaction products, an atomic or hydrogen bomb shell and a certain amount of the surrounding medium bomb instantly turns into heated to a very high temperature of gases that have respectively high pressure. The phenomenon is accompanied by colossal mechanical work.

  Chemical explosions are divided into condensed and volume explosions.

  BUT)Under condensed explosive substancesit is understood to be chemical compounds and mixtures in solid or liquid state, which under the influence of certain external conditions are capable of rapid self-propagating chemical transformation to the formation of highly heated and large gas pressure, which, expanding, produce mechanical work. Such chemical transformation of BB is customary called explosive transformation.
  

  The excitation of explosive transformation of BB is called initiating. To excite the explosive transformation of BB, it is necessary to inform him with a certain intensity the required amount of energy (initial impulse), which can be transmitted in one of the following methods:
  - mechanical (blow, punch, friction);
  - thermal (spark, flame, heating);
  - electric (heating, spark discharge);
  - chemical (reaction with intensive heat release);
  - An explosion of another charge of the explosive (explosion of a detonator capsule or adjacent charge).

  Condensed BBs are divided into groups :

  	Characteristic. Examples of matter.
  	Extremely hazardous substances Unstable. They explode even in the smallest quantities. Nitrogen trichloride; Some organic peroxide compounds; copper acetylene, formed when contacting acetylene with copper or a medustal alloy
  	Primary W. Less hazardous substances. Initiating compounds. Have very high sensitivity to impact and thermal exposure. Used mainly in detonator capsules to excite detonation in the charges of explosives. Azide lead, rattling mercury.
  	Secondary explosives (brisk explodes) The excitation of detonation in them occurs when exposed to a strong shock wave. The latter can be created in the process of their burning or with the help of a detonator. As a rule, the explosions of this group are relatively safe in circulation and can be stored for long periods of time. Dynamizes, Troil, Huxogen, Octogen, central.
  	Throwing explosives, powder Sensitivity to the blow is very small, relatively slowly burning. Ballistic powder - a mixture of nitrocellulose, nitroglycerin and other technological additives. Light from flame, spark or heating. Outdoors are quickly burning. In the closed vessel exploded. At the site of the bang of black powder containing nitrogenous potassium, sulfur and charcoal in relations 75:15:10, there remains a residue containing carbon.

  The classification of explosions can be made by types of chemical reactions:

  1. The decomposition reaction is the decomposition process, which gives gaseous products.
  2. Redox reaction - reaction in which air or oxygen reacts with the reducing agent
  3. The mixture reaction is an example of such a mixture - powder.

  B) bulk explosions There are two types:

  • Explosions of dust clouds (dust explosions) Considered as dust explosions in the shaft galley and in the equipment or inside the building. Such explosive mixtures occur during crushing, distribution, mound, moving dusting materials. Explosive dust mixtures have a lower concentration limit of explosive (NKPV)determined by the content (in grams per cubic meter) dust in the air. So for the sulfur powder of the NKPV is 2.3 g / m3. The concentration limits of dust are not constant and depend on moisture, the degree of grinding, the content of combustible substances.

  The mechanism of dust explosions in the mines lie relatively weak explosions of the gas-air mixture of air and methane. Such mixtures are considered already explosive at a 5% concentration of methane in the mixture. The explosions of the gas-air mixture cause the turbulence of air flows sufficient to form a dust cloud. The ignition of dust generates a shock wave, raising even more dust, and then a powerful destructive explosion can occur.

  Measures used to prevent dust explosions:

  1. ventilation of premises, objects
  2. moisturizing surfaces
  3. dilution of inert gases (CO 2, N2) or silicate powders

  Dust explosions inside buildings, equipment most often occur on elevators, where, due to friction of the grains, a large amount of fine dust is formed during their movement.

  • Explosions of steam clouds - The processes of the rapid transformation, accompanied by an explosive wave occurring occurring on an open airspace as a result of the ignition of the cloud containing combustible pairs.

  Such phenomena occur during the leakage of liquefied gas, as a rule, in limited spaces (rooms), where the limiting concentration of combustible elements is growing rapidly, at which the cloud is ignited.
  Measures used to prevent explosions of steam clouds:

  1. minimizing the use of combustible gas or steam
  2. no ignition sources
  3. location of installations on an open, well-ventilated area

  Most often emergency related with gaze explosions, occur during the operation of municipal gas equipment.

  To prevent such explosions, the prophylaxis of gas equipment is carried out annually. The buildings of explosive shops, structures, part of the panels are made in the walls are made easily, and the roofs are light-grade.

  Basic information about internal and external ballistics.

  The science studying the motion of the bullet (shell) is called ballistic (ballistics from the Greek word score - throwing). According to the nature of the forces acting on the bullet, Ballistics is divided into inner and external.

  Explosive substances (explosives) Unstable mixtures and chemical compounds are called under the influence of minor external influences (blow, friction, injection, heating, etc.) to make a rapid transformation into a gaseous state.

  Explosion The phenomenon of an extremely fast physical or chemical change of a substance accompanied by the same rapid transformation of its potential (hidden) energy into mechanical work.

  Chemical reaction accompanied by an explosion called explosive transformation.

  The characteristic signs of the explosion are as follows: short-term process - the speed of transition of explosives from a solid or liquid state into gaseous, i.e. In the final system of transformation products. Depending on the chemical composition and conditions under which the explosion occurs, explosive transformations occur at different speeds - from hundredths to million dollars. Thus, the shirt of smokeless powder burns in a rifle for 0.0012 seconds., 1 kg. Dynamite explodes for 0.00002 sec.; gas formation - The presence of a large amount of gaseous explosion products capable of expansion. The number of gaseous products released during explosion is expressed by approximately the following numbers: 1 liters. Pyroxilina gives 994 liters. gaseous explosion products; 1 l. Nitroglycerin gives 1121 liters. gaseous explosion products; heat release With the reaction of explosive transformation, which increases the elasticity of gas products.

  Types of explosive transformations

  Depending on the chemical composition of the explosive and the conditions of the explosion, explosive transformations occur at different speeds, under which it can happen: rapid combustion, an explosion itself, detonation.

  Fast combustionBB is called the explosive transformation process, propagating over the entire mass of centuries at a speed of no more than a few meters per second. Example - combustion in the open air grains of smoky powder flowing at a speed of 10-12 mm / s.

  In the closed volume, the combustion of the explosives proceeds more vigorously than in air, and the burning is accompanied by a sharp sound. An example is the combustion of the combat charge of smokeless powder in the barrel channel (speed of about 10 m / s). The consistent rapid combustion of the explosives is accompanied by a more or less rapid increase in the pressure of gases in the barrel channel, which as it is applied to the side of the smallest resistance, while performing the operation to move, pushing the bullet or projectile from the barrel channel.

  Actually explosion - The process of decomposition of explosives, which proceeds with a huge speed measured by hundreds of meters per second. Such an explosion is accompanied by a sharp increase in the pressure of gases at the explosion site, the blow of gases in the environment, which entails the splitting and crushing of items in close proximity to the explosion site.

  Detonation They refer to the process propagating on explosive with the highest possible velocity of explosive transformation, measured usually by thousands of meters per second (pyroxilin detonation rate - up to 6,800 m / s, nitroglycerin - 8200 m / s). By the end of the explosion, i.e. By the time, when the whole charge decompose, the gases do not have time to expand and occupy the initial volume of explosives, and therefore the huge pressure of gases immediately develops. Such a sharp pressure jump and gases lead to crushing the barriers to the smallest pieces.

  exemption of a large quantity of the energy-bound volume in a short period of time. B. leads to the formation of a strongly heated gas (plasma) with very high pressure, which has a mechanical impact (pressure, destruction) on the surrounding bodies. In a solid, it is accompanied by its destruction and crushing. B. is most often due to the liberation of the chemical energy of explosives.

  Excellent definition

  Incomplete definition ↓

  Explosion

  fast substance transformation (explosive burning), accompanied by the release of energy and the formation of compressed gases capable of producing. In the environment, an explosive wave applies. The amount of distinguished when in. Energy determines the scale (volume, area) of destruction. The magnitude of the concentration of energy in a unit of volume determines the intensity of the destruction in the focus of the explosion. Explosion Pressure, KpamaStAb Building Damage 100Full Destruction of Buildings 5350% Destruction of Buildings 28 Formerly Damage to Buildings 12 Summary Damage to Buildings (Damage to Internal Partitions, Rams, Doors, etc.) 3Malized Building Damage (split part of the glazing) Explosion pressure 5 kPa characterizing non-harmonary The damage of a person is accepted as a p about rk and h about in the definition of the category of premises and buildings, external installations. With pressure in. Below 5 kPa room, building, outdoor installation do not refer to category A or in an explosion hazard. With diffusion burning of solid and liquid substances (materials) in conditions of fire. Not implemented. However, when accumulated in a closed amount of products of thermal and heat-oxidative destruction (hydrogen, methane, carbon monoxide, etc.), V. may occur. Example serve in. Silos and bunkers on elevators, feed plants. When self-heating and the subsequent self-burning of plant raw materials, the decomposition products are accumulated in the burntable cavities and in collaboration of arches are ignited by B. PR O E K and R U E M S E M V Q. Apply in military business, mining, construction, etc.

  The explosion is an extremely rapid extraction of energy associated with a sudden change in the state of the substance, as a rule, accompanied by the same rapid conversion of energy into mechanical work, the destruction of the environment, the formation and distribution in the impact or explosive wave.

  The explosion place is a set of traces of explosive action displayed in a specific environment, identifying and fixing which is impossible without the allocation of the main signs of the explosion in general and the explosive device of a certain design in particular.

  The classifications of the explosions themselves are diverse and numerous, the criteria of which are the medium in which they are produced (ground, non-contact, underwater, etc.), the presence of an explosion products concentration in a certain direction (cumulative) and other factors. A detailed list of varieties of explosions lead R.A. Strehlow and W.E. BACER (1976):

  1) Natural explosions (lightning, volcanoes, meteorites, etc.);

  2) deliberate explosions (nuclear; explosions of military, industrial and pyrotechnic explosives; explosions of fuel and air mixtures; explosions in a cannon or weapon cutting; electrical and laser explosions; explosions in the cylinders of internal combustion engines; research explosions, etc.);

  3) Random explosions (explosions of condensed explosives; explosions of tanks under pressure, containers with superheated liquid, containers with substances undergoing uncontrolled chemical transformations, etc.).

  In criminalistic literature as a criterion of systematization, the nature of the explosion is most often considered. So, A.M. Larin with co-authors distinguish explosions: 1) physical (explosion of the steam boiler); 2) electric (zipper); 3) atomic (the explosion of a nuclear charge); 4) Chemical (explosions of brisk explosives).

  K.V. Vishnevetsky, A.I. Gaena, A.V. Gusev, V.N. Mikhayleshin offer the following explosion classification:

  ■ Depending on the type of explosive: 1) the explosion of mixed with air and the air and vapor of liquids (for example, propane, methane, petroleum products, etc.), as well as flammable, weighted dust-weighted dust (for example, coal, flour, tobacco, wood, plastic); 2) explosions of hard explosives;

  ■ Depending on the way of propagation of explosive energy: 1) the volume (the explosion, in which the defeat is applied with a shock wave arising when the cloud explosion); 2) directed (the environment moves mainly in a given direction and at the estimated distance (cumulative explosion).

  MA Mikhailov rightly recognizes the most universal and concise for the practice of combating crime Classification of explosions proposed by Yu.M. Dilsen, V.V. Martynov, A.Yu. Semenov, A.A. Shrimp, on the explosions of physical and chemical nature.

  Physical explosions (physical transformations of the system) can occur with the rapid transition of the substance into a vapor state when heated from outside, a powerful spark discharge, mixing two substances in a liquid state with a large temperature difference (for example, when water in the molten metal).

  Examples of the deliberate unlawful use of the physical explosion are the placement in the furnace stove with compressed gas, the manufacture of a self-made explosive device.

  In criminal purposes, chemical explosions are often carried out, in which the energy of explosives into the energy of compressed gases as a result of a chemical reaction occurs. Persons performing a preliminary investigation on the fact of the explosion, in most cases have to face the effects of chemical explosions characterized by the following factors:

  1) exothermic (heat release, due to which heated gaseous products to a large temperature and their subsequent expansion; the more heat and the rate of propagation of the reaction, the greater the destructive effect of the explosion);

  2) a high speed of propagation of an explosive reaction (in the form of explosive burning or detonation; determined on the basis of the minimum amount of the time required for the reaction flow);

  3) the release of a large number of gaseous products of the chemical reaction (gives an explosion to the destructive power of the shock wave arising from the pressure drop).

  The process of leaking the reaction of the chemical explosion consists of three stages. It:

  1) initiation - excitation of the explosion process caused by an external impulse (friction, heating, blow, etc.);

  2) detonation - the passage of the reaction of the conversion of an explosive inside the weight of the charge in gas at a speed exceeding the speed of the sound;

  3) the formation and propagation of the shock wave is carried out as a result of a sharp expansion of the gas mixture, which leads to a sharp pressure jump in the external environment, as a result of which the air is supplanted around the charge of an explosive. The overpressure phase continues the fraction of a second, gradually decreasing to the magnitude of the environmental pressure; At the same time, the squeezed air begins to move in the opposite direction, seeking to fill the vacuum formed in the epicenter, which leads to additional destruction of objects and the movement of individual items.

  Damaging explosion factors. The chemical explosion is accompanied by the formation of a large number of products heated to high temperatures and compressed to large pressures, which expanding, form a shock wave, which has a strong dynamic impact on the environment and objects of a real situation. The striking effect of the explosion is to cause damage to objects of a material situation and people. These manifestations in the external environment of a number of signs indicating the effects produced by an explosion are called explosion factors. The main factors of the chemical explosion are:

  1) Thermal (incendiary) action, expressed in the occurrence of foci of lightbing objects of a material situation, causing burns in open areas of the surface of the body of a person who is at a distance of 7 radii of explosives charges; The main signs of the thermal action of the explosion: a) traces of the gain; b) traces of melting;

  2) a cumulative effect, manifested in damage to the goal of a concentrated and directed jet of products of the explosion of charge and facing materials, which leads to a significant increase in the depth of the barrier;

  3) a fragmentary effect occurring in the explosion of charges placed in a solid metal shell when the shell crushing and the throwing of the formed fragments (primary) at high speed were carried out as a result of the brisk exposure; Signs of fragmentary action: a) Craters and tracks (scratches) at objects; b) cross-cutting and "blind" sobrels from the introduction of fragments in the materials obstacles; c) characteristic (multiple and different localization) human damage damage;

  4) the shock effect manifested in the defeat of the target due to the kinetic energy of the moving projectile, the material trains of which traces characteristic of the fragmentation, fugasal, fugas-fragmentation of the explosion;

  5) a fugasic effect characterized by damage (destruction) of the goal of the explosion of a discontinuous charge and the resulting shock wave, manifested in much greater space from the center of the explosion and producing irreversible changes in the surrounding environment; His signs: a) defeat people; b) movement of objects of the surroundings; c) destruction, damage and deformation of individual elements and objects in the field of action of the explosion; d) high-speed injection of elements destroyed by an explosion of objects with subsequent shock interaction with other objects of the surrounding environment;

  6) a brisk (crushing) action manifested in the ability of explosives to produce during the explosion of destruction (crushing) of the medium directly in contact with the charge; The main signs of the brisk action of the explosion: a) a funnel in the ground and other materials; b) local deformations of the zone of the plastic flow of metal; c) destruction in the form of dents, funnels, chips on high-strength elements of metal, reinforced concrete, bricks, etc.; d) local areas of complete destruction on low-force objects from wood, glass, polymeric materials, etc.; e) education on the human body of grave injuries;

  7) Special purpose (lighting, signal, noise, etc.).

  The damaging effect of the explosion on the body is shown in Figure 3.3.

  Figure 3.3 - Damage to open parts of the body during explosion.

  Thus, during an explosion, detonation products, explosives, a shock wave of the environment, fragments of an explosive device, special impact elements and substances are possessed by the damaging effect. Their aggregate is denoted by the damaging explosion factors given in Scheme 3.4.

  

  Scheme 3.4 - Classification of damaging explosion factors.

  The traumatic effect of damaging blast factors is ambiguous. Damage from the explosion is distinguished by the extreme variety: from single fragmentation wounds to complete destruction of the body of an adult. The traumatic effect of damaging factors is shown in Scheme 3.5.

  Since explosive devices are distinguished by constructive and powerful diversity, distances from the center of the explosion, relying on several conditional high-quality distances:

  a) direct contact (close, "contact", "zero" distance), when the body of the victim is in the zone of the combined effect of explosive gases;

  b) a relatively close distance (within the zone of the shock wave, but outside the zone of the action of explosive gases);

  c) a unclean distance, when only the shell fragments or composite elements of the explosive device are valid.
  

  The comparative characteristic of explosive damage at all distances is shown in Table 3.1.

  

  Scheme 3.5 - the nature of the traumatic action of damaging factors of the explosion.

  Table 3.1 - the nature of damage depending on the explosion distance (according to V.L. Popov, 2002) 62

  The distance of the explosion	Damaging	Character of damage
  1. Control of the projectile with a body or a very close distance (within the action of explosive gases)	- wave of explosive gases Pieces of explosive substances Shock wave Shards shell, fuse, secondary shells	Combined lesions: Destruction and separation of body parts Opolenial -cake Closed damage to bones and internal organs Shard wounds
  2. relatively close (within the action of the shock wave)	- Shock wave Turning and dropping body Shards shell Secondary shells	- closed and open fractures and damage to internal organs Shard wounds
  3. Close in the presence of destructive barriers	- Destruction of the barrier Shards	- closed and open damage to bones and internal organs Shard wounds
  4. Non-job	- Single fragments	- one or more fragmentation wounds

  62 Popov, V.L. Judicial Medicine: Textbook / VL. Popov. - SPb.: Peter, 2002. - P. 214-215.

  Thus, the overall characteristics of explosives, explosive devices, explosions and their traces makes it possible to determine the circle of objects under study, the directions of their research, reasonably build investigative and expert versions regarding the circumstances related to the specifics of the device and the action of explosives and explosive devices, as well as possible sources The origin of the objects of research on the fact of the explosion.

  Explosive injury is the only form of injury, as a result of which, at the same time, for a very short period of time, mechanical, thermal and chemical factors operate for a very short period of time. It is this combination that determines its originality, makes it possible to differentiate various types of explosions based on the results of forensic examination.

  Even on the topic, the overall characteristics of the explosions and their damaging factors:

  1. Characteristics of injuries and their description with the primary inspection of the corpse on the site of its detection
  2. Inspection of gunshot damage on the corpse visually detected when inspection of the scene
  3. The overall characteristics of the explosions and their damaging factors

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