Classification of explosions depending on the environment. Man-made emergencies. Fires and explosions - Abstract. General information about the explosion
Introduction
Explosion. Classification of explosions
Features of explosions
Conclusion
Used Books
Introduction
An emergency situation (ES) is a state or situation in a certain territory that has developed as a result of an accident, catastrophe, dangerous phenomenon, natural or other disaster that may or have already entailed human casualties, damage to human health or the natural environment, significant material losses, violation of the conditions of normal human life.
In most cases, man-made accidents are associated with uncontrolled, spontaneous release of matter or energy into the surrounding space. Spontaneous release of energy leads to industrial explosions, and substances - to explosions, fires and chemical pollution of the environment.
There are various classifications of emergencies. Most often, the nature of the occurrence (genesis) of an emergency is chosen as the basis for the classification. According to the nature (sphere) of occurrence, all emergencies can be conditionally divided into the following large groups:
man-made Emergencies related by origin to technical facilities or technological processes (releases of radioactive substances, accidents at hazardous chemical facilities, fires and explosions, destruction of building structures, transport accidents, etc.), including anthropogenic emergencies caused by negative influence the person himself on the technosphere (erroneous and untimely actions of operators, dispatchers, pilots, drivers, etc.)
Natural Emergencies associated with the impact of natural phenomena of a physical nature (floods, earthquakes, hurricanes, etc.) on a person and his environment, as well as biological emergency and environmental Emergency.
Social Emergencies associated with large-scale events in society and the state (wars, armed conflicts, clashes on an interethnic and interreligious basis, etc.)
Combined Emergencies that have a combined, initiated nature of various types of the above groups of emergencies.
In this work, we will consider only a small group related to man-made emergencies.
Explosion. Classification of explosions.
Explosion - the process of rapid uncontrolled physical or chemical transformation of a system, accompanied by the transition of its potential energy into mechanical work. The mechanical work done in an explosion is due to the rapid expansion of gases or vapors, whether they existed before the explosion or were formed during the explosion. The explosive process can be based on both physical (destruction of a vessel with a compressed gas or superheated liquid) and chemical transformations (detonation of a condensed explosive, rapid combustion of a gas cloud). The most significant sign of an explosion is a sharp jump in pressure in the medium, which causes the formation of a shock wave that propagates some distance from the place of explosion.
In chemical explosions, explosives can be solid, liquid, gaseous, as well as air suspensions of combustible substances (liquid and solid) in an oxidizing environment (often in air). Solid and liquid explosives in most cases belong to the class of condensed explosives (HE). When an explosion is initiated in these substances, exothermic redox reactions or thermal decomposition reactions proceed with great speed with the release of thermal energy. Gaseous explosives are homogeneous mixtures of combustible gases (vapors) with gaseous oxidants - air, oxygen, chlorine, etc. Explosive air suspensions consist of fine particles of combustible liquids (fogs) or solids (dusts) in an oxidizing environment, most often in air.
A physical explosion is most often associated with an uncontrolled release of the potential energy of compressed gases from closed volumes of machines and apparatuses. The strength of the explosion of a compressed or reduced gas depends on the internal pressure, and destruction is caused by a shock wave from an expanding gas (steam) and fragments of a ruptured tank.
The parameters that determine the power of the explosion are the energy of the explosion and the rate of its release. The energy of an explosion is determined by the physicochemical transformations that occur during various types of explosions. For steam-gas media, the explosion energy is determined by the heat of combustion of combustible substances in a mixture with air; condensed explosives - by the heat released during detonation (decomposition reactions); in physical explosions of systems with compressed gases and superheated liquids, according to the energy of the adiabatic expansion of vapor-gas media and overheating of the liquid.
Under production conditions, the following main types of explosions are possible: free air, ground, explosion in the immediate vicinity of the object, as well as an explosion inside the object (industrial facility).
During an air explosion, a shock spherical wave reaches the earth's surface and is reflected from it. At some distance from the epicenter of the explosion (the projection of the explosion center onto the earth's surface), the front of the reflected wave merges with the front of the incident wave, as a result of which the so-called head wave is formed, a vertical front propagating from the epicenter along the earth's surface.
The nature of the air shock wave during a ground explosion (outside the funnel) corresponds to the far zone of an air explosion. Thus, in both air and ground explosions, one usually considers an air shock wave propagating from an epicenter with a vertical front. When the shock wave approaches the barrier, it is reflected and the moving air masses are decelerated, which leads to an increase in excess pressure by 2–8 times.
After the initial interaction with the obstacle (obstacle), the shock wave begins to flow around it and the side and back surfaces of the obstacle already fall under the action of pressure. It seems to be in a compressed state from all sides, but the greatest pressure is on the frontal part of the obstacle.
Copying of technological objects by explosiveness is carried out according to the values of indicators Q in = (16,534) -1 * E 1/3.
The energy equivalent of an explosion of TNT W=E/4520 kg, where E is the total energy of the explosion.
According to these indicators, technological objects are divided into three categories:
An explosion inside an object is characterized by the fact that the load acts on the object from the inside. When a mixture explodes inside a partially filled object, the consequences of the explosion will be affected by the location of the explosive cloud. In the general case, the consequences of explosions inside the premises will be largely determined by the maximum possible overpressure of the explosion ∆p, which can be calculated using the following relationship:
∆р=WZ p0 H T 1/K H N 0 C B p B V C K ,
Where W is the mass of combustible gas, a pair of LVH or combustible dust suspended in the air that entered the volume of the room, kg; Z-coefficient of participation of combustible substance in the explosion; p 0 -atmospheric pressure equal to 101 kPa; H t is the heat of combustion of the substance entering the room; K n - coefficient taking into account the leakage of the room (taken equal to three); T 0 is the temperature in the room (can be taken equal to 293K); C in - heat capacity of air (can be taken equal to 1.01 kJ / (kg * K)); p in - air density (can be taken equal to 1.2 kg / m 3); V with - free volume of the room, m 3; K=k B t+1 is a coefficient that takes into account the presence of emergency ventilation in the room (k B is the air exchange rate in the room, s -1; t is the time of arrival of explosive substances in the room, s).
Features of explosions
Explosions of high-pressure systems are accompanied by the scattering of fragments. Up to 60% of the gas expansion energy is spent on communicating kinetic energy to the fragments, and 40% is spent on the formation of a shock wave. During explosions, most of the fragments (up to 80%) scatter over a distance of 200 m, a smaller part (20%) over distances up to 1000 m, individual fragments can scatter over distances up to 3 km. The directions of expansion of fragments for cylindrical vessels with reduced gases are characterized by the scheme shown in Fig. 9.4. for a safe distance for people, you can take a value exceeding 1000 m.
Large gas clouds can form from leaks or sudden rupture of sealed containers, pipelines, etc. The process of explosion or combustion of such gas clouds has a number of specific features. Gas clouds formed in the atmosphere most often have a cigar-shaped shape, elongated in the direction of the wind. The initiators of combustion or explosion in these cases are most often random. Moreover, ignition is not always accompanied by an explosion.
With poor mixing of gaseous substances with atmospheric air there is no explosion at all. In this case, when a gas or vapor-air mixture is ignited, a "combustion wave" will propagate from the place of initiation. Since the propagation of the flame occurs at a relatively low speed, the pressure does not increase in the combustion wave. In such a process, only expansion of combustion products is observed due to their heating in the flame zone. The slow burning mode of the cloud from the outer surface with a large release of radiant energy can lead to the formation of many fires at an industrial facility.
When assessing the destructive effect of an explosion of a gas cloud in open space, the dynamic pressure in the flame front will be decisive. For a flame of limiting carbohydrates, the velocity head in open space can reach 26 kPa.
Conclusion
Emergency(ES) is a state or situation in a certain territory that has developed as a result of a catastrophe or natural disaster and has caused human casualties, significant damage to human health or the natural environment.
By area of origin Distinguish between man-made, natural (physical, biological), social and combined emergencies.
By the scale of the consequences they are divided into local, local, territorial, regional, federal and transboundary.
By development structure Emergencies have the following main phases: accumulation of deviations, initiating events, active development, the action of residual and secondary damaging factors, and active elimination of consequences.
The State System for the Prevention and Elimination of Emergencies (RSChS) has the following structural levels: federal, interregional, regional, municipal and facility.
The main activities of the RSChS are the prevention and prevention of emergencies (as the main and capable of reducing damage from emergencies), emergency rescue operations and the elimination of the consequences of emergencies.
Threat State Grading System The emergency adopted in the RSChS requires greater differentiation and the introduction of additional levels of threats.
Used Books
Life safety. Textbook for students B 40 / S.V. Belov, V.A. Devisilov, A.F. Koziakov and others; Under total Ed. S.V. Belova.
Life safety: lecture notes.-M.: Yurayt-Izdat, 2008.191s.
Ecology and life safety: study guide for universities / D.A. Krivoshein, L.A. Ant, N.N. Roeva and others; Ed. L.A. Ant
man-made emergency situations. fires
Abstract >>... – consider the features man-made emergency situations For example fires. When writing ... The result of burning may be fire And explosion. Fire- this burning outside ... is accompanied by the appearance of a flame. Explosion- process extremely fast, influenced...
man-made emergency situations
Abstract >> Life safety... technogenic emergency situation. To the dangerous technogenic accidents include accidents at industrial facilities or in transport, fires, explosions ...
Ecological safety of man, biosphere and industrial facilities under conditions man-made emergency situations and accidents
Coursework >> EcologyIndustrial facilities in conditions man-made emergency situations and accidents 1. Basic concepts emergency situation- this is the situation on a certain ... substances is the possibility of their potential explosion
Explosions most commonly encountered in practice can be divided into two main groups: physical And chemical(see figure 7.2).
Physical explosions include processes that lead to an explosion and are not accompanied by a chemical transformation of matter.
Chemical explosions include processes of chemical transformation of matter, manifested by combustion and characterized by the release of thermal energy in a short period of time and in such volume that pressure waves are formed that propagate from the source of the explosion.
The most common cause of accidental explosions are combustion processes. Explosions of this kind most often occur during storage, transportation and manufacture of explosives. They occur when handling explosives and explosive substances in the chemical and petrochemical industries; in case of natural gas leaks in residential buildings; in the manufacture, transportation and storage of volatile or liquefied combustible substances; when flushing storage tanks for liquid fuels; in the manufacture, storage and use of combustible dust systems and some spontaneously combustible solid and liquid substances.
Rice. 7.2. Classification of explosions most frequently encountered in practice
At physical explosion the released energy is the internal energy of the compressed or liquefied gas (more strictly, liquefied steam). The strength of such explosions depends on the internal pressure, and destruction can be caused by a shock wave from an expanding gas or fragments of a ruptured tank. In a number of accidents, physical explosions were noted, arising from the complete destruction of tankers. Depending on the circumstances, parts of such a reservoir scattered hundreds of meters.
The same thing can happen (on a smaller scale) to portable gas bottles if the bottle falls and the pressure-reducing valve breaks. Numerous cases of such purely physical explosions of vessels with liquefied gases under pressure not exceeding 4 MPa are known.
Physical explosions should also include the phenomenon of so-called physical (or thermal) detonation, which occurs when hot and cold liquids are mixed, when the temperature of one of them significantly exceeds the boiling point of the other (for example, when pouring molten iron into water). In the resulting vapor-liquid mixture, evaporation can proceed explosively due to the developing processes of fine fragmentation of melt droplets, rapid removal from them, and overheating of the cold liquid. Physical detonation is accompanied by the formation of a shock wave with excess pressure in the liquid phase, reaching hundreds of megapascals in some cases. This phenomenon can cause major accidents in nuclear reactors and at industrial enterprises in the metallurgical, chemical and paper industries.
Energy sources of compressed gases (vapors) in closed volumes of equipment can be both external and internal. External - this is electrical energy used to compress gases and pump liquids; heat carriers, including electrical ones, providing heating of liquids and gases in closed volumes of equipment. Internal sources include the energy of exothermic physicochemical and heat and mass transfer processes in a closed volume of equipment, leading to intensive evaporation of liquid media or gas formation, an increase in temperature and pressure without internal explosive phenomena.
chemical explosions are divided into volumetric (see Fig. 7.3) and explosions of condensed explosives. The source of a chemical explosion is a rapidly flowing self-accelerating exothermic reaction of the interaction of combustible substances with oxidizing agents or thermal decomposition of unstable compounds. Under some circumstances, uncontrolled reactions are possible, accompanied by an increase in pressure in the reaction vessel, which can completely collapse if not safety valve. In this case, a shock wave and a fragmentation field can form.
Rice. 7.3. Classification of volumetric explosions
Energy carriers of chemical explosions can be solid, liquid, gaseous substances, as well as air suspensions of combustible substances (liquid and solid) in an oxidizing environment (often in air). Explosions of gas mixtures and air suspensions of combustible substances are sometimes called bulk explosions. Solid and liquid energy carriers in most cases belong to the class condensed explosives. These substances or their mixtures contain reducing and oxidizing agents or other chemically unstable compounds. When an explosion is initiated in these substances, exothermic redox reactions or thermal decomposition reactions with the release of thermal energy proceed at an enormous speed (during explosions of a condensed explosive, carbon and hydrogen atoms in the substance molecules are replaced by nitrogen atoms).
Gaseous energy carriers are homogeneous mixtures of combustible gases (vapours) with gaseous oxidants such as air, oxygen, chlorine, etc., or unstable gaseous compounds such as acetylene, ethylene (prone to thermal decomposition in the absence of oxidizing agents). The source of explosions of gas mixtures are exothermic reactions of oxidation of a combustible substance or decomposition reactions of unstable compounds.
Two-phase explosive air suspension consist of finely dispersed combustible liquids (“fogs”) or solids (dust) in an oxidizing environment, mainly in air. The source of energy for their explosions is also the heat of combustion of these substances.
A technological system is explosive if it has a store of potential energy released at such a high rate that it can generate an air shock wave (ASW) capable of causing crashes or injury to people. The amount of potential energy is determined by the corresponding physical and chemical laws of energy release.
The energy of the explosion of gas-vapor media is determined by the heat of combustion of combustible substances in a mixture with air (oxidizer); condensed explosives - according to the heat released during their detonation (decomposition reactions); in physical explosions of systems with compressed gases and superheated liquids - according to the energy of adiabatic expansion of vapor-gas media and liquid overheating.
The rate of energy release is generally expressed as power density, i.e., the amount of energy released per unit time per unit volume. In chemical explosions, the rate of energy release can be determined from the speed of propagation of detonation or flame in a gaseous medium. The velocity of detonation propagation in a solid or liquid explosive approximately corresponds to the speed of sound in a substance and is in the range 2 . 10 3 -9 . 10 3 m/s; during gas physical and chemical explosions, compression waves move at a speed close to the speed of sound in air.
Chemical explosions caused by exothermic decomposition reactions in condensed explosives or unstable compounds in the gas phase are accompanied by the formation (increase) in the number of moles of gases. For example, in the explosion of 1 kg of trinitrotoluene (TNT), which is a substance with a negative oxygen balance, approximately 20 mol of gases (vapours) are formed (0.6 - CO; 10.0 - CO 2; 0.8 - H 2 O; 6, 0 - N 2; 0.4 - NH 3; 4.7 -CH 3 OH; 1.0 - HCN) and 15 mol of carbon. Most other blasting explosives (with the exception of nitroglycerin) are also substances with a negative oxygen balance, i.e. the number of oxygen atoms in their molecules is not enough to completely convert the existing carbon atoms into CO 2 and hydrogen into H 2 O. The ability of a substance to an explosive process is subject to the laws of thermochemistry, according to which, if in a given reaction the sum of the heats of formation of products is less than the heat of formation of the initial compound, then this substance is potentially explosive. For example, if substance A, which decomposes according to the reaction A → B + C + D, is explosive, then the condition must be met:
q(A) ≥ q(B) + q(C) + q(D),
where q is the enthalpy (heat) of formation; q is positive for compounds formed with heat absorption (endothermic processes) and negative for compounds formed with heat release (exothermic processes).
Thus, it is only possible to evaluate the ability of a substance to an explosive process, and the energy and power of an explosion are determined by the reaction rate.
Energy sources of explosions can be redox chemical reactions, in which
air or oxygen interact with the reducing agent.
Along with combustible gases, reducing agents can be
fine combustible solids (dusts) or
dispersed liquids. Redox reactions under these conditions can proceed both in closed and open volumes at sufficiently high rates at which shock waves are generated that can cause significant damage.
17. What is the name of the emergency situation associated with the failure of a hydraulic structure or part of it and the uncontrolled movement of large masses of water, causing destruction and flooding of vast territories. a) Hydrodynamic accident; b) Hydrodynamic catastrophe; c) Hydrodynamic emergency.18. What signal is used to alert the population in emergency situations of a man-made nature? a) “Attention accident!” b) “Attention everyone!” What can be the evacuation at the start time? a) Local, regional, federal; b) Temporary, medium-term, long; c) Proactive, emergency. What are the names of civil defense structures that are designed to provide reliable protection people sheltered in them from the effects of all the damaging factors of a nuclear explosion, toxic substances and bacterial agents, high temperatures, from poisoning by combustion products and emergency chemically hazardous substances? a) Shelters; b) Anti-radiation shelters; c) Slots.21. What is health? diseases and physical defects.22. What is the name of a person's ability to adapt to natural, man-made and social habitats? a) Physical health; b) Spiritual health; c) Social health.23. What is the name of the component of human and social health that characterizes the ability to create and implement the necessary conditions for the birth of a child and the upbringing of a healthy generation? a) Reproductive health; b) Social health; c) Human and social health.24. What factors are necessary in order to form a system of a healthy lifestyle for a person? ecological situation in places of residence.25. What, according to the definition of the World Health Organization, is the main indicator of the state of health of the population? healthy image life; b) Life expectancy; c) Heredity.26. What is drug addiction? a) A disease that occurs as a result of the use of drugs; b) One of the varieties of drug addiction; c) The irresistible need of a person to take a drug.
Depending on the oxygen content, flames are classified as oxidizing, reducing and carburizing. 1) How do human tools differ from tools used by monkeys? 2) what features of the body structure gave a person the opportunity to playWhat is an explosion? This is a process of instantaneous transformation of the state in which a significant amount of thermal energy and gases are released, forming a shock wave.
Explosives are compounds that have the ability to undergo changes in the physical and chemical state as a result of external influences with the formation of an explosion.
Classification of explosion types
1. Physical - the energy of an explosion is the potential energy of a compressed gas or steam. Depending on the magnitude of the internal energy pressure, an explosion of different power is obtained. The mechanical impact of the explosion is due to the action of the shock wave. Fragments of the shell cause an additional damaging effect.
2. Chemical - in this case, the explosion is due to the almost instantaneous chemical interaction of the substances that make up the composition, with the release of a large amount of heat, as well as gases and steam with a high degree of compression. Explosions of these types are typical, for example, for gunpowder. Substances arising as a result of a chemical reaction acquire high pressure when heated. The explosion of pyrotechnics also belongs to this species.
3. Nuclear explosions are lightning-fast reactions of nuclear fission or fusion, characterized by a huge power of released energy, including heat. The colossal temperature at the epicenter of the explosion leads to the formation of a zone of very high pressure. The expansion of the gas leads to the appearance of a shock wave, which is the cause of mechanical damage.
The concept and classification of explosions allow you to act correctly in an emergency.
Action type
Distinctive features
Explosions differ depending on the chemical reactions taking place:
- Decomposition is characteristic of a gaseous medium.
- Redox processes imply the presence of a reducing agent with which the oxygen in the air will react.
- Reaction of mixtures.
Volumetric explosions include dust explosions, as well as explosions of steam clouds.
dust explosions
They are typical for closed dusty structures, such as mines. A dangerous concentration of explosive dust appears when carrying out mechanical work with loose materials, giving a large amount of dust. Working with explosives requires full knowledge of what an explosion is.
For each type of dust, there is a so-called maximum permissible concentration, above which there is a danger of spontaneous explosion, and this amount of dust is measured in grams per cubic meter of air. The calculated concentration values are not constant values and must be corrected depending on humidity, temperature and other environmental conditions.
Of particular danger is the presence of methane. In this case, there is an increased probability of detonation of dust mixtures. Already a five percent content of methane vapor in the air threatens with an explosion, due to which the ignition of a dust cloud follows and an increase in turbulence. There is a positive Feedback, leading to an explosion of great energy. Scientists are attracted by such reactions, the explosion theory still haunts many.
Safety when working in confined spaces
When working in closed rooms with a high content of dust in the air, it is imperative to adhere to the following safety rules:
Dust removal by ventilation;
Fight against excessive dryness of air;
Dilution of the air mixture to reduce the concentration of explosives.
Dust explosions are typical not only for mines, but also for buildings and granaries.
Steam cloud explosions
They are reactions of a lightning-fast change of state, generating the formation of a blast wave. Occur outdoors, in a confined space due to the ignition of a combustible vapor cloud. This usually happens when there is a leak.
Refusal to work with combustible gas or steam;
Refusal of ignition sources that can cause a spark;
Avoiding closed spaces.
You need to have a sound understanding of what an explosion is, what danger it carries. Failure to comply with safety rules and the illiterate use of some items leads to disaster.
Gas explosions
The most common accidents in which a gas explosion occurs occur as a result of improper handling of gas equipment. Timely elimination and characteristic definition are important. What does gas explosion mean? It occurs due to improper operation.
In order to prevent such explosions, all gas equipment must undergo regular preventive technical inspection. All residents of private households, as well as apartment buildings, are recommended an annual maintenance of the VDGO.
To reduce the consequences of an explosion, the structures of the premises in which gas equipment is installed are made not capital, but, on the contrary, lightweight. In the event of an explosion, there is no major damage and blockages. Now you imagine what an explosion is.
In order to make it easier to determine the leakage of household gas, the aromatic additive ethyl mercaptan is added to it, which causes a characteristic smell. If there is such a smell in the room, it is necessary to open the windows to ensure the supply of fresh air. Then you should call the gas service. At this time, it is better not to use electrical switches that can cause a spark. It is strictly forbidden to smoke!
The explosion of pyrotechnics can also become a threat. The storage of such items must be equipped in accordance with the standards. Poor quality products can harm the person who uses it. All this should definitely be taken into account.
An explosion is a common physical phenomenon that has played a significant role in the fate of mankind. It can destroy and kill, as well as be useful, protecting a person from threats such as flooding and asteroid attack. Explosions differ in nature, but in the nature of the process they are always destructive. This strength is their main distinguishing feature.
The word "explosion" is familiar to everyone. However, the question of what an explosion is can only be answered on the basis of what this word is used for. Physically, an explosion is a process of extremely rapid release of energy and gases in a relatively small volume of space.
The rapid expansion (thermal or mechanical) of a gas or other substance, such as when a grenade explodes, creates a shock wave (high pressure zone) that can be destructive.
In biology, an explosion means a rapid and large-scale biological process (for example, an explosion in numbers, an explosion in speciation). Thus, the answer to the question of what an explosion is depends on the subject of study. However, as a rule, it is precisely the classic explosion that is meant by it, which will be discussed further.
Classification of explosions
Explosions can have a different nature, power. Occur in various environments(including vacuum). According to the nature of occurrence, explosions can be divided into:
- physical (explosion of a burst balloon, etc.);
- chemical (for example, an explosion of TNT);
- nuclear and thermonuclear explosions.
Chemical explosions can occur in solid, liquid or gaseous substances, as well as air suspensions. The main ones in such explosions are redox reactions of the exothermic type, or exothermic decomposition reactions. An example of a chemical explosion is a grenade explosion.
Physical explosions occur when the tightness of containers with liquefied gas and other substances under pressure is violated. Also, they can be caused by the thermal expansion of liquids or gases in the composition of a solid body, followed by a violation of the integrity of the crystal structure, which leads to a sharp destruction of the object and the appearance of an explosion effect.
Explosion power
The power of explosions can be different: from the usual loud bang due to a burst balloon or exploded firecrackers to giant cosmic explosions of supernovae.
The intensity of the explosion depends on the amount of energy released and the rate of its release. When evaluating the energy of a chemical explosion, such an indicator as the amount of heat released is used. The amount of energy in a physical explosion is determined by the amount of kinetic energy of the adiabatic expansion of vapors and gases.
man-made explosions
At an industrial enterprise, explosive objects are not uncommon, and therefore such types of explosions as air, ground and internal (inside a technical structure) can occur there. When mining hard coal methane explosions are not uncommon, which is especially characteristic of deep coal mines, where for this reason there is a lack of ventilation. Moreover, different coal seams have different methane content, and therefore the level of explosive danger in the mines is different. Methane explosions are a big problem for the deep mines of Donbass, which requires increased control and monitoring of its content in the mine air.
Explosive objects are containers with liquefied gas or steam under pressure. Also military warehouses, containers with ammonium nitrate and many other objects.
The consequences of an explosion at work can be unpredictable, including tragic ones, among which the possible release of chemicals occupies a leading position.
The use of explosions
The explosion effect has long been used by mankind for various purposes, which can be divided into peaceful and military. In the first case, we are talking about the creation of directed explosions for the destruction of buildings to be demolished, ice jams on rivers, in the extraction of minerals, in construction. Thanks to them, the labor costs necessary for the implementation of the tasks set are significantly reduced.
An explosive is a chemical mixture that, under the influence of certain, easily achieved conditions, enters into a violent chemical reaction, leading to the rapid release of energy and a large amount of gas. By its nature, the explosion of such a substance is similar to combustion, only it proceeds at a tremendous speed.
External influences that can provoke an explosion are as follows:
- mechanical impacts (for example, impact);
- a chemical component associated with the addition of other components to the explosive that provoke the start of an explosive reaction;
- temperature effects (heating of the explosive or sparks on it);
- detonation from a nearby explosion.
The degree of response to external influences
The degree of reaction of an explosive to any of the influences is exclusively individual. So, some types of gunpowder ignite easily when heated, but remain inert under the influence of chemical and mechanical influences. TNT explodes from the detonation of other explosives, and it is not very sensitive to other factors. Mercury fulminate is undermined by all kinds of impacts, and some explosives can even explode spontaneously, making such compounds very dangerous and unsuitable for use.
How does an explosive detonate?
Different explosives explode in slightly different ways. For example, gunpowder is characterized by a rapid ignition reaction with the release of energy over a relatively long period of time. Therefore, it is used in military affairs to give speed to cartridges and projectiles without breaking their shells.
In another type of explosion (detonation), the explosive reaction propagates through the substance at supersonic speed, and it is also the cause. This leads to the fact that energy is released in a very short period of time and at a tremendous speed, so the metal capsules are torn apart from the inside. This type of explosion is typical for such dangerous explosives as RDX, TNT, ammonite, etc.
Explosive types
Features of sensitivity to external influences and indicators of explosive power make it possible to divide explosives into 3 main groups: propelling, initiating and blasting. Throwing include different kinds gunpowder. This group includes low-power explosive mixtures for firecrackers and fireworks. In military affairs, they are used for the manufacture of lighting and signal rockets, as a source of energy for cartridges and shells.
A feature of initiating explosives is their sensitivity to external factors. At the same time, they have low explosive power and heat dissipation. Therefore, they are used as a detonator for blasting and propellant explosives. They are carefully packaged to prevent self-destruction.
High explosives have the highest explosive power. They are used as fillings for bombs, shells, mines, rockets, etc. The most dangerous of them are hexogen, tetryl, and PETN. Less powerful explosives are TNT and plastid. Among the least powerful is ammonium nitrate. Brisant substances with high explosive power are also more sensitive to external influences, which makes them even more dangerous. Therefore, they are used in combination with less powerful or other components that lead to a decrease in sensitivity.
Explosive parameters
In accordance with the volumes and rate of energy and gas release, all explosives are evaluated according to such parameters as brisance and explosiveness. Brisatness characterizes the rate of energy release, which directly affects the destructive ability of the explosive.
Explosiveness determines the magnitude of the release of gases and energy, and hence the amount of work produced during the explosion.
In both parameters, hexogen is the leader, which is the most dangerous explosive.
So, we tried to answer the question of what an explosion is. And also considered the main types of explosions and methods of classification of explosives. We hope that after reading this article, you have got a general idea of what an explosion is.
