1. Basic principles and methods of ensuring life safety………………………………………………………………3

2. Harmful and poisonous substances: concepts and classification according to the degree of danger and toxic effect. Regulation of the action of harmful and toxic substances on humans…………………………………………….7

3. Classification and characteristics of fires……………………………..14

3.1 Damaging factors of fires………………………………….20

3.2 Ways and means of extinguishing a fire…………………………....21

3.3 Classification of buildings and structures according to the degree of fire resistance…………………………………………………………….24

3.4 Classification of premises and buildings according to the degree of explosion…………………………………………………….25

1. Basic principles and methods of ensuring life safety.

“Security is a state of protection of an individual, society, state from external and internal dangers and threats, based on the activities of people, society, the state, the world community of peoples to identify, “study”, prevent, mitigate, eliminate, “eliminate” and reflect dangers and threats capable of destroying them, depriving them of fundamental material and spiritual values, inflicting unacceptable, “unacceptable objectively and subjectively” damage, blocking the way for survival and development.”

In methodological terms, life safety is a modern complex science of fundamental and applied nature. Facts and patterns must necessarily be considered from a systematic standpoint, allowing them to be studied on the basis of certain principles, methods and procedures.

The choice of principles and methods depends on the specific operating conditions, the level of safety, cost and other criteria. They can be classified according to several criteria. On the basis of implementation, they are conditionally divided into four classes:

1. orienting (general search direction);

2. technical (aimed at the implementation of protective equipment for technical devices).

3. managerial (control over compliance with standards, responsibility);

4. organizing (organization of the working day);

The guiding principles include taking into account the human factor, the principle of regulation, and a systematic approach.

The guiding principles are fundamental ideas that determine the direction of the search for safe solutions and serve as a methodological and informational base among the guiding principles, the primary role is given to the principle of consistency, which consists in the fact that any phenomenon, action, any object is considered as an element of the system. The principle of consistency is based on the ratio of the whole and the part. The whole in its main characteristics, in meaning and role, in terms of the possibilities inherent in it, is not identical to the sum of its constituent parts. At the same time, the part, in turn, has relative independence, its inherent qualitative features and can be considered as a whole with its constituent parts, but on a smaller scale.

Each phenomenon should be studied as a certain system of its constituent elements, as a unity of interrelated and interacting objects, processes, relations.

The next guiding principle is interconnection and interdependence. The objective existence of the universal interconnection of phenomena and processes of reality, as well as the interaction of all their aspects, is due to the fact that neither in nature nor in social life are there absolutely isolated phenomena and objects. The guiding principle of destruction is that a system that leads to a dangerous result is destroyed due to the exclusion of one or more elements from it. This principle is organically connected with the principle of consistency and has the same universal meaning.

The guiding principle of risk reduction is to use solutions that improve safety but do not achieve the level desired or required by regulations.

The guiding principle for the elimination of danger is to eliminate dangerous and harmful factors, which is achieved by changing technology, replacing certain substances with safe ones, using safer equipment, improving the scientific organization of labor and other means.

To technical ones - principles that involve the use of specific technical solutions to improve safety: the principle of protection by quantity (for example, the maximum reduction of harmful emissions), the principle of protection by distance (impact harmful factor decreases due to increasing distance), protective earth, insulation, enclosures, shielding, sealing, principle weak link(use it in pressure systems: bursting discs, pressure cookers, etc.).

The technical principles are aimed at the direct prevention of the action of hazards. Among them, the following can be distinguished: the principle of protection by distance, the principle of strength, the principle of a weak link, the principle of shielding, etc.

To managerial - stimulation, the principle of responsibility, feedback and others.

Management principles define the interrelationships and relationships between the individual stages and stages of the security process. The most significant among them will be: the principle of plimovo, the principle of incentives, the principle of compensation, the principle of efficiency.

To organizational - the principle of rational organization of labor, zoning of territories, the principle of protection of time (limitation of people's stay in conditions when the level of harmful effects is on the verge of permissible)

The organizational principles include the provisions of the scientific organization of activities that implement for security purposes.

Here we can distinguish: the principle of time protection, the principle of rationing, the principle of incompatibility, the principle of ergonomics.

All these principles are interrelated and complement each other.

Based on the variety of threats and dangers, we can distinguish the main methods of ensuring life safety:

a) spatial or temporal separation of the homosphere and noxosphere (work with radioactive substances, testing aircraft engines);

b) normalization of the noxosphere (decrease in the level negative impacts, bring its characteristics to the possible ones);

c) adaptation of a person to the appropriate environment (adaptation of a person, professional selection, training, education, supplying a person with effective means of protection);

d) combination (a combination of all methods).

The life and activity of the people, the state covers various Spheres, and in each of them the action of adverse factors, dangers and threats that disrupt the normal life of a person, society and the state is possible.

2. Harmful and poisonous substances: concepts and classification according to the degree of danger and toxic effect. Regulation of the action of harmful and toxic substances on humans.

Harmful substances - substances that, upon contact with the human body in cases of violation of safety requirements, can cause work injuries, occupational diseases, or deviations in the state of health, detectable modern methods research both in the process of work and in separate periods of life of the present and subsequent generation.
Harmful substances long time operate at a low level. At the same time, all substances have the properties of toxic substances.

Potent toxic substances (SDN) are toxic chemical compounds formed in large quantities in industry and transport, which, in the event of destruction (accidents) at facilities, can easily pass into the atmosphere and cause mass destruction personnel of units and the civilian population.

By toxicity, harmful substances are divided into:

Irritant respiratory organs;

Affecting organs nervous system.

The main method of protection against harmful substances.

Exclusion or reduction of the entry of harmful substances into the working area and into a certain environment. By using less harmful substances instead of more harmful ones; replacement of dry dusty materials with wet ones; use of final products in non-dusty forms.

The use of technological processes that exclude the formation of harmful substances. (Replacement of flame heating with electric, sealing, use of eco-bioprotective technology, use of devices for cleaning the air leaving the pipe.)

When collective protection is not possible, RPE is used - personal respiratory protection equipment (respirators, gas masks).

The action of the gas mask:

Insulating - autonomous oxygen supply, that is, the organs are cut off from the surrounding air.

Filtering.

Causes and nature of air pollution: it is customary to divide harmful substances into 2 groups:

Chemical;

industrial dust.

More precise classification:

Mixtures that form vapors and gases in the air;

· Dispersed systems or aerosols.

Aerosols are divided into:

o Dust (terv. particle size more than 1 micrometer);

o Smoke (less than 1 micrometer);

o Fog (mixture with air of the smallest liquid particles, less than 10 micrometers).

The emission of a pollutant depends on the nature of the technological process, on the material used, etc.

Gases are released during the combustion of substances; fog - when spraying coolant; dust - when crushing solids, when transporting various materials, etc.; smoke - during the combustion of fuel in furnaces and power plants.

Harmful substances enter the human body:

1. Through the respiratory organs;

2. Through the gastrointestinal tract (gastrointestinal tract);

3. Through skin and mucous membranes.

They can cause both acute and chronic poisoning. Acute ones are caused by high concentrations of harmful vapors and gases and develop rapidly over a short period of time. Chronic ones develop slowly as a result of the accumulation or cumulation of time substances (material) or functional changes (functional cumulation).

The effect of chemicals on a person depends on the physico - chemical properties, the main factors that determine the severity of the consequences of exposure to a chemical, is the dose and duration of action.

Harmful substances are divided into:

1. General toxic (cause general poisoning - carbon monoxide CO (carbon monoxide), mercury, cyanide compounds, arsenic).

2. Irritant (irritates the respiratory system, mucous membranes - chlorine, ammonia, sulfur dioxide, nitrogen oxides, ozone, etc.)

3. Sensitizing (contribute to the development of allergic diseases - act as allergens - solvents, varnishes based on nitro compounds, formaldehyde, etc.).

4. Carcinogenic substances (contribute to the formation of malignant tumors: nickel and its compounds, chromium oxides, asbestos, hydrocarbon aroma (polycyclic), bitumen, asphalt, tar, oils, soot, and a number of other substances).

5. Mutagenic (affect the genetic apparatus of germ cells, lead to changes (mutations) of hereditary information: lead, manganese, formaldehyde, radioactive elements).

6. Substances affecting reproductive function (styrene, manganese, mercury).

According to the degree of exposure to harmful substances:

· Extremely dangerous;

Highly dangerous;

· Moderately dangerous;

· Low risk.

Potent toxic substances are chemical compounds that, in certain quantities exceeding the maximum allowable concentration (MPC), have a harmful effect on people, farm animals, plants, causing damage to them of varying degrees.

SDYAV can be elements of the technological process (ammonia, chlorine, sulfuric and nitric acids, hydrogen fluoride) and can be formed during fires at facilities National economy(carbon monoxide, nitric oxide, hydrogen chloride, sulfur dioxide).

The damaging effect of SDYAV on people is possible both as a result of the ingress of such substances in a drop-liquid form onto human skin, and as a result of inhalation of their vapors. According to the toxic properties of SDYAV, they mainly belong to the group of substances of general toxic and asphyxiating action. Symptoms of their poisoning in most cases are headache, dizziness, darkening of the eyes, tinnitus, increasing weakness, shortness of breath, nausea, vomiting, and in case of severe poisoning, fainting, convulsions, loss of consciousness and even death.

AT settlements the resistance of SDYAV infection will be higher than in open areas, since the influence of wind is less pronounced.

Characteristics of potent toxic substances.

With certain types professional activity workers may be exposed to harmful substances. Harmful substances can enter the human body through the respiratory system, the gastrointestinal tract, as well as the skin and mucous membranes.

The effect of harmful chemicals on the human body is due to their physical and chemical properties. The group of chemically hazardous and harmful production factors according to the nature of the impact on the human body is divided into the following subgroups:

1. General toxic action - the majority of industrial harmful substances. These include aromatic hydrocarbons, and their amido and nitro derivatives (benzene, toluene, xylene, nitrobenzene, aniline, etc.). Mercury-organic compounds, organophosphorus substances, carbon tetrachloride, dichloroethane are highly toxic.

2. Acids, alkalis, as well as chlorine-fluorine-sulfur- and nitrogen-containing compounds (phosgene, ammonia, sulfur and nitrogen oxides, hydrogen sulfide) have an irritating effect. All these substances are united by the fact that, upon contact with biological tissues, they cause an inflammatory reaction, and the respiratory organs, skin and mucous membranes of the eyes primarily suffer.

3. Sensitizing substances are substances that, after a relatively short action on the body, cause an increased sensitivity to this substance in it. With subsequent even short-term contact with this substance, a person experiences violent reactions, most often leading to skin changes, asthmatic phenomena, and blood diseases. Such substances are some mercury compounds, platinum, aldehydes (formaldehyde).

4. Carcinogenic (blastomogenic) substances, entering the human body, cause the development of malignant tumors. Currently, there is evidence of a carcinogenic hazard to humans of a relatively small group of chemical compounds found in industrial conditions. These primarily include polycyclic aromatic hydrocarbons (PAHs), which may be part of crude oil, but are mainly formed during thermal (above 350°) processing of fossil fuels ( hard coal, wood, oil, shale) or in case of their incomplete combustion.

The most pronounced carcinogenic activity is possessed by 7,12-dilithyl without (a) anthracene; 3,4-benzapyrene, 1,2-benzanthracene. Carcinogenic properties are also inherent in products of the oil refining and petrochemical industries (fuel oil, tar, cracking residue, petroleum coke, bitumen, oils, soot). Aromatic amines, which are mainly products of the aniline-dye industry, as well as asbestos dust, have carcinogenic properties.

5. Poisons with mutagenic activity affect the genetic apparatus of the germ and somatic cells of the body. Mutations lead to cell death or functional changes. This can cause a decrease in the overall resistance of the body, early aging, and in some cases serious illnesses. Exposure to mutagenic substances can affect offspring (not always the first, but possibly the second and third generations). For example, ethyleneamine, urethane, organic peroxides, mustard gas, ethylene oxide, formaldehyde, hydroxylamine have mutational activity.

6. Substances that affect reproductive function (the function of procreation) include benzene and its derivatives, carbon disulfide, chloroprene, lead, antimony, manganese, pesticides, nicotine, ethyleneamine, mercury compounds.

There are other types of classifications of harmful substances, for example, according to the predominant effect on certain organs or systems of the human body, according to the main harmful effects (suffocating, irritating, nervous (neurotropic), blood poisons, liver), according to interaction with enzyme systems, according to the average lethal dose.

It should be borne in mind that even low-hazard substances with prolonged exposure can cause severe poisoning at high concentrations.

The hazard class of a substance is established according to the GOST 12.1.007-76 table, depending on the MPC in the air working area(mg/m3), mean lethal dose when injected into the stomach (mg/kg), mean lethal concentration in air (mg/m3), possible inhalation poisoning coefficient (PPI), acute action zone, chronic action zone.

To prevent the effects of SDYAV on the human body, it is necessary to carry out a number of measures:

1. Termination of the entry of SDYAV into the body;

2. Removal of contaminated clothing;

3. The most rapid removal of poison from the body, from the skin and mucous membranes;

4. Neutralization of the poison or its decay products; elimination of the main signs of damage;

5. Prevention and treatment of complications.

It is always necessary to take into account what SDYAV is dissolved in. For example, milk has an enveloping effect, it is able to absorb some poisons (salts of Cu, Zn, Hg, Pb, etc.) converting them into less dangerous compounds.

3. Classification and characteristics of fires. Damaging factors of fires.

Classification:

- Buildings and structures according to the degree of fire resistance;

- Premises and buildings according to the degree of explosion and fire;

- Ways and means of extinguishing a fire.

A fire is an uncontrolled burning process, accompanied by the destruction of material values ​​and creating a danger to people's lives.

Combustion is a complex physical and chemical process of the transformation of combustible substances and materials into combustion products, accompanied by intense release of heat, smoke and light radiation, which is based on fast-flowing chemical reactions oxidation in an oxygen atmosphere.

Fires according to their scale and intensity are divided into types:

separate fire- a fire that has arisen in a separate building or structure. The movement of people and equipment through the built-up area between individual fires is possible without means of protection against thermal radiation.

Solid fire- simultaneous intense burning of the predominant number of buildings and structures in this building site. The advancement of people and equipment through a continuous fire area is impossible without means of protection against thermal radiation.

firestorm- a special form of a spreading continuous fire, characteristic features which are: the presence of an upward flow of combustion products and heated air; inflow of fresh air from all directions at a speed of at least 50 km/h towards the boundaries of the fire storm.

massive fire- a set of individual and continuous fires. These include:

Fires and releases of combustible liquid in oil and oil products tanks;

Fires and emissions of gas and oil fountains;

Fires in the warehouses of rubber, rubber products, rubber industry enterprises;

Fires in timber warehouses, woodworking industry;

Fires in warehouses and storage facilities for chemicals;

Fires at technological installations of enterprises of the chemical, petrochemical, oil refining industries;

Fires in residential buildings and social and cultural institutions built of wood.

Fires are characterized by a number of parameters:

The duration of a fire is the time from the moment of its occurrence until the complete cessation of combustion.

The temperature of an internal fire is the average volumetric temperature of the gaseous medium in the room.

The temperature of an open fire is the temperature of the flame.

The temperature of internal fires, as a rule, is lower than open fires.

Fire area - the area of ​​the projection of the combustion zone on the horizontal and vertical planes.

The combustion zone is a part of the space in which the preparation of combustible substances for combustion (heating, evaporation, decomposition) and their combustion takes place. It includes the volume of vapors and gases, limited by the actual combustion zone and the surface of the burning substances, from which vapors and gases enter the volume of the combustion zone.

Thermal radiation zone - a part of the space adjacent to the combustion zone, in which the thermal effect leads to a noticeable change in the state of materials and structures and makes it impossible for people to stay in it without special thermal protection (heat-protective suits, reflective screens, water curtains, etc.) .

Smoke zone - part of the space adjacent to the combustion zone and filled with flue gases in concentrations that pose a threat to human life and health or hinder the actions of fire departments.

The front of a continuous fire is the boundary of a continuous fire along which the fire spreads at the highest speed.

The speed of propagation of the continuous fire front is the speed of its movement.

Fire propagation - the process of spreading the combustion zone over the surface of the material due to thermal conductivity, thermal radiation and convection.

Fire protection is a complex of engineering, technical and organizational measures aimed at creating a fire safety facility.

And so, combustion is a chemical oxidation reaction, accompanied by the release of heat and light. For combustion to occur, three factors are required: a combustible substance, an oxidizing agent (usually atmospheric oxygen) and an ignition source (impulse). Not only oxygen, but also chlorine, fluorine, bromine, iodine, nitrogen oxides, etc. can be an oxidizing agent.

Depending on the properties of the combustible mixture, combustion can be homogeneous or heterogeneous. In homogeneous combustion, the starting materials have the same state of aggregation(for example, burning gases). Combustion of solid and liquid combustible substances is heterogeneous.

The combustion process is divided into several types.

Flash - rapid combustion of a combustible mixture, not accompanied by the formation of compressed gases.

Ignition - the occurrence of combustion under the influence of an ignition source.

Ignition - ignition, accompanied by the appearance of a flame.

Spontaneous combustion is a phenomenon of a sharp increase in the rate of exothermic reactions, leading to the combustion of a substance (material, mixture) in the absence of an ignition source.

Self-ignition - spontaneous combustion, accompanied by the appearance of a flame.

An explosion is an extremely rapid chemical (explosive) transformation, accompanied by the release of energy and the formation of compressed gases capable of producing mechanical work.

Characteristics of fires

As I noted earlier, a fire is a spontaneously developing combustion that is not provided for by technological processes, causing material damage, harm to the life and health of citizens, the interests of society and the state.

Classification of fires depending on the type of burning substances and materials.

Fire class	Class characteristic	subclass	Subclass characteristic
	Combustion of solids		Burning of solids accompanied by smoldering (e.g. wood, paper, straw, coal, textiles)
			Burning solids without smoldering (e.g. plastics)
	Combustion of liquid substances		Combustion of liquid substances insoluble in water (e.g. gasoline, ether, fuel oil) and liquefiable solids (e.g. paraffin)
			Combustion of liquid substances soluble in water (e.g. alcohols, methanol, glycerine)
	Combustion of gaseous substances		e.g. city gas, hydrogen, propane
	Burning metals		Combustion of light metals, with the exception of alkaline (for example, aluminum, magnesium and their alloys)
			Burning alkali and other similar metals (e.g. sodium, potassium)
			Combustion of metal-containing compounds (e.g. organometallic compounds, metal hydrides)

Fires are also divided into forest, peat, steppe, fires in settlements, gas, gas and oil and oil products.

Forest fires are uncontrolled burning of vegetation that spreads throughout the forest. Depending on the height at which the fire spreads, forest fires are divided into grassroots, underground and riding.

Grassroots forest fires develop as a result of the burning of the undergrowth of coniferous species, the above ground layer of litter (fallen needles, leaves, bark, deadwood, stumps) and living vegetation (moss, lichens, grasses, shrubs). The front of a ground fire with a strong wind moves at a speed of up to 1 km / h, at a height of 1.5-2 m.

Ground fires can be fleeting and common. Rapid fires are characterized by rapidly advancing flames and light gray smoke. Conventional ground fires spread relatively slowly. Differ in the complete combustion of living and dead aboveground cover.

Riding forest fires are the burning of the ground cover and forest stand biomass. Their propagation speed is 25 km/h. They develop from ground fires when drought is combined with windy weather. Riding fires can be fleeting and ordinary.

Underground (soil) forest fires are stages in the development of ground fires. They occur in areas with peat soils. Fire penetrates underground through cracks near tree trunks. Burning is slow and flameless. After the roots are burned, the trees fall, forming blockages.

Peat fires - are the result of ignition of peat layers at different depths. They cover large areas. Peat burns slowly, to the depth of occurrence. Burnt-out places are dangerous, as sections of roads, equipment, people, houses fall through them.

Steppe fires occur in open areas with dry vegetation. With a strong wind, the speed of fire spreading is 25 km/h. In cities and towns, individual (if a house or a group of buildings catch fire), mass (if 25% of buildings catch fire) and continuous (when 90% of buildings catch fire) fires are possible. The spread of fires in cities and towns depends on the fire resistance of buildings, building density, terrain and weather conditions.

Fires gas, oil, gas-oil and oil products. During operation, pressure jets (fountains) can break out onto the surface of the earth, which often become fires. Conventionally, fountains are divided into gas fountains (containing 95-100% gas), oil fountains (containing more than 50% oil and less than 50% gas), gas-oil fountains (containing more than 50% gas, less than 50% oil).

Burning of oil and oil products can occur in tanks, production equipment and when they are spilled in open areas. In the event of a fire of oil products in tanks, explosions, boiling up of a combustible substance and their release can occur.

The phenomena of emissions and boiling up of oil products are of great danger, which is due to the presence of water in them. When boiling up, the temperature (up to 1500°C) and the height of the flame rapidly increase. Such fires are characterized by rapid combustion of the foamed mass of combustible substance.

Fire in the house. One of the main reasons for its occurrence is human inattention. Defects in electrical installations can lead to a fire; careless and inept use of electrical appliances; the use of homemade electric heaters, spontaneous combustion of the TV, the inclusion of many devices in one outlet, inept (incorrect) wiring (network overload), the use of homemade fuses.

It is necessary to follow the rules for operating a gas stove.

Damaging factors of fires.

1. Open fire: Dangerous radiant streams emitted by the flame as early as 30 seconds after the start of the fire.
2. Ambient temperature: Dangerous inhalation of hot air (upper respiratory tract injury, suffocation and death) and skin burns.
3. Toxic combustion products: carbon monoxide is dangerous, as well as combustion products released from synthetic and polymeric materials. Movement coordination is impaired oxygen starvation leading to respiratory arrest and death.
4. Loss of visibility due to smoke: Dangerous violation of the evacuation of people. Evacuation becomes difficult or impossible when panic occurs.
5. Loss of visibility due to smoke: Dangerous violation of the evacuation of people. Evacuation becomes difficult or impossible when panic occurs.
6. Decrease in oxygen concentration: It is dangerous to reduce the concentration of oxygen in the air during the combustion of various substances and materials. A decrease in oxygen content by 30% causes a deterioration in the motor functions of the body.

If fires do occur, fire extinguishers are used to extinguish them.

Ways and means of extinguishing fires.

In the practice of extinguishing fires, the following principles of cessation of combustion are most widely used:

Isolation of the combustion source from air or reduction, by diluting the air with non-combustible gases, of the oxygen concentration to a value at which combustion cannot occur;

Cooling the combustion chamber below certain temperatures;

Intensive deceleration (inhibition) of the rate of a chemical reaction in a flame;

Mechanical breakdown of the flame as a result of exposure to a strong jet of gas and water;

Creation of fire barrier conditions, i.e. such conditions under which the flame propagates through narrow channels.

To extinguish fires use: water, foam, gases, inhibitors.

The fire extinguishing ability of water is determined by the cooling effect, the dilution of the combustible medium by the vapors formed during evaporation and the mechanical effect on the burning substance, i.e. burst of flame. The cooling effect of water is determined by the significant values ​​of its heat capacity and heat of vaporization. The diluting effect, leading to a decrease in the oxygen content in the surrounding air, is due to the fact that the volume of steam is 1700 times the volume of evaporated water.

Along with this, water has properties that limit the scope of its application. So, when extinguishing with water, oil products and many other combustible liquids float up and continue to burn on the surface, so water may be ineffective in extinguishing them. The fire-extinguishing effect when extinguishing with water in such cases can be increased by supplying it in a sprayed state.

Foams are used to extinguish solid and liquid substances that do not interact with water. The fire-extinguishing properties of the foam are determined by its multiplicity - the ratio of the volume of the foam to the volume of its liquid phase, resistance, dispersion and viscosity. These properties of the foam, in addition to its physical and chemical properties, are influenced by the nature of the combustible substance, the conditions for the course of a fire and the supply of foam.

Depending on the method and conditions of production, fire extinguishing foams are divided into chemical and air-mechanical. Chemical foam is formed by the interaction of solutions of acids and alkalis in the presence of a foaming agent and is a concentrated emulsion of carbon dioxide in an aqueous solution of mineral salts containing a foaming agent.

The use of chemical foam due to the high cost and complexity of organizing fire extinguishing is reduced.

When extinguishing fires with inert gaseous diluents, carbon dioxide, nitrogen, flue or exhaust gases, steam, as well as argon and other gases are used. The fire-extinguishing effect of these compositions consists in diluting the air and reducing the oxygen content in it to a concentration at which combustion stops. The fire-extinguishing effect when diluted with these gases is due to the loss of heat for heating the diluents and a decrease in the thermal effect of the reaction. A special place among fire extinguishing compositions is occupied by carbon dioxide (carbon dioxide), which is used to extinguish warehouses of flammable liquids, battery stations, drying ovens, stands for testing electric motors, etc.

It should be remembered, however, that carbon dioxide cannot be used to extinguish substances whose molecules include oxygen, alkali and alkaline earth metals, and smoldering materials. To extinguish these substances, nitrogen or argon is used, the latter being used in cases where there is a danger of the formation of metal nitrides, which have explosive properties and are sensitive to impact.

All fire extinguishing compositions described above have a passive effect on the flame. More promising are fire extinguishing agents that effectively inhibit chemical reactions in the flame, i.e. have an inhibitory effect on them. Fire-extinguishing compositions - inhibitors based on saturated hydrocarbons, in which one or more hydrogen atoms are replaced by halogen atoms (fluorine, chlorine, bromine), have found the greatest application in fire fighting.

Halocarbons are poorly soluble in water, but mix well with many organic substances. The fire-extinguishing properties of halogenated hydrocarbons increase with an increase in the sea mass of the halogen contained in them.

Halocarbon compounds are suitable for fire extinguishing physical properties. Thus, high values ​​of liquid and vapor densities make it possible to create a fire-extinguishing jet and penetration of droplets into the flame, as well as to retain fire-extinguishing vapors near the combustion source. Low temperatures freezing allows the use of these compounds at sub-zero temperatures.

AT last years powder compositions based on inorganic alkali metal salts are used as fire extinguishing agents. They are characterized by high fire extinguishing efficiency and versatility, i.e. the ability to extinguish any materials, including non-extinguishable by any other means.

Fire extinguishing devices are divided into mobile (fire trucks), stationary installations and fire extinguishers (manual up to 10 liters and mobile and stationary above 25 liters).

Classification of buildings and structures according to the degree of fire resistance.

The intensity of fires largely depends on the fire resistance of objects and constituent parts. Construction and other materials according to their behavior at high temperatures are divided into: fireproof, slow-burning, combustible.

Fire resistance of buildings - the ability of buildings to resist the effects of high temperatures over time while maintaining their operational means. The fire resistance of a building depends on the fire resistance limits of its main structural parts.

The fire resistance limit of structures is the time during which the structure performs its function in a fire.

The fire resistance limit of structures depends on the cross section, the thickness of the protective layer, the flammability of the building material, and on the ability to maintain mechanical properties when exposed to high temperatures.

The fire resistance of buildings and structures is determined by the fire resistance of the building structures that form them. The fire resistance of building structures is determined by such indicators as fire resistance, fire resistance limit and fire spread limit.

Fire resistance of a structure - the ability to maintain load-bearing or enclosing functions in a fire.

There are the following limiting types of fire resistance:

Loss of bearing capacity due to the collapse of the structure or the occurrence of limiting deformations. Designated with the letter R;

Loss of integrity as a result of the formation of through cracks or holes in the structure through which combustion products or flames penetrate the unheated surface. Referred to as E;

Loss of heat-insulating ability as a result of temperature increase on the unheated surface of the structure. Designated with the letter I.

The following limit states of load-bearing and enclosing structures for fire resistance have been established:

For columns, beams, trusses, arches and frames - only the loss of bearing capacity R;

For external load-bearing walls and ceilings - loss of bearing capacity R and integrity E;

For external non-bearing walls - loss of integrity E;

For non-load-bearing internal walls and partitions - loss of integrity E and heat-insulating capacity I;

For non-load-bearing internal walls and fire barriers - loss of bearing capacity R, integrity E and heat-insulating capacity I;

Classification of premises and buildings according to the degree of explosion and fire hazard.

All premises and buildings are divided into 5 categories:

2. Premises where technological processes are carried out using flammable liquids with a flash point above 28 ° C, capable of forming explosive and flammable mixtures, when ignited, an excess design explosion pressure of more than 5 kPa is formed.

3. Premises and buildings where technological processes are used using flammable and slow-burning liquids, solid combustible substances, which, when interacting with each other or atmospheric oxygen, can only burn. Provided that these substances do not belong to either 1 or 2.

4. Premises and buildings where technological processes are used using non-combustible substances and materials in a hot, red-hot or molten state (for example, glass melting furnaces).

5. Premises and buildings where technological processes are used using solid non-combustible substances and materials in a cold state (mechanical processing of metals).

Bibliography

1. Arustamov E.A. Life safety: Textbook / E.A. Arustomov. - M .: "Dashkov and Co", 2001. - 678 p.

2. Belov S.B. Life safety: Proc. for universities / S.B. Belov, A.I. Ilnitskaya, A.F. Koziakov. – M.: Vyssh.shkola, 2004. 606 p.

3. Maslennikova I.S. Life safety: Textbook / I.S. Maslennikova, E.A. Vlasova, A.Yu. Postnov. - St. Petersburg: SPbGIEU, 2003. - 115 p.

4. Shlender P.E. Life safety: Textbook / P.E. Shlender, V.M. Maslova, S.I. Podgaetsky. - M .: Vuzovsky textbook, 2004. - 208 p.

Unfortunately, fire is an uncontrollable element. The rescue service was able to give a definition of a fire. But more on that later. Many of us have seen apartments burn. And some were even homeless. Animals and birds in the forest suffer from fires. If a fire starts, it is urgent to call a special team. What to do if the phone is not at hand, and it is impossible to call the rescuers.

Understanding terminology

The definition of a fire is as follows: it is an uncontrolled combustion process that causes material and physical damage.

What is combustion? This is another term from the concepts and classification of fires. Many people remember from the school chemistry course that combustion is one of the types of oxidation reaction, which is accompanied by luminescence and the release of various amounts of heat. Three things are needed for a fire to start:

• combustible substances - it can be paper or wood;
• oxidizing agent - most often it is oxygen, which is part of the air;
• as well as a source of ignition: as a rule, this is the flame of a fire or its sparks.

If one of these components is missing, then the fire will either stop or not start at all.

Hazards

Scientists and physicists have identified fire factors that can lead to injury, carbon monoxide poisoning or other toxic substances, as well as the death of a person or a living organism. In addition, this trouble destroys and damages material values. Now we will consider the causes of fires that affect humans:

• sparks, as well as a raging open fire;
• high temperature of the environment or objects;
• formation of toxic products of combustion or smoke;
• no less dangerous is the reduced concentration of oxygen;
• parts of building structures, installations or units that fall on a person and crush him during a fire are very dangerous;
• explosions.

Fire class

Depending on what is burning, the fire is assigned a “letter”:

• class A is determined in cases where solid substances - paper, plastic or wood - are burning;
• class B is assigned if flammable and combustible substances and liquids (soluble and insoluble) blaze;
• class C put on fire if gases are burning;
• class D is assigned to fires and burning of metals;
• and the last fire class E is assigned to burning electrical installations.

Fire classifications

If we consider the definition of fire according to outward signs, then they are divided into: open, internal, hidden, external and at the same time external and internal. Let's take a closer look at each type.

Fire in a house or building

The fire in the building occurs due to the negligence of the owner of the premises or the guest. Faulty electrical appliances, as well as inept handling and careless use of electrical installations, lead to a fire. Self-ignition of the TV is also dangerous. Very often, fires are caused by the use of home-made heaters and other tools, poor-quality electrical wiring, and, of course, the inept use of a gas stove causes this disaster.

natural fires

This is usually an uncontrolled spontaneous movement of fire across the territory. A fire in the forest happens for reasons, both natural and anthropogenic, that is, in view of human activity. But most often in the spring, fires occur in the forest due to thunderstorms. A bolt of lightning strikes a dry tree, which instantly ignites. The wind carries the fire from one bush to another. Sometimes the elements are so large that it can be seen even from space. Natural fires are top and bottom. The latter were divided into two categories: runaway and stable. The first of them destroy the upper part of the soil, undergrowth and undergrowth. This type of fire has a high movement speed, bypasses the places marked high humidity. Most often, such fires occur in the spring, when the top layer, that is, foliage and grass, dries up. The second type of ground fire is the stable one, which moves slowly. Because of it, the entire undergrowth dies, the bark, roots of bushes and trees suffer greatly. This type of fire most often occurs in the middle of summer. Horse fire in the forest, you guessed it, covers up the bush and tree. Crown, needles and leaves suffer here. In such a fire, there are a lot of sparks, they are picked up by the wind and carried tens of meters from the epicenter. If the fire is accompanied strong wind, then the flame is thrown already tens of kilometers from the source.

Fire element in the steppe

Steppe fire creates a person a large number of problems. This is because the population pays insufficient attention to the development and prevention of fires. Since the second half of the twentieth century, when people began to develop virgin lands, the problem of steppe fires has worsened even more. Causes of fires in the steppe - human activity in the field.

underground fires

This type is a complication of a forest fire, but the human factor is also important. For example, a fire in swamps, when a person drains layers of peat. This type of fire occurs in the taiga, tundra and forest tundra, that is, in those places where there are a large number of peat deposits. In depth, it can reach 3 meters or more, and the speed of its spread reaches several hundred meters in 24 hours. The ignition of peat in swamps occurs if this surface is strongly heated by the sun. Such burning lasts several months or even several years. Rain and other precipitation can extinguish such a fire only at the initial stage. The drier the peat layer, the stronger the fire will be. To extinguish such a fire, it is necessary to use a large amount of water. It is also dangerous because firefighters can fall into burning peat. So many people died.

man-made fires

It is easy to guess that such accidents happen at nuclear power plants, gas and oil installations. When a person exploits, for example, an oil or gas well, then burning fountains (jets) of the extracted substance burst onto the surface of the earth. Their temperature reaches up to +6,000 degrees Celsius.

How to put out a fire

The fire on the street can be effectively extinguished with the help of hydrants and fire extinguishers, and the flame can also be covered with sand or even earth. Sometimes they knock down the fire with a thick blanket. If the fire occurred in an open area, then the surface around is cleaned as much as possible and they are waiting for the complete burnout of combustible substances.

If peat ignites, then the burnt areas are extremely dangerous, as mentioned above, people and equipment fall into them, but sections of roads and even entire houses also go deep. Therefore, extinguishing such fires is very difficult.

Fires in the steppes and forests are extinguished by active and abundant moistening with water. It is advisable to process the space with it long before the flame comes up. To defeat the elements, barrier strips are very useful, the width of which is 20 meters. The edges of such strips are processed with a plow or a bulldozer, after which the outer layer of soil is removed, the middle part of such areas is burned.

The organization of extinguishing fires during the ignition of oil and gas is very complex. Here you need to work in two approaches:

• First stage: prepare wells with water within a radius of 50 meters; create strategic reserves of water, sand and earth; arrange equipment and extinguishing means; digging pits for water.
• The second step is to turn off or block the path for the burning substance. In this type of work, all specialized fire extinguishing units that have available special equipment and hardware. In the Russian Federation, the Ministry of Emergency Situations has developed a very effective ways extinguishing such fires with the help of impulse installations and devices. They allow you to eliminate fires at a distance of 50 to 110 meters.

Rules of conduct in case of fire and preventive measures

In order to prevent a fire from occurring, every citizen must behave consciously and carefully so that, in view of his activity, there is no ignition of industrial premises, in houses and forests, on peat bogs and other places. In addition, safety precautions must be observed by teams of workers in workshops and in production. Smoking citizens must put out cigarette butts, throw them into the containers intended for this. It is very important to know how to use a fire extinguisher. It is also important to know that not every fire should be extinguished with water. If an electrical appliance catches fire, then in no case should a stream of water be directed at it, because in this case a person will be struck not by a fire, but by an electric shock. Before extinguishing the device, it is necessary to de-energize it, that is, disconnect it from the power source. If this is not possible, then carbon dioxide extinguishers, powder fire extinguishers should be used. The combustible mixture, as well as other incendiary substances, are extinguished with sand, chemical foam, and other powder mixtures. If you need to go through a smoky room, then this must be done by at least two people. Remember that you need to hold on to the wall so as not to lose your bearings.

You should know that you need to open the doors very carefully. They can be used as covers. If adults and children are in a burning room, they must be removed immediately. If there is time, then you need to wet a cloth or clothing, throw it over your head and cover your face. If the passage to the exit is blocked by fire, then in such cases evacuation occurs through windows and balconies using various car lifts, stationary ladders or mechanical means. Rescuers have the right to use ropes.

Fire Element Results

The consequences of fires are terrible. As a result of burning objects fail. They get hot and break down. Elements of buildings are also destroyed by fire, structures are destroyed. High temperatures cause deformation, as well as collapse of metal floors and beams. Even brick walls and pillars are subject to deformation, since with prolonged heating from 500 to 6,000 degrees Celsius, delamination occurs in the brick walls of the building. Thus, this building material is destroyed. Due to fires, equipment and vehicles fail. People die from fires, they get burns or are poisoned by carbon monoxide. This leads to disability due to damage to the central nervous system. Pets are also dying. These were the primary consequences of the fires.

Let's look at the secondary ones. When industrial and industrial premises burn, it can lead to the leakage of various pollutants or toxic substances. Water used to extinguish a fire can cause an explosion. The main damaging factors in a fire are a shock wave with air, flying fragments from exploded objects, falling debris, and the release of toxic substances during a leak. And also during a fire and explosion, a person receives thermal and mechanical injuries. Suffer from burns and the upper respiratory tract, skin, because of burning objects, a person receives craniocerebral injuries, as well as fractures, bruises and other combined lesions.

Did you know why the first firefighters wore mustaches? No, not for beauty. In those days, there were no masks. The rescuer wetted his long mustache with saliva and placed it in his nostrils to make it easier to breathe.

Conclusion

So, we have given the definition of fire, considered the classes and types of fires. We learned how the organization of fire extinguishing takes place. And also brought for you information about prevention and precautions. Remember that prevention is much easier than elimination. Observe safety precautions not only at home, but also in the workplace, in schools and in nature! Let the fire in your life crackle peacefully only in a fireplace or stove.

To date, there is a specially developed standard that establishes the symbols and classes of fires - GOST 27331-87. This document allows you to determine the type of combustion process and select the most effective means for extinguishing it. According to the conditions of heat and mass transfer with environment fires occur in fences and in open spaces. And depending on the type of burning substances and materials, they can be divided into classes and subclasses, which we will discuss in detail in our article.

1) Class A - combustion of solid combustible materials and substances. At the same time, if wood, textiles or paper smolder, the fire belongs to subclass A1, and if a non-smoldering material, such as plastic, burns, to subclass A2.

2) Class B consists of insoluble - subclass B1, soluble - B2.

3) Class C includes fires provoked by gases.

4) Class D - combustion of metals. Moreover, light metals belong to the subclass D1, alkali metals are designated D2, and metal-containing compounds - D3.

5) Class E - burning electrical installations that are energized.

6) Class F - fires and nuclear materials.

Types of fires

According to the burning area, all classes of fire are divided into spreading and not

spreading. In addition, they can differ in the amount of material damage and be massive, for example, in the forest, at large industrial enterprises and warehouses with combustible materials, as well as in settlements. Individual fires occur in a certain area, while continuous fires cover a large number of structures and are characterized by intense burning. In the absence of wind, such an element can develop into a fire storm, which is characterized by the formation of a giant turbulent column of flame that moves at high speed.

Air exchange and fire load

Ventilation-controlled fire classes are distinguished by a limited oxygen content in the room with a simultaneous excess of combustible materials and substances. In this case, the spread of fire depends on the area of ​​the supply openings or the air flow that enters through mechanical ventilation systems. If there is an excess of oxygen in the room, the combustion process will depend entirely on the fire load. In terms of their parameters, such classes of fire are very similar to a raging fire in an open space.

Volumetric and local fires

In a volumetric fire, which is controlled by ventilation, there is an intense

thermal effect on the fences. Such combustion is characterized by the presence of a gas layer between the flame torch and the surface of the fences. The whole process is accompanied by an excess of oxygen. In load control, there is usually no smoke screen.

Local fire classes are characterized by a small thermal effect on the surrounding enclosure. Their development depends on the excess air, the variety of combustible materials and substances, as well as their condition and location in a given room. It should be noted that volumetric fires, regardless of their enclosure, are called open, and local fires are called closed, since they occur with closed window and door openings.