Classification of fires and fire hazards

Purpose of classifying fires and fire hazards

1-3. The commentary provides for the existence of two classifications of fires - according to the type of combustible material and the complexity of extinguishing fires, as well as the classification of fire hazards.

The classification of fires by type of combustible material and the classification of fire hazards are defined respectively in Art. 8 and the commented Law. The purpose of the first of these classifications, in accordance with part 1 of the commented article, is to designate the scope of fire extinguishing means, and the purpose of the second, in accordance with part 3 of this article, is to justify measures fire safety necessary to protect people and property in case of fire.

The purpose of classifying fires according to the complexity of their extinguishing in accordance with part 2 of the commented article is to determine the composition of the forces and means of units fire brigade and other services necessary for extinguishing fires. With regard to this classification, the following should be noted.

As provided for in Part 4 of Art. 22 federal law"On Fire Safety" (as amended by the Federal Law of October 18, 2007 N 230-FZ), the procedure for attracting the forces and means of fire departments, fire protection garrisons to extinguish fires and conduct emergency rescue operations is approved federal body executive power authorized to solve problems in the field of fire safety.

On the basis of this norm, by order of the Russian Emergencies Ministry of May 5, 2008 N 240, the Procedure for attracting forces and means of fire departments, fire garrisons to extinguish fires and conduct rescue operations * (40) was approved, in clause 2.1.8 of which in regarding the classification of fires according to the complexity of their extinguishing, the following is provided:

for municipalities located on the territory of a constituent entity of the Russian Federation, by order of the head of the Main Directorate of the Ministry of Emergency Situations of Russia for a constituent entity of the Russian Federation, a single gradation of fire numbers (ranks) is established, including elevated fire numbers (ranks);

the increased number (rank) of a fire is established on the basis of a fire development forecast, an assessment of the situation, the tactical capabilities of the fire brigade garrison units and preliminary planning documents for fire extinguishing and emergency rescue operations. An increased number (rank) may also be announced by decision of the head of fire fighting on the basis of reconnaissance and assessment of the situation;

the highest number (rank) of a fire provides for the involvement of the maximum number of fire brigades (branches) and rescue teams in the main and special fire trucks that are in the calculation to extinguish the fire, with the simultaneous collection of personnel free from duty and the introduction of reserve equipment into the calculation;

the collection of personnel free from duty, and the introduction of reserve equipment into the calculation is also provided for when the duty guard (duty shift) leaves for a fire outside municipality, on the territory of which no more than one fire department is deployed.

Fire classification

Previously, the classification of fires was established by " fire fighting equipment. Classification of fires "* (41), put into effect by the Decree of the State Standard of the USSR of June 23, 1987 N 2246 (the standard corresponds to the international standard ISO 3941-77). GOST 27331-87 provides that the classification of fires is carried out depending on the type of burning substances and materials According to this document, the following classes and subclasses of fires are distinguished.

GOST 27331-87 (ST SEV 5637-86) also establishes fire class symbols. These symbols are used to designate devices and means intended for extinguishing fires of this class.

Later in normative documents there was a mention of an independent class of fire E - the object of extinguishing (electrical installations), which is energized. In particular, in NPB 166-97 "Fire equipment. Fire extinguishers. Operational requirements" (for these standards, see.

In accordance with the fire safety rules in the Russian Federation PPB-01-93, fires are divided into 5 classes.

Class A - fires of solid substances, mainly of organic origin, the burning of which is accompanied by smoldering (wood, textiles, paper, coal) and not accompanied by smoldering (plastic).

Class B - fires of flammable liquids or melting solids, insoluble in water (gasoline, ether, petroleum products), soluble in water (alcohol, methanol, glycerin).

Class C - gas fires.

Class D - fires of metals and their alloys.

Class E - fires associated with the burning of electrical installations.

Classification is necessary for the selection of fire extinguishing installations and primary fire extinguishing agents. The fire class is indicated in the passport of each fire extinguisher.

4 Classification of industries for fire hazard.

b, but do not explode, liquids with a flash point greater than 61°C.

5 Fire prevention

Fire prevention is based on the exclusion of the conditions necessary for combustion and the principles of safety.

Security can be achieved:

1) Measures to prevent fires

2) Signaling about emerging fires.

5.1 Fire prevention measures

organizational (correct operation of machines and intra-factory transport, proper maintenance of buildings and territories, fire safety briefing employees, organization of voluntary fire protection, issuance of orders on fire safety issues);

technical (compliance fire regulations, standards for design, installation of electrical wires and equipment, heating, ventilation, lighting, proper placement of equipment);

regime (prohibition of smoking in unspecified places, production of welding and other hot work in fire hazardous premises, etc.);

operational - timely preventive inspections, repairs and testing of process equipment.

In accordance with the rules PPB-01-93, in order to prevent fires, it is important to place production in buildings of a certain fire resistance. Fire resistance is the resistance of buildings to fire.

According to fire resistance, buildings are divided into 5 degrees. The degree of fire resistance is characterized by the flammability of the substance and the fire resistance limit. The fire resistance limit of a building is the time, expressed in hours, after which the structure loses its load-bearing or enclosing capacity. The loss of bearing capacity means the collapse of the building structure in case of fire. The loss of the enclosing capacity means the heating of the structure to a temperature, the increase of which can cause self-ignition of substances located in the adjacent room, or the formation of cracks in the structure, through which combustion products can penetrate into the neighboring rooms.

In accordance with the degree of fire resistance and the category of fire hazard of production, the number of storeys of the building, fire breaks are determined.

Reducing the fire hazard of structures is of great importance.

Many rooms have wooden partitions, cabinets, shelving, etc. Increasing the flammability resistance of wooden structures is achieved by their plastering or cladding with fireproof or slow-burning materials, deep or surface impregnation with flame retardants, coating with fire-retardant paint or coating. Similar measures should be applied to other combustible structural materials.

The process of thermal decomposition of wood proceeds in two phases:

the first phase of decomposition is observed when the wood is heated to 250 (to the ignition temperature) and goes with the absorption of heat;

the second phase - the combustion process itself goes with the release of heat. The second phase consists of two periods gas combustion formed during the thermal decomposition of wood (fiery phase of combustion) and the combustion of the resulting charcoal (smoldering phase).

The combustibility of wood is significantly reduced when it is impregnated with flame retardants. Heating wood leads to the decomposition of fire retardants with the formation of strong acids (phosphoric and sulfuric) and the release of non-combustible gases that prevent combustion and smoldering of the protected wood.

The most common flame retardants include ammonium phosphate, disubstituted and monosubstituted, ammonium sulfate, borax and boric acid. Bura and boric acid taken in a 1:1 mixture.

Thermal insulation materials include asbestos-cement sheets, gypsum-fiber, asbestos-vermiculite, perlite asbestos boards, various plasters. Protection with these materials is used only in enclosed spaces.

Paints, coatings consist of a binder, filler and pigment. The resulting film in fire retardant paints serves both fire retardant and decorative purposes (due to the pigment).

Liquid glass, cement, gypsum, lime, clay, synthetic resins, etc. are used as a binder for fire-retardant paints and coatings. Chalk, talc, asbestos, vermiculite, etc. are used as fillers. Pigments include metopane, zinc white, mummy, ocher, chromium oxide, etc.

The main methods of fire-retardant impregnation of wooden structures and products can be superficial and deep. In some cases, flame retardants are applied to the surface, in others they are impregnated in baths or in deep pressure impregnation plants.

The effectiveness of a flame retardant is measured by the time after which a sample or structural element ignites from a heat source. The cessation of combustion and smoldering after the removal of the heat source determines the quality of the flame retardant composition.

The flammability characteristics of building materials and structures have been established:

ignition time;

burning rate;

the time of cessation of combustion and smoldering after the ignition source is removed.

The burning rate is determined by the ratio of the percentage of sample weight loss during fire exposure to the test time. The study of flammability is carried out by testing standard samples of the material with conditioned heat sources, the position of these sources relative to the sample and the test time.

Fire extinguishers.

Fire extinguishing agents.

The impact of fire extinguishing agents on the fire site can be different: they cool the burning substance, isolate it from the air, remove the concentration of oxygen and combustible substances. In other words, fire extinguishing agents act on the factors that cause the combustion process.

Principles of cessation of combustion.

Isolation of the combustion chamber from air or reduction of the oxygen concentration by non-combustible gases to a value at which combustion cannot occur:

cooling the combustion chamber below certain temperatures;

intensive deceleration of the rate of a chemical reaction in a flame;

mechanical breakdown of the flame by the action of a jet of gas or water;

creation of fire-blocking conditions.

Water is used to extinguish fires chemical compounds, foam, inert gases and gas compositions, powders and various combinations of these agents.

Water is the main means of extinguishing fires. It is used in the combustion of solid, liquid and gaseous substances and materials. The exception is some alkali metals and other compounds that decompose water. Water for extinguishing is used in the form of solid (compact) jets, in atomized and mist (foggy) state, as well as in the form of steam.

The ability to extinguish a fire with water is based on its cooling effect, dilution of the combustible medium, formed during evaporation with water vapor and mechanical action on the burning substance (flame failure).

Foams are an effective and convenient fire extinguishing agent and are widely used to eliminate the burning of various substances, especially flammable and combustible liquids.

Foam is a cellular-film system consisting of a mass of bubbles (cells) of gas or air separated by thin films of liquid.

Fire-extinguishing foams are divided into two groups according to the method of formation: chemical and air-mechanical.

chemical foam in large quantities obtained in foam generators in contact with water foam generator powders, consisting of an alkaline part (bicarbonate soda), an acid part (aluminum sulfate) and a foaming agent (substances of protein origin, synthetic, various surfactants, etc.).

In chemical foam fire extinguishers foam is formed by the reaction of aqueous solutions of sodium bicarbonate containing licorice extract, sulfuric acid and iron tanning agent.

Chemical foam is approximately 80% carbon dioxide, 19.7% water and 3% foaming agent.

Air-mechanical foam is formed in generators as a result of mechanical mixing of air, water and a foaming agent and can be of low, medium and high expansion. Depending on the type of foaming agent and the foam ratio, it is used to extinguish flammable liquids and combustible liquids.

Air-mechanical foam is economical, non-conductive, harmless to people, easily and quickly obtained during a fire, and, unlike chemical foam, does not cause metal corrosion and does not damage the equipment and materials on which it comes into contact.

The main fire-extinguishing property of foam is its ability to isolate the burning substance and materials from the surrounding air, reduce the oxygen concentration in the combustion zone, as well as its cooling effect.

Gas fire extinguishers. These agents include: water vapor, carbon dioxide (carbon dioxide), inert gases (nitrogen, argon), as well as fire extinguishing compositions based on halogenated hydrocarbons, which are gases or volatile liquids (ethyl bromide, chlorobromomethane).

Carbon dioxide in the snowy and gaseous state is used in various fire extinguishers and stationary installations to extinguish fires in enclosed spaces and small open fires.

Inert gases are used to fill volumes in which, when the oxygen concentration drops to 5% or lower, hot work can be performed (cutting, welding of metals, etc.).

Powder substances are dry formulations based on sodium carbonate and bicarbonate. Powders are used to extinguish metals and various solid and liquid combustible substances and materials.

Powder formulations are non-toxic, have no harmful effect on materials and can be used in combination with water spray and foam extinguishing agents. The negative property of powders is that they do not cool burning substances, and they can ignite again from heated structures.

STATIONARY INSTALLATIONS AND FIRE EXTINGUISHING DEVICES.

Stationary fire extinguishing installations consist of permanently installed devices and devices connected by a piping system for supplying fire extinguishing agents to protected objects.

Automatic fire extinguishing installations are classified depending on the use of extinguishing agents:

water - using solid, atomized, finely atomized water jets;

water-chemical - using water with various additives (wetting agents, thickeners, etc.);

foam - using air-mechanical foam;

gas - using carbon dioxide, halogenated hydrocarbons, inert gases;

powder - using fire extinguishing powders;

combined - using several extinguishing agents.

One of the promising areas that ensures the fire safety of facilities is the installation of fire-fighting automation - sprinkler and deluge installations (terms taken from English words: to sprinkle - splash and to drench - wet). These installations are used by many commercial warehouses.

Sprinkler installations are designed for quick automatic extinguishing and localization of the fire, when water can be used as an extinguishing agent. Simultaneously with the supply of sprayed water to the fire, the system automatically gives a fire signal.

In sprinkler installations, air-mechanical foam can also be used as an extinguishing agent.

Sprinkler installations adapted for extinguishing with air-mechanical foam are equipped instead of sprinkler heads SP-2 with special foam heads (foam sprinkler OP), which allow one head to protect a floor area of ​​20 - 25 m 2. For the formation of air-mechanical foam in the installations, a 3 - 5% solution of foam concentrate PO-1 is used.

Depending on the temperature in the protected premises, sprinkler installations are divided into water, air and air-to-water.

Water sprinkler installations are installed in rooms in which the temperature is constantly maintained above 4 ° C. the pipelines of this system are always filled with water. With an increase in air temperature or exposure to a flame, fusible locks of sprinkler heads are soldered, water comes out of the holes, irrigating the protection zone.

Air sprinkler installations are installed in unheated buildings. The pipelines of this system are filled with compressed air. In this case, there is compressed air upstream of the control and alarm valve, and water after the control and alarm valve. When the sprinkler head of the air system is opened, after the air has escaped, water enters the network and extinguishes the combustion source.

Air-to-water systems are a combination of air and water sprinkler installations. The sprinkler system is activated automatically by melting the fusible lock of the sprinkler head.

Drencher installations are designed for automatic and remote fire extinguishing with water. Distinguish drencher installations of automatic and manual action. In automatic deluge installations, water is supplied to the network using a group action valve. Under normal conditions, the automatic induction valve is held in the closed position by a cable system with fusible locks. In case of fire, the lock melts, the cable breaks, the valve opens under water pressure and water enters the drenchers. In a manual deluge installation, water is supplied after the valve is opened. Unlike sprinkler systems, water sprayers (drenchers) in deluge installations are constantly in the open state.

Fire extinguishers are designed to extinguish fires and fires in their initial stage. According to the type of extinguishing agent used, they are divided into foam, gas and powder.

Foam fire extinguishers are designed to extinguish small fires of solid materials and substances and flammable liquids. They are not used to extinguish fired electrical installations that are energized, because. chemical foam is electrically conductive.

Chemical foam fire extinguishers OHP-10, OP-M.

Air-foam fire extinguishers OVP-5, OVP-10.

Carbon dioxide fire extinguishers OU-2, OU-5, OU-8 are used to extinguish various substances and materials (except for alkali metals), electrical installations under voltage, vehicles, etc.

Carbon dioxide-bromoethyl fire extinguishers OUB-3A and OUB-7A are designed to extinguish small fires of various combustible substances, smoldering materials, electrical installations under voltage.

Powder fire extinguishers OP-1, OP2B, OP-10 are designed to extinguish small fires of combustible liquids, gases, electrical installations under voltage, metals and their alloys.

Automatic aerosol fire extinguisher SOT-1 is designed to extinguish fires of solid and liquid combustible substances (alcohols, gasoline), smoldering and solid materials, electrical equipment in enclosed spaces.

The principle of operation is based on the strong inhibitory effect of a fire-extinguishing aerosol composition of ultrafine products on the combustion reactions of substances in atmospheric oxygen.

Aerosol does not harmful effects per person, easy to remove. Disposable fire extinguisher.

The UAP-A fire extinguisher automatically detects and extinguishes a fire in enclosed spaces of small volume. The fire extinguisher is installed on the ceiling in the center of the room. In the event of a fire, the fusible element is destroyed, the capacity of the fire extinguisher is opened, and a substance (freon or powder) is ejected into the volume of the room, creating an environment that does not support combustion.

FIRE ALARM.

To fight fires importance has a timely message about the fire. To report a fire, use electrical and automatic system alarms.

Successful firefighting depends on the rapid and accurate communication of the fire and location to the local fire brigade. For this, electric (EPS), automatic (APS), sound fire alarm systems can be used, which include a beep, a siren, etc. telephone and radio communications are used as a means of fire alarm.

The main elements of electrical and automatic fire alarms are detectors installed at facilities, receiving stations that register a fire that has begun, and linear structures connecting detectors with receiving stations. In receiving stations located in special premises of the fire department, round-the-clock duty must be maintained.

Basic requirements for a fire alarm:

should be located in places accessible for inspection;

sensors must be highly sensitive.

Sensors are applied thermal, smoke, ultrasonic and combined.

Sensors can be: maximum - they are triggered when the controlled parameters reach a predetermined value; differential - react to a change in the speed of a given parameter; maximally differential - they react to both.

The principle of operation of thermal sensors is to change the physical and mechanical properties of sensitive elements under the influence of temperature (fusible alloy). An alloy connects two plates. When heated, the alloy melts, the plates open the electrical circuit, and a signal is sent to the remote control.

Smoke detectors have two main methods for detecting smoke: photoelectric (IDP) and radioisotope (RID). The IDF detector detects smoke by registering light reflected from smoke particles with a photocell. The RID has an ionization chamber with a source of -particles as a sensitive element. An increase in the smoke content reduces the ionization rate in the chamber, which is recorded.

The combined detector (CI) reacts to both temperature rise and smoke.

A light fire detector (SI) registers the radiation of a flame against the background of extraneous light sources.

The ultrasonic sensor has high sensitivity and can combine security and alarm functions. These sensors respond to changes in the characteristics of the ultrasonic field that fills the protected room.

Currently, enterprises use beam and ring electric fire alarms.

Beam fire alarm TOL-10/50 is used at enterprises with round-the-clock stay of people and provides reception of signals, telephone conversation with a detector, start-up of stationary fire extinguishing installations.

Ring fire alarm system TKZ-50M is designed for 50 manual detectors. The station provides signal reception, fixing it with a recording device and automatic signal transmission to the fire department.

In rooms with non-round-the-clock stay of people, automatic fire detectors are installed. These detectors are triggered by smoke, heat, light, or both.

Reliable fire communication and signaling plays an important role in the timely detection of fires and the call of fire departments to the place of fire. According to its purpose, fire communication is divided into:

notification communication;

dispatcher communication;

According to the conditions of mass and heat exchange with environment all fires are divided into two large groups - in open space and in fences.

Depending on the type of burning materials and substances, fires are divided into classes A, B, C, D and sub-classes A1, A2, B1, B2, D1, D2 and DZ.

Class A fires are fires of solids. At the same time, if smoldering substances are burning, for example, wood, paper, textiles, etc., then fires are classified as subclass A1, unable to smolder. for example, plastics - to subclass A2.

Class B includes fires of flammable combustible liquids. They will belong to subclass B1 if liquids are insoluble in water (gasoline, diesel fuel, oil, etc.) and to class B2 - soluble in water (for example, alcohols).

If gases are subject to combustion, for example, hydrogen, propane, etc., then fires belong to class C, while burning metals - to class D. Moreover, subclass D1 emits combustion of light metals, such as aluminum, magnesium and their alloys; D2 - alkali and other similar metals, such as sodium and potassium; DZ - combustion of metal-containing compounds, such as organometallic, or hydrides.

On the basis of changes in the burning area, fires can be divided into spreading and non-spreading.

Fires are classified by size and material damage, by duration and other signs of similarity or difference. In addition, the classification should separately distinguish a subgroup of fires in open spaces - a massive fire, which is understood as a set of individual and continuous fires in settlements, large warehouses of combustible materials and industrial enterprises.

A separate fire means a fire that occurs in a separate building or structure. At the same time, intense burning of the predominant number of buildings and structures in a given building site is commonly called a continuous fire. With a weak wind or in its absence, a massive fire can turn into a fire storm.

A fire storm is a special form of fire characterized by the formation of a single giant turbulent flame with a powerful convective column of ascending flows of combustion products and heated air and an influx fresh air to the boundaries of the fire storm at a speed of at least 14–15 m/s.

Fires in enclosures can be divided into two types: air exchange controlled fires and fire load controlled fires.

Ventilation-controlled fires are understood as fires that occur with a limited oxygen content in the gaseous environment of the room and an excess of combustible substances and materials. The oxygen content in the room is determined by the conditions of its ventilation, i.e., the area of ​​the supply openings or the flow rate of air entering the fire room using mechanical ventilation systems.

Fires regulated by the fire load are understood as fires that occur with an excess of oxygen in the air in the room and the development of a fire depends on the fire load. These fires in their parameters approach fires in open space.

According to the nature of the impact on the fences, fires are divided into local and volumetric.

Local fires are characterized by a weak thermal effect on the fences and develop with an excess of air necessary for combustion, and depend on the type of combustible substances and materials, their condition and location in the room.

Volumetric fires are characterized by intense thermal effects on the fences. A volumetric fire regulated by ventilation is characterized by the presence of a gas layer of flue gases between the flame and the surface of the fence, the combustion process occurs with an excess of oxygen in the air and approaches the conditions of combustion in open space. A volumetric fire regulated by fire load is characterized by the absence of a gas (smoke) layer between the flame and the fence.

Volumetric fires in fences are commonly called open fires, and local fires, fires occurring with closed doors and window openings, are closed.

2. Classification of hostilities. Factors influencing combat operations.

Combat operations of units are classified according to two main features: by nature and purpose.

By the nature of the combat operations of the units are classified into general and private.

General combat actions are understood as those that are carried out when extinguishing all fires.

By private military operations are understood those that are carried out during the extinguishing specific types fires. They are determined by private, specific elements of the situation on fires. For example, the presence of a threat to people's lives in a fire, the need to open and dismantle structures, etc.

Combat actions are subdivided into preparatory, basic, and support operations according to their purpose.

Under the preparatory combat actions are understood those, as a result of which conditions are created for the performance of the main combat operations.

The main combat actions are understood as those, as a result of which the fulfillment of the main combat mission of the fire brigade personnel on fires is achieved.

Supporting combat operations are understood as those that result in the creation of sufficient conditions for the performance of basic combat operations.

A schematic diagram of the classification of hostilities using the example of one unit is shown in (Fig. 3.2.) From (Fig. 3.2.) it can be seen that the elimination

Rice. 3.2. Classification of combat operations of fire departments

combustion is not only the main, but also general view fighting units.

At the same time, ensuring the safety of people and animals (rescue, evacuation or protection of various means), although it belongs to the main type of combat operations of units, but is private, since it is not performed on all fires.

A distinctive feature of the unit's general combat operations is that they are carried out in strict sequence, and therefore belong to sequential processes (Fig. 3.3, "a").

Particular combat operations of the subunit are carried out, as a rule, in parallel with some general ones, such as combat deployment and elimination of burning. The set of general and private combat operations of the unit in this case will refer to serial-parallel processes and can be displayed in the form of a network model (Fig. 3.3, "b"),

Rice. 3.3 The sequence of combat operations by one unit:

a – sequential process, b – series-parallel process.




Thus, it is clear that the combat operations of several units consist of three interrelated processes:
concentration and introduction of forces and means;
localization and elimination of combustion;
the curtailment of forces and means and the return of fire departments to the unit.

The totality of these processes is the combat operations of several units, and are common, because. performed on all fires.

The combat operations of subunits are based on certain regularities that have an objective character. Thus, the interaction of the personnel of subunits in the performance of combat operations in a fire is one of the main patterns inherent in their combat operations.

In addition to interaction, there are other regularities in the combat operations of subunits, which are determined by the specific conditions in which combat operations are carried out. These conditions are understood as: the quantity and quality of the units performing a combat mission, their technical equipment, the parameters of the development of fires, dictating the need to use specific means, methods and techniques for rescuing people and extinguishing fires, etc. Consequently, the laws inherent in the combat operations of subunits are of the same objective nature as the laws in other areas of practice.

However, the existence of an objective nature of regularities in the combat operations of subunits does not in the least detract from the role of the influence of the subjective factor on these operations. On the contrary, it should be especially emphasized that the role of the subjective factor in directing them is extremely important in planning combat operations of subunits and in carrying them out. In the presence of objective conditions for success in the combat operations of subunits, their good organization and qualified command and control always lead to positive results, and bad ones to negative ones.

In the objective conditions of successful combat operations of subunits, there are only opportunities for success, but by themselves they will not lead to positive result. The success of combat operations of subunits is the result of the joint action of objective and subjective factors in the performance of the main combat mission by subunits in a fire. Therefore, the organizational skills of the commanding staff of the fire department, his ability to lead units, are one of the constantly operating factors that determine the success of the combat mission in a fire.

The combat operations of subunits are influenced not only by regularities, but also by random factors. The reason for accidents can be, first of all, the shortcomings of our activities - the poor organization of combat operations of subunits, shortcomings in their management, shortcomings in the combat operations of the personnel of subunits themselves, etc. Accidents have a certain influence on the course and outcome of combat operations of subunits, but they are not a decisive factor in the success of the main combat mission.

It should be borne in mind that in addition to accidents that have a negative impact on the course of combat operations of subunits, there may be accidents that create additional favorable opportunities for solving the problem: natural precipitation, a change in the wind in a favorable direction, etc. Therefore, in the course of combat operations, it is important to be able not only to resist the influence of unfavorable accidents, but also to use the action of accidents that are beneficial for extinguishing a fire. In this matter, the organizational skills of the commanding staff, excellent tactical and psychological training of the personnel of the units are of paramount importance.

Combat operations of subunits are always limited in space and time. They are carried out in a relatively small area and more or less transiently.

The duration of combat operations of subunits is determined by the time required to perform a combat mission in a fire, and depends on the conditions of the combat situation, the number, combat readiness and combat capability of subunits. They begin from the moment the subunits leave for a fire and end with the moment their combat readiness is restored (setting up in a combat crew) after completing a combat mission in a fire. This period of time ranges from several minutes to hours, sometimes even days, which largely depends on the content and characteristics of the combat operations of subunits in the performance of a combat mission.

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