Brief methods of extinguishing fires. Methods and means of extinguishing fires

Fire extinguishing agents and methods of their use

Source: Life safety. Tutorial. Chapter 8.

Fire extinguishing agents are used to extinguish fires and fires. Fire extinguishing agents are understood as substances that directly affect the combustion process and create conditions for its cessation (water, foam, powders).

The main methods of extinguishing fires and fires are:

Cooling of burning surfaces (spread prevention and containment);

Isolating it from air access (blocking the access of oxidizing agents);

Removing flammable substances from the combustion zone.

According to the main sign of combustion cessation, fire extinguishing agents are divided into:

Cooling action (water, solid carbon dioxide);

Diluting action (non-flammable gases, water vapor, finely sprayed water);

Insulating action (air-mechanical foam of various expansions, bulk non-flammable materials, hard fabric materials);

Inhibitory action (means of chemical inhibition of combustion reactions - methylene bromide, ethyl bromide).

Water, as a coolant, is used to cool and extinguish most flammable materials. Water is the most common extinguishing agent. The fire extinguishing effect of water is very high. It is determined by the large heat capacity of water and the large amount of heat that must be expended to turn water into steam.

When water hits a burning substance, it takes away heat for vaporization, thereby lowering the temperature of the burning substance. Turning into steam, water changes the oxygen ratio required for combustion, and combustion stops. At the same time, steam prevents air from penetrating into the burning substance. By moistening a flammable substance, water makes it difficult to burn further, since until the water evaporates, the temperature of the substance will not rise above 100 ° C, and, therefore, this substance will not burn. Water in the form of a jet also acts as a mechanical force, knocking down the flame.

At the same time, it must be remembered that it is impossible to extinguish burning electrical wiring and electrical equipment with water, since it is electrically conductive and short circuits and electric shock are possible for those who try to extinguish burning electrical wiring and electrical equipment with water. You cannot extinguish flammable liquids (petroleum products, oils, varnishes, etc.) with water, since they are lighter than water and their spread over the surface of the water will increase the combustion area.

Solid carbon dioxide is a crystalline mass. It stops the combustion of all flammable materials, with the exception of metallic sodium and potassium, magnesium and its alloys. It is not electrically conductive and does not wet flammable substances, therefore it is used when extinguishing live electrical installations, engines, as well as fires in archives, libraries, museums, exhibitions, etc.

Insulating extinguishing agents are widely used in extinguishing flammable materials. Their main purpose is to stop the access of oxidizers (oxygen, flammable vapors and gases) to the combustion zone. Foam, sand, talc, fire extinguishing powders, as well as solid fabric materials (asbestos, tarpaulin, felt blankets, carpets, rugs and other non-flammable fabrics) are used as insulating agents.

Sand and soil are successfully used to extinguish fires, especially in cases where a flammable liquid has ignited. Sand and earth, thrown with a shovel onto the burning substance, knock down the flame and isolate it from air.

Thinning agents can dilute flammable vapors and gases to a non-flammable state, or reduce the oxygen content in the air to a concentration that does not support combustion.

When diluting agents are introduced into the room, the pressure increases, air and along with it oxygen are displaced, and the concentration of non-flammable and non-combustible gases increases.

Primary fire extinguishing agents. Primary fire extinguishing equipment includes hand-held fire tools, basic fire extinguishing equipment, and portable fire extinguishers. Hand fire tools include fire and carpenter axes, crowbars, hooks, hooks, rip and cross saws, shovels and bayonet shovels, and a set for cutting electrical wires.

The ax is used for opening, dismantling light structures and insurance when moving on an inclined plane.

The crowbar is used for opening structures, punching holes and other work when it is necessary to use it as a lever.

The fire hook is used for dismantling structures in hard-to-reach places.

As a rule, a hand-held firefighting tool is located on the fire shield, painted red and in constant readiness for use.

For extinguishing inside buildings (including in all educational institutions) are used fire-fighting water pipes equipped with fire hydrants. A fire hydrant has a fire hose and a barrel. Access to fire hydrants must be free. The fire hose must be stored attached to the valve and shaft. The sleeve is rolled into a roll (circle) or placed into an accordion. The fire hose storage cabinet must be closed and sealed. The operation of the crane must be checked periodically. To do this, disconnect the hose, place a bucket under the tap and open the tap.

The sleeve must be periodically cleaned of dust and rolled, changing the location of the longitudinal folds.

In case of a fire, you need to open the cabinet, take the barrel with your right hand and roll out the sleeve with a strong jerk, and then run to the place of the fire. You need to act with a jet in such a way as to stop the spread of fire, and not follow it. The jet must be directed to the place of the strongest combustion. Vertical surfaces should be extinguished from top to bottom. If a fire develops inside structures (under the floor, in partitions), they must be opened (tear off boards, knock down plaster) to provide access to the open fire. Electrical networks, if they are located in the fire zone, must be turned off. The simplest means of extinguishing fire are hand-held fire extinguishers. These are technical devices designed to extinguish fires in their initial stage occurrence. The industry produces fire extinguishers, which are classified by type

Liquid fire extinguishers (OZh: OZh-5, OZh-10) are used mainly when extinguishing fires of solid materials of organic origin (wood, fabrics, paper, etc.). As a fire extinguishing agent, they use pure water or water with added surfactants that enhance its fire extinguishing ability. Coolant volumes of 5 and 10 liters are used. The jet range is 6-8 meters and the release time is 20 seconds. Operates at temperatures of +2°C and above. They cannot extinguish flammable liquids and burning electrical wiring.

Foam fire extinguishers (OP: OP-5, OP-10) are designed to extinguish fires using chemical or air-mechanical foams.

Chemical foam fire extinguishers (CFO) have a wide range of applications, except in cases where the extinguishing charge promotes combustion or is a conductor of electric current.

The OCP charge consists of 2 parts: alkaline (an aqueous solution of bicarbonate of soda with the addition of a small amount of foaming agent) and acidic (a mixture of sulfuric acid with iron sulfate). Chemical foam fire extinguishers are used when solid materials, as well as various flammable liquids, ignite in an area of no more than 1 square meter

, with the exception of electrical installations under voltage, as well as alkaline materials. The fire extinguisher is recommended to be used and stored at a temperature of 5 to 45°C.

The fire extinguisher is a welded steel cylinder. A neck is welded into the upper bottom, closed by a cast-iron lid with a locking device consisting of a rubber valve and a spring that presses the valve to the neck of the acid glass when the handle is closed. The handle raises and lowers the valve. There is a spray on the neck, closed with a special membrane that prevents the charge from escaping until the acid and alkali are completely mixed.

Chemical foam is formed when carbonate or bicarbonate reacts with an acid in the presence of a foaming agent. As a result of the release of a large amount of carbon dioxide, a dense cover of stable foam is obtained (layer 7-10 cm thick), which is slightly destroyed by the action of flame and does not allow liquid vapor to pass through.

The air-foam fire extinguisher is designed for extinguishing various substances and materials, with the exception of alkaline and alkaline-earth elements, as well as electrical installations under voltage.

The fire extinguishing efficiency of these fire extinguishers is 2.5 times higher than chemical foam fire extinguishers of the same capacity. The fire extinguisher supplies high-expansion air-mechanical foam.

Air-mechanical foam consists of a mixture of air (90%), water and a foaming agent. The foam mixture is harmless to humans, non-conductive and economical. The fire extinguishing effect is based on thermal and moisture insulation and cooling of flammable substances. On the surface of burning liquids, foam forms a stable film that does not collapse under the influence of flame for 30 minutes, which is sufficient to extinguish flammable and flammable liquids in tanks of any diameter. The operation of an air-foam fire extinguisher is based on the displacement of the fire extinguishing agent (foaming agent solution) under the influence of excess pressure created by the pressure of the working gas (air, carbon dioxide, nitrogen). When you press the fire extinguisher lid button, the plug of the working gas cylinder is pierced. The gas enters the fire extinguisher body through a siphon tube and creates overpressure

, under the influence of which the foaming agent solution is supplied through a siphon tube and hose to the air-foam nozzle. Due to the difference in the diameters of the hose and the nozzle, a vacuum occurs in it, as a result of which air is sucked in. The foaming agent solution, passing through the mesh nozzle, mixes with the sucked air and forms air-mechanical foam. Foam falling on a burning substance cools it and isolates it from air oxygen. Carbon dioxide fire extinguisher (OU: OU-2, OU-3, OU-5, OU-6, OU-8) is intended for extinguishing fires in electrical installations under voltage up to 10,000 volts, on electrified railway and urban transport, as well as fires in rooms containing expensive office equipment (computers, copying machines, control systems, etc.), museums, art galleries and in everyday life. Distinctive feature

Carbon dioxide, evaporating as it exits the bell, is partially converted into carbon dioxide snow (solid phase), which stops the access of oxygen to the fire and simultaneously cools the fire to a temperature of −80°C. A carbon dioxide fire extinguisher is used in the initial stage of ignition of any materials and substances, including substances that do not allow contact with water, electric motors and other electrical equipment with voltages up to 10,000 volts, and any flammable liquids. Carbon dioxide fire extinguishers are indispensable when fires occur on electric generators, when extinguishing fires in laboratories, archives, art storage facilities and other similar premises where a stream from a foam fire extinguisher or fire hydrant can damage documents and valuables. Carbon dioxide fire extinguishers are reusable products.

In the event of a fire, you need to take the fire extinguisher with your left hand by the handle, bring it as close to the fire as possible, pull out the pin or break the seal, point the nozzle at the source of the fire, open the valve or press the pistol lever (in the case of a pistol-type shut-off and starting device). The bell cannot be held with your bare hand, as it has a very low temperature.

Powder fire extinguisher (OP-2, OP-2.5, OP-5, OP-8.5) and unified powder fire extinguisher (OPU-2, OPU-5, OPU-10) are intended for extinguishing fires of flammable and combustible liquids and varnishes , paints, plastics, electrical installations under voltage up to 10,000 V. The fire extinguisher can be used in everyday life, in enterprises and in all types of transport as a primary means of extinguishing fires of classes A (solid substances), B (liquid substances), C (gaseous substances ). A distinctive feature of OPU from OP is high efficiency, reliability, long shelf life during operation in almost any climatic conditions. Storage temperature range from -35 to +50°C.

To activate the fire extinguisher, you need to pull out the pin or latch, point the fire extinguisher or the barrel of the fire extinguisher at the source of the fire, lift the lever up (or press the button to pierce the gas cylinder), and after 5 seconds begin to extinguish the fire. The operation of a powder fire extinguisher with a built-in gas pressure source is based on the displacement of the fire extinguishing composition under the influence of excess pressure created by the working gas (carbon dioxide, nitrogen).

When exposed to the shut-off and starting device, the plug of the cylinder with the working gas is pierced or the gas generator ignites. Gas enters the lower part of the fire extinguisher body through the working gas supply pipe and creates excess pressure, as a result of which the powder is forced out through the siphon tube into the hose to the barrel.

The device allows you to release powder in portions. To do this, it is necessary to periodically release the handle, the spring of which closes the barrel. The powder, falling on the burning substance, isolates it from the oxygen contained in the air. Fire extinguishers OP and OPU are reusable products.

Aerosol fire extinguishers OAX type SOT-1 are designed to extinguish fires of solid and liquid flammable substances (alcohols, gasoline and other petroleum products, organic solvents, etc.), smoldering solid materials (textiles, insulating materials, plastics, etc.) , electrical equipment in enclosed spaces. Freon is used as a fire extinguishing agent.

The operating principle is based on the strong inhibitory effect of a fire extinguishing aerosol composition made from ultrafine products on the combustion reactions of substances in air oxygen. The aerosol released when a fire extinguisher is activated does not have a harmful effect on clothing and the human body, does not cause damage to property and is easily removed by wiping, vacuuming or washing off with water. Fire extinguishers SOT-1 are disposable products.

In rooms where potent toxic substances are used or may be released (when extinguishing fires), personnel work only in special protective kits of the L-1 type, insulating (filtering) gas masks and special rubber shoes. To reduce the concentration of gas vapors, it is necessary to irrigate the volumes of premises with sprayed water. Group protection of personnel working in areas of strong thermal radiation is provided by water curtains created using spray barrels.

It is not allowed to use personnel without combat clothing and equipment for work directly near the fire zone and in smoke-filled premises. When extinguishing a fire, each worker is obliged to monitor changes in the situation, behavior building structures , state technological equipment

In order to avoid the formation of explosive concentrations inside the building, it is not allowed to extinguish the flames of burning gases or vapors of combustible and flammable liquids entering (flowing) under pressure from equipment and pipelines, without agreement with the administration of the facility. IN necessary cases and with direct control from the administration, measures are taken to stop the flow of gases and vapors (close the valves on the supply lines, release gas to the flare, etc.) and ensure cooling production equipment flame. Persons taking part in extinguishing fires are required to know the types and types of substances and materials when extinguishing which it is dangerous to use water or other fire extinguishing agents.

When working at height, safety devices should be used to prevent workers from falling. Wherein:

work on the ladder is allowed only after securing the fire hook;
at least two people are allocated to work with the barrel at height;
It is prohibited to leave the barrel unattended even after the water supply has been stopped, as well as for personnel to be on icy roofs, sagging coverings (roofs) and areas of floors with signs of burning.

Firefighting personnel are obliged to constantly monitor the appearance of dangling (broken, burnt) electrical wires in fire extinguishing areas and promptly report them to the fire extinguishing supervisor, as well as immediately warn persons working in danger zone. Until it is determined that the detected wires are de-energized, they should be considered live and appropriate safety measures should be taken. Disconnecting electrical wires by cutting is allowed when the phase voltage in the network is not higher than 220 V and only when it is impossible to de-energize the network by other means. This work should only be carried out by persons who have previously undergone practical training and are equipped with scissors for cutting electrical wires, rubber dielectric gloves and galoshes (boots), and it is necessary:

determine the section of the network where cutting wires is most accessible, safe and will ensure de-energization in the required area;
cut the external supply wires only at the insulators on the electricity consumption side, ensuring that falling (sagging) wires do not remain energized. Cut the wires starting from the bottom row and ending with the top;
cut each wire (core) separately from the others.

It is prohibited to cut multi-core wires and cables, as well as single-core wires and cables laid in groups in insulating pipes (shells) and metal sleeves. If there is hidden electrical wiring at the facility, work must be carried out after de-energizing all equipment at the facility.

It is prohibited to use foam fire extinguishers to extinguish burning energized appliances and equipment, as well as substances and materials whose interaction with foam can lead to boiling, emission, explosion, or increased combustion.

The use of bromoethyl fire extinguishing systems (both portable and stationary) indoors is permitted only with insulating gas masks. Before using a carbon dioxide (bromoethyl, powder) fire extinguisher, the nozzle (spray, spray) must be directed towards the fire. It is prohibited to touch the mouth of a working carbon dioxide fire extinguisher with an unprotected hand.

Fire extinguishing at a facility or in a building where installations (vessels) are located high pressure, is carried out after receiving information from the operating personnel about the type of installations (vessels), their contents and the safest operating procedures. When extinguishing fires it is necessary:

take measures to prevent these installations (vessels) from heating to dangerous levels;
require the facility administration to take, if possible, measures to reduce the pressure in installations (vessels) to safe limits;
organize security of the premises and remove from it all persons not related to fire extinguishing.

When extinguishing a fire in buildings and premises with the presence of chemically active substances, you should find out from the administration of the facility their nature and not allow the use of fire extinguishing agents that react with these substances, causing an explosion, flash, etc.

When extinguishing a fire at low temperatures, measures must be taken to prevent workers from hypothermia and frostbite. In case of a prolonged fire at low temperatures, it is necessary to ensure regular shifts and rest of personnel in warm rooms, organize the provision of hot tea (food) to workers, medical care etc.

When extinguishing a fire in a room with electrical installations under high voltage, it is necessary, regardless of the size of the fire and the number of operating units, to create a fire extinguishing operational headquarters, which should include responsible employees of the facility administration and the engineering and technical personnel on duty (all decisions made are coordinated with them).

Personnel are prohibited from carrying out any unauthorized activities independent actions on de-energizing power lines, electrical installations and on the use of fire extinguishing agents until written permission to extinguish the fire is received. When extinguishing a fire in a room with a large number of cables and wires in rubber and plastic insulation, the necessary measures should be taken to prevent possible poisoning by gases released during the combustion process. Personnel must work in RPE.

When extinguishing a fire in a warehouse explosives(BB) the fire extinguishing director is obliged to:

prevent the accumulation of personnel in dangerous areas;
provide for the protection of personnel and fire equipment from possible damage by a shock (blast) wave. Use cover as well military equipment for laying hose lines;
ensure that personnel comply with safety measures during evacuation, disassembly, and opening of structures in order to avoid a possible explosion of explosives from mechanical impact.

The firefighting manager may allow deviations from the established requirements set out above only if their unconditional implementation does not allow providing assistance to people in trouble, preventing the threat of an explosion (collapse) or the spread of a fire that assumes the dimensions of a natural disaster.

Features of extinguishing fires resulting from the use of nuclear weapons by the enemy.

Fires in the source of nuclear damage are characterized by the simultaneous occurrence of many sources of combustion over a large area, the presence of destruction of buildings and structures, fire water supply systems, communications, blockages on traffic routes, approaches to buildings and radioactive contamination.

Based on the situation in the source of nuclear damage, it is necessary:

go around the rubble encountered along the route of the fire brigade to the fire site, stopping to create passages if it is impossible to go around;
keep the cabin doors of fire trucks closed with the windows up along the route;
Firefighter uniform on fire trucks must strictly follow instructions. If fires not specified in the assignment are detected along the route, do not stop and do not allocate funds to eliminate them; upon arrival at your destination, report the situation to your superior fire service or to the command post of a military unit (garrison);
simultaneously with fire reconnaissance, carry out reconnaissance of the condition of water supply sources (reservoirs, hydrants, etc.) and entrances to them;
if it is necessary to use water sources with a low water level exceeding the suction height of fire pumps, as well as from water sources that are difficult to access closer than 6–7 m, use hydraulic elevators;
when deciding to extinguish fires, avoid dispersing forces and resources fire brigade, directing departments primarily to extinguish fires of the most important buildings and structures;
timely release the forces and resources of fire brigade departments and direct them to extinguish other fires; posts at the fire site should be assigned to non-staff firefighting units;
during combat deployment to a new fire, use primarily pressure hoses that were in use.

When extinguishing a fire in a source of radioactive contamination, you must:

to work in individual means protection;
monitor radiation levels and the degree of exposure of personnel;
the personnel of the fire brigade and other units involved in extinguishing the fire are divided into shifts, which are changed in such a way that people do not receive radiation above the permissible dose;
do not raise excessive dust; areas for installing cars (motor pumps) on water supply sources and the positions of trunks at ground level should be watered with water to settle dust and along with it radioactive substances;
do not lie on the ground without using mats, shields and other available materials;
in case of collapse of buildings and structures, move people aside in order to protect them from radioactive dust;
Avoid, if possible, walking on spilled water and exposing people to water jets;
remove from the compartments of the fire truck only those tools and equipment that are necessary to extinguish the fire;
in case of dangerous levels of radiation, quickly withdraw personnel to a safe area.

When leaving the fire site, carry out partial decontamination of those used in the fire. technical means and equipment and partial sanitization of personnel (before boarding the vehicle).

Methods for extinguishing napalm, pyrogel, phosphorus and other incendiary substances.

To extinguish incendiary substances and fires caused by them, water, foam, sand and fire extinguishing powders are used.

Extinguishing a burning incendiary mixture on weapons, military equipment, transport, buildings and structures is carried out:

falling asleep with earth, sand, snow;
covering with improvised means (tarpaulins, burlap, raincoats, overcoats, etc.);
knocking down the flame with freshly cut branches of trees or deciduous shrubs.

An extinguished incendiary mixture can easily ignite from a fire source, and if it contains phosphorus, it can spontaneously ignite. Therefore, extinguished pieces of incendiary mixture are carefully removed from the affected object and burned in a specially designated place.

Incendiary aerial bombs (thermite) of small caliber, the combustion of which is detected immediately after falling, are thrown out of the room with a shovel or with a hand dressed in a tarpaulin mitten or immersed in a barrel of water, at the bottom of which a layer of sand is laid.

In all cases of the occurrence and detection of fires in the areas of operation and location of troops, garrisons, warehouses, bases, first of all, fires that complicate the performance of combat missions or pose a threat to personnel, weapons, transport, military equipment and military property are localized and eliminated.

When extinguishing fires caused by incendiary substances, the forces and means of regular, non-staff units and fire service units.

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To suppress the combustion process, you can reduce the content of the combustible component, oxidizer (air oxygen), reduce the process temperature or increase the activation energy of the combustion reaction.

Fire extinguishing agents. The simplest, cheapest and most accessible is water, which is supplied to the combustion zone in the form of compact continuous jets or in spray form. Water, having a high heat capacity and heat of evaporation, has a strong cooling effect on the combustion site. In addition, during the evaporation of water, a large number of steam, which will have an insulating effect on the fire.

The disadvantages of water include poor wettability and penetrating ability in relation to a number of materials. To improve the extinguishing properties of water, surfactants can be added to it. Water cannot be used to extinguish metals, their hydrides, carbides, as well as electrical installations.

Foam are a widespread, effective and convenient means of extinguishing fires.

IN Lately Fire extinguishing agents are increasingly being used to extinguish fires. powders. They can be used to extinguish fires of solids, various flammable liquids, gases, metals, as well as live installations. Powders are recommended for use in the initial stage of a fire.

Inert thinners used for volumetric extinguishing. They have a diluting effect. The most widely used inert diluents include nitrogen, carbon dioxide and various halocarbons. These means are used if more accessible fire extinguishing agents, such as water and foam, are ineffective.

Automatic stationary installations fire extinguishing depending on the used fire extinguishing agents divided into water, foam, gas and powder. The most widely used installations are water and foam extinguishing two types: sprinkler and deluge.

sprinkler installation- most effective remedy extinguishing ordinary flammable materials in the initial stage of fire development. Sprinkler installations are switched on automatically when the temperature in the protected volume rises above a specified limit. The entire system consists of pipelines laid under the ceiling of the room and sprinklers placed on pipelines with a given distance from each other.

Deluge installations differ from sprinkler systems in the absence of a valve in the sprinkler. The deluge sprinkler is always open. The deluge system is activated manually or automatically by a signal from an automatic detector using a control and starting unit located on the main fire pipeline. The sprinkler system is activated above the fire, and the deluge system irrigates the entire protected object with water.

The simplest means of extinguishing fires is sand. It can be used in the vast majority of cases. It cools the flammable substance, makes it difficult for air to reach it and mechanically knocks out the flame. You must have at least 1-2 shovels near the sand storage area.

The most common and universal fire extinguishing agent is water. However, it cannot be used when electrical wires and live installations are on fire, as well as substances that, in contact with water, ignite or emit toxic and flammable gases. You should not use water to extinguish gasoline, kerosene and other liquids, as they are lighter than water, float, and the combustion process does not stop.

To extinguish fires at the initial stage, you can use asbestos or felt cloth, which, when tightly covering the burning object, prevents air from entering the combustion zone.

Don't forget about internal fire hydrants. They are placed, as a rule, in special cabinets adapted for their sealing and visual inspection without opening. Everyone must have a fire hose 10, 15 or 20 m long and a fire nozzle. One end of the hose is attached to the trunk, the other to the fire hydrant. The deployment of a crew to supply water to the fire is made up of 2 people: one works with the barrel, the second supplies water from the tap.

A special place is given to fire extinguishers - these modern technical devices, designed to extinguish fires in their initial stages of occurrence. The domestic industry produces fire extinguishers, which are classified according to the type of fire extinguishing agent, body volume, method of supplying the fire extinguishing agent and type of starting devices.

By type, fire extinguishing agents are liquid, foam, carbon dioxide, aerosol, powder and combined. Based on body volume, they are conventionally divided into manual compact ones with a volume of up to 5 liters, and industrial manual ones with a volume of 5 - 10 liters. stationary and mobile with a volume of over 10 liters.

Technical characteristics of fire extinguishing agents

OPs are available in three types: manual, portable and stationary. The principle of operation of the fire extinguisher: when you press the trigger lever, the seal breaks and the needle rod pierces the membrane of the cylinder. The working gas (carbon dioxide, air, nitrogen) leaves the cylinder through a dosing hole in the nipple and enters under the aerial bottom through a siphon tube. In the center of the siphon tube (in height) there is a series of holes through which part of the working gas escapes and loosens the powder. Air (gas), passing through the layer of powder, loosens it, and the powder, under the influence of the pressure of the working gas, is squeezed out through a siphon tube and thrown through a nozzle into the combustion chamber. In the working position, the fire extinguisher should only be held vertically, without turning it over.

Fire extinguishing methods

1. Cooling burning substances by applying heat-intensive fire extinguishing agents (water, foam, etc.) to their surface or mixing layers of burning liquid.

2. Diluting the concentration of flammable vapors, dusts and gases by introducing inert diluents (nitrogen, carbon dioxide, water vapor) into the combustion zone.

3. Isolation of burning substances from the combustion zone by applying insulating fire extinguishing agents (foam, sand, felt) to their surface.

4. Chemical inhibition of the combustion reaction.

The main fire extinguishing agents can be water, foam, inert gases, fire extinguishing powder compositions, and combined compositions.

Water

Fire extinguishing properties of water:

Cools the combustion zone due to high heat capacity and latent heat of vaporization;

Dilutes reacting substances with the resulting steam (the volume of steam is 1700 times greater than the volume of evaporated water);

Isolates flammable substances from the combustion zone;

A jet of water mechanically breaks off the flame.

Advantages of water: availability and cheapness, mobility, ease of transportation, chemical neutrality, non-toxicity.

Disadvantages of water:

a) comparatively heat freezing (you have to use special additives and antifreeze);

b) poor wetting ability, which makes it difficult to extinguish fibrous, dusty, smoldering materials (additives, surfactants are introduced);

c) low viscosity, hence greater spreadability and large losses of water during extinguishing (special additives increase viscosity, reducing water consumption and extinguishing time);

d) low corrosiveness of water and its electrical conductivity (natural salts contained in water and added impurities enhance these properties);

e) impossibility of extinguishing petroleum products: the area of the fire increases, the emission and splashing of burning products increases. Oil products can only be extinguished with sprayed water;

f) the impossibility of extinguishing with water in any form and any compositions containing water (for example, foams), alkali metals, metal carbides and hydrides; organometallic compounds. All these substances explode when interacting with water.

Foam

Foam is a colloidal system consisting of gas bubbles surrounded by films of liquid.

Foams are used to extinguish solid and liquid substances that do not interact with water, and primarily oil products. The main thing is the insulating effect of the foam layer. When extinguishing solid materials, foam also has a cooling effect.

There are two types of foam: chemical and air-mechanical.

Chemical foam is obtained by the interaction of acid and alkaline solutions in the presence of a foaming agent and consists of 80% carbon dioxide, 19.7% water and 0.3% foaming agent. The durability of the foam from the moment of its formation until complete disintegration is 40 minutes. Disadvantages of chemical foam: high cost, complexity of organizing the extinguishing process, high chemical activity. Currently, there is a tendency to reduce its use.

Air-mechanical foam - a mechanical mixture of air (90...99%), water (9.7...9.6%), foaming agent (0.3...0.04%).

The foam contains water, so you cannot extinguish alkali metals, metal carbides and hydrides, and organometallic compounds with foam.

Noble gases

Carbon dioxide, nitrogen, argon, and helium have the ability to quickly mix with flammable vapors and gases, reducing the oxygen concentration in the combustion zone to such a limit that combustion stops.

Carbon dioxide has the greatest phlegmatizing ability. It is used in liquefied form for volumetric extinguishing of flammable liquid warehouses, batteries, drying furnaces, etc.

Carbon dioxide is non-conductive and is suitable for extinguishing electrical installations under voltage up to 1000 V.

The maximum permissible content of carbon dioxide in the air for humans is 10%, therefore, when a burning room is filled with carbon dioxide, people must be evacuated from it.

Carbon dioxide cannot be used to extinguish alkali metals, as well as compounds whose molecules contain oxygen.

Inhibitors (phlegmatizers)

These substances act on the principle of inhibiting the chemical combustion reaction. The required quantities of inhibitors are much less than those of inert diluents. Hence the rapid creation of a phlegmatized environment with a residual oxygen content of about 18% (vol.), which is acceptable for short-term stays of people.

Freons (freons) and saturated hydrocarbon compositions based on them are used as inhibitors. These are liquids or liquefied gases. Their advantages: operation at subzero temperatures, non-electrical conductivity. Disadvantages: toxicity, high corrosiveness.

Fire extinguishing powder compositions

They have a very high fire extinguishing ability and versatility of action; they are capable of extinguishing any materials, including those that cannot be extinguished by all other means, for example, termites, alkali metals.

Complex fire extinguishing effect: inhibition of chemical reactions in the combustion zone; cooling of the combustion zone due to heat consumption for heating and decomposition of powder particles; dilution flammable environment particles of powder and products of its decomposition; fire suppression effect during surface extinguishing.

Powders are non-electrically conductive, non-toxic, and non-corrosive. Disadvantage: caking, clumping.

Combined formulations

A combination of air-mechanical foam with freons, as well as combined nitrogen-freon and carbon dioxide-freon compounds are used. With such combinations, the efficiency of extinguishing increases while reducing the scarce refrigerant by several times.

Primary fire extinguishing agents

They are designed to extinguish fires in the initial stage and include: fire water pipes, hand-held and mobile fire extinguishers, dry sand, asbestos blankets, felt mats, etc.

Fire hydrants are installed in accessible and visible places, at a height of 1.35 m from the floor. Mutual overlap of jets from fire hoses must be ensured by at least 10 m, and the radius of action of the jet must be sufficient to reach the most remote and elevated part of the building.

Chemical foam fire extinguishers OHP-10, OP-M and OP-9MM are designed for extinguishing solid and liquid substances. Their disadvantages:

Foam is electrically conductive, so you cannot extinguish live installations;

Foam contains water, so it is impossible to extinguish alkali metals, metal carbides and other substances that explode when interacting with water;

Once the fire extinguisher is activated, it cannot be stopped once the fire is extinguished;

Foam is chemically active and can cause more damage than a fire.

Carbon dioxide fire extinguishers: manual OU-5, OU-8 and mobile OU-25, OU-80, OU-400 are designed for extinguishing substances, materials and electrical installations under voltage up to 1000 V (carbon dioxide is non-conductive). Once the fire is extinguished, the fire extinguisher can be stopped by closing the valve. You cannot extinguish alkali metals, metal hydrides and compounds that contain oxygen in their molecules. Do not extinguish burning clothing on a person and do not touch the metal socket to avoid frostbite from carbon dioxide.

Powder fire extinguishers OP-10M and OP-50M are distinguished by their universal operation and are increasingly used. With the help of such fire extinguishers you can extinguish fires of all classes), using various types of fire extinguishers with different compositions powders

Automatic fire detection and extinguishing equipment

Automatic systems fire alarm(APS) are designed to detect a fire in the initial stage and alert the service fire department, as well as sending signals (commands) to turn on emergency ventilation systems, smoke removal systems, and automatic fire extinguishing devices (AFD).

The alarm system consists of fire detectors, communication lines, and receiving stations. Fire detectors are manual (activated by a person detecting a fire) and automatic, which convert a detectable sign of fire (heat, smoke, light, or a combination of these) into an electrical signal transmitted over a communication line to a receiving station.

Depending on the fire extinguishing agents used, fire extinguishing systems can be: water (sprinkler and deluge), water-foam, air-foam, gas (carbon dioxide, nitrogen, non-flammable gases), powder, combined.

At the same time as carrying out emergency rescue operations and providing assistance to victims, rescuers are involved in extinguishing the fire. In this case, information about the nature of the fire, the direction of fire spread, the likelihood of an explosion, the release of hazardous and harmful substances into the atmosphere, possible collapses, electric shocks, optimal means and methods of extinguishing is important. Rescuers begin to extinguish the fire immediately after discovering the source of ignition.

The most common means of extinguishing a fire is water. When it hits burning material, it cools it; steam is formed, which prevents the flow of oxygen to the combustion site. Water is not used when extinguishing flammable liquids whose specific gravity is less than that of water., since they, floating and spreading over the surface, increase the area of the fire. Water should not be used to extinguish substances that enter into a violent chemical reaction with it.(metallic sodium, potassium, magnesium, calcium carbite, etc.), as well as un-energized electrical wires and devices.

Sand, covering the burning surface, stops oxygen from reaching it, prevents the release of flammable gases and lowers the temperature of the burning object. Damp sand has conductive properties and therefore cannot be used when extinguishing objects under electrical voltage. Sand should not contain foreign flammable impurities.
To the means at hand Fire extinguishing systems also include asbestos and rough wool blankets, which are used to cover small fires to stop air access to them.

When extinguishing a fire, rescuers use non-mechanized and mechanized tools.

To non-motorized tools include fireman's and carpenter's axes, crowbars, hooks, hooks, rip and cross saws, shovels and bayonet shovels, buckets, and a set for cutting electrical wires. This set is designed to de-energize individual areas electrical network, under voltage of no more than 220 V. It consists of scissors, rubber boots, gloves and a mat; it is stored in a special box and assigned to one of the rescuers.

To power tools, used to perform various works when extinguishing fires, include a circular and chain saw of the Druzhba-4 type, portable backpack installations for gas cutting of metals, electric saws, slotting, pneumatic jackhammers and other devices. The most widely used in the arsenal of rescuers is the universal mechanized kit UKM-4, which consists of a motor drive, a smoke exhauster, a jackhammer, a circular saw and a chain saw. With the help of such a kit, you can pump fresh air into rooms or pump smoke out of them, punch holes in walls, cut various structures, and all this work can be performed by one person. The PDS-400 circular saw, developed on the basis of the Ural gas-powered saw, is intended for opening the fuselage of an aircraft when performing emergency rescue work. It can also be used when opening and dismantling metal structures.

When carrying out rescue operations and extinguishing fires in the upper floors of buildings, when stationary ladders and other path devices cannot be used, rescuers use fire manual ladders. There are three types of manual fire escapes: a stick ladder (LP), an assault ladder (LS) and a retractable ladder (3-KL). They are made of wood or rolled aluminum, they are simple in design and easy to use. The height of the stick ladder in working position is 3 m. The assault ladder, or hanging ladder, has a steel hook with which it is hung on the window sill of the floor above; the length of the assault ladder is 4 m.
The retractable ladder consists of three wooden legs, each of which is a frame with two inclined side posts and 12 steps. The knees of the ladder are connected to each other by metal brackets. The mechanism for extending (moving) the ladder is a rope-block device consisting of a cable, a chain, three blocks in cages and two brackets with lugs for fastening the ends of the cable. When assembled, the length of the retractable ladder is 4.5 m, in working position - about 10.7 m.
Wooden stairs 3-KL are now being replaced by metal ones (from aluminum alloy) three-legged retractable ladders L-60 with the same technical characteristics, but 10 kg lighter. There are also car fire escapes with lifting heights of 16, 30 and 45 m, and articulated car lifts with lifting heights of 18 and 30 m.

One of the most effective fire extinguishing means is fire extinguishers. The industry produces several types of them, differing in fire extinguishing composition and mechanism of action:
- foam (OP-5, OKP-10, OKVP-10) - duration of action of foam fire extinguishers is 40-70 s, jet length - 4-8 m;
- carbon dioxide (OU-1, OU-5) - duration of action - 30-60 s, jet length - 1.5-3.5 m;
- aerosol,
- carbon dioxide-bromoethyl,
- powder (OP-1 "Moment", OP-2).
Since the operating time of fire extinguishers is short, they should be used in close proximity to the fire. The extinguishing jet is directed, first of all, to areas of increased combustion, knocking down the flame from the bottom up and trying to quickly and evenly cover a large burning area with foam (carbon dioxide snow). To put into action foam fire extinguisher OP-5, (ОХП-10, ОХП-10) you need to take the device, clean the sprayer attached to it with a pin, move the handle up and throw it all the way, then turn the fire extinguisher upside down and direct a stream of foam into the fire. If there is no stream, the apparatus is turned over, shaken and, again turning it upside down, direct the stream of foam into the fire. Foam fire extinguishers are designed to extinguish fires of various materials and substances, including flammable liquids. However, these devices cannot be used when extinguishing electrical installations and live wires, as well as alkaline materials.
At the top carbon dioxide fire extinguishers OU-1 and OU-5 the handwheel of the shut-off valve is reinforced, and on the side there is a snow blower socket. To activate the device, it is necessary to turn the bell of the snow blower towards the fire, in left hand take the handle, and with your right hand turn the shut-off valve handwheel counterclockwise until it stops, directing a stream of gas (snow) to the combustion center. Cover the burning surface with the snow-like mass thrown out of the bell until the combustion stops. Carbon dioxide fire extinguishers are used to extinguish any fires, including the ignition of electrical networks and installations with a voltage of no more than 380 V.
To operate the manual powder fire extinguisher it is necessary to bring it to the source of combustion, open the valve of the gas canister and direct a stream of powder onto the flame. These fire extinguishers are designed to extinguish burning electrical installations and other fires.

When extinguishing a fire that has occurred at a facility, great importance is given to the ability to quickly use internal fire hydrants, which, together with a barrel and a fire hose (10-20 m), laid "accordion" or in a "roll", are installed in cabinets and operate from the water supply network. There are special connection heads on the valve body and hose. To activate the fire hydrant, you need to break the seal, open the cabinet door and roll out the hose in the direction of the fire. Then the hose is attached to the fire hydrant (if this has not been done previously) and, turning the handwheel of the faucet valve counterclockwise to the limit, water is released. In the case when two rescuers are working with the fire hydrant, one of them rolls out the hose and picks it up the barrel, and the other attaches the hose to the tap and lets the water flow.

After extinguishing a fire, rescuers must ensure that there is no source of fire or smoldering areas.

Forest fires

Forest fires of all the fires natural character pose the greatest danger. In the summer (July-August) the number of forest fires becomes maximum. The most fire-hazardous forest plantations include pine, deciduous and cedar forests, lichens and wild rosemary. In the event of a forest fire covering a small area, measures to localize and extinguish it are carried out by forest guards. The forces and means of civil defense, PSF, military units and other forces are involved in eliminating large forest fires. Management and coordination of the actions of the involved forces and means is carried out by specially created headquarters.

The unit that arrived at the fire scene first, immediately begins reconnaissance, during which the following is established:
- type, speed and area of fire;
- the most dangerous direction of fire spread along the front, flanks, etc.;
- presence of people in the area forest fire, as well as in places of its possible distribution;
- presence of obstacles to the spread of fire;
- the possibility of access to the fire site and the use of mechanized means of its localization and elimination;
- availability of water sources;
- safe parking areas Vehicle and likely escape routes. Helicopters, airplanes, cars, all-terrain vehicles, boats, etc. are used for reconnaissance.
Based on the results of the reconnaissance, a fire extinguishing plan is developed, which provides for:
- methods and techniques of fire extinguishing;
- deadlines individual species works;
- organization of communications;
- measures for continuous fire reconnaissance;
- security questions.

Localization and elimination of forest fires is carried out:
- extinguishing with water, fire extinguishing chemicals;
- laying barrier strips and ditches;
- starting counter fire (annealing);
- use of explosives;
- artificially causing precipitation.

Forest fires are extinguished using fire trucks, motor pumps and fire extinguishing agents. chemical substances. If the fire spreads over a large area and the capabilities of the involved ground means are insufficient, then specially equipped air means are involved in extinguishing the fire. The practice of forest fire fighting shows that strong and medium fires with insufficient forces and means are localized by annealing from support strips. Support strips can be natural (rivers, lakes, etc.) and artificial (roads, clearings, etc.) barriers. During annealing, the support strip must be closed, that is, it must surround the fire or rest its ends against obstacles that are impassable for the fire. Outside the support strip, patrolling is organized in order to detect sources of combustion.
Explosives are widely used to create barriers to the spread of severe fires in remote forest areas.

Elimination of remaining combustion sources is carried out, as a rule, by filling them with earth, pouring water or fire extinguishing solutions.

While fighting forest fires prohibited:
- move into the depths of the fire;
- be in the area between the lines of fire and oncoming fire;
- leave your place without the permission of the manager, except for obvious danger to life.

To save people from the area of a forest fire, rescuers use all available forces and means. In conditions of rapid spread of fire along a wide front, RPS are reduced to carrying out evacuations from nearby settlements, salvation material assets, farm animals and, if possible, representatives of forest fauna. During fire rescue operations, injuries and even death of rescuers are possible. Typical injuries include thermal burns, poisoning by combustion residues, fractures, wounds, bruises, electrical injuries and some others.

PSR in conditions of radioactive contamination