Material from Fire safety: terms and definitions. Fire trucks. Definition and classification. Information about changes

To successfully extinguish a fire, it is necessary to use the most suitable extinguishing agent, the choice of which should be resolved almost instantly. Choosing it correctly will reduce damage to the vessel and the danger to the entire crew.

This task is greatly facilitated by the introduction of a classification of fires and their division into four types, or classes, denoted by the Latin letters A, B, C, D. Each class includes fires associated with the ignition of materials that have the same properties during combustion and require the use of the same the same fire extinguishing agents.
Therefore, knowledge of these classes, as well as the flammability characteristics of the materials on board, is essential for successful firefighting.

Fire classification has several standards, for example: ISO 3941 (International Organization for Standards) and NFPA10 (National Fire Protection Association). Here is the last one.

Class A fires are fires involving the combustion of solid (ash-forming) combustible materials that can be extinguished with water and aqueous solutions. Such materials include: wood and wood-based materials, fabrics, paper, rubber and some plastics.

Class B fires are fires caused by the combustion of flammable or combustible liquids, flammable gases, fats and other similar substances. Extinguishing these fires is carried out by stopping the supply of oxygen to the fire or by preventing the release of flammable vapors.

Class C fires are fires that occur when live electrical equipment, conductors or electrical devices are ignited. To fight such fires, fire extinguishing agents are used that are not conductors of electricity.

Class D fires are fires associated with the ignition of combustible metals: sodium, potassium, magnesium, titanium or aluminum, etc. To extinguish such fires, heat-absorbing extinguishing agents are used, for example, some powders that do not react with burning metals.

The main purpose of developing such a classification is to assist ship crews in choosing the appropriate extinguishing agent. However, it is not enough to know that water is best remedy class A fires, because it provides cooling, or that powder is good for knocking down flames when burning a liquid, you need to be able to properly supply the extinguishing agent using accurate fire fighting techniques.

Class A fires

Class A fires

Wood and wood-based materials. Due to its widespread use, wood is very often the main combustible material. On ships, it is used as deck flooring and interior decoration bulkheads (small craft only), bedding and separation material, etc.
Woody materials contain recycled wood or wood fiber... These include some types of insulation, ceiling tiles, plywood and paneling, paper, cardboard and hardboard.

The properties of wood and wood-based materials depend on their specific type. However, all these materials are flammable, under certain conditions they carbonize, smolder, ignite and burn. As a rule, they do not ignite spontaneously.
Combustion usually requires an ignition source such as a spark, open flame, hot surface, thermal radiation. But as a result of pyrolysis, wood can turn into charcoal, the ignition temperature of which is lower than the ignition temperature of the wood itself.

Wood is composed primarily of carbon, hydrogen and oxygen, as well as small amounts of nitrogen and other elements. In a dry state, cellulose constitutes the bulk of it. Other components of dry wood include sugar, resins, minerals(of which ash is formed during wood burning).

Flammability characteristics. The ignition temperature of wood depends on factors such as size, shape, moisture content and grade. As a rule, the autoignition temperature of wood is about 200 ° С, but it is generally accepted that 100 С is the maximum temperature to which wood can be exposed for a long time without fear of its spontaneous combustion.

The combustion rate of wood and wood-based materials largely depends on the configuration of the products made of them, the amount of air around it, moisture content and other factors. But for the complete combustion of wood under the influence of heat, vapors must be released.

A slowly developing fire or heat source can gradually transfer enough energy to start pyrolysis of wood products on bulkheads and ceilings.
The flammable vapors released during this process will mix with the surrounding air. When this mixture is in the flammable range, any source of ignition can ignite the entire mass almost instantly.
This condition is called generalized outbreak. When fighting fires involving the burning of combustible materials such as trim wood paneling bulkheads and furniture in small spaces of older ships, the crew must take action against a general outbreak. On modern ships, non-combustible materials are used in cabins, corridors and other confined spaces.

For most solid combustible materials, the flame moves slowly. Before the flame can spread, flammable vapors must evolve from the solid combustible material, which are then mixed with air in a certain proportion.

Bulky, hard materials with a small surface area (such as thick logs) burn more slowly than solid materials that are thinner but larger in surface area (such as plywood sheets). Solid materials in the form of shavings, sawdust and in dusty form burn faster because the total surface area of ​​the individual particles is very large.
As a rule, the thicker the combustible material, the longer it takes for the vapors to escape into the air and the longer it will burn. How larger area surface, the faster the solid material burns, since a large area allows combustible substances to be released at a faster rate and quickly mix with air.

Combustion products. Burning wood and wood-based materials produces water vapor, heat, carbon dioxide and monoxide. The main danger to the crew is the lack of oxygen and the presence of carbon monoxide.
In addition, when wood burns, aldehydes, acids and various gases are formed. These substances alone or in combination with water vapor can, at a minimum, be highly irritating. Due to the toxicity of most of these gases, breathing apparatus is required when working in or near a fire area.

People can get burned if they come into direct contact with a flame or the heat emitted from a fire. The flame is rarely detached from the burning material for a considerable distance. However, some types of smoldering fires can generate heat, smoke and gas without visible fire, and air currents can carry them far away from the fire.

Like most organic substances, wood and wood-based materials have the ability to emit large amounts of smoke during the initial stages of a fire. In some cases, combustion may not be accompanied by the formation of visible combustion products, but usually a fire produces smoke, which, like a flame, is a visible sign of a fire.
Smoke is often the first warning of a fire. At the same time, smoke generation, which significantly impairs visibility and irritates the respiratory system, usually contributes to the occurrence of panic.

Textile and fibrous materials. Textile materials in the form of clothing, upholstery, carpets, tarpaulins, canvas, ropes and bedding are widely used on ships. In addition, they can be transported as cargo. Almost all textile materials are flammable.
This explains the large number of fires associated with the ignition of textile materials and accompanied by injuries and deaths.

Vegetable (natural) fibers, which include cotton, jute, hemp, flax and sisal, are mainly composed of cellulose. Cotton and other fibers are flammable (the autoignition temperature of cotton fibers is 400 ° C).
Their combustion is accompanied by the release of smoke and heat, carbon dioxide, carbon monoxide and water. Plant fibers do not melt. The ease of ignition, the speed of flame propagation and the amount of heat generated depend on the structure and finish of the material, as well as on the design of the finished product.

Animal fibers such as wool and silk differ from vegetable fibers in chemical composition and do not burn as easily as these fibers, rather they tend to smolder. For example, wool, which consists mainly of protein, is more difficult to ignite than cotton (the autoignition temperature of wool fibers is 600 ° C), and burns more slowly, so it is easier to extinguish.

Synthetic textiles are fabrics made entirely or primarily of synthetic fibers. These include viscose, acetate, nylon, polyester, acrylic. The fire hazard associated with synthetic fibers is often difficult to assess, as some of them shrink, melt and run off when heated.
Most synthetic textile materials are flammable to varying degrees, and the ignition temperature, burning rate and other properties during combustion differ significantly from each other.

Flammability characteristics. The combustion of textile materials depends on many factors, the most important of which are the chemical composition of the fibers, the finish of the fabric, its weight, the density of the weave of the threads and the flame retardant impregnation.

Plant fibers are highly flammable and burn well, emitting a significant amount of thick smoke. Partially burnt plant fibers can present a fire hazard even after it has been extinguished. Semi-burnt fibers should always be removed from the fire area to those places where re-ignition will not create additional difficulties. Most baled plant fibers absorb water quickly.

Bales swell and increase in weight when fed a large number water in the process of extinguishing a fire.

Wool is poorly flammable until it is exposed to strong heat; it smolders and charred, and does not burn freely. However, wool intensifies fires and absorbs large amounts of water. This factor should be taken into account when fighting a fire for a long time.

Silk is the most dangerous fiber. It is poorly flammable and does not burn well. It usually requires an external heat source to burn. Silk retains heat longer than other fibers when tanned. Moreover, it absorbs large amounts of water. Wet silk can self-ignite. When igniting a bale of silk outward signs fires appear only when the bale burns out to the outer surface.

The flammability characteristics of synthetic fibers depend on the materials used in their manufacture. Table 5.1 shows the characteristics of the flammability of some of the most common synthetic materials.
Based on laboratory tests, these specifications may not be accurate. Some plastics may appear flame retardant when tested with a small flame source such as a match.
But if the same materials are tested with a stronger flame source, they burn violently and completely burn out, producing a large amount of black smoke. Full-scale tests give the same results.

Table 5.1

Flammability characteristics of some synthetic materials

Combustion products. As previously stated, all burning materials give off flammable gases, flames, heat and smoke, which leads to a decrease in oxygen levels. The main combustion gases are carbon dioxide, carbon monoxide and water vapor.

Vegetable fibers such as jute emit large quantities of corrosive dense smoke when burned.

When wool burns, a thick grayish-brown smoke appears, and hydrogen cyanide is also produced, which is a very toxic gas. Charring the wool produces a sticky black substance that resembles tar.

The combustion product of silk is porous coal mixed with ash, which continues to smolder or burn only under strong draft conditions. Smoldering is accompanied by the release of light gray smoke, which irritates the respiratory tract. Under certain conditions, when silk is burned, hydrogen cyanide can be released.

Plastics and rubber. In the manufacture of plastics, a huge number of organic substances are used, including phenol, cresol, benzene, methyl alcohol, ammonia, formaldehyde, urea and acetylene.
Cellulose-derived plastics are composed primarily of cotton components; Many types of plastics are made from wood flour, wood pulp, paper and textiles.

The raw materials for rubber production are natural and synthetic rubbers.

Natural rubber is made from rubber latex (the sap of a rubber tree) by combining it with substances such as carbon black, oils and sulfur. Synthetic rubber is similar in some characteristics to natural rubber. Examples of synthetic rubbers are acrylic, butadiene and nooprene rubbers.

Flammability characteristics. The flammability characteristics of plastics are different. To a large extent, they depend on the shape of the products, which can be presented in the form of solid profiles, films and sheets, molded products, synthetic fibers, granules or powders. The behavior of plastics during a fire also depends on their chemical composition, purpose and reasons for sunbathing. Many plastics are flammable and, in the event of a severe fire, contribute to its intensification.

Depending on the burning rate, plastics can be divided into three groups:

1st group. Materials that do not burn at all or stop burning when the ignition source is removed. This group includes asbestos-filled phenolic resins, some polyvinyl chlorides, nylon and fluorinated hydrocarbons.

2nd group. Materials that are flammable and burn relatively slowly; when the source of ignition is removed, their combustion can stop, or it can continue. This group of plastics includes wood-filled formaldehydes and some vinyl derivatives.

3rd group. Materials that burn easily and continue to burn after removal of the ignition source. This group includes polystyrene, acrylics, some cellulose acetate and polyethylene.

A separate class is formed by the oldest, well-known type of plastics - celluloid, or nitrocellulose, which is the most dangerous of the plastics. At temperatures of 121 ° C and above, celluloid decomposes very quickly, without the need for additional oxygen from the air.
Decomposition gives off flammable vapors. If these vapors accumulate, a violent explosion can occur. Combustion of celluloid proceeds very violently, it is difficult to extinguish such a fire.

The calorific value of rubber is about twice that of other solid combustible materials. So, for example, the calorific value of rubber is 17.9-10 6 kJ, and pine wood is 8.6-10 6 kJ. Many types of rubbers soften and flow when burned, thereby contributing to the rapid spread of fire.
Natural rubber rubber decomposes slowly during initial heating, but then, at about 232 ° C and above, it begins to decompose rapidly, releasing gaseous substances, which can lead to an explosion.
The autoignition temperature of these gases is approximately 260 ° C. Synthetic rubber rubber behaves similarly, but the temperature at which it begins to decompose quickly is slightly higher.

For most plastics, depending on their components, the decomposition temperature is 350 ° C and higher.

Combustion products. Burning plastics and rubbers give off gases, heat, flames and smoke, forming combustion products that can lead to toxicity or death.

The type and amount of smoke emitted by burning plastic depends on the nature of the plastic, the additives present, ventilation, and whether the combustion is accompanied by flame or smoldering.
Most plastics decompose when heated, producing thick smoke. Ventilation helps disperse smoke, but cannot provide good visibility. Those plastics that burn with a clean flame, under the influence of fire and high temperature produce less dense smoke.

When plastics containing chlorine, such as polyvinyl chloride, which is the insulating material for cables, are burned, the main combustion product is hydrogen chloride, which has a pungent, irritating odor. Inhalation of hydrogen chloride can cause death.

Burning rubber emits dense black greasy smoke containing two toxic gases - hydrogen sulfide and sulfur dioxide. Both gases are dangerous, as inhaling them can lead to death under certain conditions.

The usual location on the ship. Although ships are built of metal and appear to be non-combustible, they always carry a large amount of flammable materials. Almost all of these materials are transported as cargo, either in cargo holds or on deck, in containers or in bulk. In addition, solid materials are widely used on a ship, the ignition of which can cause class A fires. The furnishing in the living quarters of passengers, privates and officers is usually made of materials, the ignition of which leads to class A fires. sofas, armchairs, tables, televisions, books and other items made in whole or in part from these materials.

Locations of such materials include the following:

navigating bridge where installed wooden tables, concentrated maps, astronomical yearbooks and other items made from combustible materials;

carpentry, as there may be different kinds wood;

the boatswain's pantry, which stores various types of plant cables;

metal shipping containers, which are usually lined with wood or wood-based materials underneath;

a hold where timber can be stored for a stockpile, forests, etc .;

corridors, as a large number of bags of laundry are often left here to carry them to and from the laundry.

Extinguishing class A fires. Materials most likely to catch fire are best extinguished with water, the most common extinguishing agent.

Class B fires

Class B fires

Materials, the ignition of which can lead to class B fires, are divided into three groups: flammable and combustible liquids, paints and varnishes, flammable gases. Let's consider each group separately.

Flammable and flammable liquids.Flammable liquids- these are liquids with a flash point of up to 60 ° C and below. Flammable liquids are liquids with a flash point exceeding 60 ° C. Flammable liquids include acids, vegetable oils and lubricants with a flash point exceeding 60 ° C.

Flammability characteristics. It is not the flammable and combustible liquids themselves that burn and explode when mixed with air and ignited, but their vapors. Upon contact with air, the evaporation of these liquids begins, the rate of which increases when the liquids are heated. To reduce the risk of fire, they should be stored in closed containers. When using liquids, care should be taken to minimize exposure to air.

Explosions of flammable vapors most often occur in a confined space, such as a container, tank. The force of the explosion depends on the concentration and nature of the vapor, the amount of the vapor-air mixture and the type of container in which the mixture is located.

Flash point is the generally accepted and most important factor, but not the only factor in determining the hazard posed by a flammable or combustible liquid.
The hazardousness of a liquid is also determined by its flash point, flammability range, evaporation rate, reactivity when contaminated or under the influence of heat, density and diffusion rate of vapors.
However, if flammable or flammable liquid for a short period of time, these factors have an insignificant effect on the flammability characteristics.

The combustion and flame propagation rates of various flammable liquids differ slightly from each other. The burnout rate of gasoline is 15.2 - 30.5 cm, kerosene - 12.7 - 20.3 cm of layer thickness per hour. For example, a layer of gasoline 1.27 cm thick will burn out in 2.5 - 5 minutes.

Combustion products. During the combustion of flammable and combustible liquids, in addition to the usual combustion products, some specific combustion products characteristic of these liquids are formed. Liquid hydrocarbons usually burn with an orange flame and produce thick clouds of black smoke.
Alcohols burn with a clear blue flame, emitting a small amount of smoke. The combustion of some terpenes and esters is accompanied by violent boiling on the surface of the liquid, and their extinguishing is of considerable difficulty. Burning petroleum products, fats, oils and many other substances produces acrolein, a highly irritating toxic gas.

Flammable and combustible liquids of all types are transported by tankers as bulk cargo, as well as in portable containers, including placing them in containers.

Each vessel carries a large amount of flammable liquids in the form of fuel oil and diesel fuel, which are used to prop up the vessel and generate electricity.
Fuel oil and diesel fuel are especially dangerous if they are heated before being fed to the injectors. If there are cracks in the pipelines, these fluids leak out and are exposed to ignition sources. Significant spreading of these fluids results in a very severe fire.

Other locations where flammable liquids are available include galleys, various workshops and areas where lubricating oils are used or stored. In the engine room, residual oil and diesel fuel can be found on and under the equipment in the form of residues and films.

Quenching. In the event of a fire, quickly shut off the source of flammable or combustible liquid. Thus, the flow of combustible substances to the fire will be suspended, and people engaged in fighting the fire will be able to use one of the following methods of extinguishing the fire.
For this purpose, a foam layer is used that covers the burning liquid and prevents the flow of oxygen to the fire. In addition, steam or carbon dioxide may be supplied to areas where combustion occurs. By turning off the ventilation, the oxygen supply to the fire can be reduced.

Cooling. It is necessary to cool tanks and areas under the influence of a fire using a spray or compact jet of water from the fire main.

Slowing down the spread of the flame. For this, fire extinguishing powder must be applied to the burning surface.

Due to the fact that there are no identical fires, it is difficult to establish a single method of extinguishing them.

However, when extinguishing fires associated with the combustion of flammable liquids, it is necessary to be guided by the following:

1. In case of slight spreading of burning liquid, use powder or foam fire extinguishers or a spray of water.

2. In case of significant spreading of the burning liquid, it is necessary to apply powder fire extinguishers Supported by fire hoses for foam or spray. Equipment exposed to fire should be protected with a water jet

3. When spreading a burning liquid over the surface of the water, it is necessary first of all to limit the spreading. If you succeed in this, you need to create a layer of foam that covers the fire. In addition, you can use a large volume spray jet of water.

4. To prevent flue gas from escaping from inspection and metering hatches, use foam, powder, high-speed or low-speed water spray, blown horizontally across the opening until it can be closed.

5. To fight fires in cargo tanks, a deck foam extinguishing system and (or) a carbon dioxide extinguishing system or a steam extinguishing system, if available, should be used. For heavy oils, water mist can be used.

6. To extinguish a fire in the galley, it is necessary to use carbon dioxide or powder fire extinguishers.

7. If liquid fuel equipment is on fire, use foam or water spray.

Paints and varnishes. The storage and use of most paints, varnishes and enamels, except for those that are water-based, are associated with a high fire hazard. The oils contained in oil paints are not themselves flammable liquids ( linseed oil, for example, has a flash point above 204 ° C). But paints usually contain flammable solvents, the flash point of which can be as low as 32 ° C. All other components of many paints are also flammable. The same applies to enamels and oil varnishes.

Even after drying, most paints and varnishes remain flammable, although their flammability is significantly reduced by evaporation of solvents. The flammability of a dry paint actually depends on the flammability of its base.

Flammability characteristics and combustion products. Liquid paint burns very intensely and produces a lot of thick black smoke. Burning paint can spread, so that a fire associated with burning paints resembles burning oils. Due to the formation of dense smoke and the release of toxic fumes when extinguishing burning paint indoors, use breathing apparatus.

Paint fires are often accompanied by explosions. Since paints are usually stored in tightly closed cans or drums with a capacity of up to 150 - 190 liters, a fire in the storage area can easily cause the drums to heat up, causing these containers to burst. The paint in the drums ignites instantly and explodes when exposed to air.

The usual location on the ship. Paints, varnishes and enamels are stored in painters' rooms located fore or aft under the main deck. Painting rooms should be made of steel or completely sheathed with metal. These premises can be serviced stationary system carbon dioxide extinguishing or other approved system.

Quenching. Since liquid paints contain solvents with a low flash point, water is not suitable for extinguishing burning paints. To extinguish a fire associated with the burning of a large amount of paint, it is necessary to use foam. Water can be used to cool the surrounding surfaces.
If small amounts of paint or varnish ignite, you can use carbon dioxide or dry powder extinguishers. You can use water to extinguish dry paint.

Flammable gases. In gases, molecules are not bound to each other, but are in free motion. As a result, the gaseous substance does not have its own form, but takes the form of the container in which it is enclosed.
Most solids and liquids, if their temperature rises enough, can be converted into gas. This term "gas" means the gaseous state of a substance under the conditions of the so-called normal temperatures (21 ° C) and pressure (101.4 kPa).

Any gas that burns at normal oxygen levels in the air; called flammable gas. Like other gases and vapors, flammable gases only burn when their concentration in the air is within the flammability range and the mixture is heated to the ignition temperature. Typically, flammable gases are stored and transported on board ships in one of the following three states: compressed, liquefied and cryogenic.
Compressed gas is a gas that, at normal temperature, is completely gaseous in a pressurized container.
Liquefied gas is a gas that, at normal temperatures, is partly liquid and partly gaseous in a pressurized container.
Cryogenic gas is gas that is liquefied in a container at well below normal temperatures at low and medium pressures.

Main dangers. The dangers posed by the gas in the container are different from those that arise when it leaves the container. Let's consider each of them separately, although they can exist simultaneously.

Dangers of limited scope. When a gas is heated in a limited volume, its pressure increases. In the presence of a large amount of heat, the pressure can rise so much that it will cause gas leakage or rupture of the container. In addition, contact with fire can reduce the strength of the container material, which also contributes to its rupture.

To prevent explosions of compressed gases, tanks and cylinders are equipped with safety valves and fusible links. As the gas expands in the container, the safety valve opens, resulting in a decrease in internal pressure. The spring-loaded device will close the valve again when the pressure has dropped to a safe level.
A melt metal insert can also be used, which will melt at a certain temperature. The insert plugs the hole usually found in the upper part of the container body.
The heat generated by a fire threatens a container containing compressed gas, causes melting of the insert and allows gas to escape through the hole, thereby preventing the formation of pressure in it, which leads to an explosion. But since such a hole cannot be closed, gas will escape until the container is empty.

An explosion can occur in the absence of safety devices or if they do not work. An explosion can also be caused by a rapid increase in pressure in the container, when the safety valve is unable to release the pressure at a rate that would prevent the build-up of pressure capable of causing an explosion.
Tanks and cylinders can, in addition, explode if their strength decreases as a result of contact of flames with their surfaces. The impact of flame on the walls of the container, which are above the liquid level, is more dangerous than contact with the surface that is in contact with the liquid.
In the first case, the heat emitted by the flame is absorbed by the metal itself. In the second case, most of the heat is absorbed by the liquid, but this also creates a dangerous situation, since the absorption of heat by the liquid can cause a dangerous, although not so rapid increase in pressure.
Spraying the surface of the container with water prevents a rapid increase in pressure, but does not guarantee the prevention of an explosion, especially if the flame also affects the walls of the container.

Capacity rupture. Compressed or liquefied gas has a large amount of energy held back by the container in which it is located. When a container ruptures, this energy is usually released very quickly and violently. Gas escapes, and the container or its elements scatter.

Ruptures of containers containing liquefied flammable gases under the influence of fires are not uncommon. This type of destruction is called a boiling liquid expanding vapor explosion. In this case, as a rule, the upper part of the container is destroyed, in the place where it comes into contact with the gas. The metal stretches, becomes thinner and breaks along its length.

The force of the explosion depends mainly on the amount of evaporating liquid during the destruction of the container and the mass of its elements. Most explosions occur when the container is 1/2 to about 3/4 full of liquid.
A small, uninsulated container can explode after a few minutes, and a very large container, even if not cooled with water, takes only a few hours. Uninsulated containers containing liquefied gas can be protected against explosion by supplying water to them. A water film must be supported in the top of the container where the vapors are.

Dangers associated with gas escaping from a confined volume. These hazards depend on the properties of the gas and where it leaves the container. All gases, except oxygen and air, are hazardous if they displace the air required for breathing. This is especially true for odorless and colorless gases such as nitrogen and helium, as there are no signs of their appearance.

Toxic or poisonous gases are life-threatening. If they go outside near a fire, then they block access to the fire for people who are fighting with it, or force them to use breathing apparatus.

Oxygen and other oxidizing gases are non-flammable, but they can cause inflammable substances to ignite at temperatures below normal.

Gas on skin causes frostbite which can have serious consequences with prolonged exposure. In addition, when exposed to low temperatures, many materials, such as carbon steel and plastics, become brittle and degrade.

Flammable gases escaping from the container pose a risk of explosion and fire, or both. Escaping gas when accumulating and mixing with air in limited space explodes.
The gas will burn without exploding if the gas-air mixture accumulates in an amount insufficient for an explosion, or if it ignites very quickly, or if it is in an unlimited space and can be scattered.
Thus, when flammable gas escapes onto the open deck, a fire usually occurs. But when a very large amount of gas flows out, the surrounding air or the ship's superstructure can so limit its dispersion that an explosion will occur, called an explosion on outdoors... This is how liquefied non-cryogenic gases, hydrogen and ethylene explode.

Properties of some gases. The following are the most important properties of some flammable gases. These properties explain the varying degrees of the hazards that arise in the case of the accumulation of gases in a limited volume or during their spreading.

Acetylene. This gas is transported and stored, as a rule, in cylinders. For safety reasons, a porous filler is placed inside the acetylene cylinders - usually diatomaceous earth, which has very small pores or cells. In addition, the aggregate is impregnated with acetone, a flammable material that readily dissolves acetylene.
Thus, acetylene cylinders contain significantly less gas than it seems. Several fuse-links are installed in the upper and lower parts of the cylinders, through which the gas escapes into the atmosphere if the temperature or pressure in the cylinder rises to a dangerous level.

The release of acetylene from the cylinder can be accompanied by an explosion or fire. Acetylene ignites more easily than most flammable gases and burns more quickly. This increases explosions and makes ventilation difficult to prevent explosion. Acetylene is only slightly lighter than air, so it mixes easily with air when it leaves the container.

Anhydrous ammonia. It consists of nitrogen and hydrogen and is used mainly for the production of fertilizers, as a refrigerant and a source of hydrogen required for the heat treatment of metals.
It is a fairly toxic gas, but its inherent pungent odor and irritating effect serve as a good warning of its appearance. Strong leaks of this gas caused the rapid death of many people before they could leave the area of ​​its appearance.

Anhydrous ammonia is transported to trucks, railway tank cars and barges. It is stored in cylinders, tanks and cryogenic in insulated containers.
Explosions of expanding vapors of a boiling liquid in uninsulated cylinders containing anhydrous ammonia are rare due to the limited flammability of the gas. If such explosions do occur, they are usually associated with fires of other combustible substances.

Anhydrous ammonia can explode and burn on its way out of a cylinder, but its high LEL and low calorific value greatly reduce this hazard. The release of large quantities of gas when used in refrigeration systems, as well as storage when unusually high pressure may cause an explosion.

Ethylene. It is a gas composed of carbon and hydrogen. It is usually used in chemical industry, for example, in the manufacture of polyethylene; in smaller quantities it is used for fruit ripening. Ethylene has a wide flammability range and burns quickly. While non-toxic, it is an anesthetic and asphyxiant.

Ethylene is transported in compressed form in cylinders and in a cryogenic state in insulated trucks and rail tank cars. Most ethylene cylinders are protected against overpressure bursting diaphragms.
Ethylene cylinders used in medicine can be fused or combined. safety devices... Safety valves are used to protect the tanks. Cylinders can be destroyed by fire, but not the expanding vapor of a boiling liquid, since there is no liquid in them.

When ethylene leaves the cylinder, explosion and fire are possible. This is facilitated by the wide flammability range and the high combustion rate of ethylene. In a number of cases, associated with the release of a large amount of gas into the atmosphere, explosions occur.

Liquefied natural gas. It is a mixture of substances consisting of carbon and hydrogen, the main component of which is methane. It also contains ethane, propane and butane. Liquefied natural gas used as a fuel is non-toxic, but it is an asphyxiant.

Liquefied natural gas is transported in a cryogenic state on gas carriers. Stored in insulated containers protected from overpressure by safety valves.

The release of liquefied natural gas from a cylinder into a closed room can be accompanied by an explosion and fire. Test data and experience show that LNG explosions do not occur in the open air.

Liquefied petroleum gas. This gas is a mixture of substances consisting of carbon and hydrogen. Industrial LPG is typically propane or normal butane, or a mixture of these with small amounts of other gases. It is non-toxic, but it is an asphyxiant. It is used mainly as fuel in cylinders for domestic needs.

Liquefied petroleum gas is transported in the form of liquefied gas in uninsulated cylinders and tanks on trucks, rail tank cars and gas carriers. In addition, it can be transported by sea in a cryogenic state in heat-insulated containers.
Stored in cylinders and insulated tanks. Relief valves are commonly used to protect LPG tanks from overpressure.
Some cylinders have fusible links and sometimes safety valves and fusible links together. Most of the containers can be destroyed by explosions of expanding vapors of a boiling liquid.

The release of liquefied petroleum gas from the tank can be accompanied by an explosion and fire. Since this gas is mainly used indoors, explosions are more frequent than fires. The risk of explosion is exacerbated by the fact that from 3.8 liters of liquid propane or butane, 75 - 84 m 3 of gas are obtained. An explosion may occur if large quantities of LPG are released into the atmosphere.

The usual location on the ship. Liquefied flammable gases such as LPG and natural gases, transported in bulk on tankers. In cargo ships, flammable gas cylinders are carried on deck only.

Quenching. Fires involving flammable gases can be extinguished with extinguishing powders. For some types of gases, carbon dioxide and freons should be used.
In case of fires caused by the ignition of flammable gases, a great danger for people fighting the fire is the high temperature, as well as the fact that the gas will continue to escape even after the fire has been extinguished, and this can cause a renewal of the fire and an explosion.
Powder and sprayed water jet create a reliable heat shield, while carbon dioxide and freons cannot create a barrier to thermal radiation generated during gas combustion.

It is recommended that the gas be allowed to burn until its flow cannot be shut off at the source. No attempt should be made to extinguish a fire unless the gas flow is interrupted.
As long as the flow of gas to the fire cannot be stopped, the efforts of people fighting the fire should be directed towards protecting the surrounding combustible materials from: ignition by a flame or the high temperature that occurs during a fire. For these purposes, compact or spray water jets are usually used.
As soon as the flow of gas from the container stops, the flame should go out. But if the fire was extinguished before the end of the gas outflow, it is necessary to monitor the prevention of ignition of the escaping gas.

A fire associated with the burning of liquefied flammable gases, such as LPG and natural gas, can be controlled and extinguished by creating a dense foam layer on the surface of the spreading combustible.

Class C fires

Class C fires

Electrical equipment in or near a fire can cause electric shock or burns to people fighting the fire. Next, we will consider the electrical equipment available on ships, and methods for extinguishing fires associated with its ignition.

Generators are machines that generate electrical energy. They are usually "powered by mechanisms that use steam from liquid fuel boilers or internal combustion engines that burn liquid fuel in their cylinders. Electric cables in generators are insulated with a combustible material."
Any fire involving the ignition of a generator or its prime mover poses a great risk of electric shock to people fighting the fire.

Electrical boards. Each panel has fuses and automatic devices for control and protection of lighting and power circuits. Switches, fuses, circuit breakers and terminals installed on the board have electrical contacts. These contacts, if not properly maintained, can become very hot, causing dangerous temperature increases and activation of cable and electrical protection devices. They will open the circuit if very high temperatures occur.

Switches. Required to turn the lights on and off and various devices, as well as to turn off electric motors and their controllers. In addition, the switches are used to disconnect high-voltage circuit breakers during work related to their maintenance. Switches can be air or oil. In oil circuit breakers, the circuit breaker is immersed in oil.

The main hazard associated with circuit breakers is arcing when triggered. In this respect oil switches more dangerous than airborne ones. The danger is increased by poor condition of the switch, exceeding its power or low oil level.
In the latter case, if an arc appears, the residual oil will evaporate, the case will rupture, resulting in a fire. But with correct use and maintenance, oil switches do not pose any danger.

Electric motors. Many fires are caused by electric motors. Sparks or arcs from short-circuiting motor windings or improperly operating brushes can ignite the motor insulation or nearby combustible materials. In addition, a fire in electric motors can be caused by overheating of bearings due to poor lubrication or contaminated insulation on the conductors, which interferes with normal heat dissipation.

Electrical malfunctions that can cause a fire

Short circuit. When the insulation separating the two conductors is damaged, a short circuit occurs, in which the amperage is high. An electrical overload and dangerous overheating occurs in the network if the fuse or circuit breaker does not operate, or the operation is delayed. In this case, a fire is possible.

Overloading of conductors. If the electrical load on the circuit is very high, too much current flows through it and the wiring overheats. The temperature rises so much that the insulation can ignite.
To prevent this, fuses and circuit breakers are used in electrical circuits. In the absence of proper Maintenance these devices can fail and cause a fire.

Arc. Represents electric breakdown air gap in the chain. Such a gap can be created deliberately (by closing the switch) or accidentally (for example, by loosening the contact at the terminal). In both cases, when an arc occurs, intense heating occurs. The amount of heat generated depends on the magnitude of the current and voltage in the circuit.
The temperature can be high enough to ignite any combustible material in the vicinity of the arc, including insulation, and to melt the metal from which the conductor is made. In the latter case, it is possible to scatter hot sparks and hot metal, if they hit the combustible substances, a fire occurs.

Electrical fire hazards

Electroshock. May occur as a result of contact with an object that is energized. To do this, it is absolutely not necessary to touch one of the circuit conductors - contact with any electrically conductive material in contact with live circuit elements is sufficient.

Thus, people fighting a fire face two dangers:

firstly, moving in the dark or in smoke, they can touch an energized conductor;
second, a jet of water or foam can become a conductor of electrical current from energized equipment to people supplying water or foam.

In addition, the danger and severity of electric shock increases when people extinguishing a fire stand in water.

Burns. During an electrical fire, burns account for a significant portion of the injuries. Burns can be the result of direct contact with hot conductors or electrical equipment, sparks from them hitting the skin, or the result of an electric arc. Even being at a considerable distance from the arc, you can get an eye burn.

Toxic fumes from insulation burning. Insulation electrical cables usually made of rubber or plastic. Toxic fumes from burning rubber and plastics were discussed earlier.
One of the types of plastics deserves special attention, due to its widespread use as electrical insulation and the toxicity of combustion products, is polyvinyl chloride, also known as PVC.
It releases hydrogen chloride, which can be very serious when exposed to the lungs. In addition, PVC is believed to intensify fires and increase the hazards associated with them.

Normal location on board electrical equipment, the ignition of which leads to class C fires. Electricity is necessary for the operation of any modern vessel. Equipment that generates, regulates, and supplies electricity can be found anywhere on the ship.
Some of this equipment, such as lighting fixtures, switches and cables, are well known and easily recognizable. Next, we will indicate the location of the lesser known and most dangerous electrical equipment.

Engine room. The sources of electricity on the ship are generators. Usually two of them are located in the engine room. One always works, the second turns on when the first one stops. Electricity is supplied from the generators to the main switchboard (MSB), which includes the generator control panel and switchboards and is located in the same area of ​​the engine room where the generators are located.
If a fire breaks out near the switches of the generators or the main switchboard, the engineer on duty can quickly stop the generator by mechanical means by de-energizing the main switchboard and switches.
In the same area, there is a control panel for the engine room, which contains controls for fire pumps, fans, an alarm panel in the mechanics' rooms and other equipment.

Emergency generator room. Most ships have an emergency generator with its own switchboard in case the main generator fails. It generates electricity only for emergency equipment and lighting.

The emergency generator and the shield are installed in a special room located at a certain distance from the engine room. In the event of a fire, when the emergency generator room is filled with carbon dioxide supplied from the stationary ship's system, this generator is stopped.

Corridors . At the end of some corridors are cabinets containing electrical controls. They usually house the electrical switchboards of the winches for launching boats and ladders.
Lighting boards are installed on the bulkheads of the corridors. The main part of the cables runs behind the ceilings of the corridors, for access to which there are special removable panels, which can be removed if necessary to check the spread of the fire.

Other electrical installation locations. A large number of electrical equipment is located on the navigation bridge, including a radar station, a centralized control panel for a ship, a receiving panel for a smoke fire detection system, and lighting boards.
In the lower part of the vessel, in the bow and stern, there are electrical panels for the capstan and winch motors. The power panel in a mechanical workshop is designed to control the operation of an electric welding machine, grinding and turning machines, etc. In addition, there is still a significant amount of electrical equipment located throughout the ship.
It should be noted that when fighting a fire on board, always be aware of the dangers associated with live electrical equipment.

Extinguishing class C fires. If the fire spreads to any electrical equipment, it is necessary to de-energize the corresponding circuit. But regardless of whether the circuit is de-energized or not, when extinguishing a fire, only non-conductive substances, such as fire extinguishing powder, carbon dioxide or freon, should be used.
Persons fighting a Class C fire must always assume that the electrical circuit is live. The use of water is under no circumstances allowed. Breathing apparatus should be used in rooms where electrical equipment is on fire, as burning insulation releases toxic fumes.

Class D fires

Class D fires

It is generally accepted that metals are not flammable. But in some cases, they can contribute to increased fire and fire hazard. Sparks from cast iron and steel can ignite nearby combustible materials.
Crushed metals can easily ignite at high temperatures. Some metals, especially when crushed, tend to self-ignite under certain conditions. Alkali metals such as sodium, potassium and lithium, react violently with water, releasing hydrogen; this produces heat sufficient to ignite the hydrogen.
Most metals in powder form can ignite like a cloud of dust, and a violent explosion is possible. In addition, metals can cause injury to people fighting fires through burns, injury and toxic fumes.

Many metals, such as cadmium, emit toxic fumes when exposed to the high temperature of a fire. Although the toxicity of metals varies, breathing apparatus should always be used when fighting any fires involving burning metals.

Characteristics of some metals

Aluminum. Aluminum is a light metal that conducts electricity well. In its normal form, it poses no danger in the event of a fire. Its melting point is low enough (660 ° C), so that in case of fire, the destruction of unprotected structural elements made of aluminum can occur. Aluminum shavings and sawdust burn, and there is a danger of severe explosion associated with aluminum powder. Aluminum cannot spontaneously ignite and is considered non-toxic.

Cast iron and steel. These metals are not considered flammable. They do not burn in the composition of large items, but steel wool or powder can ignite, and powdered cast iron can explode under the influence of high temperature or flame. Cast iron melts at 1535 ° C, while ordinary structural steel melts at 1430 ° C.

Magnesium. Magnesium is a lustrous white metal, soft, viscous, capable of deforming in a cold state. It is used as a base in light alloys to give them strength and ductility. The melting point of magnesium is 650 ° C.
Magnesium powder and flakes are highly flammable, but in the solid state magnesium must be heated to a temperature above its melting point before it ignites. It then burns with a very intense blazing white flame. When heated, magnesium reacts violently with water and all types of moisture.

Titanium. Titanium is a strong white metal, lighter than steel. The melting point of titanium is 2000 ° C. It is part of steel alloys, making them suitable for use at high operating temperatures. It is highly flammable in small products, and its powder is a strong explosive. However, large pieces represent small fire hazard... Titanium is not considered toxic.

The usual location on the ship. The main material from which the ship's hull is made is steel. For the superstructures of some ships, aluminum is used, as well as its alloys and other lighter metals. The advantage of aluminum is that it allows to reduce the weight of structures, and the disadvantage from the point of view of fire fighting is the relatively low temperature melting compared to steel.

In addition to the materials used in the construction of the ship itself, metals in various forms are transported on the ship as cargo. Typically, there are no restrictions on the placement of metals in solid form.
For powders of metals such as titanium, aluminum and magnesium, they should be placed in dry, isolated areas. The same is true for metals such as potassium and sodium.

It should be noted that large containers used for the transport of goods are usually made of aluminum. The walls of these containers melt and crack in the event of a fire.

Extinguishing Class D fires... Extinguishing fires associated with the combustion of most metals presents significant difficulties. Often these metals react violently with water, leading to fire spread and even explosion.
If a small amount of metal is burning in a confined space, it is recommended to allow it to burn completely. Surrounding surfaces should be protected with water or other suitable extinguishing agent.

Some synthetic fluids are used to extinguish metal fires, which, as a rule, are not available on the ship. Some success in fighting such fires can be achieved by using fire extinguishers available on ships with universal fire extinguishing powder.

Sand, graphite, various powders and salts are used with varying success to extinguish metal fires. But none of the extinguishing methods can be considered effective for fires associated with the combustion of any metal.

Water and water-based extinguishing agents such as foam should not be used to extinguish combustible metal fires. Water can cause a chemical reaction that can cause an explosion.
Even chemical reaction does not occur, water droplets falling on the surface of the molten metal will expand and spray the molten metal.
But in some cases, it is necessary to use water with caution: for example, when burning large pieces of magnesium, you can supply water only to those areas that are not yet engulfed in fire, to cool them and prevent the spread of fire. Water should never be fed to the molten metals themselves, but should be directed to areas at risk of fire spread.
A number of countries publish lists containing specifications combustible metals, which indicate the methods of extinguishing fires and the necessary extinguishing agents. Owners whose ships can be used for the carriage of flammable metals are encouraged to have such lists indicating physical and chemical characteristics of these metals.

Primary fire extinguishing means are intended for use by employees of organizations, personnel of subdivisions fire department and other persons for the purpose of fighting fires and are divided into the following types:

1. portable and mobile fire extinguishers;
2. fire hydrants and means of ensuring their use;
3. fire fighting equipment;
4. blankets to isolate the fire site.

Classification of mobile fire extinguishing equipment

Mobile fire extinguishing equipment includes transport or transportable fire trucks intended for use by personnel of fire fighting units when extinguishing fires. Mobile fire extinguishing equipment is divided into the following types:

1. fire trucks (basic and special);
2. fire planes, helicopters;
3. adapted technical means (tractors, trailers and tractors).

Classification of fire extinguishing installations

Fire extinguishing installations - a set of stationary technical means extinguishing a fire by releasing a fire extinguishing agent. Fire extinguishing installations must provide localization or elimination of fire.

Fire extinguishing installations by design are subdivided into:

• aggregate
• modular

• automatic
• automated
• manual

• aquatic
• foamy
• gas
• powder
• aerosol
• combined

• voluminous
• superficial
• locally volumetric
• locally superficial

Classification of fire-fighting equipment

Funds fire automatics are designed for automatic fire detection, warning people about it and control of their evacuation, automatic fire extinguishing and switching on of executive devices of smoke protection systems, control of engineering and technological equipment of buildings and facilities.

Fire-fighting equipment is subdivided into:

1. fire detectors;
2. fire control devices;
3. fire control devices;
4. technical means of warning and evacuation control for firemen;
5. fire notification transmission systems;
6. other devices and equipment for the construction of fire automation systems.

Classification of personal protection and rescue equipment in case of fire

Personal protective equipment for people in case of fire is designed to protect the personnel of fire departments and people from exposure dangerous factors fire. The means of rescuing people in case of fire are intended for self-rescue of personnel of fire departments and for rescuing people from a burning building, structure, structure.

Personal protective equipment for people in case of fire are divided into:

1. personal protective equipment for respiratory and vision organs;
2. personal protective equipment for firefighters.

1. individual means;
2. collective funds.