Extinguishing fires of flammable liquids and gases is based on the analysis of all options for their development. Fires that occur in tanks last longer and therefore require a large amount of money and effort to extinguish.

Tanks for storing flammable liquids and flammable liquids

For the purpose of storing flammable liquids and gases, containers made of metal, reinforced concrete, ice soil and synthetic material are used. The most popular are steel tanks. They are classified by design and capacity into:

• vertical, cylinder-shaped, with a conical or spherical roof, with a volume of 20 thousand cubic meters for storing flammable liquids and 50 thousand cubic meters for storing flammable liquids;
• vertical cylinder-shaped, with a stationary roof and a floating pontoon, with a volume of 50 thousand cubic meters;
• vertical, cylinder-shaped, with a floating roof, with a volume of 120 thousand cubic meters.

The process of fire development in a tank

Extinguishing fires in tank farms storing flammable liquids and gases depends on the complexity of the fire development process. Combustion begins due to the explosion of the gas-air mixture in the presence of an ignition source. The formation of a gassed environment occurs due to the properties of gas liquids and flammable liquids, as well as operating modes and climatic conditions around the tank. Exploding, the gas-air mixture rushes upward at high speed, often tearing off the roof of the container, after which ignition begins over the entire surface of the stored flammable liquid.

The further fate of the flame will depend on the area where it started, its dimensions, the fire resistance of the tank structure, weather conditions, the actions of workers and fire protection systems.

When storing flammable liquids and flammable liquids, for example, in reinforced concrete tanks, part of it is destroyed during an explosion, and combustion begins in this area, which over the next 30 minutes leads to complete destruction of the container and the spread of fire. Other types of containers, in the absence of external cooling, become deformed within 15 minutes, provoking a spill of flammable liquids and the spread of fire.

Foam fire extinguishing

Extinguishing flammable liquids and gases with low and medium expansion foam is the most popular way to fight fire. The advantage of foam is that it insulates the surface of the flammable liquid from the flame, which leads to a reduction in its evaporation and, accordingly, the volume of flammable gases in the air. This creates a solution of a foaming agent with cooling properties. In this way, convective heat and mass transfer is achieved, and the temperature level becomes the same throughout the entire depth of the container within 15 minutes from the start of using the foam.

Extinguishing with foam

Extinguishing flammable liquids using foam solutions of varying amounts depends on where the combustion occurs:

• low expansion rate for the lower part of the container, used for the “under-layer” extinguishing method, the fire extinguishing agent contains a fluorine-containing film-forming foaming agent, due to which, when the foam rises through a layer of flammable contents, it is not saturated with hydrocarbon vapors and retains its fire-extinguishing abilities; obtained using low-expansion foam trunks;
• medium expansion rate for surface extinguishing, foam is also inert, does not interact with flammable liquid vapors, cools the liquid, helps reduce the formation of an explosive air mixture; obtained using specialized foam generators of the GPS type.

After the extinguishing of flammable liquids and gases is completed, a thick foam layer forms on the surface of the liquid, protecting it from resumption of combustion.

When supplying fire extinguishing foam, the flame intensity should be maintained at 0.15 l/s.

Implement foam fire extinguishing allowed in three ways:

• delivery of foam concentrate using a foam lifter and other similar equipment;
• delivery of foam to the surface of burning flammable liquids and gases using monitors;
• foam delivery through sublayer extinguishing.

Water fire extinguishing

If it is not possible to extinguish flammable liquid fires using foam, it is permissible to use sprayed water, which helps cool the flammable contents to a temperature at which it cannot ignite.

In this case, the intensity of supply of the water solution should be at least 0.2 l/s.

Powder quenching

Extinguishing fires in flammable liquid storage tank farms using powder is suitable for situations where combustion occurs in the area of ​​valves, flange connections or gaps between the roof and the tank wall. The feed rate must exceed 0.3 kg/s. The powder is not able to cool the liquid, so it may be necessary to re-extinguish the flammable liquid.

Powder extinguishing – for minor fires and quick extinguishing only

To avoid such situations powder fire extinguishing combined with foam in the following ways:

• maximum extinguishing of the flame with a foam solution, after which individual flames are localized using powder;
• extinguishing the flame using a powder component followed by the supply of a foaming agent to cool the damaged surface and prevent resumption of combustion.

In this case, it is prohibited to reduce the volume of supplied fire extinguishing agents.

Tank fire control plan

It is advisable to begin extinguishing flammable liquids and gases in tanks with an assessment of the current situation, as well as with the calculation of the required means and forces. In case of such emergency situation a voluntary fire brigade should be organized, the head of which will be the person responsible for managing the process of extinguishing the flames and distributing tasks among fire extinguishing participants.

The responsible person must determine the volume of the territory in which extinguishing work will be carried out, and organize the removal of unauthorized persons from the danger zone.

Upon arrival at the fire site, the leader conducts reconnaissance and indicates to other firefighting participants the areas where maximum forces should be deployed.

Throughout the entire work, the manager’s tasks include providing all available forces and means of cooling flammable liquids and gases in tanks, as well as choosing the optimal method of fighting fire.

When the main forces are thrown into working with a burning container, it is important to protect neighboring tanks in case the damaged one collapses or the resulting gas-air mixture explodes. It is for this purpose that all fire engines are installed at a safe distance, and hose lines are laid to the work site.

Extinguishing tank farms of flammable liquids and gases directly depends on the duration of the fire, the nature of the resulting destruction of the tanks, the volume of stored liquids in the damaged and neighboring tanks, the likelihood of an explosion and subsequent emergency spill of the contents.

When designing and constructing tank farms, a sewerage system must be provided into which water can be drained during the fire extinguishing process, and devices must be designed for emergency pumping of the contents into a safe tank.

How tanks are cooled during firefighting

Extinguishing fires of flammable liquids and gases in tanks must necessarily be accompanied by cooling the contents of the damaged container. The latter needs to be cooled along the entire length of its circumference. In relation to adjacent tanks, there is also a requirement for mandatory cooling, but only along the entire length of the semicircle of the tank on the side facing the combustion zone. In some cases, it is possible not to carry out the cooling procedure for adjacent containers if there is no threat of flame spread. The water supply for cooling purposes must be at a rate of at least 1.2 l/s.

To extinguish tanks with flammable liquids and flammable liquids with a volume of 5 thousand cubic meters, it is recommended to use fire monitors, which not only provide the required water delivery power, but also have a mode of irrigation of the burning object.

The order of work with adjacent undamaged containers is such that those located on the leeward side of the fire are protected and cooled first.

The duration of operation is determined until the flame is completely eliminated and the temperature level inside the container is normalized.

Dangerous zones during combustion in tank farms

Extinguishing fires of flammable liquids and flammable liquids should also be carried out taking into account hazardous factors and areas that may reduce the effectiveness of firefighting measures:

1. Formation of zones where it is impossible to deliver fire extinguishing agent.
2. Warming up the flammable contents of the tank to a depth of 1 m or more.
3. Reduced air temperature around the fire site.
4. Ignition of several containers at the same time.

Extinguishing a real fire of flammable liquid bottling of a large area Angarsk 2014:

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Solvents, lighter fluid, petroleum, pesticides, paint, kerosene, propane, butane, gasoline, cleaning products are all flammable liquids. These tools are used everywhere, especially different kinds fuels and cleaning products that everyone has in their home. When moving or working with any of them, you must follow safety rules.

If your profession involves working with flammable materials, then you need to know all the issues related to protecting your life and others in the event of a fire. This article describes all the necessary requirements for flammable liquids.

General safety requirements

Any flammable liquid may pose a serious health hazard or fire risk if not used correctly. If the concentration of the vapor cloud reaches a certain temperature, the liquid will ignite. The substance itself, which is in a calm state, cannot ignite. Combustible liquids have a high flash point, flammable liquids have a low flash point, so they are more dangerous to humans.

What to do if any product is spilled?

If there is a spill, you must immediately open all windows and ventilate the room. Turn off all electrical equipment as they may cause sparks that could cause an explosion. If something gets on your clothes, take it off, or on your skin, wash it off with water as quickly as possible. If a large amount of flammable material is spilled, it is advisable to evacuate all employees and call the fire department.

When a fire spreads, there is no need to try to extinguish it with water; in the case of such liquids, it will only make the situation worse. A fire extinguisher is best. It should be stored close to the work area.

Always read the label carefully before using any product. To make sure you know how to properly handle flammable and combustible liquids.

List of tips:

Do not talk on the phone, listen to music or be distracted by anything else while working with flammable substances.

Working with flammable liquids requires a well-ventilated area. Because the vapors are unsafe and harmful chemicals can enter the body through the respiratory tract. Many of them are odorless.

Caution is the first rule. Make sure that the product you are working with does not come into contact with your skin or clothing.

If there is a leak, notify your manager.

Whenever you leave a room where a flammable liquid is stored, inspect the area before closing the door.

Never smoke cigarettes in an area where such substances are present. They should be kept away from open flames.

Remember that there are many hidden sources of ignition, for example in equipment.

When using metal drums, hoses, or piping, make sure they are grounded to prevent the build-up of static charges, which can become a fire hazard.

Ensure that all containers, taps, cans, pumps and other equipment used for storage are designed to handle flammable liquids.

Try to avoid flammable substances

The best way to reduce the risk of fire is to avoid such products. If possible, you can replace it with another, less flammable substance. Take a look at the current layout and determine if there are ways you can do the job more safely.

Please note the following tips to help you work correctly with flammable liquids.

Firstly, you need to take special courses in which the instructor will tell you all the nuances of working with flammable substances.

Secondly, when it comes to safety, the health of others is very important. Comply with labor safety requirements and do not risk the lives of others.

flashes and spontaneous combustion?

A flammable liquid is the minimum level at which a liquid will release vapor to a surface to ignite. The liquids themselves do not burn. A mixture of released vapors and air burns.

Gasoline, with a flash point of -43 °C, is a flammable liquid. Even at low temperatures it produces quite a lot of vapor to form a flammable mixture with air.

Phenol is a flammable liquid. It has a flash point of 79 °C (175 °F). Therefore, its level must exceed 79 °C before it can ignite in air.

The auto-ignition temperature of most common liquids ranges from 300°C (572°F) to 550°C (1022°F).

Flammability limits for explosive substances

The lower flammability limit is the proportion of vapor in the air above which a fire cannot occur because there is not enough fuel. Vapors that are higher in density than air tend to be more dangerous because they can flow across floors and accumulate in low areas.

The upper flammability limit is the proportion of vapor in the air when there is not enough air to ignite.

Flammable liquids are explosive, and these limits give a range between the lowest and highest vapor concentrations in the air. That is, using flammability limits, you can determine which substance will burn and which may explode.

For example, the lower explosive limit of gasoline is 1.4%, and the upper limit is 7.6%. This means that this liquid can ignite when in the air at a level of 1.4% to 7.6%. The vapor concentration below the explosive level is too low to ignite; more than 7.6% may cause an explosion.

Fire limits serve as guides to hot spots.

Why are such substances dangerous?

Under normal conditions room temperature flammable liquids can emit quite a lot of vapors that form flammable mixtures with air. As a result, they can pose a serious fire hazard. Flammable liquids burn very quickly. They also emit large amounts of thick, black, toxic smoke.

Flammable liquids at temperatures above their flash level can also cause a serious fire.

Spraying flammable and combustible liquids into the air will cause fire if there is an ignition source. Vapors of substances are usually invisible. They are difficult to detect unless you use special tools.

Combustible and flammable liquids are easily absorbed into wood, fabric and cardboard. Even after removing them from clothing or any other coverings, they can be dangerous and emit harmful fumes.

What danger do such liquids pose to the body?

Such substances cause great harm during a fire and explosion. They are dangerous to health. Flammable liquids can cause irreparable damage to the human body, depending on the specific material and method of exposure:

1. Inhalation of vapors.
2. Contact with eyes or skin.
3. Swallowing liquid.

Most flammable liquids and flammable substances are dangerous to humans. Many of them are stored incorrectly and undergo incompatible chemical reactions, which can cause even more harm.

Information on labels and containers should describe all the hazards associated with flammable substances that a person handles.

For example, propanol (also known as isopropanol or isopropyl alcohol) is a colorless liquid with a pungent odor, reminiscent of a mixture of ethanol and acetone. Vapors are heavier than air and can spread to long distances. High level fumes may cause headache, nausea, dizziness, drowsiness, impaired coordination of movements. The substance may also cause irritation respiratory tract or eyes.

How to properly store substances in production areas, workshops, laboratories and similar work areas

It must be recognized that for practical purposes where liquids are used it will most likely be necessary to store them in a workshop. Only a minimal amount of such substances can be placed in work area, but even these should be used during the day or changed location. Actual storage times will depend on labor activity, organizational mechanisms, fire risks in the workshop and work area. Storing flammable liquids in large quantities at home is prohibited. All responsibility will lie with the owners.

Containers for flammable liquids must be closed. They must be placed in designated areas that are away from the immediate processing area and do not compromise the workshop and work area.

Highly flammable liquids should be stored separately from other hazardous substances that may increase the risk of fire or compromise the integrity of the container or cabinet (box), for example, oxidizing agents and aggressive materials.

What if the quantity exceeds the established maximum?

materials must be stored or handled in the work area;

The size of the workshop and the number of people working there must be taken into account;

the amount of liquid processed in the workshop should not exceed the standards established by the enterprise;

the workshop must be equipped with good ventilation.

Must be from a workshop where they work with explosive substances.

Flammable liquids are liquids that emit vapors at a temperature of 61°C and below, for example ethyl ether, gasoline, acetone, alcohol.

Flammable liquids are liquids whose flash point exceeds 61°C. Heavy oil products such as diesel fuel and fuel oil are considered flammable liquids. The flash point range of these liquids is 61°C and above. Flammable liquids also include some acids, vegetable and lubricating oils, the flash point of which exceeds 61°C.

Flammability characteristics.

It is not the flammable liquids themselves that burn and explode when mixed with air, but their vapors. Upon contact with air, these liquids begin to evaporate, the rate of which increases when they are heated. To reduce the risk of fire, they should be stored in closed containers. When using liquids, care must be taken to ensure that exposure to air is as minimal as possible.

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

Flash point is the generally accepted and most important factor in determining the hazard posed by a flammable liquid.

The rates of combustion and flame propagation of flammable liquids are somewhat different from each other. The burnout rate of gasoline is 15.2-30.5, 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 liquids, in addition to the usual combustion products, some specific combustion products are formed, characteristic of these liquids. Liquid hydrocarbons usually burn orange flame and emit thick clouds of black smoke. Alcohols burn with a clear blue flame, producing a small amount of smoke. The combustion of some ethers is accompanied by violent boiling on the surface of the liquid, and extinguishing them presents significant difficulty. When petroleum products, fats, oils and many other substances burn, acrolein is formed - a highly irritating toxic gas.

Extinguishing.

If a fire occurs, quickly shut off the source of flammable liquid. This will stop the flow of flammable substances to the fire, and people involved in fighting the fire will be able to use one of the fire extinguishing methods listed below.

Cooling. It is necessary to cool containers and areas exposed to fire using a spray or compact stream of water from the fire water main.

Extinguishing. A layer of foam is used to cover the burning liquid and prevent its vapors from reaching the fire. In addition, steam or carbon dioxide. By turning off ventilation, the supply of oxygen to the fire is reduced.

Slows down the spread of flames. Fire extinguishing powder must be applied to the burning surface.

When extinguishing fires involving the combustion of flammable liquids, the following should be followed:

1. If the burning liquid spreads slightly, it is necessary to use powder or foam fire extinguishers or a spray of water.

2. If there is significant spreading of the burning liquid, it is necessary to use powder fire extinguishers foam or spray jets of water. Equipment exposed to fire should be protected using a jet of water.

3. When a burning liquid spreads over the surface of water, it is necessary, first of all, to limit it. If you succeed in doing this, you need to create a layer of foam covering the fire. Alternatively, you can use a spray of water to

4. To prevent combustion products from escaping from inspection and measuring hatches, it is necessary to use foam, powder, high or medium expansion foam, or a spray of water applied horizontally across the hole 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 spray can be used.

6. To extinguish a fire in the galley, carbon dioxide or powder fire extinguishers must be used.

7. If liquid fuel equipment burns, foam or spray water must be used.

Paints and packs

The storage and use of most paints, varnishes and enamels, except those that are water-based, is associated with a high fire hazard. Oils contained in oil paints, are not themselves flammable liquids. But these 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 continue to be flammable, although their flammability is significantly reduced when the solvents evaporate. The flammability of dry paint actually depends on the flammability of its base.

Flammability characteristics and combustion products.

Liquid paint burns very intensely, producing a large amount of thick black smoke. Burning paint can spread, so that fires associated with burning paints resemble burning oils. Due to the formation of dense smoke and the release of toxic fumes when extinguishing burning paint in an enclosed area, you should use breathing apparatus.

Paint fires are often accompanied by explosions. Since paints are usually stored tightly closed banks or drums with a capacity of up to 150-190 liters, a fire in the area where they are stored can easily cause the drums to heat up, as a result of which these containers can rupture. The paints contained in the drums ignite instantly in the presence of ignition sources and explode in the presence of oxygen in the air.

Extinguishing.

Because the liquid paints contain solvents with a low flash point; water is not always effective for extinguishing burning paints. To extinguish fires associated with combustion large quantity paint, foam must be used. Water can be used to cool surrounding surfaces. When small amounts of paint or varnish catch fire, you can use foam, carbon dioxide or powder fire extinguishers. You can use water to extinguish dry paint.

1.3 Class "C" fires

Gases

Any gas that can burn at normal oxygen levels in the air (about 21%) should be considered a flammable gas. Flammable gases and vapors of flammable liquids are capable of burning only when their concentration in the air is within the flammability range, and the mixture (flammable gas + atmospheric oxygen) is heated to the ignition temperature.

In gases, the molecules are not connected to each other, but are in free movement. As a result, the gaseous substance does not have its own shape, but takes the shape of the container in which it is enclosed.

Typically, flammable gases are stored and transported on ships in one of the following three states: compressed; liquefied; cryogenic

Compressed gas- this is a gas that, at normal temperature and pressure (+20°C; 740 mmHg) is completely in a gaseous state in a container under pressure

Liquefied gas is a gas that normal temperatures partly in a liquid and partly in a gaseous state in a container under pressure.

Cryogenic gas is a gas that is liquefied in a container at a temperature significantly below normal and at low and medium pressures.

Main hazards.

The hazards posed by gas in a container are different from those posed by gas escaping from the container. Let's look at each of them separately, although they can exist simultaneously.

Limited scope hazards. When gas is heated in a limited volume (cylinder, tank, tank, etc.), its pressure increases. If there is a large amount of heat, the pressure can increase so much that it will cause the container to rupture and leak gas. In addition, contact with fire may reduce the strength of the container material, which may also cause the container to rupture.

An explosion may occur if there is no safety devices or in case they don't work. The cause of an explosion can also be a rapid increase in pressure in the container when safety valve unable to reduce pressure at a rate that would prevent the build-up of pressure capable of causing an explosion. Tanks and cylinders can also explode when their strength is reduced as a result of flame contact with their surface. Sprinkling the surface of the container with water helps prevent rapid pressure growth, but does not guarantee the prevention of an explosion, especially if the flame also affects the walls of the container.

Capacity rupture. Ruptures of containers containing liquefied flammable gases due to fire are not uncommon. This type of destruction is called an explosion of expanding vapors of a boiling liquid. In this case, as a rule, the upper part of the container is destroyed, where it comes into contact with the gas.

Most explosions occur when the container is half to about three-quarters full of liquid. A small uninsulated container may explode within a few minutes, but a very large container, even if not cooled with water, may explode within a few hours. Uninsulated containers containing liquefied gas can be protected from explosion by spraying them with water. A film of water must be maintained on the top of the container where the vapor is located.

Hazards associated with gas escaping from a confined volume. These hazards depend on the properties of the gas and where they exit the container.

Toxic or poisonous gases are life-threatening. If they come out near a fire, they block access to the fire for people fighting the fire or force them to use breathing apparatus.

Oxygen and other oxidizing gases are not flammable, but they can cause flammable substances to ignite at temperatures below normal.

Contact of the gas with the skin causes frostbite, which can have serious consequences with prolonged exposure. Additionally, when exposed to low temperatures, many materials, such as carbon steel and plastics, become brittle and break down.

Flammable gases escaping from a container pose a risk of explosion, fire, or both. When the escaping gas accumulates and mixes with air in a confined space, it explodes. A gas will burn without exploding if the gas-air mixture accumulates in an amount insufficient to cause an explosion, or if it ignites very quickly, or if it is in an unconfined space and can disperse. If flammable gas leaks on an open deck, a fire may occur. But when a very large amount of gases leaks into ambient air, the ship's superstructure can limit its dispersion so much that an explosion occurs. This type of explosion is called an explosion outdoors. This is how liquefied non-cryogenic gases, hydrogen and ethylene, explode.

Extinguishing.

Fires involving the combustion of flammable gases can be extinguished using fire extinguishing powders or compact jets of water. For some types of gases, carbon dioxide and freons should be used. In fires caused by the combustion of flammable gases, high temperatures pose a great danger to people fighting the fire. In addition, there is a danger that gas will continue to escape after the fire has been extinguished, which could cause the fire to restart and cause an explosion. Powder and a stream of water create a reliable heat shield, while carbon dioxide and freons cannot create a barrier to thermal radiation generated during gas combustion.

It is recommended to allow the gas to burn until its flow can be stopped at the source. No attempt should be made to extinguish the fire unless this will stop the flow of gas. Until the flow of gas toward a fire cannot be stopped, firefighting efforts should be directed toward protecting surrounding combustible materials that may be ignited by the flames or heat generated during the fire. For these purposes, compact or spray jets of water 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 flow, care must be taken to prevent the escaping gas from igniting.

Fire associated with the combustion of liquefied flammable gases such as liquefied petroleum and natural gases, can be brought under control and extinguished by creating a dense layer of foam on the surface of the spread flammable substance.

1.4 Class "D" fires

Metals

It is generally accepted that metals do not ignite. But in some cases they can contribute to the intensification of the fire and fire danger. Sparks from cast iron and steel can ignite nearby flammable materials. Crushed metals can easily ignite at high temperatures. Some metals, especially when crushed, are prone to spontaneous combustion under certain conditions. Alkali metals such as sodium, potassium and lithium react violently with water to release hydrogen, producing heat sufficient to ignite the hydrogen. Most metals in powder form can ignite like a cloud of dust; a strong explosion is possible. In addition, metals can cause injury to people fighting a fire in the form of burns, injuries, and toxic fumes.

Many metals, such as cadmium, emit toxic fumes when exposed to high temperatures during a fire. When extinguishing any fires involving the burning of metals, you should always use breathing apparatus.

Characteristics of some metals.

It is a light silver-white metal, soft, fusible (density 0.862 g/cm 3, melting point 63.6°C). Potassium belongs to the group of alkali metals. In air it quickly oxidizes: 4K + O 2 = 2 K 2 O. In contact with water, the reaction occurs violently, with an explosion: 2K + 2 H 2 O = 2 KOH + H 2. The reaction proceeds with the release of a significant amount of heat, which is sufficient to ignite the released hydrogen.

Aluminum.

This light metal, a good conductor of electricity. In its normal form it poses no danger in the event of a fire. Its melting point is 660°C. This is a low enough temperature that in the event of a fire, destruction of unprotected structural elements made of aluminum can occur. Aluminum shavings and sawdust burn, and aluminum powder poses a risk of severe explosion. Aluminum cannot spontaneously ignite and is considered non-toxic.

Cast iron and steel.

These metals are not considered flammable. They do not burn in large products. But steel wool or powder can ignite, and powdered cast iron is exposed to high temperature or flame - explode. Cast iron melts at 1535°C, and ordinary structural steel at 1430°C.

It is a shiny white metal, soft, malleable, and capable of deformation when cold. 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 it must be heated to a temperature above its melting point before it will ignite. It then burns very intensely, with a brilliant white flame. When heated, magnesium reacts violently with water and all types of moisture.

It is a strong white metal, lighter than steel. Melting point 2000°C. It is part of steel alloys, allowing them to be used at high operating temperatures. In small products it is highly flammable, and its powder is highly explosive. However, large pieces pose little fire hazard.

Titanium is not considered toxic.

Extinguishing.

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

Some synthetic liquids are used to extinguish metal fires, but as a rule, they are not available on board. Some success in fighting such fires can be achieved by using fire extinguishers with universal fire extinguishing powder. Such fire extinguishers are usually found on ships.

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

Water and fire extinguishing agents water-based materials such as foam should not be used to extinguish flammable metal fires. Water can cause a chemical reaction resulting in an explosion. Even chemical reaction does not occur, drops of water falling on the surface of the molten metal will decompose with an explosion and spray the molten metal. But, in some cases, water can be used carefully: for example, when large pieces of magnesium are burning, water can be applied to those areas that are not yet on fire to cool them and prevent the spread of the fire. Water should never be applied to the molten metals themselves, but rather to areas at risk of fire spread.

This is due to the fact that water falling on the molten metal dissociates, releasing hydrogen and oxygen 2H 2 O ® 2H 2 + O 2. Hydrogen in the fire zone burns explosively.

1.5 Class "E" fires

Electrical equipment

Electrical faults that may cause a fire.

1. Short circuit.

When the insulation that separates two conductors is damaged, short circuit, at which the current strength is high. Electrical overload and dangerous overheating occur in the network. This may cause a fire.

This is an electrical breakdown of the air gap in the circuit. Such a gap can be created intentionally (by turning on a switch) or accidentally (for example, when a contact on a terminal is loosened). In both cases, when an arc occurs, intense heating occurs and hot sparks and red-hot metal can be scattered, which, if they come into contact with flammable substances, causes a fire.

In addition, during the operation of ship electrical equipment, there may be other causes of fire, such as contact resistance, overloads, as well as fires caused by violations of the rules of technical operation of electrical installations and units: leaving electrical heating devices turned on without supervision, contact of heated parts of electric drives with combustible objects ( fabrics, paper, wood) and other reasons.

Hazards associated with electrical fires.

1. Electric shock.

An electric shock can occur as a result of contact with a live object. The lethal value of current flowing through a person is 100 mA (0.1A). People fighting a fire face two dangers: firstly, when moving in the dark or in smoke, they can touch a conductor who is under tension; secondly, the stream of water or foam can become a conductor of electrical current from energized equipment to the people supplying the water or foam. In addition, the danger and severity of electric shock increases when firefighting personnel stand in water.

During an electrical fire, a significant portion of the injuries are burns. Burns can result from direct contact with hot conductors or electrical equipment, the skin being exposed to sparks flying from them, or exposure to an electric arc.

3. Toxic fumes released when insulation burns.

The insulation of electrical cables is usually made of rubber or plastic. When burned, they produce toxic fumes, and polyvinyl chloride, also known as PVC, produces hydrogen chloride, which can have very serious effects on the lungs. It is also believed to contribute to the intensification of fires and increase the hazards associated with such fires.

Extinguishing.

If the fire has spread to any electrical equipment, the corresponding circuit must be de-energized. But regardless of whether the circuit is de-energized or not, when extinguishing a fire, only non-conductive substances should be used. electricity, such as fire extinguishing powder, carbon dioxide or freon. Persons responding to a Class E fire must always assume that the electrical circuit is energized. The use of water in any form is not permitted. In a room where electrical equipment is on fire, you should use breathing apparatus, since burning insulation releases toxic fumes.

FLAMMABLE LIQUIDS (CLASS 3)

flammable liquids and fire hazard parameters

In accordance with 3rd grade dangerous goods include:

• - flammable liquids (flammable liquids), those. liquids, mixtures of liquids, solutions or suspensions (for example, paint, drying oil, varnish, etc.) having a flash point of no more than 60 °C in a closed container or no more than 66 °C in an open container;
• - liquid desensitized explosives, those. Explosives that, in order to suppress their explosive properties, are dissolved in water or other liquid substances or in substances in the form of a suspension.
• - liquids, supplied for transportation at a temperature not less than their flash point, as well as substances transported or supplied for transportation in a liquid state at elevated temperatures and emitting flammable vapors at a temperature not exceeding the maximum temperature during their transportation.

Class 3 dangerous goods do not include:

• A) flammable liquids, having a flash point above 35 °C and non-flammable, i.e. those that have passed the appropriate combustion test and their ignition temperature is not less than 100 °C, or they represent aqueous solutions containing more than 90% water (by weight);
• b) viscous non-toxic non-corrosive solutions and homogeneous mixtures, which have a flash point of at least 23 °C, but not more than 60 °C, contain no more than 20% nitrocellulose (with a mass fraction of nitrogen not more than 12.6% per dry weight of nitrocellulose) and are transported in cargo units with a capacity of less than 450 liters:
  • - the height of the separated solvent layer is less than 3% of the total height of the sample;
  • - the outflow time from a vessel with an opening diameter of 6 mm is not less than 60 s or 40 s if the viscous substance contains no more than 60% of substances of class 3.

Mixtures of substances with a flash point below 23 °C containing more than 55% nitrocellulose (regardless of nitrogen content) or nitrocellulose with a nitrogen content of more than 12.6% (by weight of dry matter) should be classified in Class 1 or Division 4.1.

Dangerous goods of class 3 are not divided into subclasses.

Depending on the additional type hazards, dangerous goods of class 3 belong to the categories given in table. 4.1.

Table 4.1

Class 3 Dangerous Goods Classification Table

The group of dangerous goods of class 3 is determined depending on the degree of danger and the requirements for their packaging according to table. 4.2.

The degree of danger of flammable liquids is determined according to the indicators and criteria established in table. 4.3.

Viscous substances, such as paints, enamels, varnishes, drying oils, adhesives and polishes, with a flash point of less than 23 ° C, can be assigned a low degree of hazard (group 3).

Table 4.2

The degree of danger of the cargo and the packaging group of dangerous goods of class 3

It is known from practice that a significant number of fires of crude oils, light petroleum products and other flammable liquids begin with an explosion, as a result of which the roof of the tank is thrown off or partially destroyed and intense combustion of the surface of the fuel develops. The possibility of a fire in flammable liquids is determined by the temperature at which the vapors flash. The lower this flash point, the greater the fire hazard the liquid poses.

When assessing the fire hazard of substances, their ability to ignite, explode and burn upon contact with water, air oxygen and other substances, as well as the nature of interaction with water-foam extinguishing agents and flammability potential are determined. Therefore, the main parameters of fire danger are:

• - flammability group;
• - flash point;
• - ignition temperature;
• - lower and upper concentration limits of ignition of vapors in air;
• - the nature of the interaction of the burning substance with water-foam extinguishing agents;
• - temperature limits for ignition of vapors in air;
• - minimum fire extinguishing concentrations of volumetric extinguishing agents;
• - burnout rate.

Flammability group. Based on flammability, substances and materials are divided into non-flammable, low-flammable and combustible.

Flash point - this is the lowest temperature of a substance at which, under special test conditions, it emits flammable vapors or gases at such a speed that they can flare up in the air from an external ignition source; stable combustion substance does not occur.

The flash point is related to the boiling point of the liquid by the approximate relationship:

Ignition temperature - this is the most low temperature a substance (or its optimal mixture with air), in which, under special test conditions, the substance emits flammable vapors or gases at such a speed that, after they are ignited by an external source, independent flaming combustion of this substance occurs.

Self-ignition temperature - this is the lowest temperature of a substance (or its optimal mixture with air), when heated to which there is a sharp increase in the rate of the exothermic reaction, leading to the occurrence flaming combustion without external source ignition

Concentration limits of ignition of vapors in air. In the case of flammable liquids, it is not the liquids themselves that burn, but their vapors. The ignition region of a vapor, gas, suspension of a liquid or solid substance in the air is the region of concentration of a given substance, within which its mixtures with air or another oxidizer are capable of igniting from an ignition source with subsequent propagation of combustion throughout the mixture arbitrarily far from the ignition source. The limiting concentrations of the ignition region are called the upper and lower concentration limits of ignition of vapor, gas or suspension, respectively.

Temperature limits for ignition of vapors in air - These are the temperatures of a substance at which the concentrations of its vapors in the air, which are in equilibrium with the liquid or solid phase, are equal to the lower or upper concentration limit of ignition, respectively.

Knowing the temperature limits of explosion of vapors of a given liquid with air, it is possible at any time to determine the degree of fire hazard or to predict its occurrence when the temperature changes.

For example, A-95 gasoline has a temperature limit for the explosion of vapors with air from minus 36 to minus 7 ° C. This means that in the specified temperature range, explosions of its vapors located above the surface of the liquid in a closed container are possible in the presence of an ignition source. At a temperature lower than the lower temperature limit, an explosion does not occur, since the vapor pressure of the flammable liquid is insufficient, and at a temperature higher than the upper temperature limit, there will be insufficient relative oxygen content in a closed volume.

It should be taken into account that as the temperature rises, the pressure of the saturated vapors of flammable liquids increases very strongly, the total pressure in the containers sharply increases and thereby increases the risk of explosion and fire. Temperature limits of explosion of vapors of some liquids are given in table. 4.4.

Table 4.4

Explosion limits of some flammable liquids

Minimum fire extinguishing concentration for volumetric extinguishing of this substance is the lowest concentration of extinguishing gas or vapor in the air that provides almost complete instantaneous (under experimental conditions) extinguishing of the diffusion flame of a substance.

Burnout rate is the amount of fuel burned per unit time per unit combustion area. This speed characterizes the intensity of combustion of a substance under fire conditions. It must be known when determining the estimated duration of a fire in tanks.

Flash point and boiling point are used as criteria for the transport danger of flammable liquids.

Among dangerous goods of class 3 there are many highly dangerous toxic substances, work with which requires compliance with strict safety regulations. Many flammable liquids exhibit corrosive properties towards metals and other materials. The dangerous properties of flammable liquids in an emergency or when handled carelessly have an adverse effect on the environment. When tank cars derail, overturn and in other cases large quantities oil, petroleum products and other flammable liquids pollute and poison environment. Due to the high toxicity and other dangerous properties, the maximum permissible concentration of petroleum products in water is determined to be 0.05 mg/l, which corresponds to sanitary and hygienic requirements.

Let's look at the basics of processes combustion of flammable liquids and other materials, since these processes ensure the safe transportation and storage of flammable substances.