4.3. Classification of flammable liquids

In accordance with the international classification and GOST 19433-88, flammable liquids include flammable liquids with a flash point not exceeding 61 ° C when tested in a closed crucible.

Flammable liquids represent the 3rd class of dangerous goods and are divided into subclasses.

Subclass 3.1- Especially dangerous flammable liquids. These are flammable liquids with a flash point of minus 18°C ​​and below in a closed crucible. In addition to a low flash point, they can have other dangerous properties: high toxicity and explosiveness, toxicity and the ability to oxidize in air to form explosives, toxicity, caustic and corrosive properties, and others.

Typical representatives of highly hazardous flammable liquids are acetone, aviation gasoline B-70, isopentane, diethyl ether. A characteristic feature of these substances is the high saturated vapor pressure under normal storage and transportation conditions. Under normal conditions, and even more so in hot weather, inside vessels, tanks with such liquids, pressure can increase significantly, which increases the risk of explosion or fire. In addition, in case of violation of the tightness of the vessel and when overflowing (pumping) into other containers, the vapors of these liquids can spread without mixing with air and ignite at a considerable distance from the vessel, causing a fire. These features cause additional requirements for storage, loading, transportation and unloading of highly hazardous flammable liquids.

Subclass 3.2- Constantly dangerous flammable liquids. These are combustible liquids with a flash point from -17 to +23°C in a closed crucible. Typical representatives of this subclass are benzene, toluene, ethyl alcohol, dioxane, ethyl acetate. Their distinctive feature is the ability of vapors to form flammable mixtures with air already at room temperature and the presence under these conditions of an explosive atmosphere in the vapor phase in closed containers and rooms. In this regard, flammable liquids of subclass 3.2 are much more dangerous than liquids of subclass 3.1. In closed containers and rooms at room temperature and atmospheric pressure, vapor concentrations of subclass 3.1 liquids in the vapor phase usually exceed the upper flammable limit; the danger arises only when the temperature drops, for example, in the cold, or when vessels with such flammable liquids are depressurized.

Subclass 3.3- Hazardous at elevated temperatures flammable liquids . These are flammable liquids with a flash point from +23 to +61°C in a closed crucible. Typical representatives of this subclass are white spirit, lighting kerosene, chlorobenzene, solvent, turpentine. The concentrations at which the vapors of these liquids can ignite in air are only created at elevated temperatures, for example, when transporting from temperate regions to southern regions, or if the liquids are heated. At normal temperatures, flammable liquids of subclass 3.3 ignite only with direct exposure to an ignition source. So, kerosene in an open container at normal temperature cannot be ignited with a torch due to the low concentration of vapors above its surface. However, cloth drenched or soaked in kerosene is easily ignited by the flame of a match. This phenomenon can be explained by the large surface of the fibers from which evaporation occurs. As can be seen from the above examples, the danger of flammable liquids depends not only on their physical and chemical properties, but also on other factors. This circumstance must be taken into account when working with various combustible liquids.

Classification of flammable liquids by additional types of danger (categories) and by degree of danger (groups) is presented in Table. 4.2.

Table 4.2

Classification table of dangerous goods class 3 (flammable)

Viscous flammable liquids and solids diluted with flammable liquids can be classified as substances with a relatively low degree of danger if the following conditions are met:

When tested for peeling within 24 hours, no more than 3% of pure solvent peels off;

The mixture contains not more than 5% of substances of high hazard class 6 (toxic substances) or class 8 (caustic and corrosive substances) or not more than 5% of substances of high hazard class 3 (flammable liquids), which requires an additional hazard label;

The capacity of the container used does not exceed 30 liters.

The degree of danger of flammable liquids (group) is determined by the flash point, boiling point and criteria in accordance with Table. 4.3.

Table 4.3

Degree and criteria of danger of flammable liquids

4.4. Self-igniting liquids

There are combustible liquids that can oxidize in air at ordinary temperatures (16 ... 20 ° C) or upon contact and chemical interaction with other substances. Under certain conditions, the heat of the oxidation process can exceed the heat transfer from the oxidizing liquid to the external environment and self-heating occurs, leading to combustion. Liquids having an auto-ignition temperature below the usual flash point are called spontaneously igniting (self-igniting).

Liquids capable of spontaneous combustion require a special regime during storage and transportation and systematic monitoring. An example of such liquids is vegetable oils (linseed, walnut, cedar and others), turpentine, flammable under certain conditions. Some self-igniting systems are given in table. 4.4.

Table 4.4

Liquids capable of self-ignition on contact

From the above examples, we can conclude that self-ignition of liquids is a redox process in which the flammable liquid exhibits the properties of a reducing agent, and the contacting substance exhibits the properties of an oxidizing agent. It should be noted that oxidizing agents have a high oxidizing ability, and liquids, respectively, a large reducing ability.

4.5. Requirements for tare and packaging of flammable liquids

Class 3 liquids are packed in airtight shipping containers. Depending on the flash point, a number of flammable liquids are packed in consumer packaging, which is placed in the outer package.

The container for the transportation of flammable liquids must be manufactured and sealed so that, under normal conditions of transportation, it protects the contents from external sources of ignition.

Glass bottles up to 60 liters must be completely closed in a wooden or fiber drum, the cushioning material is located so as to prevent damage to the container and leakage of the contents. Glass containers with a capacity of up to 5 liters are packed in a wooden box with cushioning and absorbent material upside down. On the lid of the box should be the inscription "Up". Cardboard boxes used for packaging flammable liquids must be durable and waterproof, wooden crates - durable, with closely spaced planks (planks) to minimize the risk of puncture of consumer packaging.

The volume of containers and packages of flammable liquids are presented in Table. 4.5 and 4.6.

Table 4.5

Characteristics of the transport container

Table 4.6

Characteristics of packages when using consumer packaging

4.6. Requirements for the conditions of transportation of flammable liquids

General provisions. Joint transportation of flammable liquids with the following substances or groups of substances is prohibited:

Substances capable of forming explosive mixtures;

Compressed and liquefied gases;

spontaneously combustible substances;

Bromine, nitric and sulfuric acids, organic acids (acetic, chloroacetic, formic);

Potassium permanganate, chromates and bichromates, sodium peroxides, benzoyl, etc.

Requirements for the transportation of flammable liquids in covered wagons and containers. Class 3 goods are presented for transportation in places of non-public use. It is allowed, as an exception, to receive goods of subclass 3.1 and 3.2 at public places only in the direct version of the car-wagon, and goods of subclass 3.3 - through railway warehouses if the station has special fire-resistant or separate rooms in common warehouses. The consignor is obliged to put danger signs on each cargo piece.

Cargoes of subclasses 3.1 and 3.2 are allowed to be transported only in covered wagons. Cargoes of subclass 3.1 are transported only by carload shipments. For these goods, the consignor is obliged to place at least five pieces of empty packaging in the wagon in case of damage to individual pieces. Subclass 3.3 goods in glass containers, metal and plastic cans and cans, packed in wooden or cardboard boxes, are allowed to be transported in universal containers.

Flammable liquids are accepted for transportation, as a rule, in packages on universal or specialized pallets. Stacking of pallets with flammable liquids in covered wagons should be carried out in continuous rows, excluding the mutual movement of packages, evenly over the entire area of ​​the wagon, in several tiers in height until the full use of the carrying capacity and capacity of the wagon. When loading without pallets between tiers, it is obligatory to lay flooring from boards with a thickness of at least 20 mm. In each tier, cargo items are stacked tightly to each other without leaving free space.

Requirements for the transportation of flammable liquids in tanks. Class 3 cargoes are transported in special tanks of the Ministry of Railways and in special tanks of the consignor (consignee). Some class 3 goods are transported in tanks of the general fleet of the Ministry of Railways. Special and dedicated tanks must meet the established requirements and have the inscription "Flammable". For goods of subclass 3.1, a red stripe is applied to the tank, for other goods of this class - a yellow stripe.

Acetic aldehyde and ethyl ether are transported in special consignor's tanks designed for the required pressure and having shadow protection. Ethyl ether is also allowed to be transported in tanks protected by a covered body. On such tanks, the consignor is obliged to put the necessary danger signs and an inscription corresponding to the cargo being transported.

Benzene, dimethylaniline, dichloroethane, pyridine bases are highly toxic substances and must be transported in tanks dedicated to the transport of specific products. Permanent danger signs are applied to such tanks, and instead of the warning inscription "Flammable" - the name of the cargo for which this tank is allocated. For example, benzene tanks should be labeled "Benzene".

The filling factors of tanks intended for the transportation of flammable liquids should not exceed the established values.

The most dangerous goods of class 3, which are transported under special conditions, are carbon disulfide, methanol, leaded gasoline.

Over the past decade, the tank farm for storing oil and oil products has increased, a significant number of underground reinforced concrete tanks with a volume of 10, 30 and 50 thousand m 3, metal surface tanks with a volume of 10 and 20 thousand m 3 have been built, tank designs with pontoons and floating roofs with a volume of 50 thousand m 3 , in the Tyumen region, reservoirs with a volume of 50 thousand m3 were built on a pile foundation.

The means and tactics of extinguishing fires of oil and oil products are being developed and improved.

Tank farms are divided into 2 groups.

The first one is raw stocks of oil refineries and petrochemical plants; bases of oil and oil products. This group is divided into 3 categories depending on the capacity of the park, thousand m 3 .

St. 100....................................... 1

20-100.................................... 2

Up to 20...................................... 3

The second group is tank farms, which are part of industrial enterprises, the volume of which is 4000 (2000) for underground tanks with flammable liquids, 20,000 (10,000) m 3 for liquid liquids. Numbers in parentheses are for above ground tanks.

Classification of tanks.By material: metal, reinforced concrete. By location: ground and underground. By form: cylindrical, vertical, cylindrical horizontal, spherical, rectangular. Tank pressure: at a pressure equal to atmospheric, the tanks are equipped with breathing equipment, at a pressure higher than atmospheric, i.e. 0.5 MPa, with safety valves.

Reservoirs in parks can be placed in groups or separately.

For DVZh total capacity

a group of tanks with a floating roof or pontoons is no more than 120, and with fixed roofs - up to 80 thousand m 3.

For GZh, the capacity of a group of tanks does not exceed 120,000 m 3 .

Gaps between ground groups - 40 m, underground - 15 m. Driveways 3.5 m wide with hard surface.

Fire water supply must ensure the flow of water for cooling ground tanks (except for tanks with a floating roof) for the entire perimeter in accordance with SNiP.

The supply of water for extinguishing should be 6 hours for ground tanks and 3 hours for underground ones.

Sewerage in the embankment is calculated for the total consumption: bottom water, atmospheric water and 50% of the calculated consumption for cooling tanks.

Features of the development of fires. Fires in tanks usually start with an explosion of a vapor-air mixture in the gas space of the tank and a roof blow-off or a flash of a "rich" mixture without roof blow-off, but with a violation of the integrity of its individual places.

The strength of the explosion, as a rule, is greater in those tanks where there is a large gas space filled with a mixture of oil vapor with air (low liquid level).

Depending on the strength of the explosion in a vertical metal tank, the situation can be observed:

the roof is completely torn off, it is thrown to the side at a distance of 20-30 m. The liquid burns over the entire area of ​​the tank;

the roof rises somewhat, comes off completely or partially, then lingers in a semi-submerged state in a burning liquid (Fig. 12.11);

the roof is deformed and forms small gaps in the places of attachment to the tank wall, as well as in welded

seams of the roof itself. In this case, pairs of flammable liquids burn above the formed slots. In case of fire in reinforced concrete buried (underground) tanks, the roof is destroyed by an explosion, in which large holes are formed, then during the fire, the coating may collapse over the entire area of ​​the tank due to high temperature and the impossibility of cooling their supporting structures.

In cylindrical horizontal, spherical tanks, the bottom is most often destroyed during an explosion, as a result of which the liquid spills over a large area, creating a threat to neighboring tanks and structures.

The condition of the tank and its equipment after a fire occurs determines the method of extinguishing and

Extinguishing fires of flammable and combustible liquids is based on the analysis of all options for their development. Fires that occur in tanks are longer, therefore they require a large amount of funds and forces to eliminate.

Storage tanks for flammable liquids and combustible liquids

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

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

The process of developing a fire in a tank

Extinguishing fires in tank farms for storing flammable liquids and combustible liquids depends on the complexity of the ignition 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 the GZh and flammable liquids, as well as operating modes and climatic conditions around the tank. Exploding, the gas-air mixture rushes up at high speed, often tearing off the roof of the container, after which ignition begins over the entire surface of the stored combustible liquid.

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

When storing GZH and HFL, for example, in reinforced concrete tanks, a part of it is destroyed during an explosion, and combustion begins precisely in this area, which over the next 30 minutes leads to the complete destruction of the container and the spread of fire. The remaining types of containers, in the absence of cooling from the outside, deform within 15 minutes, provoking a spill of flammable liquids and the spread of fire.

Foam fire fighting

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

Foam extinguishing

Extinguishing flammable liquids with a foam solution of various ratios depends on where the combustion occurs:

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

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

When applying fire extinguishing foam, the flame center should observe an intensity of 0.15 l / s.

Foam fire extinguishing is allowed by three methods:

• delivery of the foaming agent using a foam lifter and other similar equipment;
• delivery of foam to the surface of burning flammable liquids and combustible liquids using monitors;
• delivery of foam by subsurface quenching.

Water fire extinguishing

If it is not possible to organize the extinguishing of fires of flammable liquids with the help of foam, it is allowed to use sprayed water, which helps to cool the combustible contents to a temperature at which it cannot flare up.

In this case, the rate of supply of the aqueous solution must be at least 0.2 l/s.

Powder extinguishing

Extinguishing fires in tank farms for storage of flammable liquids with the help of powder is suitable for those situations where burning occurs in the area of ​​\u200b\u200bgate 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, therefore, repeated extinguishing of the flammable liquid may be required.

Powder extinguishing - only for small fires and quick extinguishing

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

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

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

Tank fire fighting plan

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

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

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

Throughout the work, the tasks of the manager also include providing all available forces and means for cooling flammable liquids and combustible liquids in tanks, as well as choosing the optimal method of fighting fire.

When the main forces are thrown to work with a burning tank, 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 place of work.

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

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

How tanks are cooled during fire fighting

Extinguishing fires of flammable liquids and combustible liquids 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 neighboring tanks, there is also a requirement for mandatory cooling, but only along the entire length of the semicircle of the tank on the side that faces the combustion zone. In some cases, it is allowed not to carry out the procedure for cooling adjacent containers if there is no threat of flame transfer. The water supply for cooling purposes must be at least 1.2 l/s.

To extinguish tanks with gaseous 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 output, but also have an irrigation mode for a burning object.

The sequence of work with neighboring undamaged tanks is such that those located on the leeward side of the fire are the first to be protected and cooled.

The duration of work is determined until the flame is completely eliminated, and the temperature level inside the tank is not normal.

Hazardous zones during fire in tank farms

Extinguishing fires of flammable liquids and combustible liquids should also be carried out taking into account hazardous factors and zones that can reduce the effectiveness of fire extinguishing measures:

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

Extinguishing a real fire of spilling flammable liquids in a large area Angarsk 2014:

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FLAMMABLE LIQUIDS (CLASS 3)

Flammable liquid and fire hazard parameters

In accordance with the 3rd class of 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 not more than 60 ° C in a closed vessel or not more than 66 ° C in an open vessel;
• - liquid desensitized explosives, those. Explosives which, in order to suppress their explosive properties, are dissolved in water or other liquid substances, or in substances in the form of a suspension.
• - liquid, submitted for carriage at a temperature not less than their flash point, as well as substances transported or supplied for transport 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 not supporting combustion, i.e. those that have passed the appropriate combustion test and their flash point is not less than 100 °C, or they are aqueous solutions containing more than 90% water (by mass);
• 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 not more than 20% nitrocellulose (with a mass fraction of nitrogen not more than 12.6% on a dry basis 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 time of outflow from a vessel with a hole 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 more than 12.6% nitrogen (dry weight) must be classified in Class 1 or Division 4.1.

Class 3 dangerous goods are not divided into subclasses.

Depending on the additional type of danger, dangerous goods of class 3 are classified into the categories given in Table. 4.1.

Table 4.1

Classification table of dangerous goods class 3

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 by 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, may be assigned a low degree of danger (group 3).

Table 4.2

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

It is known from practice that a significant number of fires of crude oils, light oil products and other flammable liquids begin with an explosion, as a result of which the roof of the tank is dropped or partially destroyed and intensive combustion of the fuel surface 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 of the liquid.

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

• - combustibility 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 of ignition of vapors in air;
• - minimum fire extinguishing concentrations of volumetric extinguishing agents;
• - burnout rate.

Flammability group. By combustibility, substances and materials are divided into non-combustible, slow-burning 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 rate that they can flare up in the air from an extraneous source of ignition; stable combustion of the substance does not occur in this case.

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

Ignition temperature - this is the lowest temperature of a substance (or its optimal mixture with air), at which, under special test conditions, the substance emits flammable vapors or gases at such a rate that, after their ignition by an external source, an 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 of fiery combustion without an external source of 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 area of ​​ignition of a vapor, gas, suspension of a liquid or solid substance in air is the area of ​​concentrations of a given substance, within which mixtures of it with air or another oxidizing agent are capable of igniting from an ignition source with subsequent propagation of combustion through the mixture arbitrarily far from the source of ignition. The boundary concentrations of the ignition region are called, respectively, the upper and lower concentration limits for the ignition of vapor, gas or suspension.

Temperature limits of ignition of vapors in air - these are the temperatures of a substance at which the concentrations of its vapors in 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 the explosion of vapors of a given liquid with air, it is possible at any time to determine the degree of fire danger or to foresee its onset when the temperature changes.

For example, gasoline A-95 has temperature limits of explosiveness of vapors with air from minus 36 to minus 7 °C. This means that in the specified temperature range, explosions of its vapors are possible, located above the surface of the liquid in a closed container 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 an insufficient relative oxygen content in the closed volume.

It should be borne in mind that with an increase in temperature, the pressure of saturated vapors of flammable liquids increases very much, the total pressure in the containers increases sharply, and thereby the risk of explosion and fire increases. The temperature limits of the explosive vapors of some liquids are given in Table. 4.4.

Table 4.4

Explosive limits of some flammable liquids

The minimum fire extinguishing concentration for volumetric extinguishing of a given substance called the lowest concentration of extinguishing gas or vapor in the air, providing almost complete instantaneous (under experimental conditions) extinguishing the diffusion flame of a substance.

Burnout rate called the amount of fuel burned per unit time per unit area of ​​combustion. This rate characterizes the intensity of combustion of a substance in a fire. 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 hazard of flammable liquids.

Class 3 dangerous goods include many highly hazardous toxic substances that require strict safety regulations to be followed. Many flammable liquids exhibit corrosive properties in relation to metals and other materials. Hazardous properties of flammable liquids in an emergency or in case of careless work with them adversely affect the environment. When tanks derail, overturn and in other cases, large quantities of oil, oil products and other flammable liquids pollute and poison the environment. In view of the high toxicity and other dangerous properties, the MPC of oil products in water is set at 0.05 mg/l, which complies with sanitary and hygienic requirements.

Let us consider the basics of the combustion processes of flammable liquids and other materials, since these processes determine the safe transportation and storage of combustible substances.

(PPB 01-03, items 514-525)

514. Embankments around tanks, as well as crossings through them, must be in good condition. Areas within the embankment should be leveled and covered with sand.

operation of leaky equipment and valves;

operation of tanks with distortions and cracks, as well as faulty equipment, instrumentation, supply pipelines and stationary fire-fighting devices;

the presence of trees and shrubs in the square of embankments;

installation of containers on combustible or slow-burning bases;

overflow of tanks and cisterns;

sampling from tanks during the discharge or loading of oil and oil products;

draining and loading of oil and oil products during a thunderstorm.

516. Breathing valves and flame arresters must be checked in accordance with the technical documentation of manufacturers.

When inspecting breathing fittings, it is necessary to clean the valves and screens from ice. Warming them should be done only in fireproof ways.

517. Sampling and level measurement must be carried out using equipment that excludes sparking.

518. Storage in a container of liquids with a flash point above 120 degrees. C in an amount of up to 60 m3 is allowed in underground storages made of combustible materials, provided that the floor is made of non-combustible materials and the coating is backfilled with a layer of compacted earth with a thickness of at least 0.2 m.

519. Joint storage of flammable liquids and combustible liquids in containers in the same room is allowed if their total amount does not exceed 200 m3.

520. In storage facilities for manual stacking, barrels with flammable liquids and combustible liquids must be installed on the floor in no more than 2 rows, for mechanized stacking of barrels with combustible liquids - no more than 5, and flammable liquids - no more than 3.

The width of the stack should be no more than 2 barrels. The width of the main aisles for transporting drums should be at least 1.8 m, and between stacks - at least 1 m.

521. It is allowed to store liquids only in serviceable containers. Spilled liquid must be cleaned up immediately.

522. Open areas for the storage of petroleum products in containers must be fenced with an earth rampart or non-combustible solid wall at least 0.5 m high with ramps for access to the sites.

The sites should rise 0.2 m above the adjacent territory and be surrounded by a sewage ditch.

523. Within one bunded area, it is allowed to place no more than 4 stacks of barrels measuring 25 x 15 m with gaps between the stacks of at least 10 m, and between the stack and the shaft (wall) - at least 5 m.

Gaps between stacks of two adjacent platforms should be at least 20 m.

524. Sheds made of non-combustible materials are allowed above the sites.

525. It is not allowed to spill oil products, as well as store packaging material and containers directly in storage facilities and on bunded sites.

7.3.11. flammable liquid(hereinafter LVZH) - a liquid capable of burning independently after the ignition source is removed and having a flash point not higher than 61 ° C.

Flammable liquids are classified as explosive, in which the flash point does not exceed 61 ° C, and the vapor pressure at a temperature of 20 ° C is less than 100 kPa (about 1 atm).