When receiving substances and materials, application, storage, transportation, processing and disposal.

To establish fire safety requirements for the construction of buildings, structures and fire protection systems, the classification of building materials for fire hazard is used.

Indicators of fire and explosion hazard and fire hazard of substances and materials

The list of indicators necessary to assess fire and explosion hazard and fire hazard of substances and materials depending on their aggregate state is given in Table 1 of the Appendix to Federal Law FZ-123 ("Technical Regulations on Fire Safety").

Methods for determining the fire and explosion hazard and fire hazard of substances and materials are established by fire safety regulations.

Indicators of fire and explosion hazard and fire hazard of substances and materials are used to establish requirements for the use of substances and materials and calculate fire risk.

List of indicators necessary for assessing the fire hazard of substances and materials depending on their aggregate state

Indicator of fire hazard	Substances and materials in a different aggregate state			Dusts
Indicator of fire hazard	gaseous	liquid	solid	Dusts
, millimeter	+	+	-	+
The release of toxic combustion products from a unit mass of fuel, kilogram per kilogram	-	+	+	-
Flammability group	-	-	+	-
Flammability group	+	+	+	+
Flame propagation group	-	-	+	-
Smoke generation factor, square meter per kilogram	-	+	+	-
Flame Emissivity	+	+	+	+
Fire and explosion hazard index, Pascal per meter per second	-	-	-	+
Flame spreading index	-	-	+	-
Oxygen index, volumetric percent	-	-	+	-
Concentration limits of flame propagation (ignition) in gases and vapors, volumetric percentages, dusts, kilogram per cubic meter	+	+	-	+
Concentration limit of diffusion combustion of gas mixtures in air, volumetric percentages	+	+	-	-
The critical surface density of the heat flux, Watt per square meter	-	+	+	-
The linear velocity of flame propagation, meter per second	-	-	+	-
The maximum velocity of flame propagation along the surface of the combustible liquid, meter per second	-	+	-	-
The maximum explosion pressure, Pascal	+	+	-	+
The minimum phlegmatizing concentration of gaseous phlegmatizer, volumetric percentages	+	+	-	+
The minimum energy of ignition, Joule	+	+	-	+
The minimum explosive oxygen content, volumetric percentages	+	+	-	+
The lowest working heat of combustion, kilojoule per kilogram	+	+	+	-
Normal flame propagation velocity, meter per second	+	+	-	-
The toxicity index of combustion products, grams per cubic meter	+	+	+	+
Consumption of oxygen per unit mass of fuel, kilogram per kilogram	-	+	+	-
The limiting rate of disruption of the diffusion flare, meter per second	+	+	-	-
The rate of buildup of explosion pressure, megaPascal per second	+	+	-	+
The ability to burn when interacting with water, oxygen and other substances	+	+	+	+
The ability to ignite under adiabatic compression	+	+	-	-
The ability to spontaneous combustion	-	-	+	+
The ability to exothermic decomposition	+	+	+	+
, degree Celsius	-	+	+	+
, degree Celsius	-	+	-	-
, degree Celsius	+	+	+	+
, degree Celsius	-	-	+	+
(ignition), degree Celsius	-	+	-	-
, kilogram per second per square meter	-	+	+	-
, Joule per kilogram	+	+	+	+

Classification of substances and materials ( except for building, textile and tanning materials) for fire hazard

Classification of substances and materials for fire hazard is based on their properties and the ability to form dangerous hazards of fire or explosion.

On combustibility, substances and materials are divided into the following groups:
1) incombustible - substances and materials that are unable to burn in the air. Non-combustible substances can be fire and explosive (for example, oxidants or substances that release combustible products when interacting with water, oxygen or with each other);
2) hard-burning - substances and materials that are capable of burning in the air when exposed to the source of ignition, but unable to burn themselves after its removal;
3) flammable - substances and materials capable of spontaneous combustion, as well as ignite under the influence of the source of ignition and burn themselves after its removal.

Methods of testing for the flammability of substances and materials are established by regulatory documents on fire safety.

Classification of construction, textile and tanning materials for fire hazard

Classification of building, textile and tanning materials for fire hazard is based on their properties and the ability to form dangerous fire factors.

The fire hazard of construction, textile and leather materials is characterized by the following properties:
1) flammability;
2) flammability;
3) flame propagation ability over the surface;
4) smoke-forming capacity;
5) toxicity of combustion products.

Speed of flame propagation over the surface

On the speed of flame propagation over the surface, combustible building materials (including floor carpeting), depending on the critical surface heat flux density, are divided into the following groups:

1) nonproliferation (FP1), having a critical surface heat flux density greater than 11 kilowatts per square meter;

2) weak-spreading (FP2), having a critical surface heat flux density of at least 8, but not more than 11 kilowatts per square meter;

3) moderately spreading (IS3), having a value of critical surface heat flux density not less than 5, but not more than 8 kilowatts per square meter;

4) highly propagating (FP4), having a critical surface heat flux density less than 5 kilowatts per square meter.

Smoke generating capacity

According to the smoke-forming ability, combustible building materials are divided into the following groups depending on the value of the smoke generation coefficient:

1) with a small smoke-forming ability (D1), having a smoke generation coefficient of less than 50 square meters per kilogram;

2) with a moderate smoke-forming ability (D2), having a smoke generation coefficient of at least 50, but not more than 500 square meters per kilogram;

3) with a high smoke-forming ability (D3), having a smoke production ratio of more than 500 square meters per kilogram ..

Toxicity

On the toxicity of combustion products, combustible building materials are divided into the following groups in accordance with table 2 Annex to the Federal Law No. 123-FZ:

1) low-risk (T1);
2) moderately dangerous (T2);
3) highly dangerous (T3);
4) extremely dangerous (T4).

Classification of combustible building materials by the value of the toxicity index of combustion products

Hazard Class	The toxicity index of combustion products in relation to the exposure time
Hazard Class	5 minutes	15 minutes	30 minutes	60 minutes
Low-risk	more than 210	more than 150	more than 120	more than 90
Moderately hazardous	more than 70, but not more than 210	more than 50, but not more than 150	more than 40, but not more than 120	more than 30, but not more than 90
Highly dangerous	more than 25, but not more than 70	more than 17, but not more than 50	more than 13, but not more than 40	more than 10, but not more than 30
Extremely dangerous	not more than 25	not more than 17	not more than 13	not more than 10

Classification of selected types of substances and materials

For floor carpeting, the flammability group is not determined.

Textile and tanning materials for flammability are divided into flammable and hardly flammable. Fabric (non-woven fabric) is classified as flammable material if the following conditions are met during testing:

1) the flame burning time of any of the samples tested during ignition from the surface is more than 5 seconds;

2) any of the samples tested when ignited from the surface, burns to one of its edges;

3) cotton wool lights up under any of the tested samples;

4) the surface flash of any of the samples extends more than 100 millimeters from the point of ignition from the surface or edge;

5) the average length of the char section of any of the samples tested when exposed to a flame from the surface or the edge is more than 150 millimeters.

For the classification of building, textile and leather materials, the value of the flame propagation index (I), a conditional, dimensionless index characterizing the ability of materials or substances to ignite, spread the flame over the surface and release heat should be used. By spreading the flame materials are divided into the following groups:

1) do not spread the flame over the surface, having a flame propagation index of 0;

2) slowly spreading the flame over the surface, having a flame propagation index of not more than 20;

3) quickly spreading the flame over the surface, having a flame propagation index of more than 20.

Test methods for determining classification indicators of fire hazard of construction, textile and tanning materials are established by fire safety regulations

To protect the respiratory organs from dust and aerosols, anti-dust masks and respirators are used. If harmful gases are present in the air and the vapors use universal or gas-mask respirators and gas masks. Dust mask respirators protect against aerosols at a concentration of up to 200 MPC, and universal and respiratory respirators - at a concentration of vapors and gases up to 15 MPC. . The main filter elements in respirators are 2-3 layers of gauze (respirator "petal"), microporous and fine fiber filters (respirators F-62Sh, U-2K) are used to protect against fine dust with fibrogenic action.

In gas masks, the polluted air is filtered through a layer of activated carbon. To selectively absorb certain types of toxic gases and vapors, additional nozzles are used. The advantages of personal protective equipment are freedom of movement during work, low weight and compactness. Lack of filter media - limited shelf life, difficulty breathing due to filter resistance, short operating time due to filter contamination.

Insulating PPE (pneumatic suit, pneumatic helmet) are used in works when filtering means do not provide the necessary protection of respiratory organs. They can be autonomous and hose, i.e. having their own air supply or air supply through hoses. The use of isolating PPE is associated with inconveniences: limitation of the survey, limitation of work and movement. In cases where the workplace is constant, these inconveniences are eliminated by the use of protective booths equipped with an air conditioning system and protection systems from harmful radiations and energy fields.

Fire-hazardous properties of materials.

Fire-hazardous properties of materials are characterized by their propensity to ignite. On the flammability of building structures are divided into fireproof, difficult to burn and combustible.

Diffusible materials continue to burn or smolder only if there is a source of fire. These include mineral wool plates on bituminous binder, felt impregnated with clay mortar.

Burnt materials - burn after removing the source of fire.

Fire resistance - the ability of a structure to maintain a supporting or enclosing function when exposed to fire.

The fire resistance limit is the time from the onset of the fire to the occurrence of cracks through which the flame can spread to adjacent rooms.

All buildings and structures, depending on the combustibility of materials and the fire resistance of structures are divided into 5 degrees:

In 1 degree of fire resistance all structural elements are fireproof with a fire resistance limit of 0.5 - 2.5 hours.

In 2 degrees - all structural elements are also fireproof, but with a lower fire resistance (0.25 -2.0 h).

In 3 degrees - the building is made of non-combustible and difficult to burn materials.

In 4 degrees - buildings from difficult combustible materials.

In the 5th degree - built from combustible materials.

All the production of the fire hazard of the technological process are divided into 6 categories (A, B, C, D, D, and E). The most dangerous category is A, the least is D.

Category E - Explosive production, which uses substances that can explode by interacting with water, air oxygen and explosive dust, which can explode without subsequent combustion.

The main causes of fires.

Uncontrolled combustion, causing material damage, is called a fire. If burning does not cause damage, it is called sunbathing. Fire le1-che warn than put out.

The main causes of fires in agricultural sites are:

1. Non-compliance with fire safety rules, especially the use of open fire, during welding and smoking.

2. Incorrect installation and operation of electrical equipment, lighting devices, resulting in a short circuit

3. Violation of the operating rules for heating and heating systems.

4. Self-ignition of hay, straw, sawdust, peat, coal due to violation of storage and storage rules.

5. Errors in the layout of buildings, structures and warehouses (ignoring the wind rose, non-compliance with fire breaks in the building).

Providing fire safety in the workplace

Fire safety is provided by appropriate design and planning solutions for the production premises. The fire plan provides for the presence of fire breaks between buildings and structures, which in the event of a fire prevent the spread of fire from one building to another, and also enable unhindered operation of fire equipment, evacuate people, animals and material values.

Fire breaks between production and cattle-breeding buildings are accepted:

1. Between buildings 3 degrees of fire resistance -12 m,

2. Between buildings 3 and 4 of the degree of fire resistance - 15 m,

3. Between buildings 4 and 5 of the degree of fire resistance - 18 m.

The distance from the building of 3 degree of fire resistance to open storage of hay, straw should be not less than 39 m, and from buildings 4 and 5 of fire resistance - not less than 48 m. Distance from buildings and structures of enterprises (regardless of the degree of their fire resistance) to the borders of the forest of conifers rocks should be not less than 50 m, deciduous - not less than 20 m.

On the fire breaks construction of auxiliary facilities or temporary storage of materials is not allowed.

To prevent the spread of fire, a fire-extinguishing wall-firewall device is used. It rests directly on the foundation and should rise above the burnt roof by at least 0.6 m, and above the fireproof roof - by 0.3 m.

If it is not possible to comply with firebreaks, the firewall (an external barrier) or the construction of such a wall inside the building is also necessary at the end of the tallest building, with the purpose of dividing it into separate sections (an internal barrier).

An important fireproof requirement when designing agricultural facilities is the justified area of the building. The area of buildings of 3 degrees of fire resistance should not exceed 3000 m2, 4 degrees - 2000 m2, 5 degrees - 1200 m. The area of buildings and structures of 1 and 2 degrees of fire resistance is not limited.

In cattle-breeding premises, at least 2 exits for evacuation of animals must be provided, and in rooms divided into sections there must be at least 1 outlet from each section. All the doors on the evacuation routes must open towards the exit. According to the standard, the width of the entrance gate for barns and stables should be at least 2 m, for ovcharins - 2.5 m, for pigs - 1.5 m. The width of the passage in the premises for animals must be at least 1.5 m.

In all premises it is forbidden to clutter evacuation routes, attics, spaces under stairs and at emergency exits. Do not smoke and use open flame (for example, when heating frozen pipes).

Providing fire safety is one of the key tasks in the construction and operation of modern high-rise buildings, large business centers and shopping and entertainment complexes. The specifics of such buildings - the large extent of evacuation routes - dictate the increased requirements for fire safety of the building structures and materials used. And only when these requirements are observed on a par with the solution of other technical and economic problems, the building is properly designed.

According to the Federal Law of the Russian Federation of July 22, 2008, No. 123-FZ "Technical Regulations on Fire Safety Requirements", the choice of building materials directly depends on the functional purpose of the building or premises.

Classification of building materials is often carried out based on the scope of the products. By this criterion, it is divided into constructive, insulating and finishing, as well as structural-insulating and constructive-finishing solutions.

From the standpoint of fire safety, the optimal classification is proposed in Article 13 of the "Technical Regulations", which divides building materials into two types: combustible and non-combustible. In turn, combustible materials are divided into 4 groups - low-combustible (G1), moderately combustible (G2), normally combustible (G3) and, finally, highly flammable (G4).

In addition, they are evaluated by criteria such as flammability, the ability to spread the flame over the surface, smoke-forming ability and toxicity. Set of these indicators allows you to assign a specific class of fire hazard class: from KM0 - for non-combustible materials to KM1-KM5 - for combustible.

Natural properties of materials

The key factor that determines the fire hazard of materials is the raw materials from which they are made. In this dependence, they can be divided into three large groups: inorganic, organic and mixed. Let us consider in more detail the properties of each of them. Let's start with mineral materials that belong to a group of inorganic and, along with metal structures, serve to create a rigid framework - the foundation of modern buildings.

The most common mineral building materials are natural stone, concrete, brick, ceramics, asbestos cement, glass, etc. They belong to non-combustible (NG), but even with a small addition of polymeric or organic substances - no more than 5-10% of the mass - their properties change. The fire danger increases, and from NG they become a category that is difficult to burn.

In recent years, widespread use has been made of products based on polymers belonging to inorganic materials and being combustible. At the same time, the membership of a particular material to the flammability group depends on the volume and chemical structure of the polymer. There are two main types of polymer compounds. These are thermosets that form a coke layer when heated, which consists of non-flammable substances and protects the material from the effects of high temperatures, preventing combustion. Another type is thermoplastics (they melt without creating a heat-shielding layer).

Regardless of the type, polymer building materials can not be converted to non-combustible, but it is possible to reduce their fire hazard. For this, fire retardants are used - various substances that contribute to an increase in fire resistance. Fire retardants for polymeric materials can be divided into three large groups.

The first includes substances that carry out chemical interaction with the polymer. These flame retardants are used primarily for thermosetting plastics, without deteriorating their physicochemical properties. The second group of fire retardants - intumescent additives - under the influence of a flame forms a foamed cellular coke layer on the surface of the material, which prevents combustion. And, finally, the third group are substances that mechanically mix with the polymer. They are used to reduce the flammability of both thermoplastics, thermosets and elastomers.

Of all the organic materials, wood and its products - wood chipboards, wood fiber boards, plywood, etc. - were the most widely used in the construction of modern buildings. All organic materials belong to the group of combustible, and their fire hazard increases with the addition of various polymers. For example, paint and varnish materials not only increase the combustibility, but also contribute to a more rapid spread of the flame over the surface, increase smoke formation and toxicity. In this case, other toxic substances are added to CO (carbon monoxide), the main combustion product of organic materials.

To reduce the fire hazard of organic building materials, as in the case of polymeric substances, they are treated with flame retardants.

Inflicted on the surface, under the influence of high temperatures, fire retardants can turn into foam or release a non-combustible gas. In both cases, they impede the access of oxygen, preventing the burning of wood and the spread of flame. Effective flame retardants are substances containing diammonium phosphate, as well as a mixture of sodium phosphate and ammonium sulfate.

With regard to mixed materials, they consist of organic and inorganic raw materials. As a rule, construction products of this type do not stand out in a separate category, but belong to one of the previous groups, depending on which raw materials prevail. For example, fiberboard, consisting of wood fibers and cement, is considered organic, and bitumen - inorganic. Most often, the mixed type belongs to the group of combustible products.

Increased requirements for fire safety of large shopping and entertainment and office centers, as well as high-rise buildings dictate the need to develop a complex of fire-fighting measures. One of the most important is the advantageous use of non-flammable and low-combustible materials. In particular, this applies to the load-bearing and enclosing structures of the building, the roof, as well as materials for finishing the evacuation routes.

According to the classification of NPB 244-97, the required certification in the field of fire safety is subject to finishing, facing, roofing, waterproofing and heat insulation materials, as well as floor coverings. Consider these categories for fire hazard.

Finishing and facing materials

There are many finishing and facing materials, among which there are polystyrene tiles, PVC and DSP panels, wallpaper, films, ceramic tiles, fiberglass, etc. Most products of this type are combustible. In rooms with a large population of people, as well as in buildings where evacuation is difficult due to the large area and number of storeys, the finishing materials can create an additional threat to life and health of people, causing smoke, releasing toxic products of combustion and contributing to the rapid spread of flames. Therefore, it is necessary to choose materials not lower than class KM2.

Depending on the surface on which they are applied, the finishing materials may have different properties. For example, in combination with combustible substances, conventional wallpaper can prove to be highly flammable, and applied to a non-flammable base - as low-burning. Therefore, when choosing finishing and facing materials, one should be guided not only by data on their fire hazard, but also by the properties of the bases.

For the finishing of premises with a large number of people and evacuation routes, the use of organic products, in particular MDF panels, which are most often referred to as G3 and G4 groups, is unacceptable. To finish the walls and ceilings in the trading halls, you can not use materials with a higher fire hazard than the class KM2.

Paper-based wallpapers are not included in the list of products subject to compulsory certification, and they can be used as a finishing material for premises with increased requirements for fire safety, taking into account that the base will be incombustible.

As a replacement, MDF panels use drywall with an external coating of decorative film. Thanks to the gypsum base, gypsum board belongs to non-combustible materials, and the decorative film based on polymers transfers it to group G1, which allows it to be used for finishing almost any functional purpose, including vestibules. Today, drywall is widely used for the construction of partitions - independent building structures. This must be taken into account when determining their class of fire hazard.

Floor coverings

The flammability of floor coverings is subject to less stringent requirements than to finishing and facing materials. The reason is that in case of fire the floor is in the zone of the lowest temperature in comparison with the walls and ceiling. At the same time, for materials serving as a floor covering, an important role is played by such an indicator as the spread of a flame over a surface (RP).

Due to the convenience of installation and high performance characteristics, wide use in the quality of floor coverings in corridors, foyers, halls and foyers of buildings has received "linoleum" - various types of roll polymer coatings. Practically all materials of this type belong to the group of highly combustible (G4) and have a high smoke production rate. Even at a temperature of 300 ° C they support combustion, and when heated above 450-600 ° C they ignite. In addition, the products of burning linoleum include toxic substances - carbon dioxide, CO and hydrogen chloride.

Therefore, they should not be used as a floor covering for corridors and halls where, according to the requirements, materials not lower than KM3 should be used, not to mention vestibules and staircases for which more stringent requirements apply. The same can be said about the laminate, which consists of organic and polymeric materials and, regardless of the type, refers to the number of highly flammable - unsuitable for evacuation routes.

The most favorable, in terms of fire safety, are ceramic tiles and granite. They belong to the group KM0 and are not included in the list of materials subject to certification in the field of fire safety. Such products are suitable for premises of any functional purpose. In addition, semi-rigid tiles made of polyvinyl chloride with a large amount of mineral filler (group KM1) can be used as flooring in corridors and halls.

Roofing and waterproofing materials

Usually the fire hazard of roofing materials is indicated in the certificates in the form of a group of flammability. The least danger is the roofing of metal and clay, and the largest - materials based on bitumen, rubbers, rubber-bitumen products and thermoplastic polymers. Although they give the roofing materials high performance characteristics - water and vapor tightness, frost resistance, elasticity, resistance to negative atmospheric influences and cracking.

One of the most fire-hazardous are roofing and waterproofing materials, which include bitumens. They self-ignite even at a temperature of 230-300 ° C. In addition, bitumen has a high smoke-forming ability and a burning rate.

Bitumens are widely used in the production of rolls (ruberoid, glassine, ruberoid, insula, hydroisol, foilizol) and mastic roofing and waterproofing materials. Virtually all bitumen-based roofing materials belong to the G4 group. This imposes restrictions on their use in buildings with increased requirements for fire safety. So, they must be laid on a non-flammable basis. In addition, gravel backfilling is carried out on top of it, and also fire sprinkles that separate the roof of the building into separate segments are arranged. This is necessary in order to localize the fire and prevent the spread of fire.

Today, dozens of types of waterproofing materials are represented on the market - polyethylene, polypropylene, polyvinylchloride, polyamide, thiocarbon and other membranes. Regardless of the species, they all belong to the group of flammable. The most safe, in terms of fire safety, are the waterproofing membranes related to the G2 flammability group. As a rule, these are materials based on polyvinyl chloride with the addition of flame retardants.

Thermal insulation materials

Thermal insulation materials, subject to certification in the field of fire safety, can be divided into five groups. The first of these is expanded polystyrene. Due to their relatively low cost, they are widely used in modern construction. Along with good thermal insulation properties, this product has a number of serious shortcomings, including short-lived, insufficient moisture resistance and vapor permeability, low resistance to ultraviolet and hydrocarbon fluids, and most importantly - high flammability and emission of toxic substances during combustion.

One of the varieties of expanded polystyrene is extruded polystyrene foam. It has a more ordered structure of small closed pores.

This production technology increases the moisture resistance of the material, but does not reduce its fire hazard, which remains so high. Ignition of expanded polystyrenes occurs at a temperature of 220 to 380 OC, and self-ignition corresponds to a temperature of 460-480 OC. When burning styrofoam produce a large amount of heat, as well as toxic products. Regardless of the type, all materials in this category belong to the G4 flammability group.

As a thermal insulation in the composition of plaster facade systems, it is recommended to install expanded polystyrene with the obligatory arrangement of fireproof cuts from stone wool - non-combustible material. Due to the high fire hazard, the use of materials of this group is unacceptable in ventilated facade systems, since they can significantly increase the flame propagation velocity along the facade of the building. When using combined roofing, polystyrene foam is laid on a non-flammable stone wool base.

The next kind of thermal insulation material - polyurethane foam - is a non-melting thermoset plastic with a cellular structure, the voids and pores of which are filled with a gas with low thermal conductivity. Due to the low ignition temperature (from 325 oC), the strong smoke-forming ability, as well as the high toxicity of combustion products, including hydrogen cyanide (hydrocyanic acid), polyurethane foam has an increased fire hazard. In the production of polyurethane foam, fire retardants are actively used that can reduce flammability, but, at the same time, increase the toxicity of combustion products. In general, the use of polyurethane foam in buildings with increased requirements for fire safety is severely limited. If necessary, it can be replaced by a two-component material - polyisocyanurate foam, which has a lower flammability and flammability.

Resole foam plastic, made of resole phenol-formaldehyde resins, belong to the group of hard-combustible. In the form of plates of medium density, they are used for thermal insulation of external fences, foundations and partitions at a surface temperature of no higher than 130 ° C. Under the influence of the flame, the resolving foams are charred, retaining their overall shape, and have a small smoke-producing capacity compared to expanded polystyrene. One of the main drawbacks of this category of materials is that when they are degraded, they release a set of highly toxic compounds, in addition to carbon monoxide, formaldehyde, phenol, ammonia and other substances that pose a direct threat to life and health of people.

Another type of insulation - glass wool, for the production of which the same materials are used as in the manufacture of glass, as well as waste from the glass industry. Glass wool has good thermal characteristics, and its melting temperature is about 500 ° C. However, due to some features, the thermal insulation with a density of less than 40 kg / m3 belongs to the NG group.

The list of thermal insulation materials includes stone wool, which consists of fibers produced by their rock formations of the basalt group. Stone wool has high heat and sound insulation characteristics, resistance to loads and various types of impact and durability. Materials of this group do not emit harmful substances and do not have a negative impact on the environment. Stone wool is the most reliable material in terms of fire safety: it is non-flammable and has a fire class of KM0. Rock wool fibers can withstand temperatures up to 1000 ° C, so that the material effectively prevents the spread of flame. Thermal insulation of stone wool can be used without restriction in the number of storeys of the building.

Fire risk assessment of thermal insulation was carried out in the framework of specialized seminars organized by VNIIPO MES. They were accompanied by full-scale fire tests, in which common types of heat-insulating materials - expanded polystyrene, polyurethane foam, resilient foam and stone wool - participated. Under the influence of the open burner flame, the expanded polystyrene melted to form burning drops during the first minute of the experiment, the polyurethane foam burned for 10 minutes. For 30 minutes of testing, the resoated polystyrene was charred, and the stone wool did not change its original shape, proving its belonging to non-combustible materials.

The second part of the tests - simulating the fire of a roof with a heat-insulating layer - showed that a burning melt of expanded polystyrene penetrating into internal premises promotes the spread of fire and the appearance of new fires. Thus, according to the test results, conclusions were drawn about the high fire hazard of the most commonly used insulation materials.

Summing up, it is necessary to note once again the importance of effective fire-fighting measures in the process of designing and building buildings. One of the central places is occupied with the assessment of fire hazard and a competent choice of building materials, based on current standards and standards and taking into account the functional purpose and individual features of the building. The use of modern materials makes it possible to ensure full compliance with fire safety requirements, ensuring the safety of life and health to people who will be in the building after completion of construction.

Roman Ilyaguyev

Press service of the company Rockwool Russia

CABLING
WITH INSULATION FROM SESITOPOLYETHYLENE

When preparing the materials, we used "Recommendations for the laying and installation of cables with XLPE insulation 10, 20 and 35 kV" (information from RusCable .Ru), taking into account other data on the cable of the cross-linked polyethylene.

1. Basic Provisions

Any enterprise operating electrical networks with a voltage of 6-10 kV or higher uses power cables.

Cable lines have a huge advantage over air lines, since they take up less space, are safer, more reliable and more convenient to operate.

The overwhelming majority of cables used in Russia and CIS countries - with impregnated paper insulation (PBI) have numerous shortcomings:

High damageability;

Load capacity limitations;

Restrictions on the difference in gasket levels;

Low manufacturability of installation of couplings.

At present, given the above disadvantages, cables with paper insulation are actively replaced by cables with XLPE insulation.

The leading energy systems of the country, when building new cable lines or repairing existing ones, are actively using cables with XLPE insulation.

The transition of pulp with paper impregnated insulation (BPI) to cables with cross-linked polyethylene (SPE) insulation is associated with ever-increasing demands of operating organizations on the technical parameters of cables. In this regard, the advantages of cables from EIT are obvious.

In the table (according to the GROUP OF COMPANIES "Forum Electro"), the main indicators of the medium-voltage cable are given:

Main factors	Type of cable insulation
Main factors	impregnated paper	cross-linked polyethylene
1 Long-term permissible operating temperature, ° С
2. Temperature at overloads, ° С
3. Resistance to short-circuit currents, ° С
4. Load capacity,%
When laying in the ground
When laying in the air
5. Level difference at laying, m	not less than 15	without limitation
6. The complexity of installation and repair	high	low
7. Reliability indicators - specific damageability, - pcs / 100 km year
In lead shells	about 6 *
In aluminum casings	about 17 *	10-15 times lower

_______________

* According to the ISS Mosenergo, A.S. Svistunov. Direction of works on development.

Advantages of the cable made of cross-linked polyethylene are:

Higher reliability in operation;

Increase of the working temperature of cores of cable with insulation from SPE to 90 ° C, which ensures a high capacity of the cable;

Hard insulation, which allows to lay a cable with insulation from SPE on the sites with a large difference in heights, incl. vertical and inclined reservoirs;

The use of polymeric materials for insulation and sheath, providing the possibility of laying the cable from SPE without preheating at temperatures up to -20 ° C;

Less weight, diameter and bend radius of the cable, which facilitates laying on difficult routes;

Low moisture absorption;

Specific damage to the cable with insulation from EIT is 1-2 orders of magnitude lower than that of a cable with impregnated insulation;

High thermistor resistance at short circuit;

Insulating material allows to reduce dielectric losses in the cable;

Large length of cable;

lower costs for the reconstruction and maintenance of cable lines;

More ecological installation and operation (absence of lead, oil, bitumen);

Increase the service life of the cable.

The application of a cable with insulation from SPE to 6-10 kV allows solving many problems of power supply reliability, optimizing, and in some cases even changing the traditional network schemes.

Currently, in the US and Canada, the proportion of cables with SPE insulation is 85%, in Germany and Denmark -95%, and in Japan, France, Finland and Sweden, medium-voltage distribution networks use only cable with SES isolation.

2. Technology of cross-linking polyethylene

Polyethylene is currently one of the most widely used insulating materials in the manufacture of cables. But initially thermoplastic polyethylene has serious disadvantages, the main of which is a sharp deterioration of mechanical properties at temperatures close to the melting point. The solution to this problem was the use of cross-linked polyethylene.

The cables are required for the insulation material used. The crosslinking or vulcanization process on modern cable plants takes place in a neutral gas medium at high pressure and temperature, which allows obtaining a sufficient degree of cross-linking throughout the entire thickness of the insulation.

The term "crosslinking" (vulcanization) implies the processing of polyethylene at the molecular level. Cross-links formed during crosslinking between polyethylene macromolecules create a three-dimensional structure that determines the high electrical and mechanical characteristics of the material, less hygroscopicity, a greater range of operating temperatures.

There are three main methods of cross-linking polyethylene: peroxide, silane and radiation. In the world cable industry, the first two are used in the production of power cables.

Peroxide cross-linking of polyethylene takes place in a neutral gas medium at a temperature of 300-400 ° C and a pressure of 20 atm. It is used in the manufacture of cables of medium high voltages.

Silane cross-linking takes place at a lower temperature. The application sector of this technology covered cables of low and medium voltage.

The first Russian producer of cable with SPE-insulation in 1996 was ABB Moskabel, which uses peroxide cross-linking technology. For the first time in Russia, the output of a cable made of silanol-cross-linked polyethylene was mastered in Perm at OAO Kamkabel in 2003.

There are some features of the production and operation of such cables.

3. The construction of cables SPE.

Basically, the cables are produced in single-core version (), but they are also produced in the three-fluid version (), and the use of various types of casings and the possibility of sealing allows the cable to be used both for laying in the ground and for cable constructions, including for group laying:

Cables with insulation from EIT	Abbreviation	Areas of use
From PE		laying on the ground
Reinforced from PE	Pu	laying on the ground in difficult areas
From PVC plastic compound		in cable facilities, in industrial premises - in dry ground
From PVC plastic compound of low combustibility		group gasket - in cable facilities - in production premises
Cables with longitudinal sealing	r, 2r, rg (after the shell designation)	for laying in soils with high humidity in moist, partly flooded premises

Additional designations for cables with sealing elements in the structure:

"R" -sealing of the metal screen with water-blocking tapes;

"2g" - an over-sealed screen an aluminopolymer tape;

"Gzh" - a conductive vein uses a water-blocking powder or threads.

Cable construction with SPE insulation for low and medium voltage:

1. A conductive multi-wire sealing vein:

Aluminum (АПвПг, АПвПуг, АПвВг, АПвВнг-LS, АПвПу2г);

Copper (PvPg, PvPug, PvVg, PvVng-LS, PvPu2g).

2. Electrically conductive screen of silanol-crosslinked polyethylene composition.

3. Isolation of silanol-cross-linked polyethylene.

4. Electrically conductive screen made of silanol-crosslinked polyethylene composition.

5. Water-absorbing conductive tape.

6. Screen of distorted wires.

7. Copper tape.

8.Dividing coat:

Water-blocking conductive tape (АПвПу2г, ПвПу2г);

Electro-insulating creped paper (APvPg, PvPg, APvPug, PvPug, APvBg, PvVg);

Lenta alum polyethylene (АПвПу2г, ПвПу2г).

9. The shell:

Polyvinylchloride plastic (APvBg, PvVg);

Polyvinylchloride plastic of reduced fire hazard (APvVng-LS, PVVng-LS);

Polyethylene (АПвПг, ПвПг, АПвПуг, ПвПуг, АПвПу2г, ПвПу2г).

Fig. 1 . Single-core cable

Fig. 2 . Three-core cable

4. Peculiarities of mounting power cables with cross-linked polyethylene insulation

1) Laying cables with XLPE insulation is recommended at an ambient temperature of at least 0 ° C. It is allowed to lay cables with SPE insulation without heating at an ambient temperature of at least -15 ° C for cables with PVC and plastic sheath -20 ° C for cables with a polyethylene sheath. At lower ambient temperatures, the cable should be heated at least 48 hours in a heated room or by using a special device to a temperature of at least 0 ° C, with the installation being carried out within a short time (no more than 30 minutes). After laying the cable must be immediately filled with the first layer of soil. The final backfilling and compaction of the soil is carried out after the cable has been cooled. Cabling at ambient temperatures below -40 ° C is not allowed.

2) The minimum bend radius of cables with XLPE insulation should be at least 15D н н for single and three-core cables and 12Dh for three stranded cables, whereDh -The outer diameter of the cable or the diameter of the twist for three twisted cables. If the bending control is carefully checked, for example by applying the appropriate template, the bending radius of the cable can be reduced to 8Dh. In this case, it is recommended to heat the cable in a place where the temperature is bending at 20 ° C.

3) Unwinding the cable with XLPE insulation from the drum must be performed with the required number of pass-through and corner rollers. The unwinding method used must ensure the integrity of the cable. During the laying, the traction of the SPE cables should be carried out using a tensioning stocking placed on the outer shell or a conductive vein with a wedge grip. Efforts arising during the cable pulling with XLPE sine insulation with a multiwire aluminum core should not exceed 30 N / mm 2 of the nominal conductor cross-section, the cable with a coiled aluminum wire (with the marking "Auger") - 25 N / mm 2, cable with copper core - 50 N / mm 2. If at the same time three single-core cables with one common steel stocking are laid, the calculation of the stress intensities takes into account:

1nominal sections of the core, if the cables are twisted together;

2 nominal conductor cross-sections if the cables are not twisted.

The pulling forces of the cable when laying must be calculated when designing the cable line and are taken into account when ordering the cable. The traction winch should be equipped with devices that allow controlling the cable pulling force, register the tension force during the whole cable traction process and automatically disconnect the traction winch if the pulling force exceeds the permissible value.

4) Cables with XLPE crosslinked silicone should be stacked with a margin in length 1¸ 2%. In trenches and on solid surfaces inside buildings and structures, a reserve is created by laying the cable with a "snake", and by cable structures (brackets) this stock is created by the formation of a sagging arrow. Do not stack the cable in the form of rings (turns).

5) Metal cable structures must be grounded in accordance with the current documentation.

6) When laying the cable line, the cables of the SPE of the three phases must be laid parallel to the triangle or in one plane. Other ways of location should be agreed with the manufacturer.

7) When laying in the plane, the distance in the light between two adjacent cables of one cable line must be at least the outer diameter of the cable of the EIT.

8) Triangulation of the cables are fastened along the length of the cable line (with the exception of the sections near the couplings) at a distance of 1¸ 1,5 m, on the bends of the route - 1 m. When laying in the ground, it should be noted that when backfilling with earth, the cables do not need to change their position. Cables laid in the plane in cable structures in the air must be fixed along the length of the line at a distance of 1¸ 1,5 m. Staples and other fasteners for fastening single-core cables to the SPE, as well as attaching tags to the cables must be made of non-magnetic material. When fixing the cables, it is necessary to take into account the possible thermal expansion of the cables and the mechanical loads occurring in the short-circuit mode.

9) All ends of the cable after cutting must be sealed with heat shrinkable cap to prevent moisture from penetrating from the environment. During the laying of the cables, the condition of the shells and protective capsules must be checked.

5. Methods of routing cables

Cables made of polyethylene can be laid in the ground (trench), in cable constructions (tunnels, galleries, trestles), in blocks (pipes), in production rooms (in cable channels, on walls).

When laying cables in the ground, it is recommended that no more than six wires be laid in one trench. With more cables, it is recommended that they be laid in separate trunks. Cabling can be carried out by single cables, and connected in a triangle.

Cabling in tunnels, overpasses and galleries is recommended when the number of cables going in one direction more than twenty. Cable laying in blocks is applied in conditions of great cramping along the road, at intersections by railroad tracks and passageways, with the probability of spilling metal, etc.

When laying pometalloconstruktsiyu possible use of various types of fastenings in the view, clits or attachment points.

Examples of fixing the cable using staples (Fig.,,).

All dimensions are in millimeters. Fasteners (bolts, nuts, washers) are not shown.

D - the outer diameter of the cable,S - thickness of the gasket (from 3 to 4 mm).

Fig. 3 . Fastening of one cable

Notation:

1-cable; 2 - clamp (bracket) of aluminum or aluminum alloy; 3 - a lining of a razor or polyvinyl chloride .

Fig. 4 . Mounting of three cables in a bundle (in a triangle)

Notation:

1 cable; 2- clamp (bracket) of aluminum or aluminum alloy with a thickness of 5 mm; 3 - gasket made of rubber or polyvinylchloride, thickness 3 ¸ 5mm.

Fig. 5 . Mounting of three cables

Notation:

1 cable; 2- clamp (bracket) made of aluminum or aluminum alloy; 3- gasket made of rubber or polyvinyl chloride.

6. Cable laying technology

Cable laying is carried out by a team of 5-7 people.

Approximate scheme of the deployment of workers when pulling the cable:

The drum, the brake - 1 person;

The cable of the cable is 1 man;

Cable descent into the trench (entrance, exit from the tunnel) - 1 person;

On the winch - 2 people;

Maintenance of the end of the cable - 2 people.

In addition, it is necessary to provide for one person:

At each corner of the turn;

At each passage of the pipes through partitions or floors, at the entrance to the cell or building.

At the same time pulling three cables behind the device for grouping the cables there must be 2 people to fasten the cable in a triangle.

The speed of the pad should not exceed 30 m / min and should be selected depending on the nature of the route, weather conditions and traction efforts.

If the traction force is exceeded, the gasket must be stopped and the installation and correctness of the linear and corner rollers checked, the presence of lubricant (water) in the pipes, and the cable checked for possible wedging in the pipes. The further pulling of the cable is possible only after the cause of exceeding the permissible pulling forces has been eliminated.

When descending the cable into the trench or entering the tunnel, make sure that the cable does not slip from the rollers and does not rub against the pipes and walls in the aisles. At the entrance to the pipes it is necessary to ensure that the protective covering of the cables of the pipe edges is not damaged.

If the cable cover is damaged, it is necessary to stop the gasket, inspect the damage site and take a decision on the method of repairing the shell.

Accompanying the end of the cable should ensure that the cable goes along the rollers, if necessary, adjust the rollers, and also guide the end of the cable.

The cable is pulled in such a way that when laying it over the project, the distance of the opening of the end clutch or from the conditional center of the coupling is at least 2 m. When determining the reserve, it should be borne in mind that the remainder of the cable on the drum should be sufficient for mounting the coupling. Disconnect the traction cable and remove the stocking or gripping from the end of the cable. In the event that there is a cable on the drum for several sections of the route, or if the length of the cable is much longer than the length of the segment, you must cut the cable.

After trimming the cable, it is necessary to seal the ends of the cables by capping. For a more reliable sealing of cable ends, it is possible to use double capping. The inner cap is to be deposited on the electrically conductive layer by cable insulation, an anarchal cap is placed on the inner cap and on the cable sheath. It is also possible to apply a layer of melted bitumen to the cable cut-off beforehand.

If necessary, the ends of the cable should be brought into the chambers, wells, cable rooms. At the same time it is necessary to observe the permissible bend radii of the cable. Remove the cable from the rollers, lay it down and secure it to the project.

When laying in vrasrshhee produce a dusting of the cable with a sand-gravel mixture or a small soil with a thickness of at least 100 mm and conduct a cable sheath test.

Journal "Pricing isometric rationing in construction", November 2010 No. 11

Often when reading such headlines, the first one arises: "I do not want to read, the topic is not the most pleasant, and God forbid that there should never be a fire." However, such a topic does not at all speak only of how these or other constructions can behave during a fire. Such information warns of a possible risk and allows you to build your house in such a way that it is as much as possible protected from a fire and at the same time protects you.

Categories of materials by degree of flammability

What should I single out first? Obviously, these are categories on which materials are divided according to the degree of inflammability. There are only three:

Non-flammable - they are not exposed to fire, that is, do not burn, do not char and do not smolder.
Difficult fire - can smolder and char and do this until the moment there is a source of open fire nearby.
Combustible - ignite and smolder under the influence of fire and do this even after the source is liquidated.

Those that are obtained by inorganic origin are considered materials belonging to the second group, that is, incombustible. They include:

Natural materials like stone, sand,, buta, marble, gravel, limestone and others.

Artificial materials are also clay bricks after firing. It can also be hollow and porous. Lightweight brick, which has burnishing additives that are easy to land. Stones from ceramics (hollow). Lime brick, which did not pass the firing stage. Blocks, as well as stones that are made of heavy and lightweight concrete and can be either solid or hollow. Wall stones, which are made from a mixture of soil and concrete, as well as products for cladding and architectural elements.

Reliable stone

During a fire, parts of the construction made of or artificial stones show their best qualities and are the embodiment of reliability.

The main requirement for walls and partitions made of natural and artificial stone is gas tightness. If the stone or brickwork is strong and does not contain cracks, it is an excellent barrier from the fire point of view. During the collapse of floors, partial or full, the load on the walls and partitions becomes different.

Metal is just as popular as stone. However, he loses in comparison with him in terms of fire resistance. Fifteen minutes after the onset of exposure to direct fire, changes occur regarding the degree of elasticity of metal products, as well as their fluidity. This leads to a change in the state of the compressed rod.

Combining properties

Difficult combustible materials combine the properties of both combustible and non-combustible. Of these, buildings are built with specified parameters. These include fire resistance, resistance to the influence of an aggressive environment, sound heat conduction, compression, and others.

To difficultly combustible include concrete, used for asphalting, as well as materials containing concrete with a small content of organic aggregate, and materials containing gypsum. Also here include their materials from various polymers and wood, which has been treated with flame retardants. Felt, which was soaked in clay mortar, cement fiberboard and others.

What burns well and how to protect it

To combustible materials, which are of organic origin, are peat slabs, wood, polystyrene, linoleum, rubber, etc. Plastics have a very big drawback - when burning, they emit smells, which are products of thermal decomposition and are extremely harmful to health.

In order to increase the degree of fire resistance of products made of wood and plastics, various protective measures are applied. The wood is carefully treated with flame retardants, and additives are added to the plastics that reduce the flammability of the products.

How is fire resistance achieved?

Fire resistance is an important parameter that needs special attention. He talks about how long the material can survive when exposed to high temperatures. However, it should be noted that in addition to fire, the design has a significant impact of the operational load, as well as the pressure of water jets, the amount of water in the static position, and the falling structures. In order to determine the degree of fire resistance of a material, it is exposed to temperatures ranging from 550 to 1200 degrees, since it is these temperatures that arise in a fire.

Elements of the building and their degree of fire hazard

Now is the time to proceed to examine the various parts of buildings and the degree of their fire hazard.

The foundation is the underground part of the building, its base. It is he who perceives all the load from the building's constructions. It does not have any fire protection requirements, because the foundation is made of such materials, the fire resistance limit of which is much higher than that of walls and ceilings.

The wall performs functions not only bearing, but also enclosing. It transfers all perceived loads to the foundation and exerts pressure on it. The walls are divided into internal and external, longitudinal and transverse. It is the bearing walls that perceive the pressure, transferring it to the foundation.

The base is part of the outer wall. It protrudes slightly from the plane of the wall and looks like a pedestal on which it rests. Performs the function of protecting the wall from mechanical damage.

The cornice is a horizontal protrusion that either is in the upper part of the wall, ending it, or is located above the window and door apertures. It removes water that flows from the roof of the building so that it does not fall on the wall, window or door.

Niche - a recess in the wall, which is used either to house a built-in or wall cabinet, as well as for appliances that heat the room, and for various decorative purposes.

The parapet is a small wall that runs along the edge of the roof. Now this wall is replaced by a metal railing, which is also called a parapet.

Balcony - an open area with fences, which is issued from the plane of the wall. The loggia is part of the premises and is open on the facade. Balconies with loggias are not only useful area and decoration of the building, but also protect from smoke and fire during a fire. In addition, they serve as evacuation routes for people, and also help firefighters reach the place of fire.

Fire wall - separates the compartments in order to prevent the spread of fire. They also separate rooms with combustible and non-combustible structures. Such walls are made only of materials not subject to combustion.