When receiving substances and materials, application, storage, transportation, processing and disposal.
To establish requirements fire safety to the design of buildings, structures and systems fire protection classification of building materials according to fire hazard is used.
Indicators of fire and explosion hazard and fire hazard of substances and materials
The list of indicators necessary to assess the fire and explosion hazard and fire hazard of substances and materials, depending on their state of aggregation, is given in Table 1 of the Appendix to Federal law FZ-123 (" Technical regulations on fire safety").Methods for determining indicators of fire and explosion hazard and fire hazard of substances and materials are established regulatory documents on fire safety.
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.
| Fire danger indicator | Substances and materials in various states of aggregation | Dust | ||
| gaseous | liquid | hard | ||
| Safe experimental maximum clearance, millimeter | + | + | - | + |
| Release of toxic combustion products per unit mass of fuel, kilogram per kilogram | - | + | + | - |
| Flammability group | - | - | + | - |
| Flammability group | + | + | + | + |
| Flame propagation group | - | - | + | - |
| Smoke generation coefficient, square meter per kilogram | - | + | + | - |
| Flame emissivity | + | + | + | + |
| Fire and explosion hazard index, Pascal per meter per second | - | - | - | + |
| Flame Spread Index | - | - | + | - |
| Oxygen index, volume percent | - | - | + | - |
| Concentration limits of flame propagation (ignition) in gases and vapors, volume percentages, dusts, kilogram per cubic meter | + | + | - | + |
| Concentration limit of diffusion combustion gas mixtures in the air, volume percentage | + | + | - | - |
| Critical surface density heat flow, Watt per square meter | - | + | + | - |
| Linear speed of flame propagation, meter per second | - | - | + | - |
| Maximum speed of flame propagation along the surface flammable liquid, meter per second | - | + | - | - |
| Maximum explosion pressure, Pascal | + | + | - | + |
| Minimum phlegmatizing concentration of gaseous phlegmatizing agent, volume percentage | + | + | - | + |
| Minimum ignition energy, Joule | + | + | - | + |
| Minimum explosive oxygen content, volume percentage | + | + | - | + |
| Lower working heat of combustion, kilojoule per kilogram | + | + | + | - |
| Normal flame propagation speed meter per second | + | + | - | - |
| Indicator of toxicity of combustion products, gram per cubic meter | + | + | + | + |
| Oxygen consumption per unit mass of fuel, kilogram per kilogram | - | + | + | - |
| The maximum speed of breakdown of the diffusion torch, meter per second | + | + | - | - |
| Explosion pressure rise rate, megaPascal per second | + | + | - | + |
| Ability to burn when interacting with water, air oxygen and other substances | + | + | + | + |
| Ignition ability under adiabatic compression | + | + | - | - |
| Capacity for spontaneous combustion | - | - | + | + |
| Exothermic decomposition ability | + | + | + | + |
| Ignition temperature, degrees Celsius | - | + | + | + |
| Flash point, degrees Celsius | - | + | - | - |
| Self-ignition temperature, degrees Celsius | + | + | + | + |
| Smoldering temperature degrees Celsius | - | - | + | + |
| Temperature limits of flame propagation (ignition), degrees Celsius | - | + | - | - |
| Specific mass burnout rate, kilogram per second per square meter | - | + | + | - |
| Specific heat of combustion, Joule per kilogram | + | + | + | + |
Classification of substances and materials ( excluding construction, textile and leather materials) by fire danger
The classification of substances and materials by fire hazard is based on their properties and ability to form dangerous fire or explosion factors.Based on flammability, substances and materials are divided into the following groups:
1) non-flammable- substances and materials that cannot burn in air. Non-flammable substances can be fire-explosive (for example, oxidizers or substances that release flammable products when interacting with water, air oxygen, or with each other);
2) flame retardant- substances and materials capable of burning in air when exposed to an ignition source, but unable to burn independently after its removal;
3) flammable- substances and materials capable of spontaneous combustion, as well as ignite under the influence of an ignition source and burn independently after its removal.
Test methods for the flammability of substances and materials are established by fire safety regulations.
Classification of construction, textile and leather materials by fire hazard
The classification of building, textile and leather materials by fire hazard is based on their properties and ability to form fire hazards.The fire hazard of building, textile and leather materials is characterized by the following properties:
1) flammability;
2) flammability;
3) ability to spread flame over a surface;
4) smoke generating ability;
5) toxicity of combustion products.
Speed of flame spread over the surface
According to the speed of flame spread over the surface, flammable Construction Materials(including floor carpets) depending on the value of the critical surface heat flux density are divided into the following groups:1) non-proliferative (RP1), having a critical surface heat flux density of more than 11 kilowatts per square meter;
2) low propagation (RP2) having a critical surface heat flux density of at least 8, but not more than 11 kilowatts per square meter;
3) moderate spreading (RP3) having a critical surface heat flux density of at least 5, but not more than 8 kilowatts per square meter;
4) highly propagating (RP4), having a critical surface heat flux density of less than 5 kilowatts per square meter..
Smoke generating ability
According to their smoke-generating ability, combustible building materials, depending on the value of the smoke generation coefficient, are divided into the following groups:1) with low smoke-generating ability (D1) having a smoke generation coefficient of less than 50 square meters per kilogram;
2) with moderate smoke-generating ability (D2) having a smoke generation coefficient of at least 50, but not more than 500 square meters per kilogram;
3) with high smoke-generating ability (D3), having a smoke generation coefficient of more than 500 square meters per kilogram..
Toxicity
Based on the toxicity of combustion products, combustible building materials are divided into the following groups in accordance with table 2 appendices to Federal Law No. 123-FZ:1) low-hazard (T1);
2) moderately hazardous (T2);
3) highly hazardous (T3);
4) extremely dangerous (T4).
| Hazard Class | Indicator of toxicity of combustion products depending on exposure time | |||
| 5 minutes | 15 minutes | 30 minutes | 60 minutes | |
| Low hazard | more than 210 | more than 150 | more than 120 | more than 90 |
| Moderately dangerous | 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 hazardous | 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 | no more than 25 | no more than 17 | no more than 13 | no more than 10 |
Classification of certain types of substances and materials
For floor carpets, the flammability group is not determined.Textile and leather materials are divided into flammable and low-flammable based on flammability. A fabric (non-woven fabric) is classified as a flammable material if the following conditions are met during testing:
1) the flame combustion time of any of the samples tested when ignited from the surface is more than 5 seconds;
2) any of the samples tested when ignited from the surface burns out to one of its edges;
3) cotton wool catches fire 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) average length The charring area of any of the samples tested when exposed to flame from the surface or edge is more than 150 millimeters.
To classify construction, textile and leather materials, the value of the flame propagation index (I) should be used - a conditional dimensionless indicator characterizing the ability of materials or substances to ignite, spread flame over the surface and generate heat. Based on flame propagation, materials are divided into the following groups:
1) not spreading flame over the surface, having a flame propagation index of 0;
2) slowly spreading flame over the surface, having a flame spread index of no more than 20;
3) quickly spreading flame over the surface, having a flame spread index of more than 20.
Test methods for determining fire hazard classification indicators for construction, textile and leather materials are established by fire safety regulations
Construction Decoration Materials According to their flammability, they are divided into three main groups:
Non-combustible materials- Materials that are exposed to an ignition source (sparks, fire, electric current, high temperature, chemical reaction etc.) do not ignite or burn (natural and artificial inorganic materials - stone, concrete, reinforced concrete, etc.);
Difficult to combustible materials- Materials that burn under the influence of ignition sources but are incapable of full independent combustion (asphalt concrete, plasterboard, wood impregnated with antipyrites agents, fiberglass, fiberglass, etc.);
Combustible materials- Materials and substances that will remain burning after removal of the ignition source.
Use of non-combustible materials
Non-combustible materials are used in construction and repair for finishing floors, partitions, walls and ceilings of buildings and premises, as well as for cladding facades. The main characteristic of these materials is their resistance to high temperatures.
The INFRACHIM company offers consumers a wide range of innovative non-combustible building materials that have successfully passed all laboratory studies and tests and are confirmed by all necessary certificates and sanitary and epidemiological reports.
TPK INFRACHIM materials can be used in crowded places; they are environmentally friendly materials that are absolutely safe for humans and animals. They do not emit toxic and toxic substances at the time of heating and have a number of advantages compared to competitors' products.
Non-combustible materials and their features
The non-flammable materials offered by our company are easy to use, reliable and durable. These products have low indicators for such parameters as change in shape in a wet state, water absorption, change in size after heating, thermal conductivity of the material, and high indicators for the following characteristics: strength and bending in a dry/moisture-saturated state, impact strength, tensile strength , density. The materials, as a rule, are lightweight, which makes them easy to transport and install. Most materials have a perfectly smooth surface, both on the inside and outside.
Non-combustible materials are intended for the production of construction and finishing works indoors and outdoors. They are used for finishing work on almost any building, production premises, hotels, restaurants, hostels, water parks, administrative buildings, etc., etc.
With the help of non-combustible finishing materials, it is possible to carry out external cosmetic work, i.e. finishing external walls, facades, pediments, cornices, columns, etc. In addition, the products offered are ideal as a basis for laying metal tiles or soft roofs. These materials are quite hard, which allows them to have good heat-insulating and sound-proofing qualities. They are widely used in the construction of ventilated facades of buildings.
Non-combustible finishing materials have a relatively low weight, which makes them easy to transport without the use of special expensive equipment, and also to be installed by finishing crew workers. They will keep their appearance and will last for many years.
A short excursion into history:
About the cause of fires in the Middle Ages, for example, the same thing was always said: “by chance” and “by the will of God.” The fact that fire was associated with the wrath of God is extremely characteristic of medieval consciousness. Medieval people had very little knowledge about the world around them, but thanks to this naivety and lack of education, their lives were full of miracles.
Today our knowledge is sufficient not only to determine the causes of the fire, but also to, if not prevent it (“the will of chance” is still relevant today), then at least optimize its elimination and minimize the destructive consequences and do not rely on a miracle, but create it yourself.
A common cause of fire is a short circuit power cable and its fire, which quickly spreads along the cable route. Imagine a typical industrial enterprise. If a fire spreads at a temperature of 500 degrees, softening and collapse of seemingly strong structures can occur in a matter of minutes. metal structures. And even concrete cannot withstand temperatures of 1000 degrees. That is, the task is to prevent the spread of fire if it has already appeared.
The cause of the fire at the Ostankino TV tower was the excess of the permissible load on the feeders - the cables transmitting the signal high power from the equipment to the antenna, - excessive load caused overheating and fire of the cables inside the tower. The total damage from the fire at the Ostankino TV tower is estimated at hundreds of millions of dollars, and the moral damage to television viewers who were left “blind” and deprived of a daily dose of information is almost impossible to assess. What could stop the spread of fire if a fire did occur? Miracle? No! Non-flammable polymer materials.
Many countries have already adopted special restrictions on the use of flammable fuels. polymer materials in civil and industrial construction, in production and operation Vehicle(airplanes, cars, buses, trolleybuses, trams, railway cars, ships), at power plants and in electrical networks, in the space and cable industries. So, reducing the flammability and combustibility of polymers and creating fireproof materials is an urgent problem for polymer chemistry. This task is complicated by another urgent requirement of our time - the environmental friendliness of fire retardant additives - fire retardants.
Fire retardants prevent the combustion of polymer materials and are among the most important components of plastics. When polymer materials burn, complex physical and chemical processes occur inside and on the surface of the condensed phase, as a result of which the polymer is converted into combustion products heated to a high temperature.
Features of storage of non-combustible materials
These materials should be stored in dry rooms with normal humidity levels. If these basic storage conditions are observed, the products will perfectly retain their appearance and last for many years.
Regarding the supply of non-combustible materials, please contact the company's sales department by contact numbers.
Combustible substances and materials are divided into three groups based on flammability:
· highly flammable;
· substances of “medium flammability”;
· flame retardant.
Flammable– flammable substances of increased fire hazard, which, when stored outdoors or indoors, can ignite without preheating upon short-term (up to 30 s) exposure to a low-energy ignition source (from a match flame, spark, cigarette, heating of electrical wiring).
To flammable gases include almost all flammable gases, for example, H 2, NH 4, CO, C 3 H 8, natural gas, etc.).
For flammable liquids(flammable liquids) include flammable liquids with flash t. not > 61 0 C in a closed crucible (c.c.) or 66 0 C in an open crucible (o.c.), flammable liquids can be divided into three groups according to fire hazard:
1. especially dangerous;
2. constantly dangerous;
3. dangerous when elevated temperature.
1.To especially dangerous flammable liquids include, for example, acetone C 2 H 6 O, gasoline - B70, isopentane C 5 H 12, diethyl ether C 4 H 10 O, having t flash. not > 18 0 C (w.t.) or 13 0 C (b.t.). In hot weather, the pressure inside the vessel increases; if the seal is broken, vapors of these liquids can spread over a considerable distance from the vessel, causing a fire.
2. Constantly dangerous flammable liquids are, for example, benzene C 6 H 6, toluene C 7 H 8, ethyl alcohol C 2 H 5 OH, dioxane C 4 H 8 O 2, ethyl acetate C 4 H 8 O 2 with t flash. from –18 0 to +23 0 (w.t.) or from –13 0 to 27 0 (b.t.) are characterized by the ability to form an explosive atmosphere in the vapor-air phase of closed vessels.
Table 1.1
Classification of substances and materials by flammability
| Flammability group | Definition according to GOST | Examples of substances and materials |
| 1. Flammable | Capable of spontaneous combustion, as well as ignition 1 and self-burning after removal of the ignition source | Solid organic: wood 2, coal, peat, rubber 3, cotton, cardboard, rubber 4, stearic acid 5, etc.; inorganic: metals (potassium, sodium, lithium, aluminum, etc. and their compounds); non-metallic: (sulfur, phosphorus, silicon, etc. and their compounds), including dust (organic - coal, wood, sugar, flour, etc.; inorganic - iron, aluminum, silicon, sulfur, etc.) |
| Liquid: oil and petroleum products 6, alcohols 7, acids 8, paraffins 9, hydrocarbons 10, etc., including synthetic materials that melt when heated | ||
| Gaseous: hydrogen, hydrocarbons 11, ammonia, etc., as well as vapors of flammable liquids | ||
| 2. Low flammability | Capable of igniting in air from an ignition source, but unable to burn after its removal | Consisting of flammable and non-flammable materials: fiberglass SK-9A, fiberglass FN-F, felt, foam concrete filled with polystyrene, trichlorethylene C 2 HCl 3, weak aqueous solutions of alcohols, etc. |
| 3. Non-flammable | Not capable of burning in air | Asbestos fabric, asbestos-glass fabric, foam asbestos, metals used in construction, building materials: sand, clay, gravel, cement and products made from them (brick, concrete), etc. |
Notes to the table 1.1.
1 Spontaneous combustion is a combustion that occurs in the absence of a visible ignition source. For example, oily rags, metal shavings, sawdust, yellow phosphorus, liquid hydrogen phosphorous vapor P 2 H 4 .
2 Wood mainly consists of fiber (C 6 H 10 O 5) n.
3 Rubber is an unsaturated hydrocarbon (C 5 H 8)x, where x = 1000...3000.
4 Rubber - rubber after mixing with sulfur, subjected to vulcanization (heating to a certain temperature).
5 Stearic acid C 18 H 36 O 2 (or C 17 H 35 COOH) – flammable solid – component lard
6 Petroleum products: gasoline, kerosene, naphtha, diesel fuel, lubricating oils, fuel oil, etc.
7 Alcohols: methyl CH 4 O, ethyl C 2 H 6 O (C 2 H 5 OH), n-propyl C 3 H 8 O; n-butyl C 4 H 10 O; n-amyl C 5 H 12 O, etc.
8 Acids: formic (methane) C 2 H 2 O 2; acetic (ethane) C 2 H 4 O 2; olinic (octadecene) O 2, etc.
9 Paraffins, conventional formula C 26 H 54, are liquid and solid (melt when heated), obtained from certain types of petroleum products.
10 Liquid hydrocarbons: saturated (alkanes: pentane C 5 H 12, hexane C 6 P 14, etc.); unsaturated (alkenes: 1-pentene C 5 P 10, 1-hexene C 6 H 12, 1-octene C 8 H 16, etc.); cyclic (naphthenes: cyclopentane (CH 2) 5, cyclooctane (C 2 H 8), etc.; aromatic (benzene C 6 H 6, toluene C 7 H 8, etc.).
11 Gaseous hydrocarbons: saturated (alkanes: methane CH 4, ethane C 2 H 6, propane C 3 H 3, butane C 4 H 10, etc.); unsaturated (ethylene C 2 H 4, propylene C 3 H 6, butylene C 4 H 8, etc.).
These features impose additional safety requirements for their transportation, storage and use.
3. Hazardous at elevated temperatures flammable liquids include, for example, white alcohol C 10.5 H 21.3 lighting kerosene, chlorobenzene C 6 H 5 Cl, solvent, turpentine, etc., having a flash point above 23 0 ... 61 0 (w.t.) or 27 0 ... 66 0 (b.t.). In hot shops (at elevated temperatures), vapors of these liquids can ignite in the air; at normal temperatures (~ 20 0 C), these substances ignite only in the presence of an ignition source.
Highly flammable solids(materials): celluloid, polystyrene, wood shavings, peat slabs (ignite from the flame of a match, alcohol lamp, gas burner).
Medium flammability: wood, coal, paper in bundles, fabric in rolls (requires an ignition source with high energy capable of heating to ignition temperature).
Flammable: urea (urea) CH 4 ON 2, getinax grade B (pressed paper treated with resole-type synthetic resin), wood after fire-retardant treatment, polyvinyl chloride board.
A special class of flammable substances are pyrophoric and explosive substances.
Pyrophoric - capable of self-ignition in open air (liquid phosphorus, liquid hydrogen phosphide P 2 H 4, etc.).
Explosives are substances capable of rapid exothermic transformation with the formation of compressed gases (explosion) without the participation of atmospheric oxygen (nitroglycerin, nitromethane, trinitrotuluene C 6 H 2 (N 2 O) 3 CH 3, ammonium nitrate NH 4 NO 3).
All substances are divided into flammable, low-flammable and non-flammable.
Substances that can burn independently after the ignition source is removed are called flammable.
Substances that do not burn in air are called non-flammable.
Occupying an intermediate position flame retardant substances that ignite when exposed to an ignition source, but stop burning when it is removed.
All flammable substances are divided into the following main groups:
1. Combustible gases (GG)– substances capable of forming flammable and explosive mixtures with air at temperatures not exceeding 50 °C. GG includes individual substances: ammonia, acetylene, butadiene, butane, hydrogen, methane, carbon monoxide, propane, hydrogen sulfide, formaldehyde, as well as flammable liquid and gas vapors.
Flammable gases are explosive at any ambient temperature.
There are:
Light gas: which at a temperature of 20 °C and a pressure of 100 kPa has a density of less than< 0,8 по отношению к плотности воздуха (т.е. относительную плотность).
Heavy gas:> 1.2. if the relative density is in between, then both possibilities should be considered.
Liquefied gas: which, at a temperature below 20 °C or a pressure above 100 kPa, or under the combined action of both these conditions, turns into a liquid.
2. Flammable liquids (flammable liquids)– substances capable of burning independently after removal of the ignition source and having a flash point not higher than 61 ° C (in a closed crucible). These liquids include individual substances: acetone, benzene, hexane, heptane, xylene, methyl alcohol, carbon disulfide, styrene, acetic acid, chlorobenzene, ethyl alcohol, as well as mixtures and technical products: gasoline, diesel fuel, kerosene, solvents.
Explosive flammable liquids are those whose 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.).
3. Flammable liquids (FL)– substances capable of burning independently after removal of the ignition source and having a flash point above 61 ° C (in a closed crucible) or 66 ° C (in an open crucible). GZ includes the following individual substances: aniline, hexyl alcohol, glycerin, ethylene glycol, as well as mixtures and technical products, for example, transformer oil, vaseline, castor oil.
GLs with a flash point > 61 °C are classified as fire hazardous, but those heated under production conditions to a flash point or higher are classified as explosive.
4. Combustible dusts (GP)– solid substances in a finely dispersed state. HP in the air (aerosol) is capable of forming explosive mixtures with it. Dust (aerogel) settled on walls, ceilings, and equipment surfaces is a fire hazard.
According to the degree of explosion and fire hazard, GPs are divided into four classes.
1 class– the most explosive are aerosols that have a lower concentration limit of flammability (explosiveness) (LCEL) of up to 15 g/m 3 (sulfur, naphthalene, rosin, mill dust, peat, ebonite).
2nd grade– explosive – aerosols having an LEL value from 15 to 65 g/m 3 (aluminum powder, flour dust, hay dust, shale dust).
3rd grade– the most fire hazardous are aerogels with an LFL value of more than 65 g/m 3 and a self-ignition temperature of up to 250 °C (tobacco, elevator dust).
4th grade– fire hazardous – aerogels with an LFL value of more than 65 g/m 3 and a self-ignition temperature of more than 250 °C (sawdust, zinc dust).
To determine the likelihood of a flame occurring, the flammability of substances and various materials is of primary importance. This characteristic determines the fire hazard category of structures, premises, and industries; allows you to choose the right means to eliminate outbreaks.
The flammability group of all material components of an object determines the success of fire fighting and minimizes the likelihood of casualties.
Features of various substances
It is known that substances can be in different states of aggregation, which are important to take into account when determining the flammability group. GOST provides for classification based on quantitative indicators.
If a substance can burn, the flammability group G1 is more optimal for fire safety than G3 or G4.
Has flammability great importance for finishing, heat-insulating, building materials. On its basis, the fire hazard class is determined. So, plasterboard sheets have flammability group G1, stone wool– NG (does not burn), and insulating polystyrene foam belongs to the G4 flammability group, and reduce it fire danger The use of plaster helps.
Gaseous substances
When determining the flammability class of gases and liquids, standards introduce such a concept as a concentration limit. By definition, this is the maximum concentration of a gas in a mixture with an oxidizer (air, for example), at which a flame can spread from the point of ignition to any distance.
If such a limit value does not exist and the gas cannot spontaneously ignite, then it is called non-flammable.
Liquid
Liquids are called flammable if there is a temperature at which they can ignite. If a liquid stops burning in the absence of an external heating source, then it is called slow-burning. Non-flammable liquids do not ignite at all in the air atmosphere under normal conditions.
Some liquids (acetone, ether) may flash at 28 ℃ and below. They are considered especially dangerous. Liquids that ignite at 61…66 ℃ and above are classified as flammable (kerosene, white spirit). Tests are carried out in an open and closed crucible.
Solid
In the construction industry, the most relevant is the determination of the flammability group of solid materials. It is preferable to use substances of the flammability group G1 or NG, as they are the most resistant to ignition.
Classification
The intensity of the combustion process and the conditions under which it occurs determine the likelihood of a fire intensifying and an explosion occurring. The outcome of the incident depends on the totality of the properties of the feedstock.
General division
According to the national fire and explosion hazard standard, substances and various materials made from them are divided into the following groups:
- absolutely non-flammable;
- difficult to burn;
- flammable.
They cannot burn in air, which does not exclude interaction with oxidizing agents, with each other, and with water. Consequently, some members of the group pose a fire hazard under certain conditions.
Compounds that are difficult to combust include those that burn when ignited in air. As soon as the source of fire is eliminated, the burning stops.
Under certain conditions, flammable substances ignite on their own or in the presence of a fire source and continue to burn intensely.
The classification of flammability of construction raw materials and products is discussed in a separate updated standard. National construction standards take into account the categories of all types of products used in work.
According to this classification, non-combustible building materials (NG) are divided into two groups depending on the test mode and the values of the indicators obtained.
Group 1 includes products in which the temperature inside the oven increases by no more than 50 ℃. The reduction in sample mass does not exceed 50%. The flame does not burn at all, and the heat released does not exceed 2.0 MJ/kg.
Group 2 NG includes materials with the same indicators of temperature increase inside the furnace and weight loss. The difference is that the flame burns for up to 20 seconds, the heat of combustion should not be more than 3.0 MJ/kg.
Flammability classes
Combustible materials are examined according to similar criteria and are divided into 4 groups or classes, which are designated by the letter G and the number next to it. For classification, the values of the following indicators are taken into account:
- temperature of gases released with smoke;
- degree of size reduction;
- amount of weight reduction;
- flame retention time without a combustion source.
G1 refers to a group of materials with a smoke temperature not exceeding 135 ℃. The loss of length is 65%, weight loss is 20%. The flame itself does not burn. Such construction products are called self-extinguishing.
G2 includes a group of materials with a smoke temperature not exceeding 235 ℃. The loss of length is 85%, weight loss is 50%. Self-combustion lasts no more than 30 seconds.
G3 includes materials whose smoke temperature does not exceed 450 ℃. The loss of length is more than 85%, weight loss is up to half. The flame itself burns for no more than 300 seconds.
The G4 flammability group includes materials with a smoke temperature exceeding 450 °C. Loss of length exceeds 85%, weight loss – more than 50%. Self-combustion lasts more than 300 seconds.
It is acceptable to use the following prefixes in the name of each flammability group in order of increasing digital index:
- weak;
- moderately;
- Fine;
- highly flammable materials.
The given flammability indicators, along with some other characteristics, must be taken into account when developing project documentation and drawing up estimates.
The ability to generate smoke, the toxicity of combustion products, the speed of possible fire spread, and the likelihood of rapid ignition are also of great importance.
Class confirmation
Samples of materials are tested in laboratories and in open areas according to standard methods separately for non-combustible and combustible building materials.
If the product consists of several layers, the standard requires testing for the flammability of each layer.
Determinations of flammability are carried out on special equipment. If it turns out that one of the components is highly flammable, then this status will be assigned to the product as a whole.
The installation for carrying out experimental determinations should be located in a room with room temperature, normal humidity, and without drafts. Bright sunlight or artificial light in the laboratory should not interfere with readings from the displays.
Before starting to study the sample, the device is checked, calibrated, and warmed up. Then the sample is fixed in the holder of the internal cavity of the furnace and the recorders are immediately turned on.
The main thing is that no more than 5 seconds have passed since the sample was placed. The determination is continued until a temperature balance is achieved, at which the changes do not exceed 2 °C over 10 minutes.
At the end of the procedure, the sample along with the holder is removed from the oven, cooled in a desiccator, weighed and measured, assigning them to the flammability group NG, G1, and so on.
Flammability test method
All building materials, including finishing, facing, paint and varnish coatings, regardless of homogeneity or multi-layering, are tested for flammability using a single method.
Preliminarily prepare 12 units of identical samples with a thickness equal to real values during operation. If the structure is layered, samples are taken from each surface.
The samples are then kept at room temperature and normal ambient humidity for at least 72 hours, weighing periodically. Aging should be stopped when constant weight is reached.
The installation has a standard design and consists of a combustion chamber, an air supply system and the removal of released gases.
The samples are placed in the chamber one by one, measurements are taken, weight loss, temperature and amount of gaseous products released, and burning time without a flame source are recorded.
By analyzing all the obtained indicators, they determine the level of flammability of the material and its belonging to a certain group.
Application in construction
When constructing buildings, several different types building materials: structural, insulating, roofing, finishing with different purposes and loads. All products must have certificates available and be presented to potential buyers.
You should familiarize yourself with the parameters characterizing safety in advance and know exactly what each abbreviation and numbers can mean. The law requires the use of only materials of flammability group G1 or NG for the frames of building ceilings.