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Combustible substances and materials. What substances are called non-combustible Non-combustible organic substances

Today, mankind uses a wide variety of combustible substances. There are already quite a few types of them and they all have some kind of their own, unique characteristics. What are these substances? This is the raw material that can continue to burn after the ignition source is removed.

Gases and liquids

Today there are several groups of combustible substances.

You can start consideration with gases - the GG group. This category includes those substances that can be mixed with air, forming an explosive or flammable atmosphere, at a temperature not exceeding 50 ° C. In this group of gases, certain individual volatile compounds can be attributed. It can be ammonia, acetylene, butadiene, hydrogen, isobutane and some others. Separately, it should be said that this also includes vapors that are released during the evaporation of flammable liquids (flammable liquids), representing the following category.

The group of flammable liquids includes those liquid combustible substances that will continue to burn after the ignition source is removed, and their flash point does not exceed the threshold of 61 degrees Celsius for a closed crucible. If this vessel is of an open type, then the threshold will rise to 66 degrees. Such liquid substances include acetone, benzene, hexane, heptane, isopentane, styrene, acetic acid and many others.

Flammable liquids and dust

It would seem that fuel is the same thing, but in practice this turned out not to be the case. They are divided into two different categories. Even though their ignition parameters are the same and some liquids belong to both groups, there is a main difference. GZH also includes oil-based substances. This, for example, can be castor or transformer.

Next, it is worth mentioning such a combustible substance as dust. HP is a solid substance, which is currently in a finely dispersed state. Once in the air, such dust can form an explosive structure with it. If such particles settle on walls, ceilings and other surfaces, they can cause a fire.

HP classes

Separately, it is worth noting that there are classes of combustible substances and materials. For example, dust is divided into three categories depending on the degree of fire and explosion hazard.

The first class is the most dangerous aerosols, which have a lower explosive (flammable) concentration limit (LEL) up to 15 g / m 3. This includes sulfur, mill, ebonite or peat dust.
The second class includes those particles in which the LEL limit is in the range from 15 to 65 g/m 3 . They are considered more explosive.
The third category is the most fire hazardous. This is a group of liquid aerogels, in which the LEL is more than 65 g/m 3 and the autoignition temperature is up to 250 degrees Celsius. Such properties are possessed by tobacco or elevator, for example, dust.

General characteristics

What are combustible substances and why? There are several specific characteristics, with which liquid, dust, gases and other substances can be classified as combustible.

For example, the degree of flash is a value that characterizes the lower temperature limit at which the liquid will form flammable vapors. However, it should be noted here that the presence of a source of fire near such a vapor-air mixture will only cause its combustion, without a stable effect of burning the liquid itself.

If earlier it was said about the lower concentration limit, then there is also an upper one. NKV or VKVV are, respectively, the values upon reaching which, ignition or explosion of liquid, dust, gases, etc. can occur. All types of combustible substances have these limits. However, it is important to note here that if the concentration is lower or, conversely, higher than the specified limits, then nothing will happen even if there is a source of open fire in the immediate vicinity of the substance.

solid raw materials

Here it is worth mentioning that solid combustible substances behave somewhat differently than dust, liquid or gas. When heated to certain temperature this group of raw materials behaves individually, and it depends on its characteristics and structure. For example, if you take sulfur or rubber, then when heated, they first melt and then evaporate.

If we take, for example, coal or paper and some other substances, then when heated, they begin to decompose, leaving behind gaseous and solid residues.

Another very important point: the composition of combustible substances and their chemical formula strongly affects the direct combustion process itself. There are several stages into which this phenomenon is divided. Simple substances such as anthracite, coke or soot, for example, are heated and smolder without any sparks, as they chemical composition is pure carbon.

Complex ones include, for example, wood, rubber or plastic. This is due to the fact that their chemical composition is quite complex, and therefore there are two stages of their combustion. The first stage is a process of decomposition, which is not accompanied by the usual release of light and heat, but the second stage is already considered combustion, and at this time heat and light begin to be released.

Other substances and characteristics

Naturally, solids also have a flash point, but for obvious reasons, it is much higher than that of liquid or gaseous substances. Flash point limits are between 50 and 580 degrees Celsius. It should be said separately that such a common combustible material as wood has a threshold of 270 to 300 ° C, depending on the species of the tree itself.

Gunpowder and explosives have the highest combustion rate among solids. This is due to the fact that both of these substances have a sufficiently large amount of oxygen, which is quite enough for their complete combustion. In addition, they may well burn under water, underground, as well as in a completely sealed environment.

Wood

It is worth saying a little more about this combustible solid material, since today it is one of the most common. The reason for this is that it is one of the most affordable. Here it is worth mentioning that in fact wood is a substance with a cellular structure. All cells are filled with air. The degree of porosity of any rock exceeds 50% and increases, which indicates that the concentration of solid matter in relation to air is not too high. It is because of this that it lends itself to combustion quite well.

If we conclude, we can say that in the world there are a large number of various combustible substances that cannot be dispensed with in everyday life, but at the same time it is necessary to be extremely careful when using them, using them only for their intended purpose.

Insulation of residential buildings has been and remains a priority in a large-scale and individual construction. But insulation with soft materials also has a downside - it must be a non-combustible material, fireproof and environmentally friendly, since heat-resistant materials are needed when insulating many places in a structure, from the floor and walls to chimneys and ventilation.

Modern high-temperature thermal insulation is not only protecting housing from heat leakage to the outside, but also ensuring the safety of living, since refractory insulation reduces the risk of fires to zero. The versatility of such thermal insulation allows them to be used in industrial, industrial and domestic construction projects of any type.

How to classify non-combustible wall insulation, according to what parameters and characteristics, you need to know in more detail, since when choosing a fire-resistant insulation for different buildings, premises and operating conditions, it is necessary to take into account all possible risk factors.

Parameters and characteristics of heaters

The oxygen index characterizes the fire safety properties by displaying the minimum amount of oxygen per unit volume of the thermal insulation material. According to the values of the oxygen index, there are three thresholds for the flammability of heaters:

40% - composite polymers;
31% - non-combustible heat-insulating materials from fibrous and cellular components;
20% - combustible heaters.

Fibrous heat insulators are mainly represented by non-combustible heaters made of mineral substances, for example, glass or basalt. Such high-temperature thermal insulation is able to withstand temperatures of ˃ +500°C, therefore its use is recommended for highly specialized places and structures:

For insulation with cylindrical foil elements different kind pipelines;
For thermal insulation of PVC window and door frames with thin mats or slabs using the flashing method;
For insulation of walls, ceilings, floors and roofs with basalt materials.

According to GOST 4640-93, mineral heat-resistant wool can be stone, glass, slag, and according to the oxygen index (30%) it must belong to the NG class - non-combustible materials.

Thermal conductivity and moisture absorption of thermal insulation materials

Thermal conductivity is the main operational characteristic of any insulation. Thermal conductivity does not depend on the density of the material, so when choosing a heater, you should pay attention to this fact. The lower the thermal conductivity, the warmer the building or room protected by such insulation will be.

The next important parameter is moisture absorption. There is always water vapor in the atmosphere, and at a certain concentration in the insulation, they can turn into condensate, which immediately reduces the thermal conductivity properties. To prevent the formation of condensate, vapor barrier layers are used, for example, if it is a heater for a bath, where the humidity will always be high.

Fire resistance is the ability to resist open fire. This parameter is important for the chimney, for stoves and chimneys, as well as for other elements. heating system exposed to intense heat. In such risk areas, heat-resistant insulation should always be used - mineral wool, slag wool and similar materials.

The table shows the types of heaters that have high heat-resistant characteristics:

Properties	slag wool	glass wool	Mineral wool	BTV	BSTv
Maximum temperature, 0 С	≤ 250	-60/+450	≤ 300	-190/+700	-190/+1000
Ø, µm	4,0-12,0	4,0-12,0	4,0-12,0	5,0-15,0	1,0-3,0
Moisture absorption per day, ≤ %	1,95	1,75	0,095	0,035	0,025
prickly	There is	There is	Not	Not	Not
Binders for surface bonding	There is	There is	There is	There is	Not
, W/(m K)	0,40-0,48	0,038-0,046	0,077-0,12	0,038-0,046	0,033-0,038
The volume of binding components in the insulation, %	2,5-10	2,5-10	2,5-10	2,5-10	–
Flammability class (NG/G)	non-combustible material	non-combustible material	non-combustible material	non-combustible material	non-combustible material
Evaporation of toxins	There is	There is	There is	If a binder is used	Not
Heat capacity, J/kg K	1000	1050	1050	500-800	800-1000
Vibration resistance	Not	Not	Not	Not	There is
compressive strength, %	–	–	40	40	31,2
Elasticity, %	–	–	60	71	75,5
Deformation temperature, 0 C	250-300	450-500	600	700-1000	1100-1500
Fiber length, mm	16,0	15,0-50,0	16,0	20,0-50,0	50,0-70,0
Noise reduction coefficient	0,75-0,82	0,75-0,92	0,75-0,95	0,75-0,95	0,95-0,99
% in the aquatic environment	7,85	6,25	4,55	1,65	1,65
Chemical resistance (weight reduction), % in an alkaline environment	7,05	6,05	6,45	2,75	2,75
Chemical resistance (weight reduction), % in an acid environment	68,75	38,95	24,05	2,25	2,25

Mineral wool thermal insulation material is a non-combustible insulation that goes on sale in the form of rolls and mats. Slab mineral wool is easier to insulate the roof, floor surfaces and walls. Mats insulate pipelines and curved surfaces, industrial equipment and elements of building structures.

Mineral refractory wool is made from cullet glass, quartz sand, soda ash and other additives that form fibers when melted. Fibrous heat-resistant cotton wool is impregnated with resins and falls under the press. The insulation must have high heat resistance, mineral wool is an excellent non-combustible material, since its sintering occurs at a temperature of ≥ 1000 ° C. Because of this high parameter, the refractory material is effective for insulating saunas and baths, heat-resistant walls and partitions, for chimney chimneys, etc.

The most effective parameters that non-combustible mineral wool has:

Small coefficient of thermal conductivity;
High sound absorption coefficient;
High coefficient of vapor permeability.

Foam glass is a refractory material in terms of environmental friendliness with high temperature melting point (≥ 450°C), non-flammable. Foam glass production options:

Blocks (plates) have a width of 650 x 450 mm, 600 x 600 mm, 600 x 500 mm, a thickness of 30-120 mm, and are used to insulate vertical planes. Mounted on cement mortar with an offset, just like fireclay or silicate bricks;
Granulated foam glass is used as bulk insulating material;
Foam glass in the form of crushed stone, crumbs or battle of different fractions is also used as backfill.

Granules or crushed stone from foam glass are effective in insulating the floor and attic. The table shows the main characteristics of the material:

Characteristics and properties	Meaning
Dimensions (length, width), mm	475x400, 400x200, 400x250, 400x125	600x450
Thickness, mm in increments of 10 mm	60, 80, 100, 110	30-160
Density, 10%, kg / m 3	170-190	130
Thermal conductivity of dry insulation, W (m K)	0,08	0,046
Thermal conductivity of the condition "A", W (m K)	0,08	0,046
Thermal conductivity of condition "B", W (m K)	0,09	0,046
Vapor permeability, mg/(m h Pa), ≤	0,03	0,0005
Compressive strength, MPa	0,7	1,67
Bending strength, MPa	–	0,5
Moisture permeability during short-term and partial immersion, ≤	5%	0.5, kg / m 2
Moisture permeability during long-term immersion, kg / m 2, ≤	5%	0.5, kg / m 2
Operating temperature 0 С	-30/+400	-260/+480
Flammability group	NG (non-combustible material)	NG (non-combustible material)

Non-combustible electrical wiring

Electrical wires must comply with the following rules:

To be laid in non-combustible metal trays, cable channels, corrugated hoses or in non-combustible fabric;
The connection is made only by soldering, as well as using connectors or contact plates;
In rooms with high humidity, heat-resistant moisture-proof lamps are installed;
Wiring is done with a fireproof cable or wire.

The correct term is flame retardant cable or flame retardant cable. Fire-resistant cable (wire) can work not only in the wiring of buildings, but also in all kinds of fire extinguishing systems. The table contains a short list of the names of such products:

Aerated concrete blocks for wall insulation

Non-combustible insulation with high fire resistance parameters is aerated concrete with low density. For thermal insulation of walls, ceilings, floors and attics, aerated concrete blocks with density ≤ D 400.

There are two negative points when using such products:

A layer of insulation will be required more than usual. For example, the thickness of the mineral wool can be two times less than the layer of aerated concrete for the same quality of insulation. Therefore, the use of aerated concrete can have critical consequences for the insulation of small buildings or premises;

dry blocks

Blocks with 4% moisture

The accuracy of the geometric parameters of products in width - 0.7 mm, in length and height - 0.8 mm

Additional insulation of the aerated concrete layer is carried out with mineral wool - it is attached to the frame or in layers using dowels with wide caps. The disadvantage of such thermal insulation is that mineral wool will have to be protected by decorative finishing materials- siding, clapboard, etc.

Non-combustible substances and materials

"... 1) non-combustible - substances and materials that are unable to burn in air. Non-combustible substances can be fire and explosion hazardous (for example, or substances that emit combustible products when interacting with water, atmospheric oxygen or with each other);..."

A source:

Federal Law No. 123-FZ of July 22, 2008 (as amended on July 10, 2012) "on requirements fire safety"

"... - non-combustible material - a material that, when heated to 750 `C, does not burn and does not emit combustible gases in an amount sufficient for their self-ignition;..."

A source:

Ministry of Transport of the Russian Federation of 12.02.2004 N 12 "On fire safety rules during hot work on ships located at the berths of seaports and ship repair enterprises"

Official terminology. Akademik.ru. 2012 .

See what "Non-combustible substances and materials" are in other dictionaries:

non-combustible (non-combustible) substances and materials- Substances and materials that are not capable of burning in air. Non-combustible substances can be fire and explosion hazardous (for example, oxidizing agents or substances that emit combustible products when interacting with water, atmospheric oxygen or with each other) [GOST ... ... Technical Translator's Handbook

Substances dangerous- substances that have a potential hazard to humans. According to the potential danger, cause a fire, increase the dangerous factors of a fire, poison the environment (air, water, soil, flora, fauna, etc.), affect a person ... ... Russian encyclopedia of labor protection

fire retardant materials- materials whose reduced flammability is achieved special processing(fire protection). Fire protection methods include: applying a layer of non-combustible or low-flammable substances to the surface of materials; introduction to the composition ... ... Great Soviet Encyclopedia

Fire safety- This article should be wikified. Please format it according to the rules for formatting articles ... Wikipedia

Fire safety- Fire safety is a state of protection of an individual, property, society and the state from fires. " Fire safety"An illiterate phrase that occurs to mean "fire safety." Contents 1 ... ... Wikipedia

Nanotechnology- (Nanotechnology) Contents Contents 1. Definitions and terminology 2.: history of origin and development 3. Fundamental provisions Scanning probe microscopy Nanomaterials Nanoparticles Self-organization of nanoparticles The problem of formation ... ... Encyclopedia of the investor

combustibility- the ability of a substance, material, product to self-burning. According to G., substances, materials, products, structures are divided into: 1) combustible capable of self-combustion after the ignition source is removed; 2) slow-burning capable of ... ... Encyclopedia of technology

COMBUSTION- An exothermic reaction proceeding under conditions of its progressive self-acceleration. By combustibility, substances and materials are divided into three groups: non-combustible (non-combustible) substances and materials that are not capable of burning in air. Non-flammable substances ... ... Comprehensive security and anti-terrorist protection of buildings and structures

flammability Encyclopedia "Aviation"

flammability combustibility - the ability of a substance, material, product to self-burning. According to G., substances, materials, products, structures are divided into: 1) combustible - capable of self-combustion after the ignition source is removed; ... ... Encyclopedia "Aviation"

To determine the likelihood of a flame, the combustibility of substances and various materials is of primary importance. This characteristic determines the category of fire hazard of structures, premises, industries; allows you to choose the right means to eliminate foci.

The combustibility group of all the material components of the object determines the success of the fire fighting, 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 a classification based on quantitative indicators.

If the substance can burn, the combustibility group G1 is the most optimal for fire safety than G3 or G4.

Flammability has great importance for finishing, heat-insulating, building materials. Based on it, the fire hazard class is determined. So, drywall sheets have a flammability group G1, stone wool- NG (does not burn), and to insulate polystyrene foam belongs to the G4 combustibility group, and reduce it fire hazard the use of plaster helps.

Gaseous substances

Determining the flammability class of gases and liquids, the standards introduce such a concept as the concentration limit. By definition, this is the limiting concentration of a gas in a mixture with an oxidizing agent (air, for example), at which a flame can spread from the ignition point to any distance.

If such a boundary value does not exist, and the gas cannot spontaneously ignite, then it is called non-combustible.

Liquid

Liquids are called combustible if there is a temperature at which they can ignite. If the liquid ceases to burn in the absence of an external source of heating, then it is called slow-burning. Non-flammable liquids do not ignite at all in an air atmosphere under normal conditions.

Some liquids (acetone, ether) may flare at 28℃ and below. They are considered especially dangerous. Flammable liquids at 61 ... 66 ℃ and above are classified as flammable (kerosene, white spirit). Tests are carried out in open and closed crucible.

Solid

In the field of construction, the most relevant is the determination of the combustibility group of solid materials. It is preferable to use substances of the flammability group G1 or NG, as the most resistant to ignition.

Classification

The intensity of the combustion process and the conditions of its course determine the probability of intensifying the fire, the occurrence of an explosion. The outcome of the incident depends on the totality of the properties of the feedstock.

General division

According to the national standard of fire and explosion hazard, substances and various materials from them are divided into the following groups:

absolutely non-combustible;
difficult to burn;
combustible.

They cannot burn in air, which does not exclude interaction with oxidizing agents, with each other, with water. Consequently, some members of the group under certain conditions represent a fire hazard.

Hard-to-combustible compounds are compounds that burn when ignited in air. As soon as the source of fire is eliminated, combustion stops.

Combustible substances under certain conditions ignite themselves or in the presence of a source of fire, continue to burn intensively.

Classification by combustibility of building raw materials and products is considered in a separate updated standard. Building national standards take into account the categories of all types of products used in the work.

According to this classification, non-combustible building materials (NC) are divided into two groups depending on the test mode and the values of the indicators obtained in this case.

Group 1 includes products, in the study of which the temperature inside the furnace increases by no more than 50 ℃. The sample weight reduction does not exceed 50%. The flame does not burn at all, and the released heat 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 up to 20 seconds, the calorific value should not be more than 3.0 MJ / kg.

Flammability classes

Combustible materials are examined according to similar criteria, divided into 4 groups or classes, which are denoted 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 emitted 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 ℃. Loss of length fits into 65%, weight - 20%. The flame itself does not burn. Such building products are called self-extinguishing.

G2 includes a group of materials with a smoke temperature not exceeding 235 ℃. Loss of length fits into 85%, mass - 50%. Self-burning lasts no more than 30 seconds.

G3 refers to materials whose smoke temperature does not exceed 450 ℃. Loss of length is more than 85%, weight - up to half. The flame itself burns no more than 300 seconds.

The combustibility group G4 includes materials whose smoke temperature exceeds 450 °C. Loss of length exceeds 85%, weight loss - more than 50%. Self-burning continues for more than 300 seconds.

It is permissible to use the following prefixes in the name of each flammability group in order of increasing digital index:

weak;
moderately;
fine;
highly combustible materials.

The given flammability indicators, along with some other characteristics, must be taken into account when developing project documentation, budgeting.

The ability to form smoke, the toxicity of combustion products, the rate of possible spread of fire, 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 provides for a test for combustibility of each layer.

Flammability determinations are carried out on special equipment. If it turns out that one of the components has a high flammability, 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 displays.

Before starting the study of the sample, the device is checked, calibrated, warmed up. Then the sample is fixed in the holder of the inner 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 reached, at which the changes do not exceed 2 °C within 10 minutes.

At the end of the procedure, the sample together with the holder is removed from the furnace, cooled in a desiccator, weighed and measured, classifying them as flammability groups NG, G1, and so on.

Flammability test method

Everything Construction Materials, including finishing, facing, paint and varnish types of coatings, regardless of uniformity or multilayerness, are examined for combustibility by a single method.

Pre-prepare 12 units of identical samples with a thickness equal to the actual values during operation. If the structure is layered, samples are taken from each surface.

Then the samples are kept at room temperature and normal ambient humidity for at least 72 hours, periodically weighed. Holding should be terminated when constant weight is reached.

The unit has a standard design and consists of a combustion chamber, an air supply system and an exhaust gas exhaust system.

Samples are placed in turn into the chamber, measurements are taken, weight loss, temperature and amount of evolved gaseous products, burning time without a flame source are recorded.

Analyzing all the obtained indicators, determine the level of combustibility of the material, its belonging to a certain group.

Application in construction

When building buildings, several different types building materials: constructive, insulating, roofing, finishing with different purposes and loads. Certificates must be available for all products and presented to potential buyers.

You should familiarize yourself with the parameters that characterize security in advance, know for sure what each abbreviation and numbers can mean. The law requires that only materials of the combustibility group G1 or NG be used for building ceiling frames.

Substances and materials are combustible if they are able to ignite spontaneously, as well as ignite from an ignition source and burn independently after its removal.

In turn, all combustible materials are included in one or another combustibility group.

The essence of the method for determining combustibility groups is to determine the degree of damage to the material, the time of self-burning, the temperature of the flue gases at a fixed thermal effect on the samples in the combustion chamber.

Combustible building materials (according to GOST 30244), depending on the values of the combustibility parameters, are divided into four combustibility groups: G1, G2, G3, G4 in accordance with the table below. Materials belong to a certain combustibility group, provided that all the values of the parameters set by the table for this group correspond.

Flammability parameters
Combustibility group of materials	Flue gas temperature T, FROM	Degree of damage along the length S L ,%	Degree of damage by weight Sm, %	Duration of self-burning t c.r , from
G1	≤135	≤65	≤20	0
G2	≤235	≤85	≤50	≤30
G3	≤450	>85	≤50	≤300
G4	>450	>85	>50	>300

Note - For materials of combustibility groups G1 - G3, the formation of burning melt drops during testing is not allowed.

For testing in the FGBU SEU FPS IPL in the Republic of Mordovia, it is necessary to provide 12 samples with dimensions of 1000 × 190 mm. The thickness of the samples should correspond to the thickness of the material used in real conditions. If the thickness of the material is more than 70 mm, the thickness of the specimens shall be 70 mm. During the preparation of samples, the exposed surface should not be processed.

Testing of samples is carried out in the thermophysical laboratory at the Shaft Furnace test facility.

(1 - combustion chamber; 2 - sample holder; 3 - sample; 4 - gas-burner; 5 - air supply fan; 6 - combustion chamber door; 7 - diaphragm; 8 - ventilation pipe; 9 - gas pipeline; 10 - thermocouples; 11 - exhaust hood; 12 - viewing window).

During the tests, the temperature of the flue gases and the behavior of the material under thermal exposure are recorded.

After the end of the test, the length of the segments of the undamaged part of the samples is measured and their residual mass is determined.

The intact part of the sample is considered to be that which has not burned or charred either on the surface or inside. Soot deposition, discoloration of the sample, local chipping, sintering, melting, swelling, shrinkage, warping or change in surface roughness are not considered damage. The measurement result is rounded to the nearest 1 cm.

The undamaged part of the samples remaining on the holder is weighed. The weighing accuracy must be at least 1% of the initial mass of the sample.

Processing of the results is carried out according to the method of GOST 30244-94.

After testing and paying the cost of the test, the employees of the testing fire laboratory prepare reporting documentation.