Low-flammable substances and materials. What substances are called non-flammable Examples of non-flammable substances
Today, humanity uses a wide variety of flammable substances. There are already quite a few types of them and they all have their own unique characteristics. What are these substances? These are materials that can continue to burn after the source of ignition has been removed.
Gases and liquids
Today there are several groups of flammable substances.
You can start your consideration with gases - the GG group. This category includes those substances that can mix with air, forming an explosive or flammable atmosphere at a temperature not exceeding 50 ° C. This group of gases includes certain individual volatile compounds. This can be ammonia, acetylene, butadiene, hydrogen, isobutane and some others. It is worth mentioning separately that this also includes the vapors that are released during the evaporation of flammable liquids (flammable liquids), which represent the next category.
The flammable liquids group includes those liquid flammable substances that will continue to burn after the source of ignition is removed, and their flash point does not exceed the threshold of 61 degrees Celsius for a closed crucible. If this vessel open type, then the threshold will increase 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 flammable 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 combustion parameters are the same and some liquids belong to both groups, there is a main difference. Oil-based substances are also classified as GI. This, for example, can be castor or transformer.
Next, it’s worth talking about such a flammable substance as dust. GP is a solid substance that 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.
GP classes
It is also worth noting that there are classes of flammable 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, whose lower concentration limit explosiveness (ignition) (LEI) up to 15 g/m 3 . This may include sulfur, mill dust, ebonite or peat dust.
- The second class includes those particles for 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 auto-ignition temperature is up to 250 degrees Celsius. Tobacco or elevator dust, for example, has these properties.
General characteristics
What flammable substances are such and why? There are several specific characteristics, having which liquid, dust, gases and other substances can be classified as flammable.
For example, the flash degree is a value characterizing lower limit temperature at which the liquid will form flammable vapors. However, it should be noted here that the presence of a fire source near such a steam-air mixture will only cause its combustion, without a stable combustion effect of the liquid itself.
If earlier we talked about the lower concentration limit, then there is also an upper one. LVPV or VKPV are, respectively, values that, upon reaching, may cause ignition or an explosion of liquid, dust, gases, etc. All types of flammable substances have these limits. However, it is important to note here that if the concentration is lower or, conversely, higher specified limits, then nothing will happen even if there is a source open fire in close proximity to the substance.
Solid raw materials
It is worth mentioning here that solid flammable substances behave somewhat differently than dust, liquid or gas. When heated to a certain temperature this group raw materials behave individually, and this depends on its characteristics and structure. For example, if you take sulfur or rubber, when heated they first melt and then evaporate.
If we take, for example, coal or paper and some other substances, when heated, they begin to decompose, leaving behind gaseous and solid residues.
Another very important point: composition of flammable substances and their chemical formula strongly influences 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, heat up and smolder without any sparks, since they chemical composition is pure carbon.
Complex materials 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, solid substances also have a flash point, but for obvious reasons it is much higher than that of liquid or gaseous substances. Flash point limits range from 50 to 580 degrees Celsius. It is worth mentioning separately that such a common flammable material, like wood, has a threshold of 270 to 300 ° C, depending on the type of tree itself.
Gunpowder and explosives have the highest combustion rates among solid substances. This is due to the fact that both of these substances have enough a large number of oxygen, which is quite enough for their complete combustion. In addition, they can easily burn underwater, underground, or in a completely sealed environment.
Wood
It’s worth saying a little more about this flammable 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 saying 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 is increasing, which indicates that the concentration of solid matter in relation to air is not too high. It is because of this that it can burn quite well.
If we draw a conclusion, we can say that there is a large number of various flammable substances in the world, which cannot be avoided in life. Everyday life, but at the same time you must be extremely careful when using them, using them only for their intended purpose.
Non-flammable substances and materials
"...1) non-flammable - substances and materials that are unable to burn in air. Non-combustible substances can be fire and explosive (for example, substances that release flammable products when interacting with water, air oxygen or with each other);..."
Source:
Federal Law of July 22, 2008 N 123-FZ (as amended on July 10, 2012) "on requirements fire safety"
"...- non-flammable material - a material that, when heated to 750 `C, does not burn and does not emit flammable gases in quantities sufficient for their self-ignition;..."
Source:
Ministry of Transport of the Russian Federation dated 02/12/2004 N 12 "On fire safety rules when carrying out 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:
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COMBUSTION- An exothermic reaction that occurs under conditions of its progressive self-acceleration. Based on flammability, substances and materials are divided into three groups: non-flammable (non-combustible) substances and materials that are not capable of burning in air. Non-flammable substances... ... Comprehensive provision of security and anti-terrorist protection of buildings and structures
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Based on flammability, substances and materials are divided into the following groups:
1) non-flammable - substances and materials that are unable to burn in air. Non-flammable substances may be fire and explosion hazards (for example, oxidizers or substances that release flammable products when
interaction with water, air oxygen or with each other);
2) low-flammability - 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.
37. Measures to prevent the possibility of fires and explosions.
Fire prevention in design and construction industrial enterprise includes addressing the following issues:
· increasing the fire resistance of buildings and structures;
· zoning of the territory;
· use of fire breaks;
· use of fire barriers;
· ensuring safe evacuation of people in case of an emergency
· fire prevention;
· ensuring the removal of smoke from the premises in case of fire.
Under fire resistance understand the ability building structure resist influence high temperature in fire conditions and perform their normal operational functions. The time (in hours) from the start of testing a structure for fire resistance until the moment at which it loses its ability to maintain load-bearing or enclosing functions is called fire resistance limit . A loss bearing capacity is determined by the collapse of the structure, the loss of enclosing capacity is determined by the formation of cracks in the supporting structures, through which combustion products and flames can penetrate into adjacent rooms. The degree of fire resistance of buildings is determined by the fire resistance of its structures according to SNiP 21-01–97 “Fire safety of buildings and structures”. The fire resistance of buildings and structures can be increased by plastering structures, fire-retardant impregnation of wood with antipyrines - chemicals that make it non-flammable, and coating structures with fire-retardant paints.
Based on the degree of fire resistance, buildings and structures are divided into 5 main groups:
1st degree » The main elements are made of fireproof materials, and bearing structures have increased resistance to fire.
2nd degree » The main elements are made of fireproof materials (fire resistance limit of at least 2 hours)
3rd degree "C" stone walls and wooden plastered partitions and coverings
Grade 4 » Wooden plastered buildings
Grade 5 » Wooden buildings not plastered
Territory zoning consists in grouping enterprises into separate complexes of objects related by functional purpose and sign fire danger. In this case, structures with increased fire danger are located on the leeward side. Unimpeded passage of fire trucks to any building must be ensured. To prevent fire from spreading from one building to another, they are located at a certain distance from each other, called fire break . To limit the spread of fire inside a building, they are designed fire barriers . These include walls, ceilings, doors with a fire resistance rating of at least 2.5 hours. When designing and constructing buildings, it is necessary to provide escape routes workers in case of fire. IN production premises As a rule, there should be at least two emergency exits. The minimum width of the corridor or passage is determined by calculation, but must be at least 1.0 m. The width of the emergency exit industrial building accepted in
depending on total number people evacuating through this exit, and must be at least 0.8 m. Special literature also regulates other conditions for ensuring the safe evacuation of people in case of fire. Removal of gases and smoke from burning rooms is carried out through window openings, as well as aeration lamps and using special smoke hatches.
Elimination of conditions for the formation of a flammable environment:
1. Use of non-flammable substances and materials;
2. Limitation of mass and (or) volume of flammable substances and materials;
3. Use the most safe ways placement of flammable substances and materials;
4. Isolation of the flammable environment from ignition sources;
5. Maintaining a safe concentration of oxidizer and flammable substances in the environment;
6. Reducing the concentration of the oxidizer in the flammable environment in the protected volume;
7. Maintaining the temperature and pressure of the environment at which the spread of flame is excluded;
8. Mechanization and automation of technological processes associated with the circulation of flammable substances;
9. Installation of fire hazardous equipment in separate rooms or in open areas;
10. Application of protection devices production equipment preventing the release of flammable substances into the room;
11. Removal from premises, technological equipment and communications of fire hazardous industrial waste, dust deposits, and fluff.
Elimination of conditions for the formation of ignition sources in a flammable environment (or introduction into it):
1. Use of electrical equipment corresponding to the class of fire hazard and (or) explosive zone, category and group of explosive mixture;
2. Use of fast-acting agents in the design protective shutdown electrical installations;
3. Application of equipment and modes of conduct technological process, eliminating the formation of static electricity;
4. Lightning protection device for buildings, structures, structures and equipment;
5. Maintaining a safe heating temperature for substances, materials and surfaces that come into contact with a flammable environment;
6. Application of methods and devices for limiting the energy of a spark discharge in a flammable environment to safe values;
7. Use of spark-proof tools when working with flammable liquids and combustible gases;
8. Elimination of conditions for thermal, chemical and (or) microbiological spontaneous combustion of circulating substances, materials and products;
9. Elimination of contact with air of pyrophoric substances;
10. The use of devices that exclude the possibility of flame spreading from one volume to an adjacent one.
Fire extinguishing properties of water.
Water is the most common fire extinguishing agent. Once in the combustion zone, water heats up and evaporates, absorbing a large amount of heat. When water evaporates, a large amount of steam is formed, which makes it difficult for air to reach the combustion site.
A strong jet of water can knock down the flames, making it easier to extinguish the fire. Water is not used to extinguish alkali metals, calcium carbide, flammable and combustible liquids whose density less water, because they float and continue to burn on the surface
water. Water conducts well electricity, therefore it is not used to extinguish live electrical installations.
Carbon dioxide fire extinguishers
Carbon dioxide fire extinguishers(OU-2A, OU-5, OU-8) are used to extinguish electrical installations under voltage up to 1000 V and some materials.
When receiving substances and materials, application, storage, transportation, processing and disposal.
To establish fire safety requirements for the design of buildings, structures and systems fire protection classification is used building materials on fire danger.
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 diffusion combustion gas mixtures in the air, volume percentage | + | + | - | - |
| Critical surface heat flux density, 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) according to fire danger
The classification of substances and materials by fire hazard is based on their properties and ability to form fire or explosion hazards.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, combustible building 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 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 | 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) the average length of the charred section 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
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, ethanol, 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, oils: 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 LEL value of more than 65 g/m 3 and a self-ignition temperature of more than 250 °C ( sawdust, zinc dust).