Flammable and hardly combustible liquids, solid combustible and hardly combustible substances and materials (including dust and fibers), substances and materials that can only burn when interacting with water, air oxygen or with each other, provided that the premises in which they are (address) are not categorized or.
Premises of category B1 should be equipped with automatic fire protection systems in accordance with the requirements of SP 5.13130.2009 "Fire protection systems. Automatic fire alarm and fire extinguishing installations. Design rules and regulations":
Buildings should be equipped with an automatic fire extinguishing system:
- warehouses of category B for fire hazard with storage on racks with a height of 5.5 m and more - regardless of the area and number of storeys.
- warehouses of category B for fire hazard with a height of two floors or more - regardless of the area.
An automatic fire extinguishing system should be equipped with the following premises:
- warehouse designation of category B1 for fire hazard (except for premises located in buildings and structures for processing and storage of grain) when they are located in the basement and basement floors - regardless of the area.
- for warehouse purposes of category B1 for fire hazard (except for premises located in buildings and structures for processing and storing grain) when they are located in above-ground floors - from 300 m 2 and more.
- for industrial purposes of category B1 in terms of fire hazard (except for premises located in buildings and structures for processing and storing grain) when they are located in the basement and basement floors - regardless of the area.
- for industrial purposes of category B1 in terms of fire hazard (except for premises located in buildings and structures for processing and storing grain) when they are located in above-ground floors - from 300 m 2 and more.
The premises should be equipped with an automatic fire alarm system:
- warehouse designation of category B1 for fire hazard (except for premises located in buildings and structures for processing and storage of grain) when they are located in the above-ground floors - less than 300 m 2.
- for industrial purposes of category B1 in terms of fire hazard (except for premises located in buildings and structures for processing and storing grain) when they are located in the above-ground floors - less than 300 m 2.
Buildings and premises of category B1 should be equipped with fire warning and control systems for people in accordance with the requirements of SP 3.13130.2009 "Fire protection systems. Warning and evacuation control system in case of fire. Fire safety requirements".
- SOUE type 1 it is necessary to equip production and warehouse buildings, parking lots, archives, book depositories (building category B by fire hazard) with the number of floors not exceeding one. It is allowed to combine the warning system with intercom.
- SOUE type 2 it is necessary to equip production and warehouse buildings, parking lots, archives, book depositories (building category B for fire hazard) with the number of floors from 2 to 8.
- laboratories;
- pantries;
- utility room;
- archives.
Who determines the class of explosion hazard of areas in the premises
Specialists from the design organization - a technologist or an electrical engineer - will help to determine which category of the PUE the room belongs to. First of all, the foreman will determine the presence and number of zones in the room that are different in terms of explosion and fire hazard.
In this case, the following criteria are taken into account:
- the name and characteristics of the explosive and fire hazardous substances and materials stored in the room;
- the quantitative volume of the explosive mixture relative to the free volume of the room;
- availability of technological equipment, during the operation of which it is possible to release GH or flammable liquids;
- footage of the room;
- other explosive factors.
The classification of explosive and fire hazardous zones and the categorization of premises are carried out at the stage of development of design documentation, even before the start of construction work at the facility.
Classes of hazardous areas of premises according to PUE
On the basis of whether a leak of an explosive mixture is possible during the operation of technological equipment, classes of explosive zones are distinguished in the room.
They also take into account the likely duration and frequency of the presence of the mixture in the room, setting 3 types of leakage depending on this: constant, 1 and 2 degrees.
Explosion hazard zones in a room are classified as follows:
- 0 - the presence of a hazardous gas mixture is observed for 1 hour or more;
- B-I - explosive mixtures are formed during normal operation of the equipment;
- B-Ia - explosive mixtures are formed in the event of equipment malfunction or as a result of an accident;
- C-Ib - the same, if GG have a lower concentration limit (NPKV) of 15% or more, a pungent odor, as well as production facilities that are associated with the circulation of hydrogen;
- B-Ig - areas near outdoor installations with GG, flammable liquids;
- В-II - during normal operation of the equipment, explosive mixtures are formed in a concentration of 65 g (or less) per 1 cubic meter;
- B-IIa - the formation of an explosive mixture in a concentration of 65 g (or less) per 1 cubic meter. possible due to equipment damage or accident.
The Rules contain exceptions that are possible when defining hazardous areas. The PUE describes in detail each class of the zone, and also gives the classes of zones of rooms adjacent to the explosive zone of another room.
Classes of fire hazardous zones according to PUE
According to the danger of fire in various zones of the premises, they are divided into 4 classes:
- P-I - zones in rooms where GZ are located, having t flashes above 61 degrees;
- P-II - areas in rooms where it is possible to release combustible dust or fibers with NPKV above 65g per cubic meter;
- P-IIa - zones in rooms where solid GW are located in such an amount that the specific fire load is equal to 1 MJ per 1 square meter. or more;
- P-III - zones outside the room where GJ circulate, having t flashes above 61 degrees. (or solid GW).
Categories of premises for explosion and fire hazard
The categorization of premises according to PUE is carried out based on the characteristics of substances and materials that are circulated in the room. In total, 5 main categories are distinguished, which have a letter designation - from A to D, in order of decreasing explosion and fire hazard.
- Premises of category A have an increased explosion and fire hazard due to the fact that they contain highly flammable gases and flammable liquids.
- Category B - explosive and fire hazardous premises.
- Category B - fire hazardous premises. 4 subcategories - B1 - B4, which are determined by the value of the specific fire load.
- Premises of category G are characterized by a moderate fire hazard, non-combustible substances (materials) circulate in them in a hot, incandescent or molten state.
- Category D - premises with reduced fire hazard - non-combustible substances (materials) are used in a cold state.
The category of the room determined according to the PUE, as well as the class of the zone, is indicated on a plate that is hung on the front door. For example, a plate with the designation "A / B-I" indicates that the room is characterized by an increased fire and explosion hazard and, during normal operation of the equipment, explosive mixtures are formed in it.
Approximate price for calculating fire hazard categories
| Room area | Fire hazardous (B1, B2, B3, B4, G, D) | Explosive (A and B) |
| less than 100 m2 | up to 25 rubles / m2 | up to 60 rubles / m2 |
| 101 - 200 m2 | up to 18 rubles / m2 | up to 45 rubles / m2 |
| 201 - 300 m2 | up to 15 rubles / m2 | up to 35 rubles / m2 |
| 301 - 400 m2 | up to 10 rubles / m2 | up to 30 rubles / m2 |
| 401 - 1000 m2 | up to 8 rubles / m2 | up to 25 rubles / m2 |
Departure of a specialist - free
is freeStages of work
Visit of a specialist to the object
At a convenient time for you, our specialist goes to inspect your object (the visit of a specialist is free). Based on the results of the inspection, a commercial proposal is drawn up for the calculation of categories.
Conclusion of an agreement to determine the categories of premises for explosion and fire hazard and the zone class according to PUE.
Delivery to the customer
You will receive a report on the determination of the categories of premises for explosion and fire hazard and the zone class according to PUE.
The choice of fire protection option depends on the category of fire hazard: fire extinguishing (hundreds of thousands of rubles), fire alarms (tens of thousands of rubles) or simply primary fire extinguishing means (fire extinguisher from 500 rubles). You can familiarize yourself with the calculation of the fire hazard category in more detail in this section.
Measures to ensure fire safety are taken even at the design and construction stage of production, warehouse and office premises, which must comply with certain legislative norms and rules. The calculation of the categories of premises for fire safety allows you to determine how to protect a particular place from fire in accordance with its purpose. During the reconstruction or modernization of production, similar calculations are also performed.
Each room is assigned a specific security category. After the completion of construction or changes in the design of buildings and premises, installation of equipment, the owner or tenant of real estate is obliged to create a fire safety system. The group of companies "ExpertPartner" performs in St. Petersburg all the necessary work on the design, installation, service and repair of fire systems, taking into account the category of premises and facilities.
Fire and explosion hazard categories:
- Increased (A): premises where flammable liquids and combustible gases, substances, materials are stored. Their total number and production volumes for which they are needed are taken into account. If there are automatic fire extinguishing installations in the room, then the hazard category is reduced;
- Explosion hazard and fire hazard (B): it includes premises where there is a flammable liquid and combustible dust with a flash point from 28 to 61 degrees;
- Fire hazard or category B1 - B4: poorly burning liquids, materials that can ignite from contact with water or oxygen in the air are stored in the premises;
- Moderate hazard (D): This category of rooms contains materials in a molten, hot state, including non-combustible. They also include various substances burned in the form of fuel;
- Reduced fire hazard (E): all rooms containing non-flammable substances, materials in a cold physical and chemical state
Category calculation parameters
The calculation takes into account: the geometry and dimensions of the room, the volume of materials and substances that can cause a fire or explosion (taking into account the height and area they occupy). The material of the floor and ceiling in this room also affects. According to the "Rules for the installation of electrical installations", the class of zones in the room is determined: division into zones according to the categories of explosion or fire hazard. In the presence of equipment, it is necessary to provide protection from fire for the power supply circuit of machines and devices by placing the electrical circuit in a special explosion-proof housing.
Having performed the calculation of the categories of premises for fire safety even at the construction stage, creating an effective fire alarm, you can ensure the necessary level of safety, preventing human casualties and significant material damage.
This time I will share my thoughts on calculating room categories B1-B4.
Despite the seeming simplicity of Appendix B of SP 12.13130.2009, concerning the definition of the category B1-B4 of premises, there are several points in this document that I would like to draw your attention to.
The correct definition of the category of the premises allows not only to apply adequate fire safety requirements, but also allows, in some cases, to have a positive economic effect in the design of fire protection of an object.
But some provisions of SP 12.13130.2009 at this stage do not allow to fully adequately assess the fire safety of the facility.
So, the room belongs to category B1-B4 if it is accessed by:
- flammable and hardly combustible liquids,
- solid combustible and hardly combustible substances and materials (including dust and fibers),
- Substances and materials capable of only burning when interacting with water, atmospheric oxygen or with each other.
At the same time, according to the calculation results, this room should not be classified as category A or B for explosion and fire hazard.
The assignment of a room to the B1-B4 category is based on a comparison of the specific fire load with the limit value in a particular area.
For premises that, according to the results of the calculation, should be classified as category B4 in terms of fire hazard, it is necessary to compare the distances between the sections with the limiting ones, and the area of the sections with a fire load should not exceed 10 m 2.
Often, without calculating whether the premises belong to category A or B, but only by the properties of the circulating substances and materials, it can be established that the premises will belong to any of the categories B1-B4.
Let me give you an example.
Diesel fuel with a flash point of 55 ° C is stored in the warehouse. According to SNiP 23-01-99 "Construction climatology" for the area under consideration, the maximum temperature is 35 ° C, the temperature in the room is not maintained and cannot rise as a result of any accident.
In this case, it is not necessary to calculate whether the premises belong to either category A or category B, since:
- the flash point of diesel fuel exceeds 28 ° С;
- the ambient temperature is lower than the flash point of diesel fuel.
In principle, the calculation of premises of category B1-B4 is reduced only to finding the heat of combustion of specific substances and materials in the presence of all other data concerning the features of the location of the fire load.
At the same time, SP 12.13130.2009 does not clearly define how the area of the fire load is determined.
I mean, it is not entirely clear at what distance between the sections they can be considered separate sections, and at what distance they will be considered one section.
As practice shows, someone takes the area occupied by combustible materials, someone takes into account the area under the shelving sections (along with the aisles). Those. There is no unified approach among engineers and designers on this matter.
If you read SP 12.13130.2009 directly, it turns out that you need to take only the area that is under fire load. At the same time, for premises of category B1-B3, the maximum distance is not entered.
What results this leads to, I will show with an example.
There are two areas with a fire load in the room: the first is wood with a total weight of 1000 kg on an area of 30 m 2, the second is polypropylene with a total weight of 1200 kg on an area of 20 m 2. The heat of combustion of wood and polypropylene is assumed to be 13.8 and 44 MJ / kg, respectively. In this case, we obtain two sections with a specific fire load equal to 460 and 264 0 MJ / kg, respectively.
In this case, the premises will be categorized as B1 in terms of fire hazard.
Consider a situation in which these materials are located in separate stacks close to each other. In this case, there will already be one section for placing the fire load.
The specific fire load in this case will be equal to 1332 MJ / m 2. The room category will already be either B3 or B2.
Similar problems arise quite often for warehouses, in which both rack and floor storage is practiced. When placing the same materials in the form of identical products, it may turn out that in the composition of one large area it will be possible to distinguish several areas with a specific fire load that significantly exceeds the maximum for this category of fire hazard.
Another important point is bringing the premises to category B4 for fire hazard.
In some cases, assignment of a room to this category allows not only to get away from fire extinguishing, but also from fire alarm systems. But it is not for nothing that the developers have laid down such strict requirements in the joint venture regarding the classification of the premises as category B4. For such premises, as mentioned above, the following conditions must be met simultaneously:
- specific fire load in the areas should not exceed 180 MJ / m 2;
- the area of the plots should not exceed 10 m 2;
- the distance between the sections should be more than the limiting ones.
The last point deserves, in my opinion, special attention. Let me explain why.
First, the joint venture gives the value of the critical heat flux for a very limited list of substances and materials, most of which are no longer found in production. In the domestic literature, you can find all the same plate as in the joint venture, and there are still no benefits to the joint venture, but it may soon appear ...
Secondly, the joint venture does not provide for a decrease in the limiting distances by placing any fire barriers, for example, screens, between the areas where the fire load is located. Agree, it is much cheaper to make a screen made of non-combustible materials than to mount a fire extinguishing system at the facility and provide for other measures.
Finally, I would like to note that the information provided here is not a reason for deviating from the requirements of the joint venture itself, as well as from the calculation methods set forth in it. Whatever the document is, at the moment we should be guided by what we have.
The critical density of incident radiant fluxes for some substances and materials will be given in the next article.
For all fire safety measures, it is important to assess the premises. After all, the occurrence and rate of spread of fire directly depends on the combustibility of the materials that are in the structures, as well as on the technological nuances of production at the facilities.
Main classification
Depending on the materials, liquids or gases in buildings, 5 degrees of danger are emitted. At the same time, the categories of premises are also evaluated separately. When dividing them according to the degree of danger, the presence of flammable substances in them and their quantity are taken into account. Also, an important role is played by the characteristics of technological processes that take place in these premises.
The fire hazardous properties of materials are determined as a result of research and calculations according to established rules, depending on the surrounding parameters.
Category A
The greatest attention is paid to structures and premises, which are assigned a class of increased explosion and fire hazard. It depends on the substances and materials inside.
So, category A is assigned to those rooms in which flammable liquids and flammable gases are located. At the same time, their flash point is not more than 28 o C. To assign such a category of premises for fire hazard, it is necessary that the indicated substances are stored there in an amount that will be sufficient for the formation of explosive vapor-air mixtures. When ignited, an overpressure exceeding 5 kPa must develop.
Also, this category is assigned if there are materials or other substances in the room that can burn or explode even when interacting with oxygen from the air, water or among themselves. In this case, the generated overpressure must exceed 5 kPa.
Examples of class A premises
The easiest way to figure out how exactly the hazard category of a room is determined is to consider which structures are classified as class A. So, this group includes:
- warehouses where fuels and lubricants, gasoline and containers intended for their maintenance are stored;
- stations designed for the production, storage, processing, pumping and spilling of flammable liquids (flammable liquids);
- points for processing and washing containers from flammable liquids;
- acetylene and hydrogen stations;
- stationary alkaline and acid battery installations;
- pantries and paint shops, in which solvents, varnishes, nitro-paints and other flammable liquids are used, the flash point of vapors in which is less than 28 ° C.
Professionals should be aware of which substances fall into the indicated category. So, they include acetylene, hydrogen, natural gas, vapors of nitro-solvents and gasoline.
Hazard class B
But these are not all categories of premises that are considered fire hazardous. True, one must understand that class A structures are those buildings that belong to the group of increased explosiveness. The next group is less scary.
Rooms of category B include those in which flammable liquids are stored, the flash point of which is over 28 ° C, flammable liquids, fibers and dust. In this case, the condition must be met that their number is sufficient for the design pressure to exceed 5 kPa during ignition.
Examples of category B premises
There is a fairly large list of buildings and structures that can be safely attributed to class B. The specified fire category of the premises can be assigned:
- workshops where the preparation and transportation of coal dust, powdered sugar, wood flour is carried out;
- production facilities for the production of hay flour, grinding and bagging areas of mills, grain grinders;
- workshops that specialize in painting and use paints, varnishes with a flash point of more than 28 ° C, and places for their storage;
- diesel fuel warehouses, pumping, unloading racks for its pumping;
- ammonia refrigeration units;
- fuel oil facilities of boiler houses and power plants;
- industries engaged in the manufacture of products from fiberglass and plastics.
Also, category B can be assigned to those rooms in which parts are washed and wiped using kerosene or gasoline. It also includes washing stations, where they are engaged in cleaning tanks from diesel fuel, fuel oil and other substances, the flash point of which is more than 28 ° C.
Class B buildings
The following categories of premises for fire hazard are no longer so scary. So, for buildings, warehouses and other structures that belong to class B, other requirements are put forward. These premises include those in which there are flammable or hardly combustible materials, substances, liquids. They are capable of burning only when interacting with air, water, among themselves, but at the same time they do not belong to category A or B.
For each room, a subgroup can also be allocated within the limits B1-B4. It is determined depending on the location of the fire hazard and its concentration.
Examples of class B premises
The following can be classified as buildings, structures of category B:
- joinery, sawmills, woodworking or combined workshops;
- peat warehouses, coal racks, closed storage areas for coal, fuel and lubricants, with the exception of gasoline;
- grain cleaning areas of mills, feed kitchens;
- workshops where primary dry processing of cotton and flax is carried out;
- textile, garment factories, paper industry workshops;
- warehouses for oil paints and varnishes, diesel fuel;
- oil and lubrication facilities of factories;
- car garages;
- libraries, archives, dressing rooms;
- bitumen and asphalt plants;
- transformer substations.
At the same time, it is important to understand that one and the same structure can be assigned to different hazard classes. This is due to the fact that the definition of the category of the premises is carried out on the basis of what can be the maximum possible concentration of hazardous substances. The calculation is made for each specific conditions individually.
Category D, D
The safest are those premises that are assigned to the last two groups. In buildings of category G, there may be non-flammable materials and substances in a hot, molten or simply hot state, as well as solids, liquids or flammable gases. They can be processed with heat, flames or sparks and are used as fuel.
Examples of buildings of class D and D
The safest are the premises of category G and D. The specialists include the following in the first group:
- metal stamping and hot rolling shops;
- roasting shops located in brick, lime kiln, cement plants;
- forges, boiler rooms, engine rooms of diesel power plants;
- welding, smelting, foundry, forging shops;
- departments specializing in the repair of internal combustion engines.
- departments of cold rolling of metals;
- irrigation pumping, blowing, compressor stations;
- workshops for processing meat, fish, dairy and meat products;
- greenhouses, except for those heated by gas.
Definition of building categories A and B
Before assigning a certain hazard class, experts inspect all premises. Based on the summarized volume of areas and the categories assigned to them, it is determined to which group the entire building belongs. The calculation is carried out based on certain standards.
So, for example, class A will be assigned if the premises of category A occupy more than 5% of the total area or 200 m 2. If their total number does not exceed 25% (but not more than 1000 m 2) and they are equipped with automatic fire extinguishing installations, then the building will not be classified as group A.
If the security categories of premises were established and it was determined that more than 5% of the total area or 200 m 2 belong to class A and B in the building, then it can be assigned to group B. However, this is possible if it cannot be attributed to category A. The situation is different in cases where the premises are equipped with automatic fire extinguishing installations. Class B will not be assigned if the summed areas belonging to categories A and B do not exceed 25% or 1000 m 2.
Buildings belonging to hazard classes C, D, D
It is not enough to know how the determination of the category of the premises is carried out. In most cases, it is important to assign a fire rating to the entire building. So, if the total area of premises that are classified as categories A, B, B1, B2, B3 is more than 5% (or more than 10% if there are no areas related to groups A and B), then the structure will be classified as class B. But this is possible only on condition that it does not belong to category A or B. True, a building will not be assigned to group B if the number of the indicated areas is not more than 25% or 3500 m 2 and it is equipped with automatic fire extinguishing installations.
If it was determined that in the building the categories of premises for explosion and fire hazard are divided between groups A, B, B1-C3, D, and their total number exceeds 5% of the total area, then it can be attributed to class D. If the structure is equipped with automatic extinguishing devices fires, then it will not be attributed to group D, provided that the total area of premises A, B, B1-B3, D is not more than 25% or 5000 m 2.
Determination method
In order to find out how dangerous a building is, it is important to understand what categories of premises prevail in it for explosion and fire hazard. To begin with, select and justify the required design option. It is determined according to a certain method. The calculation is based on the assumption that in the event of an emergency, the most dangerous option will develop.
It is important to determine what amount of substances that can form explosive mixtures can enter the room. Experts carry out calculations for situations when:
- an accident occurs in one of the vehicles;
- all the contents of the device go into the room;
- there is a leak from the pipelines that power the device for the period that is necessary to turn them off;
- the evaporation of liquid begins from the surfaces on which it has spilled, which have been freshly painted, and from containers.
In order to correctly determine the fire category of the room, it is necessary to take into account not only the possible amount of combustible air mixtures, but also the free volume of the room. It is defined as the difference between its total capacity and the space occupied by all the technological equipment located there. If it is impossible to calculate it, then it is considered that it accounts for 80% of the total.
After selecting the required design option, the possible overpressure is directly determined. For flammable substances, gases, flammable liquids, special formulas are used. The categories of premises are determined based on what kind of atoms of combustible substances will be in the room. In this case, the maximum possible indicator is taken as the design temperature. Also take into account the mass of combustible gases, liquids, their coefficient in combustion, initial and maximum possible pressure. The formula also includes the volume of the room.
Classification of residential buildings
As a rule, the calculation of categories of premises for fire safety is carried out for warehouses, workshops, production facilities and other industrial facilities. It is not used for residential properties. This is due to the fact that, as a rule, they do not store explosive substances, flammable liquids and materials.
But it will not be superfluous to find out that the category of living quarters for electrical safety can be determined. This also affects the likelihood of fires. For example, in rooms with high humidity, there can be problems when using unprotected electrical appliances and their control devices. So, the dangerous areas include kitchens, verandas, vestibules, attics, attics of heated houses, sheds, sheds, cellars, hotbeds, greenhouses.
