The construction of various buildings, which should be really solid and durable, provides for the need to ensure not only the mechanical strength of the installed structures and resistance to various influences from the outside, but also protection from the possible occurrence of fires, and therefore the applicable fire hazard classes were even established in the current legislation . A competent project involves taking into account a large number of factors that accompany the standard "mechanical" sopromat.
Relevance of the problem
Of course, to avoid premature loss of material properties, which could lead to critically irreversible deformation, maximum allowable loads and various weather conditions should be taken into account, but along with this, one of the most important factors that should be taken into account during the design process any room is what it will include fire hazard classes. After all, even at the time of project development, you need to decide on possible risk factors and available ways to eliminate them.
Not everyone correctly understands that the fire hazard classes of a building depend not only on what materials are used to erect load-bearing structures or floors of a building, and not even on how flammable and combustible materials were used in the decoration of the premises. A news digest regarding emergencies over any period of time always indicates that in the overwhelming majority of cases, such problems arise from an explosion, and in particular this relates to an explosion of domestic gas. There are also many other reasons, examples of which can be found even in everyday life, and on which classes of fire the buildings are divided, it directly depends on where a person can really feel safe, and where there is a threat to him even from other people, making various mistakes.
At the household level, everyone approximately understands how dangerous sparking wiring is, as well as household appliances and heating devices that, if improperly maintained or used, can ultimately lead to a fire. At the same time, one should not forget that such situations are the result of negligence or carelessness, by analogy with how a fire can occur in a large-scale production due to smoldering of an improperly folded oiled rag.
What it is?
Fire hazard classification of premises in accordance with official documents is based on planned factors. They do not depend on any accidental events, as well as carelessness or malicious intent on the part of a person. Fire hazard itself is an objective characteristic that must be taken into account in order to avoid the possibility of fire with the further development of large fires.
In modern production facilities, quite often you can find various substances that, when mixed with air, provoke the danger of not only fires, but also explosions. This includes all kinds of flammable gases, as well as flammable and flammable liquids. A special role in this case is given to inorganic compounds, which include, in particular, nitric acid, fertilizers, soda, as well as many other substances. Classification of premises for fire hazard also includes production, in the technological cycle of which the presence of dusty combustible materials is provided. With rapid ignition, they can also explode. It is not for nothing that modern standards are more and more often beginning to use the combined concept of “fire and explosion hazard”.
Categories
The use or storage inside a certain room of flammable or explosive materials under certain conditions provides for their division into fire hazard categories. There are five in total.
Category A
Fire hazard category A provides for a possible explosion of various combustible gases or flammable liquids, which themselves can form vapor-gas fire hazardous mixtures. The maximum flash point of mixtures that belong to this category in accordance with current standards is not more than 28 ° C, and therefore the operation mode of such production facilities is under especially close control, and also requires the adoption of regular and timely safety measures.
Various materials and substances that can burn or explode when interacting with each other, as well as in contact with oxygen or water, are also grounds for the fire hazard of the premises to be equal to category A.
Category B
Fire hazard category B provides for steam and air or dust-air mixtures with a flash point exceeding 28 ° C as the main hazard factor. Such production facilities are characterized by the fact that in them the cause of a possible fire or explosion are all kinds of combustible fibers and dust, as well as flammable liquids.
Category B
The fire hazard categories themselves, which do not provide for the possibility of an explosion, include the following three categories. Category B is assigned mainly to various production facilities that use slow-burning or combustible substances and materials that are in solid or liquid state. Any materials and substances that are located in enterprises with this hazard class should in no case be a threat of explosion and can only burn if there is interaction with oxygen, water or with each other. If an object is assigned category B for fire hazard, then this indicates that the substances in the premises do not belong to the previous two categories. This is a rather important condition - such materials should be completely absent at the enterprise.
Category D
It is assigned to those rooms in which the technological cycle provides for the processing of non-combustible materials and substances. In this case, the fire hazard is due to the fact that non-combustible substances, being in a hot, hot or molten state, emit sparks, flame or radiant heat. The use of fuel is another reason for the category G to be assigned to a certain object. In addition, it is customary to assign it if the territory of production utilizes or burns flammable liquids, gases or solids.
Category D
Fire hazard categories are completed by category D. It is mainly intended for those industries where non-combustible substances and materials are used in the cold state. In other words, there is practically no fire hazard here.
Dangerous objects
Fire category is an important factor. In accordance with it, the basic requirements for the layout and design of the room, as well as the mode of production and use of this facility are determined. Category accounting is carried out in the process of organizing specialized fire protection. This primarily refers to the prescription of its necessary technical equipment. The fire hazard category also makes requirements for the disposition of various fire hazardous premises located on the territory of this enterprise. This characteristic largely determines the necessary planning and construction measures to ensure security, regulates the exact order of placement regarding each other and other objects of the enterprise, as well as structures and buildings with a high probability of fire.
Main objects
Among the objects in which there is an increased fire hazard of the premises, it is worth highlighting the following:
- various oil refineries, as well as production facilities operating in the pulp and paper or chemical industries;
- enterprises where various products of oil or gas processing are used as energy carriers or raw materials;
- oil and gas pipelines;
- any means of transport that transport flammable or explosive materials;
- terminals of specialized fueling stations;
- all kinds of food industry enterprises;
- enterprises that use a variety of paints and varnishes;
- military and any production warehouses that contain fire and explosive substances or materials.
Fire hazard
Fire in various enterprises, as in principle in the conditions of the modern electrified world, in the majority of cases occurs due to various damage to the wiring, as well as to units and machines under high voltage. Among other things, the standard fire hazard zones are characterized by possible malfunction of heating systems, furnaces, tanks containing flammable liquids, as well as many other emergency situations.
Reducing the real fire hazard of the room is quite possible - it is enough to simply limit the total number of simultaneously used and stored combustible materials or substances. It is also recommended to use specialized sealed containers and equipment. The fire hazard of the premises is reduced due to the arrangement of emergency discharge of various flammable liquids. The installation of special means and barriers also excludes the possibility of spillage or spreading of flammable liquids in case of fire.
Among other things, it is possible to reduce the fire hazard of a room by regularly cleaning not only the building itself, but also communications and surfaces, as well as by regulating workplaces where the use of hazardous materials is provided. Prevention includes the implementation of systematic operational, technical, organizational and operational measures, which should be closely monitored by the enterprise management.
Classes
Ultimately, it is worth considering possible fire hazard classes in comparison with the already specified characteristics of industrial premises. You also need to correctly understand that this concept differs from the above categories, which are aggregate, integral characteristics, as well as fire hazard itself, as a real factor working in a certain place and depending on the implementation of the established safety regulations.
The class of the room is a category complementary to the concept, which is a differential characteristic of the premises regarding the risk of the corresponding situations in them. Classification of this kind is carried out both individually in relation to each element of the production system, and in general for all its components, which can affect the possible appearance and further development of a fire. It is worth noting that in accordance with the requirements established by applicable law, several classes for substances, equipment, materials, electrical wiring, as well as various structural elements, are distinguished.
Thus, combustible dust can be divided into four main classes:
- The most dangerous aerosols that have a lower concentration limit corresponding to a real ignition risk of less than 15 g per cubic meter of air. In particular, among such substances, rosin, sulfur, peat dust, naphthalene, as well as ebonite and mill dust can be distinguished.
- Explosive substances are aerosols in which the lower concentration limit is at the level of 15-65 g for each cubic meter of air. Such substances include aluminum powder, lignin, as well as flour, hay and shale dust.
- The third class includes the most flammable substances - aerogels, in which the lower concentration limit exceeds 65 g per cubic meter of air, and the ignition temperature is less than 250 ° C. To illustrate such substances, we can mention tobacco and elevator dust.
- The last, fourth class of fire hazard includes aerogels with a NPCV level of more than 65 g / m 3 , and at the same time an ignition temperature of 250 ° C. The most common representatives of this class are wood sawdust and zinc dust.
The greatest importance in the concept of fire hazard class is given to the classification of various fire hazard zones of the enterprise. It is customary to define such zones as a space that is inside or outside its premises, in which various combustible substances and materials are periodically or constantly circulating.