Classification of fires: classes of fire and its varieties

Today there is a specialdeveloped standard establishing the symbols and classes of fires - GOST 27331-87. This document allows you to determine the type of combustion process and select the most effective means for extinguishing it. Under the terms of heat and mass transfer with the environment, fires occur in fences and in open spaces. And depending on the type of burning substances and materials, they can be divided into classes and subclasses, which we will discuss in detail in our article.

What classes are the fires divided into?

1) Класс А – горение твердых горючих материалов и substances. At the same time, if wood, textiles or paper is smoldering, the fire belongs to subclass A1, and if a non-smoldering material, such as plastic, burns, to A2 class.

2) Class B is made up of flammable combustible liquids: insoluble - subclass B1, soluble –B2.

3) Class C includes fires triggered by gases.

4) Class D - metal burning. Moreover, light metals belong to the D1 subclass, alkali metals are designated D2, and metal-containing compounds - D3.

5) Class E - burning electrical installations that are energized.

6) Class F - fires of radioactive waste and nuclear materials.

Types of fire

According to the burning area, all fire classes are divided into spreading and not

spreading.In addition, they may differ in the amount of material damage and be widespread, for example, in the forest, in large industrial enterprises and warehouses with combustible materials, as well as in settlements. Separate fires occur in a particular area, while solid fires cover a large number of structures and are characterized by intense burning. In the absence of wind, such elements can develop into a fire storm, which is characterized by the formation of a giant turbulent column of flame, which moves with great speed.

Air exchange and fire load

Classes of fire regulated by ventilationdiffer in the limited content of oxygen in the room with a simultaneous excess of combustible materials and substances. In this case, the spread of fire depends on the area of ​​the air inlets or the air flow that enters through mechanical ventilation systems. If there is an excess of oxygen indoors, the combustion process will be completely dependent on the fire load. By their parameters, such classes of fire are very similar to raging fire in open space.

Bulk and local fires

In case of a volume fire, which is regulated by ventilation, intense

thermal effects on fencing.Such burning is characterized by the presence of a gas interlayer between the flame torch and the surface of the enclosures. In this case, the whole process is accompanied by an excess of oxygen. When fire control fire load smoke screen is usually absent.

Classes of fire occurring locally,characterized by a small thermal effect on the surrounding fence. Their development depends on excess air, a variety of combustible materials and substances, as well as their condition and location in a given room. It should be noted that voluminous fires, regardless of their fencing, are called open, and local fires are closed, since they occur with closed window and door openings.