Classification of fires: classes of fire and its varieties

To date, there is a specially developed standard that establishes symbols and classes of fires - GOST 27331-87. This document allows us to determine the variety of the combustion process and to select the most effective means for its suppression. According to the conditions of heat and mass exchange with the environment, fires occur in fences and in open spaces. And depending on the variety 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 divided into fires?

1) Class A - combustion of solid combustible materials and substances. In this case, if there is a smoldering of wood, textiles or paper, the fire belongs to subclass A1, and if the non-glowing material, for example plastic, is burning, to subclass A2.

2) Class B is flammable combustible liquid: insoluble - subclass B1, soluble -B2.

3) Class C includes fires, provoked by gases.

4) Class D - combustion of metals. And light metals belong to the subclass D1, the alkaline ones are denoted by D2, and the metal-containing compounds are D3.

5) Class E - combustion of electrical installations that are under voltage.

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

Types of fires

In the area of burning, all fire classes are divided into propagating and not Spreading. In addition, they may differ in the amount of material damage and be massive, for example in the forest, in large industrial enterprises and warehouses with combustible materials, as well as in settlements. Individual fires occur in a certain area, while solid fires cover a large number of structures and are characterized by intense burning. In the absence of wind, this element can develop into a fire storm, which is characterized by the formation of a giant turbulent column of flame, which moves at high speed.

Air exchange and fire load

Classes of fire, controlled by ventilation, are characterized by a limited oxygen content 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 supply air holes or the air flow that flows through the mechanical ventilation systems. If excess oxygen is observed in the room, the combustion process will depend entirely on the fire load. By their parameters, such fire classes are very similar to the raging fire in the open space.

Volumetric and local fires

With a volumetric fire, which is regulated by ventilation, there is an intense Thermal impact on fences. Such combustion is characterized by the presence of a gas layer between the flame torch and the surface of the fences. The whole process is accompanied by an excess of oxygen. When the fire is regulated by a fire load, the smoke screen is usually not available.

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