What conditions contribute to the spread of fire? What is the difference between linear and volumetric fire propagation?

The following conditions contribute to the spread of fire: the accumulation of a significant amount of combustible substances and materials in production and storage areas; the possibility of the spread of flame and combustion products to adjacent plants or to neighboring rooms; the sudden appearance in the fire of factors accelerating its development; late detection of a fire and untimely reporting about it to the fire department; absence or malfunction of stationary and primary fire extinguishing means; improper actions of people when fighting a fire.
With the linear spread of the fire, the movement of the flame occurs on the surface of the combustible substances in any direction and in one or another plane (for example, the movement of the flame on the surface of a combustible liquid, along combustible structures). The surface covered by the flame in this case may be in the form of a circle, rectangle or figure. Accordingly, the distribution of fire is distinguished circular, rectilinear, angular, etc.
Volumetric fire spreads within the boundaries of one room and between rooms, within a building and between buildings. In this case, the spread of fire is possible as a result of the emission of a flame, the transfer to a considerable distance of burning structural elements (smut) and unburned particles.

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