How is deflagration characterized?

Deflagration is characterized as the propagation of a combustion zone at a velocity that is less than the speed of sound. This type of combustion typically occurs in solid or liquid fuels and is generally associated with relatively low-pressure waves. The flames in deflagration travel through the unburned fuel mixture, transferring heat through conduction and convection, which allows the combustion to spread at subsonic speeds.

Understanding the nature of deflagration is crucial in fire and explosion investigations, as it helps differentiate between various types of combustion phenomena. For instance, it is important for investigators to distinguish between deflagration and detonation, the latter being defined by the propagation of the combustion wave at supersonic speeds. This distinction influences how investigations are approached and the potential hazards assessed.

The other choices provided do not accurately capture the defining characteristics of deflagration. Rapid oxidation accompanied by a loud noise may be associated with explosive events, but it does not specifically define deflagration or relate to its speed characteristics. Immediate ignition of combustible materials pertains more to ignition processes rather than the propagation characteristics that distinguish deflagration.