What type of combustion occurs without the presence of flames?

Smoldering combustion is characterized by a slow, low-temperature, and often flameless reaction in which solid materials, typically organic, undergo oxidation. This type of combustion occurs when there is insufficient oxygen for rapid combustion to take place, leading to a gradual release of heat and emissions of smoke and gases instead of flames.

In this process, the material will produce heat and may glow, especially if it is a carbon-based material like wood or coal. Smoldering combustion can persist for extended periods, making it particularly insidious as it can occur unnoticed and potentially lead to more intense combustion if conditions change, such as increased oxygen availability.

This distinguishes smoldering from other forms of combustion, such as rapid combustion, which involves flame, explosive combustion that occurs very quickly, often with a blast effect, and flash combustion characterized by brief, intense flames. Understanding each type of combustion is crucial for fire investigators in assessing fire dynamics and mechanisms.