Which process describes ignition initiated by an external heat source?

The process of ignition initiated by an external heat source is best described as piloted ignition. In this context, piloted ignition occurs when a combustible material is heated by an external source to a temperature sufficient to start combustion. This requires a pilot flame, spark, or other synergistic heat source to provide the initial heat.

Understanding this process is crucial for firefighters, as it informs how fires start and can assist in preventing ignition scenarios when responding to emergencies. Factors such as the temperature, duration of exposure, and the nature of the combustible material all play roles in piloted ignition.

In contrast, autoignition refers to ignition that occurs without an external ignition source, typically at a specific temperature and pressure, highlighting the difference between spontaneous combustion and external heat sources. Chemical ignition pertains to the initiation of combustion through a chemical reaction, which is a different mechanism than the heat-induced start of fire associated with piloted ignition. Flame ignition generally refers to a fire that is started or propagated through flame presence but does not encompass the notion of external heat as a necessary starter, which is specific to piloted ignition.