Which term describes the lowest temperature at which a substance can ignite?

The term that describes the lowest temperature at which a substance can ignite is the "flash point." This point is critical in understanding fire safety because it indicates the minimum temperature at which enough vapor is produced by a substance to form an ignitable mixture with air. Knowing the flash point helps firefighters and safety personnel assess the risks associated with handling and storing flammable materials.

The flash point is a key factor in classifying substances and determining their hazardous properties. Materials with low flash points can ignite readily at lower temperatures, which necessitates stricter safety measures during transportation and storage.

Other terms in the context of fire science include the fire point, which is the temperature at which a substance will sustain combustion; LEL (Lower Explosive Limit), which describes the lowest concentration of a vapor in air that can ignite; and UEL (Upper Explosive Limit), which indicates the highest concentration of vapor in air above which ignition cannot occur. While these terms relate to flammability and fire behavior, they do not define the lowest temperature at which a substance can ignite like the flash point does.