What is the temperature at which a flammable liquid ignites without an external ignition source?

The temperature at which a flammable liquid ignites without an external ignition source is referred to as the ignition temperature, also known as the autoignition temperature. This is the specific point at which the material's vapor or gas phase becomes capable of igniting solely due to the heat present in the environment, without the presence of an open flame or spark.

Understanding ignition temperature is crucial for safety in firefighting and hazardous materials operations because it indicates the conditions under which a substance will spontaneously ignite. This concept helps first responders assess risks in scenarios where flammable liquids are present, allowing them to take appropriate precautions or measures to prevent fires.

In contrast, the flash point is the lowest temperature at which a liquid can produce enough vapor to form an ignitable mixture with air, but ignition does not occur without an external spark or flame. The fire point is the temperature at which a liquid produces enough vapor to sustain combustion when ignited. The boiling point is the temperature at which a liquid turns into vapor, which does not necessarily indicate flammability or ignition capability. Thus, the ignition temperature is the most accurate term for describing the temperature that leads to spontaneous ignition.