What is the main difference between flash point and fire point?

The main difference between flash point and fire point lies in their definitions and the temperatures at which they occur.

Flash point is the lowest temperature at which a liquid can form an ignitable mixture in air. At this temperature, the liquid emits enough vapor to create a flammable mixture in the air, but it does not sustain combustion. This means that upon ignition, the flame may go out once the heat source is removed.

On the other hand, fire point is the temperature at which a liquid can not only form an ignitable mixture but also sustain combustion for a certain period. It is typically higher than the flash point.

Understanding this distinction is critical, as the flash point indicates the flammability risk and safety management of a substance, while the fire point gives further insight into its combustion properties.

Thus, the statement that flash point is lower than fire point accurately reflects the understanding that these two temperatures represent different thresholds in the combustion of a liquid substance.