Difference Between Flash Point and Auto-Ignition Temperature

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Difference Between Flash Point and Auto-Ignition Temperature

You should be cautious when working with flammable liquids and chemicals. You don't want to ignite combustible substances and start a fire. Two key concerns for flammable substances are their flash point and auto-ignition temperature, but what’s the difference between these two terms?

What Is the Flash Point?

The flash point is the lowest degree that a chemical can ignite in the presence of an ignition source. Substances with low flash points are considered flammable or combustible, while others with much higher flash points are considered safer and non-flammable.

The hotter the flammable liquid, the more flammable vapors that liquid will emit. Flammable liquids can combust if they're near an ignition source. For example, acetone is a highly flammable liquid because its flash point is 0°F. Kerosene is also considered highly flammable, with a flash point of 100°F.

What Is the Auto-Ignition Temperature?

The difference between a substance’s auto-ignition temperature and flash point is that an auto ignition removes the ignition source from the equation. At its auto-ignition temperature, a substance can spontaneously combust without a flame, spark, or another ignition source—hence the term auto-ignite.

Naturally, a substance’s auto-ignition temperature is much higher than its flash point. We typically only worry about auto-ignitions in industrial settings where temperatures can get exceedingly hot. To return to our previous examples, while acetone has a 0°F-flash point, its auto-ignition temperature is over 800°F. Kerosene, meanwhile, had a much higher flash point temperature, but its auto-ignition temperature is much lower at only 428°F.

How To Find the Flash Point and Auto-Ignition Temperature

Knowing a chemical substance’s flash point and auto-ignition temperature is valuable to store and handle them safely. These temperatures and other important safety information can be found in the chemical’s Safety Data Sheet, including its melting point, boiling point, and flammability.

If handling or storing any flammable chemical substance, it’s wise to know its flash point and auto-ignition temperature to ensure the safety of your facility.


Flammable substances with low flash points and auto-ignition temperatures can be exceptionally dangerous, so precautions should always be taken when storing or handling them. Any flammable substances should be stored in secure containers, away from ignition sources, and in temperature-controlled environments.

Flammable substances should only be handled by qualified professionals with the proper safety gear and flame-resistant (FR) clothing. If you need FR garments, the FR Outlet has a wide inventory of all kinds of FR clothing, like FR unlined bibs. Shop FR Outlet today to stay safe while handling flammable and dangerous materials.

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