What is the minimum temperature required for a fuel in air to begin self-sustaining combustion?

The minimum temperature required for a fuel in air to begin self-sustaining combustion is known as the fire point. This temperature is significant because it indicates the point at which the fuel will not only ignite but maintain combustion independently. Once the fire point is reached, the fuel can produce enough vapor to support continuous burning without the need for an external ignition source.

In contrast, the flash point is the lowest temperature at which a fuel can vaporize to form an ignitable mixture in air, but it does not guarantee that combustion will continue once initiated. The ignition point is often synonymous with the fire point but is more focused on the initial spark necessary to start combustion. Similarly, the term combustion threshold is not commonly used in the context of combustion temperatures and lacks a specific definition related to self-sustaining combustion. Thus, the fire point is the precise term that aligns with the concept of maintaining combustion after ignition has occurred.