What is the ignition temperature?

What is the ignition temperature?

• A. The lowest temperature at which a fuel will ignite in the presence of air and continue to burn
• B. The point at which a liquid turns into gas
• C. The minimum temperature for any chemical reaction to start
• D. The temperature at which oxygen will support combustion of any material

Answer: (A)

Ignition temperature is the minimum temperature at which a fuel will ignite in the presence of air and continue to burn. In other words, once the substance reaches that heat and there is an ignition source, the chemical reactions with oxygen proceed fast enough to sustain a flame. Below this temperature, heat may cause warming or vaporization, but a flame won’t start or be sustained. This concept is different from the flash point, which is about when enough vapor is present to form an ignitable mixture with air, not about sustaining combustion. It’s also different from the autoignition temperature, which is the temperature at which a material will ignite on its own, without an external flame or spark. For many fuels, the ignition temperature is higher than the temperature needed to produce flammable vapors (flash point) but lower than the autoignition temperature, meaning a flame can be started with an external heat source and then will burn if kept at or above that ignition point.