What is the lowest temperature at which a liquid gives off enough vapors to ignite, but without sustained burning?

• A. Flash point
• B. Fire point
• C. Ignition temperature
• D. Boiling point

Answer: (A)

Flammability terms describe when vapors above a liquid can ignite. The lowest temperature at which enough vapors are produced to ignite in the presence of an ignition source, but without a sustained flame, is the flash point. At the flash point, a brief flash can occur if a spark or flame is introduced, but the flame won’t continue burning unless the temperature is raised further to reach the fire point. The fire point is higher because it’s the temperature where there is enough energy to sustain combustion. The ignition temperature (autoignition temperature) is the temperature at which the vapor-air mixture will ignite on its own, without any external flame or spark, and is typically higher still. The boiling point is simply the temperature at which the liquid boils and becomes vapor, not about ignition.