Which statement correctly defines the fire point?

Which statement correctly defines the fire point?

• A. The temperature at which vapors ignite spontaneously without an ignition source
• B. The temperature at which vapors ignite and sustain a flame immediately
• C. The temperature at which the liquid boils at its boiling point
• D. The temperature at which vapors will continue to burn after ignition

Answer: (D)

Fire point is the temperature at which vapors will continue to burn after an ignition source is removed. At this temperature there’s enough vapor and heat so that once a flame is started, combustion can be sustained without continuous external flame. It sits above the flash point, which is the lower temperature where vapors can momentarily ignite when exposed to a flame but may not keep burning once the flame is gone. The idea that vapors ignite spontaneously without a flame describes autoignition, not fire point, and boiling point relates to when the liquid itself boils, not how its vapors burn. So the statement that vapors will continue to burn after ignition best captures what fire point means.

Fire point is the temperature at which vapors will continue to burn after an ignition source is removed. At this temperature there’s enough vapor and heat so that once a flame is started, combustion can be sustained without continuous external flame. It sits above the flash point, which is the lower temperature where vapors can momentarily ignite when exposed to a flame but may not keep burning once the flame is gone. The idea that vapors ignite spontaneously without a flame describes autoignition, not fire point, and boiling point relates to when the liquid itself boils, not how its vapors burn. So the statement that vapors will continue to burn after ignition best captures what fire point means.