Flash point, fire point and autoignition temperature are three temperatures that describe how a flammable liquid is affected by temperature.
Normally the autoignition temperature is greater than the fire point which is greater than the flash point.
Term
|
Meaning
|
Ignition Source Required?
|
flash point
|
lowest temperature at which the liquid will vaporize and form an ignitable mixture with air
|
yes, repeatedly
|
fire point
|
temperature at which vapor will continue to burn once ignited
|
yes
|
autoignition temperature
|
temperature at which a fire will occur without an ignition soucre
|
no
|
Each of these temperatures is affected by:
(1) the amount of oxygen present
(2) the presence of other flammable liquids
(3) the presence of flame retardants
(4) atmospheric pressure
Significance:
(1) The lower the flash point the greater the hazard.
(2) At a high enough temperature even a flammable liquid of low hazard can burn.
Flash Point
|
Hazard
|
> 93°C (> 200°F)
|
very low
|
66 to 93°C
|
low to moderate
|
38 to 66°C
|
moderate to high
|
-18 to 38°C
|
high to extreme
|
< -18°C (< 0°F)
|
extreme
|