Flash Point and Autoignition Temperatures of Common Vehicle Fluids
Laboratory Measurements
Laboratory flashpoint measurements provide useful information regarding the temperature at which a fluid may release enough vapor to sustain a flame in ideal conditions. Autoignition temperature measurements require more interpretation. In the laboratory, autoignition is measured by placing samples inside nearly closed chambers, without airflow, and with the benefit of instrumentation to identify even fragile and fleeting ignition events. The values shown in the following table tell us the lowest possible ignition temperatures for the fluids listed when under ideal circumstances.
The values in the table are presented for general reference and as such do not need to be memorized. The tabulated values provide a way to compare the relative flammability of various fluids and can be used as a resource for practical fire investigations.
Fluids | Flashpoint [12] oF | Autoignition Temperature [13] oF |
Automatic Trans. Fluid [ 2, 4] | 302-383 | 410-417 |
Brake Fluid [ 2, 4, 10, 11] | 210-375 | 540-675 |
Compressor Oil ( PAG and ester) [ 4, 8] | 392-500 | 410-714 |
Coolant | ||
Ethylene Glycol (100%) [ 1, 2, 4] | 232-260 | 725-775 |
Ethylene Glycol (90%) [ 2] | 270 | N/A |
Propylene Glycol (100%) [ 1, 4] | 210-230 | 700 |
Diesel Fuel [ 1, 2, 3, 4] | 100-204 | 350-625 |
Ethanol (in gasohol) [ 1, 3, 5] | 55 | 685 |
Gasoline (50-100 octane) [ 1, 2] | -36 to -45 | 536-853 |
Gasoline (unleaded) [ 4] | -45 | 495-833 |
Engine Oil (conventional and synthetic) [ 1, 2, 4] | 300-495 | 500-700 |
Methanol (in windshield fluid) [ 1, 2, 3, 4, 5,14] | 52-108 | 725-878 |
Power Steering Fluid [ 2, 4] | 300-500 | 500-700 |
Refrigerants | ||
R134a 140 KPa (5.5 Psig) [ 7] | 350 | |
R134a[ 7,15,16] | 1370-1418 | |
Freon 12 [17] | >1382 | |
HCFC-22 [ 9] | Flammable at 60 psig | |
Hydrocarbon Refrigerants | Flammable | Flammable |
Starter Fluid (ethyl ether) [ 5,18] | -49 | 320 |
Note about the table: When various sources had different flashpoint or autoignition temperature values for the same material, the range in the table was increased to include all values found.
To utilize flammability characteristics in investigations, it is necessary to also have measurements made in vehicle environments.
To view references for this page before continuing click here,