Flash Point Defined

[Mopar1973Man]

Flash point DefinitionThe flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture in air. At this temperature the vapor may cease to burn when the source of ignition is removed. A slightly higher temperature, the fire point, is defined as the temperature at which the vapor continues to burn after being ignited. Neither of these parameters are related to the temperatures of the ignition source or of the burning liquid, which are much higher. The flash point is often used as one descriptive characteristic of liquid fuel, but it is also used to describe liquids that are not used intentionally as fuels.(gasoline) is designed for use in an engine which is driven by a spark. The fuel should be premixed with air within its flammable limits and heated above its flash point, then ignited by the spark plug. The fuel should not preignite in the hot engine. Therefore, gasoline is required to have a low flash point and a high autoignition temperature.Diesel is designed for use in a high-compression engine. Air is compressed until it has been heated above the autoignition temperature of diesel; then the fuel is injected as a high-pressure spray, keeping the fuel-air mix within the flammable limits of diesel. There is no ignition source. Therefore, diesel is required to have a high flash point and a low autoignition temperature.Petrol: Flash point: > -43 °C (-45 °F [negative, below freezing point of water at +32 F]) Autoignition temperature: 246 °C (475 °F) Diesel: Flash point: >62 °C (143 °F) Autoignition temperature: 210 °C (410 °F) Jet Fuel: Flash Point: >38 °C (100 °F) Autoignition Temperature: 210 °C (410 °F) Kerosene: Flash point: >38-72 °C (100-162 °F) Autoignition temperature: 220 °C (428 °F) Diesel varies between 126F and 204F (52C-96C/WJ). Jet fuels also vary a lot. Jet A and jet A-1 have a FP between 100F and 150F (38C-66C/WJ), close to that of off the shelf kerosene. However, both Jet B and FP-4 have a FP between -10F thru +30F (-23C/-1C/WJ)