AIM: To determine the flash and fire point of bitumen


Pensky-Marten Closed Tester, Thermometer


Bituminous material leave out volatiles at high temperatures depending upon their grade. These volatile vapours catch fire causing a flash. The flash point is the lowest temperature at which flash occurs due to ignition of volatile vapours when a small flame is brought in contact with the vapours of a bituminous product, gradually heated under standardised condition. When bituminous material is further heated to a higher temperature, the material itself catches and continues to burn; the lowest temperature causing this is the fire point. Fire point is always higher than flash point.

The flash point of a material is the lowest temperature at which vapour of a substance momentarily take fire in the form of flash.

The fire point is the lowest temperature at which the material gets ignited and burns under specific conditions of test.


All parts of cup are cleaned and dried thoroughly. Material is filled into cup upto filling mark. Lid is placed to close the cup in a closed system. All accessories including thermometer of specified range are suitably fixed. Bitumen sample is then heated. Stirring is done at regular intervals. The test flame is lit and applied at intervals depending upon expected flash and fire point. First application is made at about 17°C below actual flash point and then at every 1°C. Stirring is discontinued during the application of the test flame.


Flash point of bitumen =

Fire point of bitumen =


The minimum value of flash point by Pensky Martens closed type apparatus is 175°C for all grades of bitumen.


  1. The flash point is the lowest temperature, to which a lubricant must be heated before its vapor, when mixed with air, will ignite but not continue to burn. The fire point is the temperature at which lubricant combustion will be sustained. The flash and fire points are useful in determining lubricants volatility and fire resistance. The flash point can be used to determine the transportation and storage temperature requirements for lubricants. Lubricant producer can also use flash point to detect potential product contamination. A lubricant exhibiting a flash point significantly lower than normal will be suspected of contamination with volatile products. Products with flash points less than 38 deg C (100 deg F) will usually require special precautions for safe handling. The fire point for a lubricant is usually 8 to 10 percent above the flash point.

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