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Transportation Engineering Lab Experiments

Flash and Fire Point Test of Bituminous Material


To determine the flash and fire point of given bitumen samples by Pensky-Martens closed tester

IS Standards used:IS: 1209-1978

Need and scope:Bituminous materials leave out volatiles at high temperatures depending upon their grade. These volatile catch fire causing a flash. This condition is very hazardous, and it is therefore essential to qualify this temperature for each bitumen grade.

Flash Point:the flash point of a material is the lowest temperature at which the vapour of the substance momentarily takes fire in the form of flash under specified condition of test.

Fire Point:The fire point is the lowest temperature at which the material gets ignited and burns under specified condition of test

Apparatus Required:

  1. Pensky-Martens closed tester consisting of cup, lid, stirrer, shutter, flame exposure device.
  2. Thermometer (0-350°C) with sensitivity of 0.1°C.

Experimental procedure:

  1. The material is filled in the cup up to a filling mark.
  2. The lid is placed to close the cup in a closed system. All accessories including thermometer of the specified range are suitably fixed.
  3. The bitumen sample is then heated. The flame is lit and adjusted in such a way that the size of a bleed is of 4mm diameter.
  4. The heating is done at the rate of 5°C to 6°C per minute.
  5. The stirring is done at the rate of approximately 60 revolutions per minute.
  6. The test flame is applied at intervals depending upon the expected flash and fire points.
  7. First application is made at least 17°C below the actual flash point and then at every 1°C to 3°C
  8. The stirring is discontinued during the application of the test flame.

Observations and Calculation:

Sl. No Description Test-01 Test-02 Test-03 Test-04 Mean value
1 Grade of bitumen
2 Rate of heating time (min)
3 Temperature
4 Flash point
5 Fire Point

General remarks:

Viva Questions

  1. What is the utility of determination of flash point
  2. Should a good binder possess higher flash point?
  3. What are the flash and fire points?