FLASH POINT AND FIRE POINT

Updated: May 1, 2020

AIM

To determine the flash point and the fire point of asphaltic

bitumen and fluxed native asphalt, cutback bitumen and blown

type bitumen as per IS: 1209 - 1978.

PRINCIPLE

Flash Point - The flash point of a material is the lowest

temperature at which the application of test flame causes the

vapours from the material to momentarily catch fire in the form of

a flash under specified conditions of the test.

Fire Point - The fire point is the lowest temperature at which the

application of test flame causes the material to ignite and burn at

least for 5 seconds under specified conditions of the test.

APPARATUS


PENSKY - MARTENS APPARATUS

i) Pensky-Martens apparatus

ii) Thermometer- Low Range : -7 to 110oC, Graduation 0.5oC

High Range : 90 to 370oC, Graduation 2oC

SAMPLE

The sample should be just sufficient to fill the cup upto the mark

given on it.

PROCEDURE

A) FLASH POINT

i) Soften the bitumen between 75 and 100oC. Stir it thoroughly

to remove air bubbles and water.

ii) Fill the cup with the material to be tested upto the filling

mark. Place it on the bath. Fix the open clip. Insert the

thermometer of high or low range as per requirement and

also the stirrer, to stir it.

iii) Light the test flame, adjust it. Supply heat at such a rate

that the temperature increase, recorded by the thermometer

is neither less than 5oC nor more than 6oC per minute.

iv) Open flash point is taken as that temperature when a flash

first appears at any point on the surface of the material in

the cup. Take care that the bluish halo that sometimes

surrounds the test flame is not confused with the true flash.

Discontinue the stirring during the application of the test

flame.

v) Flash point should be taken as the temperature read on the

thermometer at the time the flash occurs.

B) FIRE POINT

i) After flash point, heating should be continued at such a rate

that the increase in temperature recorded by the

thermometer is neither less than 5oC nor more than 6oC per

minute.

ii) The test flame should be lighted and adjusted so that it is of

the size of a bead 4mm in dia.

REPORTING OF RESULTS

i) The flash point should be taken as the temperature read on

the thermometer at the time of the flame application that

causes a distinct flash in the interior of the cup.

ii) The fire point should be taken as the temperature read on

the thermometer at which the application of test flame

causes the material to ignite and burn for at least 5

seconds

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