FLASH POINT AND FIRE POINT OF BITUMEN

DETERMINATION OF FLASH POINT AND FIRE POINT OF BITUMEN

TEST STANDARD: IS 1448-Part 69: 2013

Determination of flash point and fire point of petroleum product bitumen using Cleveland open cup apparatus, it is applicable to petroleum products having an open cup flash point above 79°C, except fuel oils.

APPARATUS: Cleveland open cup apparatus, cleaning solvent, thermometer partial immersion type, Shield, approximately 460 mm square and 610 mm high, and having an open front steel wool

PROCEDURE: Place the apparatus on a level and steady surface in a draught free room. Shield the top of the apparatus from strong light by any suitable means, to permit detection of the flash point. Wash the test cup with an appropriate solvent to remove any traces of gum or residue remaining from a previous test. Dry the test cup using a stream of clean air to ensure complete removal of the solvent used. If any deposits of carbon are present, remove them by rubbing with steel wool.

Before use, cool the test cup to at least 56 °C below the expected flash point. Support the thermometer in a vertical position with the bottom of the bulb 6 mm from the bottom of the test cup, and located at a point halfway between the centre and side of the test cup on a diameter perpendicular to the arc (or line) of the sweep of the test flame, and on the side opposite to the test flame applicator.

Verify the correct functioning of the apparatus at least once a year by testing a certified reference material (CRM) The result obtained shall be equal to or less than R / Sqrt (2) from the certified value of the CRM, where R is the reproducibility of the method. It is recommended that more frequent verification checks are made using secondary working standards (SWSs)

Sampling: Place samples in tightly sealed containers, appropriate to the material being sampled, and for safety purposes, ensure that the sample container is only filled to between 85 % to 95 % of its capacity. Store the samples in conditions to minimize vapour loss and pressure build-up. Avoid storing the samples at temperatures in excess of 30°C.

Sample handling-Sub-sampling: Subsample at a temperature at least 56°C below the expected flash point. If an aliquot of the original sample is to be stored prior to testing, ensure that the container is filled to more than 50 % of its capacity.
Heat the sample in its container in a heating bath or oven at a temperature not exceeding 56 °C below the expected flash point. Avoid overheating the sample as this could lead to the loss of volatile components. The results of flash point determinations may be affected if the sample volume falls below 50 % of the container capacity. Record the ambient barometric pressure using a barometer in the vicinity of the apparatus at the time of test. It is not considered necessary to correct the barometric pressure reading to 0°C, although some barometers are designed to make this correction automatically.

Fill the test cup at ambient or elevated temperature so that the top of the meniscus is exactly at the filling line. If too much sample has been added to the test cup, remove the excess using a pipette or other suitable device; however, if there is sample on the outside of the apparatus, empty, clean and refill it. Destroy or remove any air bubbles or foam on the surface of the sample whilst maintaining the correct level of test portion in the test cup. If a foam persists in the final stages of the test, discard the result. Light the test flame and adjust it to a diameter between 3, 2 mm and 4, 8 mm, the size of the comparison bead if one is mounted on the apparatus. Apply heat initially so that the rate of temperature rise of the test portion is 14 °C/min to 17 °C/min. When the test portion temperature is approximately 56 °C below the expected flash point, decrease the heat so that the rate of temperature rise for the last (23± 5) °C before the expected flash point is 5 °C/min to 6 °C/min. During the test, take care to avoid disturbing the vapours in the test cup by careless movements or breathing near the test cup.

Starting at least (23±5) °C below the expected flash point, apply the test flame when the temperature read on the thermometer reaches each successive 2°C mark. With a smooth continuous motion, taking approximately 1s, pass the test flame in one direction across the centre of the test cup, at right angles to the diameter which passes through the thermometer, either in a straight line or along the circumference of a circle having a radius of at least 150 mm. The centre of the test flame shall move in a horizontal plane not more than 2mm above the plane of the upper edge of the test cup. For the next test flame application, pass the flame in the opposite direction. If a skin forms over the test portion, carefully move it aside and continue the determination. Record as the observed flash point, the temperature of the test portion, read on the thermometer, when application of the test flame causes the vapour of the test portion to ignite and propagate across the surface of the liquid. Do not confuse the true flash point with the bluish halo that sometimes surrounds the test flame. When the temperature at which the flash point is observed is less than 18 °C from the temperature of the first application of the test flame, the result is not valid. Repeat the test using a fresh test portion, adjusting the temperature of the first application of the test flame
until a valid determination is obtained when the flash point is 18 °C above the temperature of the first application of the test flame.

Determining fire point:

To determine the fire point, continue heating so that the test portion temperature increases at a rate of 5 °C/min to 6 °C/min. Continue the application of the test flame at 2°C intervals until the vapour of the test portion ignites and continues to burn for at least 5s. Record the temperature at this point as the observed fire point of the sample. If the fire persists for more than 5s, extinguish it with a cover made of metal or other fire-resistant material fitted with a handle

Report the corrected flash point or fire point, rounded to the nearest even number, in degrees Celsius.

Repeatability, r: The difference between two test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material, would in the long run, in the normal and correct operation of the test method, exceed the following values in only one case in twenty.

Flash point, r = 8 °C
Fire point, r = 8 °C

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