OBJECTIVE: This method describes a test procedure for determining the flash and fire points (Cleveland Open Cup Tester) of all petroleum products except fuel oils and those having an open cup flash below 1750F. The flash point is the temperature at which a bituminous material, during heating, will evolve vapors that will temporarily ignites or flash when a small flame is brought in contact with them. The fire point is the temperature at which the evolved vapors will ignite and continue to burn.
To make the test, the material is heated in an open cup, and at intervals a small flame is applied near its surface. The lowest temperature at which application of the test flame causes the vapors to ignite is recorded as the flash point while the temperature at which the vapors ignited and burn for at least 5 seconds is recorded as the fire point. The flash and fire point test is purely a safety test. It indicates the maximum temperature to which the material can be safely heated.
PROCEDURE
1. Clean the cup with an appropriate solvent and remove all gums, carbon deposit, and oxide coating from the inside of the cup with fine steel wool until a bright metallic surface is presented.
2. Support the thermometer in a vertical position with the bottom of the bulb 1/4 inch (0.635 cm) from the bottom of the cup and above a point halfway between the center and back of the cup.
3. Fill the cup at any convenient temperature so that the top of the meniscus is exactly at the filling line. When too much sample has been added to the cup, remove the excess, using a spoon or other suitable device; however, if there is sample on the outside of the apparatus, empty, clean. Destroy any air bubbles appear on the surface of the sample.
4. Light the test flame and adjust it to a diameter of 1/8 to 3/16 in. (0.08 cm).
5. Apply heat initially so that the rate of temperature rise of the sample is 25 to 300F (13.9 to 16.7°C) per minute. When the sample temperature is approximately 100°F (560C) below the anticipated flash point, decrease the heat so that the rate of temperature rise for the last 500F (27.8°C) before the flash point is 10 + 1°F (5.5 + 0.6°C) per minute.
6. Record as the flash point the temperature read on the thermometer when a flash appear at any point on the surface of the sample but do not confuse the true flash with the bluish halo that sometimes surrounds the test flame.
7. To determine the fire point, continue heating so that the sample temperature increases at rate of 10 ± 1°F (5.5 ± 0.60C) per minute. Continue the application of the test flame at 50F (2.8°C) intervals until the vapor ignites and continues to burn for at least 5 sec. Record the temperature at this point as the fire point.
CALCULATION AND REPORT
Observe and record the barometric pressure at the time of the test. When the pressure differs from 760 mm Hg, correct the flash or fire point, or both, by means of the following equations:
 Corrected flash or fire point, or both = F + 0.06(760-P) or
 Corrected flash or fire point, or both = C + 0.03(760-P) Where:
F = observed flash or fire point, or both, to the nearest 5°F
C = observed flash or fire point, or both, to the nearest 2°C.
P = barometric pressure, mm Hg.