ASTM D3934 for flash/no flash test-equilibrium method by a closed-cup apparatus
10. Procedure
10.1 Fill the test cup with the appropriate amount of specimen for the cup being used at a temperature that is at least 20°F (10°C) below the specified test temperature, corrected for barometric pressure (Note 4). Remove bubbles on the surface of the specimen. Wipe the inside of the cover with a clean cloth or absorbent tissue paper.
NOTE 4 - Correct the temperature at which the test is to be performed in accordance with the appropriate equation:
°F = S - 0.06 (760 - P)
°C = T - 0.03 (760 - P)
°F = S - 0.42 (101.3 - B)
°C = T - 0.23 (101.3 - B)
where:
°F, °C = test temperature when the barometric pressure differs from 760 mm of Hg (101.3 kPa),
S(T) = specified flash point, °F (°C), and
P(B) = actual barometric pressure, mm of Hg (kPa).
10.2 Immediately after filling the cup, place the cover in position and support the cup in the bath so that the cover is horizontal and the cup is immersed in direct contact with the water and with the surface of the specimen at the same level as the liquid in the bath.
10.3 Light the flame of the ignition device and adjust it to the size of a bead of diameter 5/32 in. (4 mm).
10.4 Adjust the temperature of the specimen to within 1.0°F (0.5°C) of the minimum corrected test temperature and hold at this temperature for 10 min. Apply the test flame by opening the slide, inserting and removing the nozzle of the ignition device, and closing the slide again, over a period of 2.5 +/- 0.5 s. While the test flame is inserted observe whether there is a flash.
NOTE 5 - When the vapor mixture under test is near the flash-point temperature, application of the test flame may give rise to a halo; however, the material is only deemed to have flashed if a comparatively large blue flame appears and propagates itself over the surface of the liquid. If a large blue flame does not appear as a flash but instead a continuous luminous flame burns in the orifice when the slide is opened and the ignition flame introduced, then the flash point is much lower than the test temperature. In such circumstances, if further classification is desired, test a fresh specimen at the temperature limit for the next lower flash point classification.
10.5 Repeat the test using a fresh specimen.
