ASTM D3278 test method for flash point of liquids
ASTM D3278 standard test methods for flash point of liquids by small scale closed-cup apparatus
TEST METHOD A - FLASH/NO FLASH
10. Procedure - Ambient to 110°C (230°F)
10.1 Inspect the inside of the test cup, lid, and shutter mechanism for cleanliness and freedom from contamination. Use an absorbent tissue to wipe clean, if necessary. Lock the cover lid tightly in place.
10.2 Switch the heater on, if not already at stand-by. To rapidly approach the specification flash temperature of the material under test, turn the heater dial fully clockwise (Note 8) causing the heater signal (red) light to glow. When the thermometer indicates a temperature of about 3°C (5°F) below the specification or target flash-point temperature, reduce the heat input to the test cup by slowly turning the heater control dial counter clockwise until the signal light goes out (Note 9).
NOTE 8 - When a desired temperature is dialed on the controller, the elapsed time to reach this temperature may be greater than if the controller is turned "full on", but less attention is required.
NOTE 9 - The test cup temperature is stable when the signal light slowly cycles on and off.
10.3 Determine the barometric pressure to determine the corrected specification temperature at that barometric pressure (see 15.1).
10.4 After the test-cup temperature has stabilized at the specification or target flash point, charge the syringe with the sample being tested and insert the tip of the syringe into the filling orifice (Fig. A1.1), taking care not to lose any material. Discharge the specimen into the test cup by completely depressing the syringe plunger, then remove the syringe. If the material has a viscosity greater than 45 SUS at 38°C (100°F) or equivalent of 9.5 cSt at 25°C (77°F), raise the lid and discharge the contents of the syringe directly into the cup. Immediately close the lid tightly.
10.5 Set the 1-min timing device. In the meantime, open the gas control valve and light the pilot and test flames. Adjust the test flame size with the pinch valve to match the size of the 5/32-in. (4-mm) diameter flame gage.
10.6 After 1 min has elapsed, observe the temperature. If at the specification temperature (accounting for the differences of the barometer reading from 760 mm), apply the test flame by slowly and uniformly opening the slide fully and closing completely over a period of approximately 2 1/2 s (Note 10), watching for a flash (Note 11) while the flame is inserted.
NOTE 10 - When inserted, the nozzle of the ignition device should intersect the plane of the underside of the cover (see A1.1).
NOTE 11 - The material is considered to have flashed only if a comparatively large blue flame appears and propagates itself over the surface of the liquid. Occasionally, particularly near the actual flash-point temperature, application of the test flame may give rise to a halo; this effect should be ignored.
10.7 Turn off the test and pilot flame. Clean the apparatus in preparation for the next test.
11. Procedure - 0°C (32°F) to Ambient
11.1 If the specification or target flash point is at or below ambient temperature, cool the sample to 5 to 10°C (10 to 20°F) below that point by some convenient means.
11.2 Cool the tester to approximately the temperature of the sample by inserting the cooling block (Fig. A2.1) filled with a cooling mixture (Note 12 and Note 13) into the sample well. Dry the cup with a paper tissue to remove any collected moisture prior to adding the specimen using a precooled syringe.
NOTE 12 - Precaution: Be careful in handling the cooling mixture and cooling block; wear gloves and goggles. Mixtures such as dry ice and acetone can produce severe frost bite.
NOTE 13 - Caution: Be careful when inserting the cooling block into the tester cup to prevent damage to the cup.
11.3 Introduce the specimen as in 10.4. Allow the temperature to rise under ambient conditions or increase the temperature of the cup by rotating the heater controller clockwise slowly until the specification temperature adjusted for barometric pressure is reached. Determine whether the material flashes as in 10.5 and 10.6.
11.4 Turn off the test and pilot flames. Clean the apparatus.
