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 B - FINITE FLASH POINT
12. Procedure - Ambient to 110°C (230°F)
12.1 Preliminary or Trial Test:
12.1.1 Follow steps 10.1-10.5, omitting the barometric reading and using an estimated finite flash point instead of specification flash-point temperature.

12.1.2 After 1 min has elapsed, observe the temperature. Apply the test flame by slowly and uniformly opening the slide fully and closing completely over a period of 2 1/2 s (Note 10), watching for a flash (Note 11) while the flame is inserted.

12.2 If a flash is observed, proceed as in 12.3. If no flash is observed, proceed as in 12.4.

12.3 Using a temperature 5°C (9°F) lower than the temperature observed in 12.1.2, repeat 12.1 (Note 4). If a flash is still observed, repeat at 5°C lower intervals until no flash is observed.

NOTE 14 - Never make a repeat test on the same specimen. Always take a fresh portion for each test.

12.3.1 After establishing the approximate flash point, repeat 12.1 with a new specimen, but stabilizing the test temperature at which no flash occurred previously. Observe if a flash occurs at this temperature. If not, increase the temperature by making a small adjustment to the temperature controller so that an increase of 0.5°C (1°F) occurs within 1 min. Test for a flash at each 0.5°C interval, recording the temperature at which the flash actually occurs. Record the barometric pressure. Clean the tester.

12.3.1.1 Repeat 12.3.1 with a new specimen. Calculate the corrected mean temperature in accordance with 15.2. Turn off pilot and test flames and clean the tester.

12.4 Using a test temperature 5°C (9°F) higher than the temperature observed in 12.2, repeat 12.1 (Note 14). If no flash is observed, repeat at 5°C higher intervals until a flash is observed.

12.4.1 After establishing the approximate flash point (12.4) with new specimens, make two determinations of the flash point in accordance with 12.3.1 and calculate the corrected mean temperature in accordance with 15.2.

13. Procedure - 0°C (32°F) to Ambient Temperature
13.1 Preliminary or Trial Test:
13.1.1 Cool the sample to 3 to 5°C (5 to 10°F) below the expected flash point.

13.1.2 Cool the tester to approximately the temperature of the sample by inserting the cooling block filled with a cooling medium into the sample well. (Precaution - See Note 12 and Note 13.)

13.1.3 Introduce the specimen using a precooled syringe as in 10.4. Set the 1-min timing device. After 1 min observe the temperature, then apply the test flame by slowly and uniformly opening the slide fully and closing completely over a period of 2 1/2 s, watching for a flash (Note 11) while the flame is inserted. Record the temperature.

13.2 If a flash is observed, proceed as in 13.3. If no flash is observed, proceed as in 13.4.

13.3 Take a new specimen and recool the sample cup to 5°C (9°F) below the previous temperature (13.1.3). After 1 min, check for a flash as in 13.1.3. If the material flashes, repeat at 5°C lower intervals until no flash is observed.

13.3.1 After establishing the approximate flash point, repeat 13.1.1 and 13.1.3 with a new specimen but stabilizing the test temperature at which no flash occurred previously. Observe if a flash occurs at this temperature. If not, increase the temperature by making a small adjustment to the temperature controller so that an increase of 0.5° C (1°F) occurs within 1 min. Test for a flash at each 0.5°C interval, recording the temperature at which the flash actually occurs. Record the barometric pressure.

13.3.1.1 Repeat 13.3.1 with a new specimen. Calculate the corrected mean in accordance with 15.2. Turn off pilot and test flames and clean the tester.

13.4 Using a test temperature 5°C (9°F) higher than the temperature observed in 13.1.3, repeat 13.1.3 (Note 14). If no flash is observed, repeat at 5°C higher intervals until a flash is observed.

13.4.1 After establishing the approximate flash point (13.4), make the determinations of the flash point in accordance with 13.3 and calculate the corrected mean in accordance with 15.2.

14. Clean-up of Apparatus and Preparation for Next Test
14.1 Unlock the lid assembly of the tester and raise to the hinge stop. Soak up liquid with an absorbent paper tissue and wipe dry. Clean the underside of the lid and filling orifice. A pipe cleaner may be of assistance in cleaning the orifice.

14.2 If the material is a viscous liquid or contains dispersed solids, after soaking up most of the specimen add a small amount of a solvent suitable for the sample to the cup. Then soak up the solvent and wipe clean the interior surfaces of the cup with an absorbent tissue paper.

NOTE 15 - If necessary to remove residual high boiling solvent residues, moisten tissue with acetone and wipe dry.

NOTE 16 - If any further cleaning is necessary, remove the lid and shutter assembly. Disconnect the silicone rubber hose and slide the lid assembly to the right to remove. If warm, handle carefully.

14.3 After the cup has been cleaned, its temperature may be rapidly increased to some stand-by value by turning the temperature control dial to an appropriate point.

NOTE 17 - It is convenient to hold the test cup at some stand-by temperature (depending on planned usage) to conserve time in bringing the cup within the test temperature range. The cup temperature may be quickly lowered by inserting the aluminum cooling block filled with an appropriate cooling mixture into the cup.

14.4 The syringe is easily cleaned by filling it several times with acetone or other compatible solvent, discharging the solvent each time, and allowing the syringe to air dry with the plunger removed. Replace the plunger, and pump several times to displace any solvent vapor with air.

15. Correction for Barometric Pressure
15.1 Determine the corrected specification flash point to be used in Test Method A by the following equations:
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 = flash point to be observed to obtain the specification flash point at standard pressure, °C (°F),
S(T) = speciflcation flash point, °C (°F), and
P(B) = ambient barometric pressure, mm Hg (kPa).

NOTE 18 - The barometric pressure used in this calculation must be the ambient pressure for the laboratory at the time of test. Many aneroid barometers, such as those used at weather stations and airports, are precorrected to give sea-level readings. These must not be used.

15.2 When the barometric pressure in Test Method B differs from 760 mm Hg, correct the flash point temperature, A, by means of the following equations:
A = F + 0.06 (760 - P)
= C + 0.03 (760 - P)
= F + 0.42 (101.3 - B)
= C + 0.23 (101.3 - B)
where:
F(C) = observed flash point, °C (°F), and
P(B) = ambient barometric pressure, mm Hg (kPa).