ASTM D7236 Standard Test Method for Flash Point by Small Scale Closed Cup Tester (Ramp Method)
11. Procedure
11.1 Set the test cup temperature to 15 °C +/- 5 °C below the expected flash point temperature.
11.2 When the test cup is at the required temperature, charge a clean and dry syringe (6.2), adjusted to a temperature at least 10 °C below the expected flash point, with a 2 mL test specimen. Close the sample container immediately after withdrawal of the test specimen, to minimize any loss of volatile components.
11.3 Carefully transfer the syringe to the filler orifice and discharge the test specimen into the test cup by fully depressing the syringe plunger. Remove the syringe.
11.4 Ignite the pilot and test flames. Adjust the test flame to conform to the size of the 4 mm gauge ring. Reset the flash detector (A1.9). Start the test.
NOTE 8 - The ignition of the test flame and control of the gas supply may be automated on some instruments.
11.5 The test cup is heated automatically at such a rate that the temperature, as indicated by the temperature sensor, increases by 1.5 °C/min to 2.5 °C/min. The test flame is dipped into the test cup, as the shutter is slowly and uniformly opened and closed over a 2 s to 3 s period, at 1 °C intervals for temperatures up to and including 100 °C and thereafter every 2 °C for temperatures over 100 °C.
11.5.1 Observe the first two dips ofthe flame for continuous burning in the orifice. If a continuous luminous flame burns in the orifice when the slide is opened and the test flame is introduced, then the flash point lies considerably below the test temperature. In such cases, discontinue the test and repeat the test with a fresh test specimen using a lower expected flash point.
11.5.2 Application ofthe test flame may cause a blue halo or an enlarged flame prior to the actual flash point. This is not a flash and shall be ignored by the flash detector.
11.6 Record the displayed and held temperature of the temperature sensor when the application of the test flame causes a flash to be automatically detected.
11.7 Record the ambient barometric pressure using a barometer (6.3) in the vicinity of the apparatus at the time of the test.
NOTE 9 - It is not considered necessary to correct the barometric pressure reading to 0 °C, although some barometers are designed to make this correction automatically.
11.8 When the temperature at which the flash is observed is less than 10 °C or greater than 30 °C from the start temperature of the test, the result is not valid. Repeat the test using a fresh test specimen adjusting the temperature of the first application of the test flame until a valid determination is made.
12. Calculation
12.1 Barometric Pressure Conversion - If the barometric pressure reading is measured in a unit other than kilopascals, convert to kilopascals using one of the following equations:
Reading in hPa x 0.1 = kPa
Reading in mbar x 0.1 = kPa
Reading in mmHg x 0.1333 = kPa
12.2 Correction ofDetected Flash Point to Standard Atmospheric Pressure - Calculate the flash point corrected to a standard atmospheric pressure of 101.3 kPa, Tc, using the following equation:
Tc = TD + 0.25(101.3 - p)
where:
TD = the detected flash point temperature at ambient barometric pressure, expressed in degrees Celsius, and
p = the ambient barometric pressure, expressed in kilopascals.
NOTE 10 - This equation is strictly correct only within the barometric pressure range from 98.0 kPa to 104.7 kPa.
