ASTM D6422 Standard Test Method for Water Tolerance (Phase Separation) of Gasoline-Alcohol Blends
9. Procedure
9.1 Shake the sample to redissolve any water that may have settled out during storage.
9.2 Carry out steps 9.3-9.5 as promptly as possible to minimize vaporization losses and absorption of water from the atmosphere.
9.3 Rinse out the test container with a portion of the sample to be tested by either pouring a small portion directly from the sample container or by using a 5-mL pipette. If using the 5-mL pipette, draw the specimen from approximately the center of the sample container to minimize the chance of atmospheric moisture coming in contact with the specimen taken. Drain the specimen used to rinse the test container.
9.4 Using a pipette, draw a sufficient quantity of test specimen from approximately the center of the sample container and dispense a volume into the rinsed test container so that the bottom of the test specimen meniscus is at the marked line. Alternatively, pour a test specimen directly from the sample container so that the bottom of the test specimen meniscus is at the line. If the test specimen has phase separated, as defined in 3.1.3 or 3.1.3.1, terminate the test and obtain a new sample for analysis.
9.5 Insert a thermometer through a centrally bored Viton rubber, or equivalent material stopper, as specified in 6.3. Seal the test container that holds the test specimen by snugly fitting the stopper into the test container opening. Position the thermometer at approximately the center of the fuel sample (see Fig. 1).
NOTE 6 - Caution: Avoid forcing the thermometer through the stopper to minimize the potential for injury.
9.6 Place a gasket around the test container, approximately 25 mm from the bottom, and place a disk on the bottom of the jacket in the cooling bath. Place the disk and jacket into the cooling medium a minimum of 10 min before the test container is inserted.
9.7 Depending upon the time of year and geographic location at which the fuel may be used, set-up the appropriate number of cooling baths with the temperatures kept between the ranges shown in Table 1.
9.8 Insert the test container in the jacket of Bath 1. The sample is not to be swirled or shaken while in the jacket. Take the first temperature reading at 14°C (57°F).
9.9 At 2°C (4°F) intervals, remove the test container from the jacket in the cooling bath and shake vigorously for 5 to 10 s. Wipe the exterior of the test container with a towel moistened with isopropyl alcohol to remove any condensation, and observe the condition of the test specimen for no more than 5 s against a light colored, illuminated background. Monitor the cooling rate while in the jacket, so as to not exceed 2°C (4°F)/min.
NOTE 7 - It is likely that the test specimen will get hazy prior to actual phase separation. Although the observation of a hazy test specimen is not a criterion for failure, the temperature at which the haze forms may be of importance to the user of the test method.
9.10 If the test specimen has not phase separated and has not reached the test temperature identified in Table 13 of Specification D4814, return the test container to the jacket. If the test specimen has phase separated, record the temperature and go to 9.17. If the test specimen has not phase separated and has reached the maximum test temperature above which the fuel must not phase separate, in accordance with Table 13 of Specification D4814, for the time of year and location for intended use, go to 10.1. If the user of the test method is interested in determining the actual phase separation temperature of the test specimen, even though it meets the seasonal and geographical requirement of Table 13 in Specification D4814, the option exists for continuing the test.
9.11 When the test specimen temperature reaches + 10°C (50°F) and has not phase separated or reached its intended test temperature, transfer the test container to Bath 2, maintained at a temperature between -18 and -15°C (0 and 5°F).
9.12 Repeat steps 9.9 and 9.10 for the test specimen in Bath 2 until the test specimen reaches a temperature of -8°C (18°F).
9.13 When the test specimen temperature reaches -8°C (18°F) and has not phase separated or reached its intended test temperature, transfer the test container to Bath 3, maintained at a temperature between -35 and -32°C (-31 and -26°F).
9.14 Repeat steps 9.9 and 9.10 for the test specimen in Bath 3 until the test specimen reaches a temperature of -24°C (-11°F).
9.15 When the test specimen temperature reaches -24°C (-11°F) and has not phase separated or reached its intended test temperature, transfer the test container to Bath 4, maintained at a temperature between -52 and -49°C (-62 and -56°F).
9.16 Repeat steps 9.9 and 9.10 for the test specimen in Bath 4 until the test specimen reaches a temperature of -42°C (-44°F).
9.17 Allow the test specimen to warm at ambient temperature. Shake the sample vigorously after each temperature rise of 2°C (4°F), and observe. Record a warming phase recombination temperature. Average the temperature results obtained upon cooling and warming to determine the phase separation temperature.
