ASTM D3117 Test Method for Wax Appearance Point of Distillate Fuels
8. Procedure
8.1 Ensure that the temperature measuring device is in calibration. For liquid-in-glass temperature measuring devices, see the Annex on Calibration in Test Method D445.
NOTE 2 - Because ambient temperatures are well above the range of ASTM Thermometer 62C, the liquid-in-glass thread will extend upward into the expansion chamber. During cooling, the liquid-in-glass temperature measuring device must be examined to make certain that no separation is observed in the liquid.
8.2 Sample temperature shall not be lower than 10°C when starting the measurement. Dry the specimen by filtration through a lintless filter paper.
8.3 Assemble the unit as shown in Fig. 3.
8.4 With the oil at 10°C or above, introduce a 25 more or less 1-mL specimen into the tube. Add three drops of anhydrous isopropanol.
8.5 Adjust the stopper, temperature measuring device, and stirrer so that the bottom of the temperature measuring device is 25 mm above the bottom of the specimen tube and the stirrer does not break the surface at the upper end of its stroke.
8.6 When the stopper has been firmly seated, start the stirrer, raise the cooling bath around the specimen tube, and cool rapidly to 2°C.
8.7 Once the temperature reading is below 2°C, adjust the bath height to keep the cooling rate between 1 and 2°C/min. The preferred cooling rate is 1.5°C/min.
8.8 Continue cooling until wax distinctly appears when the specimen tube is examined by transmitted light. This is manifested by the appearance of very small wax crystals which make the stirring pattern quite obvious. An example of the change observed is shown in Fig. 4 and Fig. 5. Observe the temperature reading immediately to the nearest 0.2°C.
NOTE 3 - The wax appearance point should not be misinterpreted to be the appearance of the very first crystals. The temperature at which a distinct swirl of wax particles around the stirrer occurs is the correct interpretation.
