ASTM D2265 standard test method for dropping point of lubricating grease over wide temperature range
9. Procedure
9.1 Insert empty test tubes in every test tube well and a thermometer having a range from -5 to 400°C in the thermometer well of the oven.
9.2 Turn on the oven and select the lowest aluminum block oven temperature setting from the four listed below that will result in an observed dropping point at or below the corresponding maximum observed dropping point shown for that oven temperature setting.
9.3 Select and use test tubes and accessories E-1, E-2, and E-3 to minimize wobble of the thermometer. All components must be at room temperature prior to the test. Place the components E-1 through E-4 on the thermometer in the order shown by the thermometer assembly (F) Fig. 1. Adjust the bushing E-3 and the bushing support ring E-4 so that E-4 is about 25 mm from the tip of the thermometer. Place the cup support C in tube B. Insert the thermometer depth gage E-5 and the thermometer assembly in the tube. Position the thermometer so that the tip bottoms in the gage. Adjust the bushing E-2 and the thermometer clamp E-1 so that the bushing shoulders on the top edge of the tube.
9.4 Fill the grease cup by pressing the larger opening into the grease to be tested until the cup is filled. Remove excess grease flush with the top edge of the cup with a spatula. Gently press the cup, held in a vertical position with the smaller opening at the bottom, down over the metal rod E-6, Fig. 1, until the latter protrudes about 25 mm. Press the rod against the cup in such a manner that the rod makes contact at both the upper and lower peripheries of the cup. Maintain this contact, rotating the cup on the rod along the index finger to give it a spiral-like motion down the rod to remove a conical section of the grease which adheres along the rod. As the cup approaches the end of the rod, carefully slip the rod out of the cup so that a smooth film of reproducible thickness remains inside the cup. See Fig. 3.
9.5 Remove the thermometer assembly and depth gage from the tube. Place the grease cup on the cup support in the test tube and carefully reinsert the thermometer assembly. Make no further adjustment as the thermometer bulb is now positioned to provide adequate clearance between the tip of the bulb and grease sample in the cup.
9.6 After making certain that the oven temperature has stabilized, remove an empty tube from the oven and gently insert the tube assembly, G, (Fig. 1) in its place. Exercise care to ensure that the cup remains upright in the cup support. If the cup is tilted, the thermometer bulb can come in contact with the film of grease and result in an erroneous value.
9.7 When the first drop of material falls free of the cup orifice and reaches the bottom of the test tube, record both the temperature of the cup and of the oven to the nearest degree. Certain greases, for example, some simple soap compositions, or those containing some types of polymers can form a drop with a tailing thread which can hold until the drop reaches the bottom of the test tube. The temperature in the cup when the drop reaches the bottom of the test tube is recorded as the observed dropping point.
NOTE 1 - The aluminum block oven can accommodate up to six samples of the same or different greases so that multiple determinations can be made simultaneously.