ASTM D6335 Determination of High Temperature Deposits by Thermo-Oxidation Engine Oil Simulation Test
11. Procedure
11.1 When the reaction chamber is 100 +/-5°C, pour the test sample into the reaction chamber. Using the speed dial on the right side of the instrument, set the stir bar speed to 50. The sample temperature should reach 100°C in approximately 15 min.
11.2 Set the pump speed to 999, using the dial on the front panel of the instrument. Allow the pump to flush out 10 mL of fluid into the 10 mL graduated cylinder placed at the open end of the pump outlet tube. When flushing is complete, set the pump dial to 000 to stop the pump. Discard the 10 mL of oil.
11.3 Use hexane to rinse off an unused rod, both on the outside and down the center. Clean each of the three sections of the rod with 4/0 steel wool by stroking (up and down action) each section 20 times while turning the rod. Rinse the rod with acetone inside and out. Using a pipe cleaner soaked in acetone, clean the interior of the rod. Repeat the interior cleaning with a clean pipe cleaner through the rod in the opposite direction. Dry the rod with a vacuum while holding the rod between the thumb and index finger. Handle the rod as little as possible to avoid adding mass from oils on the skin and be sure not to set the rod down until after a mass is taken. Take extra care not to touch the center area of the rod where the deposits are formed. Weight the rod to 0.1 mg and record as the initial mass.
11.4 Slide the pre-weighed rod into the clean depositor rod casing with an even amount of the rod protruding from either end. Slide a new petroleum and temperature resistant o-ring over each end of the rod, and slide them up to the depositor rod casing. Place the ceramic isolators over each end of the rod with the thin portion pointing toward the end of the rod. Place the nuts on the end, and start to secure them, but do not tighten. Align the rod in the depositor rod casing until the shoulder between the deposit area and the bus bar connection areas of the rod can be seen through the inlet or outlet connections of the depositor rod casing. When this is achieved, the securing nuts may be tightened with a wrench.
11.5 Place the depositor rod casing/test rod assembly vertically in the bus bars, and slide the overtemp thermocouple in the bottom of the rod at the same time. Slide this in as far as it will go without bending it (be sure the rod has not shifted within the depositor rod casing). Make certain that the larger connection on the depositor rod casing is at the top. Connect the top end by placing the rod into the indentation of the bus bar and swinging the cap over the rod. Insert the hex screw to begin the securing process. The top of the rod should be approximately 2 mm above the top of the circular bus bar cap. Tighten all four hex screws. The gap in the bus bar should be the same on both sides of the depositor rod for the top and bottom bus bars. A solid contact between the rod and the bus bars is all that is required.
NOTE 3 - Do not over tighten.
11.6 The open end of the pump outlet tube can now be connected to the input connection of the depositor rod casing. The drain tube may now also be connected to the outlet connection of the depositor rod casing and finger tightened. Use a wrench to tighten the end caps on the two open fronts of the depositor rod casing. The unit assembly should now be complete.
11.7 Set the pump dial to 999 once again to complete the fluid flow through the entire system. When the system is completely filled with test fluid and the oil is flowing out of the drain tube back into the reactor, set the pump dial to the setting determined from the pump speed calibration to give a flow rate of 0.49 mL/min (0.40 g/min flow rate with TPC pump calibration fluid).
11.8 Place the depositor rod thermocouple down the center of the test rod. A caliper may be used to ensure proper depth of the thermocouple as determined by the thermocouple depth calibration. Be careful to prevent bends in the thermocouple, which may slightly change it's depth within the rod.
11.9 Turn on the main heat switch on the front panel of the instrument to start the test, and press the START/STOP button on the controller.
