ASTM D6335 Determination of High Temperature Deposits by Thermo-Oxidation Engine Oil Simulation Test
12. Test Completion
12.1 The instrument will indicate that the test is finished when MAN (for manual) flashes on the control display. Test time is 1 h, 54 min. When the test is complete, turn off the main heat switch, set the pump dial to 000, turn off the reaction chamber heater control, and remove the reaction chamber heating jacket.

NOTE 4 - Caution: The reactor and the reactor heating jacket are hot.

12.2 Place a 25 mL beaker beneath the connection between the depositor rod casing inlet and pump outlet, and remove the pump outlet connection, making sure to catch any oil that drips out.

12.3 Carefully remove the depositor rod casing drain tube and rinse it with hexane into a 600 mL beaker.

12.4 Loosen the hex screws on the bus bars. One hex screw will need to be removed on the top bus bar and the others loosened to get the depositor rod casing out of the bus bars.

12.5 Place the depositor rod casing in the 600-mL beaker. Remove residual oil and loose deposits by squirting hexane into the casing containing the rod.

12.6 Remove the securing nuts, ceramic isolators and o-rings from the assembly. This should be done gently so that the deposits on the rod are not disturbed.

12.7 Carefully remove the depositor rod from the casing by pulling it straight out so that the deposits remain intact on the rod. Return the depositor rod casing to the 600 mL beaker.

12.8 Hold the end of the rod with the thumb and index finger, and rinse the inside and outside of the rod with hexane into the beaker. Rinse the rod well, especially the deposit area. Oil will sometimes become trapped in the crevices of the deposits, which adds unwanted mass to the rod.

12.9 After rinsing the rod, use a vacuum or very low pressure air to completely dry the inside of the rod.

NOTE 5 - Do not use a dry air source to dry the rod.

12.10 Carry the rod between the thumb and index finger to the balance and weigh to the nearest 0.1 mg. Do not set the rod down before weighing. Leave the rod on the balance for a minute to make sure that all of the solvent has been removed. A loss in mass indicated that further drying is needed before a final mass can be recorded. When a constant mass is obtained, record the value and place the rod back into the plastic tube.

12.11 Place the 600-mL beaker under the drain pipe of the reaction chamber, and turn the valve to allow the oil in the reaction chamber to drain. Thoroughly rinse the depositor rod casing with hexane, and remove it from the beaker.

12.12 Disconnect the pump inlet tube from the pump but leave is connected to the reaction chamber. Allow the reaction chamber to cool, then rinse it thoroughly with hexane and drain into the beaker.

NOTE 6 - Caution: Do not use hexane when the chamber is hot. Fumes are flammable.

12.13 With the 25-mL beaker from 12.2 beneath the pump outlet tube, set the pump speed to 999 and empty the oil from the tube and pump into the beaker. When the oil is completely exhausted, set the pump to 000. Remove the pump inlet tube from the reaction chamber and flush it with hexane into the 600-mL beaker.

12.14 Add the oil in the 25-mL beaker to the contents of the 600-mL beaker, rinsing the 25-mL beaker with hexane.

12.15 Rinse the reaction chamber with hexane from where the pump inlet tube was connected and drain it into the 600-mL beaker.

13. Fluid Filtering
13.1 To assemble the filter cartridge, stack five polypropylene disks in the plastic filter holder, screw the top and bottom parts together, and tighten to seal. The use of five disks compensates for the gaps and passages that may occur in the filters.

NOTE 7 - Optional one-piece filter cartridges8 may be used. If so, start at 13.2.

13.2 Record the tare mass of the filter cartridge as the preclean filter mass. Attach the top of the filter cartridge to the Luer lock connection of the filter funnel and the bottom to the filter flask. Connect the vacuum source to the side arm of the filter flask. The vacuum should be off. See Fig. 3.

13.3 Pour 5 mL of hexane through the system ten times (a total of 50 mL) to remove any solubles from the filters. It may be necessary to apply vacuum briefly to break the vapor lock. Turn the vacuum on and allow the filters to dry for 15 min.

13.4 Weigh the filter cartridge. Repeat drying and weighing the filter cartridge until constant mass is reached. Record this mass as the postclean filter mass.

13.5 When the postclean filter weight is established, connect the filter cartridge to the filter system again, and slowly pour the contents of the 600-mL beaker through the filter with the vacuum on. Rinse down the sides of the funnel with about 10 mL of hexane, and then add 100 mL of hexane through the filters in 10-mL aliquots. This should be done with the vacuum off to allow the hexane to percolate through the filters and ensure a thorough rinse. Once again, turn the vacuum on briefly to remove vapor lock and to keep the hexane flowing through the filters.

13.6 When filtering is complete, allow the filter cartridge to air dry for 15 min.

13.7 Remove the filter cartridge from the filter assembly and weigh. Return the cartridge to the filter assembly and dry for 5 min more and reweigh. Repeat until the mass of the cartridge is constant. Record this mass as the final filter mass.

14. Cleaning
14.1 The TEOST apparatus components need to be cleaned of the oil residue remaining from the test before another test is run. This can be done by rinsing the components with hexane. If the components are to be used right away, then an air source or vacuum can be used to facilitate the drying. The reaction chamber, the pump inlet tube, the pump outlet tube, and the depositor rod casing drain tube shall all be cleaned prior to use.

14.2 In addition to rinsing with hexane, the inner walls of the depositor rod casing shall be scrubbed to remove any deposit residues. Use a .22 caliber brass brush to scrub the inside of the casing, and then wash it again with hexane.

NOTE 8 - The brush will need to be replaced occasionally due to the wearing of the brass bristles.

14.3 The pump inlet and outlet tubes both have finger nuts on each end. The fittings are sealed with petroleum and temperature resistant o-rings. New o-rings should be used for every other run to ensure the seal. The depositor rod o-rings should be replaced every run.

15. Calculation
15.1 Rod Deposits - The rod deposits are obtained by subtracting the initial rod mass from the final rod mass and recording to 0.1 mg.
Rod deposits = Final rod mass - Initial rod mass

15.2 Filter Deposits - The filter deposits are obtained by subtracting the postclean filter mass from the final filter mass and recording to 0.1 mg.
Filter deposits = Final filter mass - Postclean filter mass

15.3 Total Deposits - The sum of rod and filter deposits equal the total deposits.
Total deposits = Rod deposits + Filter deposits