ASTM D6557 Standard Test Method for Evaluation of Rust Preventive Characteristics of Automotive Engine Oils
9. Procedure
9.1 Turn the three-way valve to two-way open, activate the syringe pumps, and eject 1 mL of acid solution into a waste beaker at a speed of 0.1 mL/min.
9.1.1 Make sure that the retaining brackets properly align all 24 syringe plungers.
9.2 Adjust the acid solution flow rate to 0.193 mL/h (test flow rate), and run for 1 h to ensure that all syringe plungers are properly aligned at the retaining brackets of the pusher block.
9.3 Set the actual air flow rate to 40 mL/min.
9.3.1 Monitor the airflow rate with the calibrated flow meter connected to the reference air capillary tubing. Refer to the calibration chart developed in Annex A1 to determine the actual air flow rate setting.
9.4 Turn the three-way valves to the three-way open position, and dry the nominal 1295 mm lengths of capillary tubing with air for 30 min.
9.5 Measure and record the airflow rates of all lines, and then shut off the main airflow valve.
9.6 Connect the long capillary tubing (that is, the nominal lengths of 1295 mm) to the short capillary tubing from the test tubes.
9.7 Connect all 24 stopper vent lines to the top of the test tubes.
9.7.1 TFE-fluorocarbon thermometer adapters are used as stoppers, 19/22 joint.
9.7.2 Attach the vent lines to barbed tee connectors (clear polypropylene tubing, with an I.D. of 3.2 mm).
9.7.3 Then, connect the vent outlets to a gas venting manifold (8 port inlet with hose barbs, size 6.4 mm; use vinyl tubing with an I.D. of 3.2 mm by an O.D. of 6.4 mm (see Fig. 7).
9.7.4 Finally, connect the gas venting manifold's outlet to a condensate trap flask (with a side arm) having a capacity of 1000 mL, placed such that gravity drains the condensate from the test tubes. Make sure that all of the capillary tubes are free to move with the shaker platform.
9.8 Set the shaker temperature to maintain (48 +/- 0.1) °C, as measured in an actual oil sample, and warm up the entire system to the control temperature in the oil sample for a period of 1 h. Refer to the calibration chart developed in Annex A2 to determine the shaker temperature setting.
9.9 Following the 1 h warm-up period, turn on the shaker, set the shaker speed to 300 r/min, and ensure that each ball freely rotates against each syringe wall.
9.10 Start introducing the acid solution at an actual flow rate of 0.193 mL/h. Refer to the calibration chart developed in Annex A3 to determine the actual flow rate setting.
9.11 Turn on the main airflow valve; check and adjust, if necessary, the upstream pressure (that is, upstream from the three-way valves) to ensure that the actual air flow rate is 40 mL/min.
9.12 Maintain the above test conditions for 18 h.
9.13 At the end of the test, stop the syringe pumps, shut off the airflow, and turn off the shaker.
9.14 Disconnect the acid/air delivery tubes from the test tube assembly, and remove the stoppers from the test tubes.
NOTE 4 - The preceding procedure described the use of three multiple syringe pumps and 24 test tubes. However, as a minimum, one multiple syringe pump with a maximum of 10 test tubes can also be utilized.
