ASTM D2893 for oxidation characteristics of extreme-pressure lubrication oils
6. Preparation of Apparatus
6.1 Cleaning of Oxidation Cells - Clean glassware with a suitable cleaning solution. (Warning - Causes severe burns. A recognized carcinogen. Strong oxidizer, contact with other material may cause fire. Hygroscropic.)
NOTE 3 - While other suitable cleaning solutions are now available, the round robin used glassware cleaned with chromic acid. Other cleaning solutions such as NoChromix and Micro Clean have been found suitable. In a referee situation, glassware shall be cleaned by a cleaning solution satisfactory to all parties involved.
7. Procedure
7.1 Adjust the heating bath to a temperature high enough to maintain the oil in the desired number of oxidation cells at the required temperature of 95 more or less 0.2°C (Test Method A) or 121 more or less 1.0°C (Test Method B). Determine the viscosity at 100°C by Test Method D445/IP71 and the precipitation number by Test Method D91, on each sample.
7.2 Pour 300 mL of each oil sample into a test tube and immerse the test tube in the heating bath so that the heating medium is at least 50 mm above the level of the oil sample. Place the corks and air delivery tubes in the test tubes making sure that the lower ends of the tubes are within 6 mm of the bottoms of the test tubes.
7.3 Connect the air delivery tubes to the dried air supply through the flowmeters. Adjust the flow of air to 10 more or less 0.5 L/h. Check the temperature of the oil samples and the rate of air flow every hour and make necessary adjustments. Once the oil samples have reached the desired temperature of 95 more or less 0.2°C (Test Method A) or 121 more or less 1.0°C (Test Method B), initiate the start of the test.
NOTE 4 - When using multi-cell baths, one way of checking the temperature of the oil samples can be to use a dummy cell in the bath, similar to the way it is used in Test Method D943.
7.4 Maintain the air flow and bath or block temperature constant, checking them periodically for the duration of the test.
7.5 Remove the test tubes from the bath or block 312 more or less 1 h (13 days) after the start of the test. Mix each oil sample thoroughly and test them for viscosity at 100°C by Test Method D445/IP71 and precipitation number by Test Method D91.
8. Calculation
8.1 Calculate the kinematic viscosity increase as follows:
Viscosity increase, % = [(B - A)/A] x 100
where:
A = kinematic viscosity on original sample, and
B = kinematic viscosity after oxidation.
9. Report
9.1 On the original sample, and on the oxidized sample at the termination of test, report the precipitation number determined in accordance with Test Method D91.
9.2 Report the percent increase in viscosity at 100°C as determined in Section 8.
