OXIDATION STABILITY OF INHIBITED MINERAL OILS: D943
(Equivalent Test Method: ISO 4263)
EXPLANATION
This test method is widely used for specification purposes and is considered of value when estimating the oxidation stability of lubricants, especially those that are prone to water contamination. However, the correlation between these results and the oxidation stability of a lubricant in field service may vary markedly. This test method evaluates the oxidation stability of inhibited steam-turbine oils in the presence of oxygen, water, and copper and iron metals at elevated temperature. This test method is also used for testing other oils such as hydraulic and circulating oils having a specific gravity less than that of water and containing rust and oxidation inhibitors.
TEST SUMMARY
The oil sample is contacted with oxygen in the presence of water and an iron-copper catalyst at 95° C. The test continues until the measured total acid number of the oil is 2.0 mg KOH/g or above. The number of test hours required for the oil to reach this value is called the oxidation lifetime.
TEST PRECISION
Repeatability: 0.192 X
Reproducibility: 0.332 X
Where X is the mean value.
