BASE NUMBER IN LUBRICANTS BY COLOR INDICATOR TITRATION: D5984
EXPLANATION
This is a semi-quantitative field test method used on new and used lubricating oils. These samples can contain base constituents present as additives or as degradation products formed during service. A decrease in the measured base number is often used as a measure of lubricant degradation. This test method uses reagents that are considered less hazardous than those used in other alternate base number methods. It uses pre-packaged reagents for field use where laboratory equipment is unavailable and quick results are at a premium. This test method covers base numbers in the range 0 to 20. Higher base numbers can be determined by diluting the sample or using a smaller sample size. Results obtained by this test method are similar to those obtained by Test Method D2896. No general relationship between bearing corrosion and base number is known.
TEST SUMMARY
The sample is dissolved in iso-octane and alcoholic hydrochloric acid. The solution is mixed with NaCl solution and the aqueous and organic phases are allowed to separate. The aqueous phase is then decanted off and titrated with NaOH solution using methyl red indicator. When the solution color changes from magenta to yellow, the base number is read off the side of the titrating buret.
TEST PRECISION
Repeatability: 0.09 base number units
Reproducibility: 1.91 base number units
This test method has no bias.
