SAE ARP5991 PDF

Test Method for the Determination of Water Concentration in Polyol Ester and Diester Aerospace Lubricants by Coulometric Karl Fischer Titration
standard by SAE International, 09/12/2016

SAE ARP5991 – Test Method for the Determination of Water Concentration in Polyol Ester and Diester Aerospace Lubricants by Coulometric Karl Fischer Titration

The test method describes the procedure for the direct determination of water concentration in polyolester and diester based aerospace lubricants by the commercially available automated coulometric KarlFischer titration instrument. The method was validated to cover the water concentration range of 150 to3500 \gmg/g. The method may also be suitable for the determination of water concentrations outside thisrange and for other classes of fluids, however, the precision statement shall not be applicable for suchuses.Knowledge of the water concentration in polyol and diester aerospace lubricants is required since thepresence of excess amounts of water can lead to hydrolysis of the lubricant, resulting in corrosion and wear of the lubricated components and degradation of the lubricant. Significant variability observed in inter-laboratory Karl Fischer test results for these lubricants highlighted the need for a standardized Karl Fischer test procedure, specifically suited for these lubricants.