Water acc. to Karl Fischer (volumetric)

OELCHECK test instrument: Mettler Toledo V20 – volumetric KF titrator
Sample volume: 3 ml
Unit: ppm and/or mg/kg
Values determined: Water using K.F.
Range of values: 1,000 - 1m ppm
Investigation for: Lubricants with high water contents, HFC fluids
Brief description: In the volumetric Karl Fisher method, water is not removed by heating, instead the sample is injected directly into the measuring cell. Instead of electrically producing the iodine required for measurement, it is present in a solution which is continuously added in small amounts with a burette. Here, an electrochemical reaction takes place between the water and the KF solution.

When the water has reacted, unused iodine remains in the solution and is detected by the indicator electrode, titration is complete. The water content is calculated from the used volume of titration solution rather than from the amount of electricity used.
Conclusion: The water content in a lubricant should not exceed certain permissible values, depending on oil type and use. Too much water in the oil can cause problems such as corrosion, cavitation or oil oxidation.