Test equipment

Mettler Toledo Karl Fischer Titrator

Sample size

30ml (recommended), 10ml (minimum)


ASTM D6304


Ppm (parts per million), or %

Test methodology

In this method, water reacts quantitatively with the Karl Fischer reagent (mixture of iodine + other solvents). The water in the sample reacts with the iodine. When the water is no longer free to react with iodine, an excess of iodine depolarizes the electrodes, signalling the end of the test.

Notes (application)

Water is a common contaminant found in lubricating oils. It causes corrosion to metal surfaces, lubricant degradation, and poor lubrication. Water can be present in three forms in lubricating oils, dissolved, emulsified, and free water: karl fisher tests for all 3 forms of water, down to very low levels of 10ppm.

Suitable for systems

Most lubricant systems. Diesel engine oils (in general) is not necessary to test for karl fisher.