Water by Karl Fischer

Water contamination can be a significant problem. Many of the most important functions of lubricants are compromised by the presence of water. Any increase in moisture content can reduce the lubricating properties of the oil and can result in compromised mechanical performance giving rise to conditions such as Hydrogen Embrittlement. Water may also result in fluid degradation shortening oil life and giving rise to Oxidation and Acidification. A weighed portion of sample is heated in a sealed sample vial. A stream of dry gas, typically air is passed through the sample and carries over any water vapour that is liberated into the titration vessel containing the titration solvent. Iodine for the Karl Fischer reaction is produced coulometrically in the vessel at the anode.  When all the water has been titrated, an electrometric end point detector detects excess iodine and the titration is terminated. Results are quoted in either % w/w or ppm w/w.