ACCURATE TOTAL WATER MEASUREMENT FOR ON-SITE ANALYSIS OF TURBINE OILS BY INFRARED SPECTROSCOPY
Regular and reliable measurement of water contamination in turbine
oil is an important part of successful turbine operation. Turbine
manufacturers typically recommend an alarm limit around 500 – 1000
ppm water which is above the saturation limit of water for turbine oils.
The traditional ASTM method E2412 measures dissolved water by
correlating a peak around 3350 cm-1 to the water concentration,
however above the saturation limit the water contamination in the oil
exists as free water and cannot be quantified with this method. In this
paper, a new technique for determining water contamination in turbine
oils by infrared spectroscopy is described for portable on-site analysis.
The method utilizes a simple sample preparation technique for
accurate, repeatable measurement of water-in-oil samples and uses a
principle component regression calibration model specific for turbine
oils with accuracy ±250 ppm (total water <1000 ppm) and repeatability
between two measurements of <30%.