This procedure focuses on the application of Fourier Transform Infrared (FT-IR) technology for tracking the depletion of additives, the accumulation of contaminants, and the degradation of base stocks within machinery lubricants, hydraulic fluids, and other fluids commonly used in mechanical operations. Key contaminants identified and monitored are water, soot, ethylene glycol, fuels, and incorrect oil. The oxidation, nitration, and sulfonation of base stocks are also assessed as indicators of degradation. The primary goal of this monitoring is to assess the operational health of a machine by analyzing the fault conditions observed in the oil.
This guide provides measurement and data interpretation parameters to enable operators of various FT-IR spectrometers to compare results using consistent methodologies. The methodology is rooted in trend analysis and distribution response analysis derived from mid-infrared absorption measurements. While calibrating to establish physical concentration units may be feasible, it is often unnecessary or impractical. Warning or alarm thresholds—indicating when maintenance should be recommended or required—can be determined through statistical analysis, historical records of the same or similar equipment, interlaboratory tests, or other methods, in conjunction with correlations to equipment performance. These thresholds may consist of fixed maximum or minimum values for direct comparison to a single measurement or could be based on the rate of change in the measured response. This practice outlines distribution analysis but does not exclude the use of rate-of-change warnings and alarms.