ASTM E2412 Condition Monitoring of In-Service Lubricants by Trend Analysis
ASTM E2412 Standard Practice for Condition Monitoring of In-Service Lubricants by Trend Analysis Using Fourier Transform Infrared (FT-IR) Spectrometry
4. Summary of Practice
4.1 Periodic samples are acquired from the engine or machine being monitored. An infrared absorbance spectrum of the sample is acquired, typically covering the range of 4000 to 550 cm(-1), with sufficient signal-to-noise (S/N) ratio to measure absorbance areas of interest. Exact data acquisition parameters will vary depending on instrument manufacturer but most systems should be able to collect an absorbance spectrum adequate for most measurements in less than one minute. Features in the infrared spectrum indicative of the molecular level components of interest (1,7) (that is, water, fuel, anti-freeze, additive, degradation, and so forth) are measured and reported. Condition alerts and alarms can then be triggered according to both the level and the trends from the monitored system.
5. Significance and Use
5.1 Periodic sampling and analysis of lubricants have long been used as a means to determine overall machinery health. Atomic emission (AE) and atomic absorption (AA) spectroscopy are often employed for wear metal analysis (for example, Test Method D5185). A number of physical property tests complement wear metal analysis and are used to provide information on lubricant condition (for example, Test Methods D445, D2896, and D6304). Molecular analysis of lubricants and hydraulic fluids by FT-IR spectroscopy produces direct information on molecular species of interest, including additives, fluid breakdown products and external contaminants, and thus complements wear metal and other analyses used in a condition monitoring program (1,3-7).
