1.1 This test method pertains to monitoring soot in diesel crankcase engine oils as well as in other types of engine oils where soot may contaminate the lubricant as a result of a blow-by due to incomplete combustion of in-service fuels. 1.2 This test method uses FT-IR spectroscopy for monitoring of soot build-up in in-service petroleum and hydrocarbon based lubricants as a result of normal machinery operation. Soot levels in engine oils rise as soot particles contaminate the oil as a result of exhaust gas recirculation or a blow-by. This test method is designed as a fast, simple spectroscopic check for monitoring of soot in in-service hydrocarbon based lubricants with the objective of helping diagnose the operational condition of the machine based on measuring the level of soot in the oil. 1.3 Acquisition of FT-IR spectral data for measuring soot in in-service oil and lubricant samples is described in Standard Practice D 7418. In this test method, measurement and data interpretation parameters for soot using both direct trend analysis and differential (spectral subtraction) trend analysis are presented. 1.4 This test method is based on trending of spectral changes associated with soot in in-service petroleum and hydrocarbon based lubricants. For direct trend analysis, values are recorded directly from absorbance spectra and reported in units of 100*absorbance per 0.1 mm pathlength. For differential trend analysis, values are recorded from the differential spectra (spectrum obtained by subtraction of the spectrum of the reference oil from that of the in-service oil) and reported in units of 100*absorbance per 0.1 mm pathlength (or equivalently absorbance units per centimeter). Warnings or alarm limits can be set on the basis of a fixed maximum value for a single measurement or, alternatively, can be based on a rate of change of the response measured. (1) In either case, such maintenance action limits should be determined through statistical analysis, history of the same or similar equipment, round robin tests or other methods in conjunction with the correlation of soot levels to equipment performance. 1.5 This test method is primarily for petroleum/hydrocarbon based lubricants but is also applicable for ester based oils, including polyol esters or phosphate esters.
Currently, there are no standard test methods for the FT-IR condition monitoring of soot in in-service oils and lubricants, although soot has been measured by FT-IR spectrometry for some time as one of the parameters specified in Standard Practice E2412, Standard Practice for Condition Monitoring of In-Service Lubricants by Trend Analysis using Fourier Transform Infrared (FT-IR) Spectrometry. Standard Practice E2412 provides a generalized, multi-parameter protocol for condition monitoring of in-service petroleum and ester lubricants by FT-IR spectroscopy and details a variety of acceptable instrument settings as well as parameters for different lubricant types. However, for an inter-laboratory cross-check program, specific instrument settings should be defined since different cell window materials, apodizations, background collection techniques, etc. will result in variations in the final spectrum obtained. Therefore,ASTM Standard Practice D 7418, created using Standard Practice E 2412 as a guide, details specific instrument settings and FT-IR spectral acquisition protocols for in-service condition monitoring. This test method describes the measurement of soot in in-service oils and lubricants employing the FT-IR spectral data acquired according to the protocol specified in Standard Practice D 7418 for both direct trending and differential trending approaches.
Fourier transform infrared spectroscopy; infrared; IR; condition monitoring; soot; direct trend analysis; differential trend analysis; lubricants; oils; in-service petroleum lubricants; hydrocarbon based lubricants.
The title and scope are in draft form and are under development within this ASTM Committee.
Citing ASTM Standards
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