New Test Method for Condition Monitoring of Glycol in In-Service Petroleum- and Hydrocarbon-Based Lubricants by Trend Analysis Using Fourier Transform Infrared (FT-IR) Spectrometry
1. Scope
1.1 This test method pertains to monitoring of glycol in in-service petroleum and hydrocarbon based lubricants such as diesel crankcase and gasoline crankcase oils, as well as other types of lubricants where glycol or ethylene glycol based antifreeze may contaminate the lubricant as a result of a leak in the cooling system. Glycol may also become present in in-service petroleum and hydrocarbon based lubricants via contamination from polyalkylene glycol (PAG) based lubricants such as brake fluids.
1.2 This test method uses FT-IR spectroscopy for monitoring of glycol in in-service hydrocarbon based lubricants as a result of normal machinery operation. This test method is designed as a fast, simple spectroscopic check for monitoring of glycol or ethylene glycol in in-service lubricants with the objective of helping diagnose the operational condition of the machine based on measuring the level of glycol contamination in the lubricant.
1.3 Acquisition of FT-IR spectral data for measuring glycol in in-service oil and lubricant samples is described in Standard Practice D7418. In this test method, measurement and data interpretation parameters for glycol 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 glycol in in-service lubricants. For direct trend analysis, values are recorded directly from absorbance spectra and reported in units of 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. In either case, such maintenance action limits should be determined through statistical analysis, history of the same or similar equipment,
Keywords
spectrometry
Rationale
Ballot Rational: This method is being developed as a stand-alone test method to test for glycol contamination in hydrocarbon based lubricants in preparation for the possible withdrawal of E2412, Practice for Condition Monitoring on In-Service Lubricants by Trend Analysis using Fourier Transform Infrared (FT-IR) Spectrometry. Reference to D7418 method will provide all the proper details for specific instrument setting and protocol for acquiring FT-IR spectral data. This method will provide detail in measuring glycol contamination contents in a hydrocarbon based lubricant for both direct trending and differential subtraction analyzes. The precision of the test method has not yet been determined by a formal interlaboratory study.
