ASTM D7414-22

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Designation: D7414 − 21 D7414 − 22
Standard Test Method for
Condition Monitoring of Oxidation in In-Service Petroleum
and Hydrocarbon Based Lubricants by Trend Analysis
Using Fourier Transform Infrared (FT-IR) Spectrometry
This standard is issued under the fixed designation D7414; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers monitoring oxidation in in-service petroleum and hydrocarbon based lubricants such as in diesel
crankcase, motor, hydraulic, gear and compressor oils, as well as other types of lubricants that are prone to oxidation.
1.2 This test method uses Fourier Transform Infrared (FT-IR) spectrometry for monitoring build-up of oxidation products in
in-service petroleum and hydrocarbon based lubricants as a result of normal machinery operation. Petroleum and hydrocarbon
based lubricants react with oxygen in the air to form a number of different chemical species, including aldehydes, ketones, esters,
and carboxylic acids. This test method is designed as a fast, simple spectroscopic check for monitoring of oxidation in in-service
petroleum and hydrocarbon based lubricants with the objective of helping diagnose the operational condition of the machine based
on measuring the level of oxidation in the oil.
1.3 Acquisition of FT-IR spectral data for measuring oxidation in in-service oil and lubricant samples is described in Practice
D7418. In this test method, measurement and data interpretation parameters for oxidation 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 oxidation of in-service petroleum and hydrocarbon
based lubricants. Warnings or alarm limits can be set on the basis of a fixed minimum value for a single measurement or,
alternatively, can be based on a rate of change of the response measured, see Ref (1).
1.4.1 For direct trend analysis, values are recorded directly from absorption spectra and reported in units of absorbance per 0.1 mm
pathlength.
1.4.2 For differential trend analysis, values are recorded from the differential spectra (spectrum obtained by subtraction of the
absorption 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 centimetre).
1.4.3 In either case, 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 oxidation changes to equipment performance.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.96.03 on FTIR Testing Practices and Techniques Related to In-Service Lubricants.
Current edition approved Dec. 1, 2021Oct. 1, 2022. Published January 2022October 2022. Originally approved in 2009. Last previous edition approved in 20182021 as
D7414 – 18.D7414 – 21. DOI: 10.1520/D7414-21.10.1520/D7414-22.
The boldface numbers in parentheses refer to a list of references at the end of this standard.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7414 − 22
NOTE 1—It is not the intent of this test method to establish or recommend normal, cautionary, warning, or alert limits for any machinery. Such limits
should be established in conjunction with advice and guidance from the machinery manufacturer and maintenance group.
1.5 This test method is for petroleum and hydrocarbon based lubricants and is not applicable for ester based oils, including polyol
esters or phosphate esters.
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
–1
1.6.1 Exception—The unit for wave numbers is cm .
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.8 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D445 Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
D664 Test Method for Acid Number of Petroleum Products by Potentiometric Titration
D974 Test Method for Acid and Base Number by Color-Indicator Titration
D2896 Test Method for Base Number of Petroleum Products by Potentiometric Perchloric Acid Titration
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D4739 Test Method for Base Number Determination by Potentiometric Hydrochloric Acid Titration
D5185 Test Method for Multielement Determination of Used and Unused Lubricating Oils and Base Oils by Inductively
Coupled Plasma Atomic Emission Spectrometry (ICP-AES)
D7412 Test Method for Condition Monitoring of Phosphate Antiwear Additives in In-Service Petroleum and Hydrocarbon Based
Lubricants by Trend Analysis Using Fourier Transform Infrared (FT-IR) Spectrometry
D7415 Test Method for Condition Monitoring of Sulfate By-Products in In-Service Petroleum and Hydrocarbon Based
Lubricants by Trend Analysis Using Fourier Transform Infrared (FT-IR) Spectrometry
D7418 Practice for Set-Up and Operation of Fourier Transform Infrared (FT-IR) Spectrometers for In-Service Oil Condition
Monitoring
D7624 Test Method for Condition Monitoring of Nitration in In-Service Petroleum and Hydrocarbon-Based Lubricants by Trend
Analysis Using Fourier Transform Infrared (FT-IR) Spectrometry
E131 Terminology Relating to Molecular Spectroscopy
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 Definitions—For definitions of terms relating to infrared spectroscopy used in this test method, refer to Terminology E131. For
definitions of terms related to in-service oil condition monitoring, refer to Practice D7418 and Terminology D4175.
3.2 machinery health, n—qualitative expression of the operational status of a machine subcomponent, component, or entire
machine, used to communicate maintenance and operational recommendations or requirements in order to continue operation,
schedule maintenance, or take immediate maintenance action.
4. Summary of Test Method
4.1 This test method uses FT-IR spectrometry to monitor oxidation levels in in-service petroleum and hydrocarbon based
lubricants. The FT-IR spectra of in-service oil samples are collected according to the protocol for either direct trend analysis or
differential trend analysis described in Practice D7418, and the levels of oxidation are measured using the peak height or area
measurements described herein.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
D7414 − 22
5. Significance and Use
5.1 A large number of compounds, such as aldehydes, ketones, esters, and carboxylic acids, are produced when oils react with
–1 –1
atmospheric oxygen. Oxidation is measured using a common FT-IR spectral feature between 1800 cm and 1670 cm1670 cm
caused by the absorption of the carbonyl group present in most oxidation compounds. These oxidation products may lead to
increased viscosity (causing oil thickening problems), acidity (causing acidic corrosion), and formation of sludge and varnish
(leading to filter plugging, fouling of critical oil clearances and valve friction). Monitoring of oxidation products is therefore an
important parameter in determining overall machinery health and should be considered in conjunction with data from other tests
such as atomic emission (AE) and atomic absorption (AA) spectroscopy for wear metal analysis (Test Method D5185) and physical
property tests (Test Methods D445), base reserve (Test Method D2896 and D4739), acid number tests (Test Methods D664 and
D974) and other FT-IR oil analysis methods for nitration (Test Method D7624), sulfate by-products (Test Method D7415), and
additive depletion (Test Method D7412), which also assess elements of the oil’s condition, see Refs (1-6).
6. Interferences
6.1 Various additive packages, especially those containing esters and carboxylic acids, such as some viscosity index improvers,
pour point depressants, and rust inhibitors, can give false positives for oxidation. In addition, oils mixed with any synthetic ester
based oil products will also give very high values for oxidation. One should trend the in-service oil against the new oil to help
identifyRefer to Practice D7418 these interferences. In some oils the contributions from additive packages and synthetic ester based
oils may be so h
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