ASTM D7844-22a

Standard Test Method for Condition Monitoring of Soot in In-Service Lubricants by Trend Analysis using Fourier Transform Infrared (FT-IR) Spectrometry

SIGNIFICANCE AND USE
5.1 An increase in soot material can lead to increased wear, filter plugging and viscosity. Monitoring of soot 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), physical property tests (Test Methods D445 and D2896), and other FT-IR oil analysis methods for oxidation (Test Method D7414), sulfate by-products (Test Method D7415), nitration (Test Method D7624), and additive depletion (Test Method D7412), which also assess elements of the oil’s condition (1-6).
SCOPE
1.1 This test method pertains to field-based 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 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 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 D7418. 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 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).2 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.  
1.4.1 Interpretation of soot values reported as a percentage is more widely understood within the industry. As an alternate reporting option, an equation to convert the soot absorbance value generated from Procedure A (direct trend) analysis to percent is provided. This equation is based on the Beer-Lambert law which states that concentration is directly proportional to absorbance.
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 primarily for petroleum/hydrocarbon based lubricants but is also applicable for ester based oils, including polyol esters or phosphate esters.  
1.6 This method is intended as a field test only, and should be treated as such. Critical applications should use laboratory based methods, such as Thermal Gravimetric (TGA) analysis described in Standard Method D5967, Annex A4.  
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 th...

General Information

• Status: Published
• Publication Date: 30-Sep-2022
• ICS: 75.160.20 - Liquid fuels
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.96.03 - FTIR Testing Practices and Techniques Related to In-Service Lubricants

Relations

• Refers: ASTM D445-24 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Apr-2024
• Refers: ASTM D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 15-Dec-2023
• Refers: ASTM D445-23 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Nov-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023
• Refers: ASTM D5185-18 - Standard Test Method for Multielement Determination of Used and Unused Lubricating Oils and Base Oils by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES)
• Effective Date: 01-Apr-2018
• Refers: ASTM D5967-17 - Standard Test Method for Evaluation of Diesel Engine Oils in T-8 Diesel Engine
• Effective Date: 01-May-2017
• Refers: ASTM D445-16 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 15-Dec-2016
• Refers: ASTM D5967-15a - Standard Test Method for Evaluation of Diesel Engine Oils in T-8 Diesel Engine
• Effective Date: 01-Oct-2015
• Refers: ASTM D5967-15 - Standard Test Method for Evaluation of Diesel Engine Oils in T-8 Diesel Engine
• Effective Date: 01-Apr-2015
• Refers: ASTM D5967-14 - Standard Test Method for Evaluation of Diesel Engine Oils in T-8 Diesel Engine
• Effective Date: 01-Oct-2014
• Refers: ASTM D445-14e1 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Jul-2014
• Refers: ASTM D445-14 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Jul-2014
• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM E177-13 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2013
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013

Overview

ASTM D7844-22a provides a standardized test method for the condition monitoring of soot in in-service lubricants by trend analysis using Fourier Transform Infrared (FT-IR) spectrometry. Developed by ASTM International, this standard is primarily intended for use with diesel crankcase engine oils and other engine oils where soot contamination may occur due to incomplete fuel combustion and blow-by. Effective soot monitoring is crucial for assessing the health of lubricated machinery and supporting informed maintenance decisions.

This field-based method enables rapid and straightforward monitoring of soot buildup in lubricants, supporting proactive maintenance through trend analysis. While designed for use with petroleum or hydrocarbon-based lubricants, it is also applicable to ester-based oils, such as polyol and phosphate esters.

Key Topics

• Soot in Lubricants: Soot accumulation can cause increased engine wear, filter plugging, and oil viscosity changes. Routine soot monitoring helps identify early signs of potential machinery problems.
• FT-IR Spectrometry: The method employs FT-IR spectrometry, which detects changes in oil spectra associated with soot content by either direct trend analysis (measuring absorbance at a specific wavelength) or differential trend analysis (comparing in-service oil spectra with unused reference oil).
• Trend Analysis Techniques:
  • Direct Trend Analysis: Values are recorded from absorbance spectra and reported in units of 100 × absorbance per 0.1 mm pathlength.
  • Differential Trend Analysis: Values are obtained from the subtraction of the reference oil spectrum from the used oil spectrum.
• Reporting and Interpretation: Data is trended over time and can be reported as absorbance values or converted to more familiar percentage soot content using a prescribed calculation. Results should be compared relative to unused oils of the same formulation rather than against unrelated formulations.
• Interference and Limitations: High water content, sludge, or other insolubles in oil samples can interfere with FT-IR analysis of soot. The standard is not intended to set specific maintenance thresholds; action limits should be determined using machinery history and expert input.

Applications

• Machinery Health Monitoring: Enables maintenance professionals to monitor engine and equipment health by tracking soot accumulation in engine oil. Early detection of abnormal soot levels supports timely interventions, reducing the risk of catastrophic failures.
• Field-Based Diagnostics: The method is designed for field testing, offering a fast alternative to laboratory-based approaches for non-critical applications. For critical machinery, laboratory methodologies such as Thermal Gravimetric Analysis (TGA) (see ASTM D5967) may be preferred.
• Complementary Testing: The soot monitoring method should be used in conjunction with other oil condition monitoring tests, such as:
  • Wear metal analysis (ASTM D5185)
  • Physical property measurement (ASTM D445, D2896)
  • Monitoring oxidation (ASTM D7414), sulfate by-products (ASTM D7415), nitration (ASTM D7624), and additive depletion (ASTM D7412) via FT-IR

Related Standards

• ASTM D7418 - Practice for Set-Up and Operation of FT-IR Spectrometers for Oil Condition Monitoring
• ASTM D5185 - Multi-element Wear Metal Determination by ICP-AES
• ASTM D445 - Kinematic Viscosity of Oils
• ASTM D2896 - Base Number of Petroleum Products
• ASTM D7414 - Condition Monitoring of Oxidation in Oils by FT-IR
• ASTM D7415 - Condition Monitoring of Sulfate By-Products in Lubricants by FT-IR
• ASTM D7624 - Nitration Monitoring in Lubricants by FT-IR
• ASTM D7412 - Additive Depletion Monitoring in Lubricants by FT-IR
• ASTM D5967 - Thermal Gravimetric Analysis for Oils in Critical Applications

By adhering to ASTM D7844-22a, oil sampling and condition-based maintenance programs can be enhanced with efficient, field-deployable tools for managing soot-related risks in a variety of engines and lubricated equipment. This standard supports increased equipment reliability and extends lubricant life through informed monitoring practices.

Standards Content (Sample)

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.
Designation: D7844 − 22a
Standard Test Method for
Condition Monitoring of Soot in In-Service Lubricants by
Trend Analysis using Fourier Transform Infrared (FT-IR)
Spectrometry
This standard is issued under the fixed designation D7844; 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* be based on a rate of change of the response measured (1). In
either case, such maintenance action limits should be deter-
1.1 This test method pertains to field-based monitoring soot
mined through statistical analysis, history of the same or
in diesel crankcase engine oils as well as in other types of
similar equipment, round robin tests or other methods in
engine oils where soot may contaminate the lubricant as a
conjunction with the correlation of soot levels to equipment
result of a blow-by due to incomplete combustion of in-service
performance.
fuels.
1.4.1 Interpretation of soot values reported as a percentage
1.2 This test method uses FT-IR spectroscopy for monitor-
is more widely understood within the industry.As an alternate
ing of soot build-up in in-service lubricants as a result of
reporting option, an equation to convert the soot absorbance
normal machinery operation. Soot levels in engine oils rise as
value generated from Procedure A (direct trend) analysis to
soot particles contaminate the oil as a result of exhaust gas
percent is provided. This equation is based on the Beer-
recirculation or a blow-by. This test method is designed as a
Lambert law which states that concentration is directly propor-
fast, simple spectroscopic check for monitoring of soot in
tional to absorbance.
in-service lubricants with the objective of helping diagnose the
NOTE 1—It is not the intent of this test method to establish or
operational condition of the machine based on measuring the
recommendnormal,cautionary,warning,oralertlimitsforanymachinery.
level of soot in the oil.
Suchlimitsshouldbeestablishedinconjunctionwithadviceandguidance
1.3 Acquisition of FT-IR spectral data for measuring soot in
from the machinery manufacturer and maintenance group.
in-service oil and lubricant samples is described in Standard
1.5 Thistestmethodisprimarilyforpetroleum/hydrocarbon
Practice D7418. In this test method, measurement and data
based lubricants but is also applicable for ester based oils,
interpretation parameters for soot using both direct trend
including polyol esters or phosphate esters.
analysis and differential (spectral subtraction) trend analysis
are presented.
1.6 This method is intended as a field test only, and should
be treated as such. Critical applications should use laboratory
1.4 This test method is based on trending of spectral
changesassociatedwithsootinin-servicelubricants.Fordirect based methods, such as Thermal Gravimetric (TGA) analysis
trend analysis, values are recorded directly from absorbance described in Standard Method D5967, Annex A4.
spectra and reported in units of 100*absorbance per 0.1 mm
1.7 This standard does not purport to address all of the
pathlength. For differential trend analysis, values are recorded
safety concerns, if any, associated with its use. It is the
from the differential spectra (spectrum obtained by subtraction
responsibility of the user of this standard to establish appro-
of the spectrum of the reference oil from that of the in-service
priate safety, health, and environmental practices and deter-
oil) and reported in units of 100*absorbance per 0.1 mm
mine the applicability of regulatory limitations prior to use.
pathlength (or equivalently absorbance units per centimeter).
1.8 This international standard was developed in accor-
Warnings or alarm limits can be set on the basis of a fixed
dance with internationally recognized principles on standard-
maximum value for a single measurement or, alternatively, can
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
This test method is under the jurisdiction of ASTM Committee D02 on
Barriers to Trade (TBT) Committee.
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 Oct. 1, 2022. Published October 2022. Originally
approved in 2009. Last previous edition approved in 2022 as D7844 – 22. DOI: The boldface numbers in parentheses refer to the list of references at the end of
10.1520/D7844-22A. 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
D7844 − 22a
2. Referenced Documents and the levels of soot are measured using the absorption
3 intensity measurement described herein. The values obtained
2.1 ASTM Standards:
for the sample of the in-service oil are compared to the value
D445 Test Method for Kinematic Viscosity of Transparent
for a sample of new reference oil using either direct trend
and Opaque Liquids (and Calculation of Dynamic Viscos-
analysis or differential trend analysis approaches.
ity)
D2896 TestMethodforBaseNumberofPetroleumProducts
5. Significance and Use
by Potentiometric Perchloric Acid Titration
5.1 An increase in soot material can lead to increased wear,
D4175 Terminology Relating to Petroleum Products, Liquid
filter plugging and viscosity. Monitoring of soot is therefore an
Fuels, and Lubricants
important parameter in determining overall machinery health
D5185 Test Method for Multielement Determination of
and should be considered in conjunction with data from other
Used and Unused Lubricating Oils and Base Oils by
testssuchasatomicemission(AE)andatomicabsorption(AA)
Inductively Coupled Plasma Atomic Emission Spectrom-
spectroscopy for wear metal analysis (Test Method D5185),
etry (ICP-AES)
physical property tests (Test Methods D445 and D2896), and
D5967 Test Method for Evaluation of Diesel Engine Oils in
other FT-IR oil analysis methods for oxidation (Test Method
T-8 Diesel Engine
D7414), sulfate by-products (Test Method D7415), nitration
D7412 Test Method for Condition Monitoring of Phosphate
(Test Method D7624), and additive depletion (Test Method
Antiwear Additives in In-Service Petroleum and Hydro-
D7412),whichalsoassesselementsoftheoil’scondition (1-6).
carbon Based Lubricants byTrendAnalysis Using Fourier
Transform Infrared (FT-IR) Spectrometry
6. Interferences
D7414 Test Method for Condition Monitoring of Oxidation
in In-Service Petroleum and Hydrocarbon Based Lubri- 6.1 Refer to Practice D7418 for a list of common interfer-
cants byTrendAnalysis Using FourierTransform Infrared ents affecting the quality of all FTIR generated spectra.
(FT-IR) Spectrometry
6.2 When the sample has increased baseline (soot >2.5 %)
D7415 Test Method for Condition Monitoring of Sulfate
or interferent peak present, follow the optional procedure in
By-Products in In-Service Petroleum and Hydrocarbon
Practice D7418 Section 11 depending on measurement accu-
Based Lubricants by TrendAnalysis Using Fourier Trans-
racy needs.
form Infrared (FT-IR) Spectrometry
6.3 High levels of water (>5 %) will interfere with the soot
D7418 Practice for Set-Up and Operation of Fourier Trans-
measurement in internal combustion engine crankcases. Other
form Infrared (FT-IR) Spectrometers for In-Service Oil
interferences include high levels of sludge or insolubles.These
Condition Monitoring
interferences will increase the measured soot values.
D7624 TestMethodforConditionMonitoringofNitrationin
In-Service Petroleum and Hydrocarbon-Based Lubricants
7. Apparatus
by Trend Analysis Using Fourier Transform Infrared
7.1 Fourier Transform Infrared Spectrometer, equipped
(FT-IR) Spectrometry
with sample cell, filter and pumping system (optional) as
E131 Terminology Relating to Molecular Spectroscopy
specified in Standard Practice D7418.
E177 Practice for Use of the Terms Precision and Bias in
ASTM Test Methods
7.2 FT-IR Spectral Acquisition Parameters—Set FT-IR
E691 Practice for Conducting an Interlaboratory Study to
spectral acquisition parameters according to instructions in
Determine the Precision of a Test Method
Standard Practice D7418.
3. Terminology
8. Sampling
3.1 Definitions—For definitions of terms relating to infrared
8.1 Obtain a sample of the in-service oil and the reference
spectroscopy used in this test method, refer to Terminology
oil according to the protocol described in Standard Practice
E131. For definitions of terms related to in-service oil condi-
D7418.
tion monitoring, refer to Practice D7418 and Terminology
D4175.
9. Preparation and Maintenance of Apparatus
9.1 Rinse, flush and clean the sample cell, lines and inlet
4. Summary of Test Method
filter according to instructions in Standard Practice D7418.
4.1 This test method uses FT-IR spectrometry to monitor
9.2 MonitorcellpathlengthasspecifiedinStandardPractice
soot levels in in-service lubricants.The test method is meant to
D7418.
serve as a field-based method to provide an indicator of soot
level. The FT-IR spectra of in-service oil samples are collected
10. Procedure and Calculation
accordingtotheprotocoldescribedinStandardPracticeD7418
10.1 Collect a background spectrum according to the pro-
cedure specified in Section
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7844 − 22 D7844 − 22a
Standard Test Method for
Condition Monitoring of Soot in In-Service Lubricants by
Trend Analysis using Fourier Transform Infrared (FT-IR)
Spectrometry
This standard is issued under the fixed designation D7844; 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 pertains to field-based 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 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 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
D7418. 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 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.
1.4.1 Interpretation of soot values reported as a percentage is more widely understood within the industry. As an alternate reporting
option, an equation to convert the soot absorbance value generated from Procedure A (direct trend) analysis to percent is provided.
This equation is based on the Beer-Lambert law which states that concentration is directly proportional to absorbance.
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.
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 July 1, 2022Oct. 1, 2022. Published August 2022October 2022. Originally approved in 2009. Last previous edition approved in 20212022 as
D7844 – 21.D7844 – 22. DOI: 10.1520/D7844-22.10.1520/D7844-22A.
The boldface numbers in parentheses refer to the 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
D7844 − 22a
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.
1.6 This method is intended as a field test only, and should be treated as such. Critical applications should use laboratory based
methods, such as Thermal Gravimetric (TGA) analysis described in Standard Method D5967, Annex A4.
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)
D2896 Test Method for Base Number of Petroleum Products by Potentiometric Perchloric Acid Titration
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D5185 Test Method for Multielement Determination of Used and Unused Lubricating Oils and Base Oils by Inductively
Coupled Plasma Atomic Emission Spectrometry (ICP-AES)
D5967 Test Method for Evaluation of Diesel Engine Oils in T-8 Diesel Engine
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
D7414 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
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.
4. Summary of Test Method
4.1 This test method uses FT-IR spectrometry to monitor soot levels in in-service lubricants. The test method is meant to serve
as a field-based method to provide an indicator of soot level. The FT-IR spectra of in-service oil samples are collected according
to the protocol described in Standard Practice D7418 and the levels of soot are measured using the absorption intensity
measurement described herein. The values obtained for the sample of the in-service oil are compared to the value for a sample of
new reference oil using either direct trend analysis or differential trend analysis approaches.
5. Significance and Use
5.1 An increase in soot material can lead to increased wear, filter plugging and viscosity. Monitoring of soot 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), physical
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
D7844 − 22a
property tests (Test Methods D445 and D2896), and other FT-IR oil analysis methods for oxidation (Test Method D7414), sulfate
by-products (Test Method D7415), nitration (Test Method D7624), and additive depletion (Test Method D7412), which also assess
elements of the oil’s condition (1-6).
6. Interferences
6.1 Refer to Practice D7418 for a list of common interferents affecting the quality of all FTIR generated spectra.
6.2 When the sample has increased baseline (soot >2.5 %) or interferent peak present, follow the optional procedure in Practice
D7418 Section 11 depending on measurement accuracy needs.
6.3 High levels of water (>5 %) will interfere with the soot measurement in internal combustion engine crankcases. Other
interferences include high levels of sludge or insolubles. These interferences will increase the measured soot values.
7. Apparatus
7.1 Fourier Transform Infrared Spectrometer, equipped with sample cell, filter and pumping system (optional) as specified in
Standard Practice D7418.
7.2 FT-IR Spectral Acquisition Parameters—Set FT-IR spectral acquisition parameters according to instructions in Standard
Practice D7418.
8. Sampling
8.1 Obtain a sample of the in-service oil and the reference oil according to the protocol described in Standard Practice D7418.
9. Preparation and Main
...