ASTM D7412-22

Standard 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

SIGNIFICANCE AND USE
5.1 Antiwear additives are commonly used in petroleum and hydrocarbon based lubricants to prevent machinery wear by forming a chemical barrier activated by frictional heat. Antiwear additives that are phosphate based can be measured by FT-IR spectroscopy using the phosphate absorption band. Initially, phosphate antiwear additives will decompose and form a protective film by binding to metal surfaces and through oxidative mechanisms, and so a decrease in the level of phosphate antiwear additive relative to that in the new oil is expected during normal machinery operation. Subsequently, significant depletion of phosphate antiwear additives due to oxidation or hydrolysis can occur when the lubricant is subjected to high temperatures and high levels of moisture. This usually occurs prior to the point where the oxidation of the lubricant begins to accelerate, making trending of phosphate antiwear additives a useful indicator of the lubricant’s remaining in-service life. Monitoring of phosphate antiwear additive depletion 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), and nitration (Test Method D7624), which also assess elements of the oil’s condition, see Refs (1-6).
SCOPE
1.1 This test method covers monitoring phosphate antiwear additives in in-service petroleum and hydrocarbon based lubricants such as various types of engine oils, hydraulic oils, and other lubricants that are formulated for protection against wear. Typical phosphate antiwear additives include zinc dialkyldithiophosphates, trialkyl phosphates, and triaryl phosphates.  
1.2 This test method uses Fourier Transform Infrared (FT-IR) spectrometry for monitoring of phosphate antiwear additive depletion in in-service petroleum and hydrocarbon based lubricants as a result of normal machinery operation. Monitoring the depletion of phosphate antiwear additives in in-service lubricants can indicate unusual wear or severe operating conditions of the machine. This test method is designed as a fast, simple spectroscopic check for monitoring of phosphate antiwear additives 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 phosphate antiwear additives in the oil.  
1.3 Acquisition of FT-IR spectral data for measuring phosphate antiwear additives in in-service oil and lubricant samples is described in Practice D7418. In this test method, measurement and data interpretation parameters for phosphate antiwear additives 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 phosphate antiwear additives in 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).2  
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 centimeter).  
1.4.3 In either case, maintenance action limits should be determined through statistical analysis, history of the same or simila...

General Information

• Status: Published
• Publication Date: 30-Sep-2022
• ICS: 75.100 - Lubricants, industrial oils and related products
• 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 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 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
• Refers: ASTM D445-12 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 15-Apr-2012
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM E177-10 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2010
• Refers: ASTM E131-10 - Standard Terminology Relating to Molecular Spectroscopy
• Effective Date: 01-Mar-2010

Overview

ASTM D7412-22 is a standardized test method developed by ASTM International for the condition monitoring of phosphate antiwear additives in in-service petroleum and hydrocarbon-based lubricants. This method utilizes Fourier Transform Infrared (FT-IR) spectrometry to monitor and analyze the depletion of phosphate-based antiwear additives, such as zinc dialkyldithiophosphates, trialkyl phosphates, and triaryl phosphates, within engine oils, hydraulic oils, and other lubricants formulated to prevent machinery wear.

By trending spectral changes associated with these additives, this standard helps industry professionals diagnose machinery operational status, determine the need for maintenance actions, and optimize lubricant replacement schedules. Regular monitoring of antiwear additive depletion provides an early indication of lubricant degradation and machine health, supporting proactive maintenance programs.

Key Topics

• Phosphate Antiwear Additives: Essential for reducing friction and wear, phosphate-based additives form a protective barrier on metal surfaces during operation, decomposing over time due to oxidation and hydrolysis, especially under high temperature and moisture.
• FT-IR Spectrometry: The standard employs FT-IR spectrometry, measuring phosphate absorption bands for accurate, non-destructive analysis of lubricant condition without extensive sample preparation.
• Trend Analysis: Users can apply direct trend analysis (measuring absorbance values directly from sample spectra) or differential trend analysis (comparing spectra of in-service oils to reference oils). Both processes allow for effective tracking of additive levels over the lubricant’s service life.
• Condition Monitoring: Monitoring additive depletion acts as an early-warning system before catastrophic machinery wear or lubricant oxidation occurs, giving valuable insight into both the oil's and equipment's operational health.
• Action & Alarm Limits: The method supports setting warning or alarm limits based on fixed minimum values or the rate of change, enabling timely maintenance actions to avoid equipment failures.

Applications

ASTM D7412-22 is widely used in industries that rely on the optimal operation of equipment and machinery, including:

• Industrial Maintenance: Enables proactive monitoring in power plants, manufacturing facilities, and heavy equipment operations by identifying lubricant degradation prior to major equipment wear.
• Fleet & Transportation Services: Vital for engine oil condition monitoring across vehicle fleets, ensuring engines are protected against wear through timely oil changes based on actual oil condition rather than fixed intervals.
• Hydraulic Systems: Essential for assessing the health of hydraulic oils in critical systems, minimizing unplanned downtime and maintaining efficient operations.
• Oil Analysis Laboratories: Offers a standardized, rapid method for in-service oil analysis, supporting predictive maintenance strategies and providing additional diagnostic data when used alongside other test methods (such as wear metal, oxidation, sulfate, and nitration analysis).

Related Standards

Monitoring the condition of phosphate antiwear additives is most effective when integrated with complementary ASTM standards for a comprehensive lubricant health assessment, including:

• ASTM D7418: Practice for the set-up and operation of FT-IR spectrometers for in-service oil monitoring.
• ASTM D5185: Test method for wear metal analysis using atomic emission spectroscopy.
• ASTM D445: Kinematic viscosity determination.
• ASTM D2896: Base number determination by potentiometric titration.
• ASTM D7414: Monitoring oxidation in lubricants via FT-IR.
• ASTM D7415: Monitoring sulfate by-products by FT-IR.
• ASTM D7624: Monitoring nitration in lubricants using FT-IR.

ASTM D7412-22 provides a robust, efficient methodology for the assessment of lubricant additive condition, serving as a core tool in industrial maintenance, oil analysis, and equipment reliability programs. Incorporating this standard helps organizations achieve optimal machinery performance, reduce operating costs, and extend equipment life by ensuring adequate antiwear protection through regular, science-based oil monitoring.

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: D7412 − 22
Standard 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
This standard is issued under the fixed designation D7412; 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* value for a single measurement or, alternatively, can be based
on a rate of change of the response measured, see Ref (1).
1.1 This test method covers monitoring phosphate antiwear
1.4.1 For direct trend analysis, values are recorded directly
additives in in-service petroleum and hydrocarbon based lubri-
fromabsorptionspectraandreportedinunitsofabsorbanceper
cants such as various types of engine oils, hydraulic oils, and
0.1 mm pathlength.
otherlubricantsthatareformulatedforprotectionagainstwear.
1.4.2 For differential trend analysis, values are recorded
Typical phosphate antiwear additives include zinc dialkyl-
from the differential spectra (spectrum obtained by subtraction
dithiophosphates, trialkyl phosphates, and triaryl phosphates.
of the absorption spectrum of the reference oil from that of the
in-service oil) and reported in units of 100*absorbance per
1.2 This test method uses Fourier Transform Infrared (FT-
0.1 mm pathlength (or equivalently absorbance units per cen-
IR) spectrometry for monitoring of phosphate antiwear addi-
timeter).
tive depletion in in-service petroleum and hydrocarbon based
1.4.3 In either case, maintenance action limits should be
lubricants as a result of normal machinery operation. Monitor-
determined through statistical analysis, history of the same or
ing the depletion of phosphate antiwear additives in in-service
similar equipment, round robin tests or other methods in
lubricants can indicate unusual wear or severe operating
conjunction with the correlation of changes in the level of
conditions of the machine. This test method is designed as a
phosphate antiwear additives to equipment performance.
fast, simple spectroscopic check for monitoring of phosphate
NOTE 1—It is not the intent of this test method to establish or
antiwear additives in in-service petroleum and hydrocarbon
recommendnormal,cautionary,warning,oralertlimitsforanymachinery.
based lubricants with the objective of helping diagnose the
Suchlimitsshouldbeestablishedinconjunctionwithadviceandguidance
operational condition of the machine based on measuring the
from the machinery manufacturer and maintenance group.
level of phosphate antiwear additives in the oil.
1.5 This test method is for petroleum and hydrocarbon
1.3 Acquisition of FT-IR spectral data for measuring phos- based lubricants and is not applicable for ester based oils,
including polyol esters or phosphate esters.
phate antiwear additives in in-service oil and lubricant samples
is described in Practice D7418. In this test method, measure-
1.6 The values stated in SI units are to be regarded as
mentanddatainterpretationparametersforphosphateantiwear
standard. No other units of measurement are included in this
additives using both direct trend analysis and differential
standard.
-1
(spectral subtraction) trend analysis are presented.
1.6.1 Exception—The unit for wave numbers is cm .
1.4 This test method is based on trending of spectral 1.7 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
changes associated with phosphate antiwear additives in in-
responsibility of the user of this standard to establish appro-
service petroleum and hydrocarbon based lubricants. Warnings
priate safety, health, and environmental practices and deter-
or alarm limits can be set on the basis of a fixed minimum
mine the applicability of regulatory limitations prior to use.
1.8 This international standard was developed in accor-
dance with internationally recognized principles on standard-
This test method is under the jurisdiction of ASTM Committee D02 on
ization established in the Decision on Principles for the
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 2021 as D7412 – 21. DOI: The boldface numbers in parentheses refer to a list of references at the end of
10.1520/D7412-22. 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
D7412 − 22
Development of International Standards, Guides and Recom- and hydrocarbon based lubricants. The FT-IR spectra of
mendations issued by the World Trade Organization Technical in-service oil samples are collected according to the protocol
Barriers to Trade (TBT) Committee. for either direct trend analysis or differential trend analysis
described in Practice D7418, and the levels of phosphate
2. Referenced Documents
antiwear additives are measured using the peak height or area
measurements described herein.
2.1 ASTM Standards:
D445 Test Method for Kinematic Viscosity of Transparent
5. Significance and Use
and Opaque Liquids (and Calculation of Dynamic Viscos-
ity)
5.1 Antiwearadditivesarecommonlyusedinpetroleumand
D2896 Test Method for Base Number of Petroleum Products
hydrocarbon based lubricants to prevent machinery wear by
by Potentiometric Perchloric Acid Titration
forming a chemical barrier activated by frictional heat. Anti-
D4175 Terminology Relating to Petroleum Products, Liquid
wear additives that are phosphate based can be measured by
Fuels, and Lubricants
FT-IR spectroscopy using the phosphate absorption band.
D5185 Test Method for Multielement Determination of
Initially, phosphate antiwear additives will decompose and
Used and Unused Lubricating Oils and Base Oils by
formaprotectivefilmbybindingtometalsurfacesandthrough
Inductively Coupled Plasma Atomic Emission Spectrom-
oxidative mechanisms, and so a decrease in the level of
etry (ICP-AES)
phosphate antiwear additive relative to that in the new oil is
D7414 Test Method for Condition Monitoring of Oxidation
expected during normal machinery operation. Subsequently,
in In-Service Petroleum and Hydrocarbon Based Lubri-
significant depletion of phosphate antiwear additives due to
cants byTrendAnalysis Using FourierTransform Infrared
oxidation or hydrolysis can occur when the lubricant is
(FT-IR) Spectrometry
subjected to high temperatures and high levels of moisture.
D7415 Test Method for Condition Monitoring of Sulfate
Thisusuallyoccurspriortothepointwheretheoxidationofthe
By-Products in In-Service Petroleum and Hydrocarbon
lubricant begins to accelerate, making trending of phosphate
Based Lubricants by TrendAnalysis Using Fourier Trans-
antiwear additives a useful indicator of the lubricant’s remain-
form Infrared (FT-IR) Spectrometry
ing in-service life. Monitoring of phosphate antiwear additive
D7418 Practice for Set-Up and Operation of Fourier Trans-
depletion is therefore an important parameter in determining
form Infrared (FT-IR) Spectrometers for In-Service Oil
overall machinery health and should be considered in conjunc-
Condition Monitoring
tion with data from other tests such as atomic emission (AE)
D7624 TestMethodforConditionMonitoringofNitrationin
and atomic absorption (AA) spectroscopy for wear metal
In-Service Petroleum and Hydrocarbon-Based Lubricants
analysis (Test Method D5185), physical property tests (Test
by Trend Analysis Using Fourier Transform Infrared
Methods D445 and D2896) and other FT-IR oil analysis
(FT-IR) Spectrometry
methods for oxidation (Test Method D7414), sulfate by-
E131 Terminology Relating to Molecular Spectroscopy
products (Test Method D7415), and nitration (Test Method
E177 Practice for Use of the Terms Precision and Bias in
D7624), which also assess elements of the oil’s condition, see
ASTM Test Methods
Refs (1-6).
E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
6. Interferences
3. Terminology 6.1 Refer to Practice D7418 for a list of common interfer-
ents affecting the quality of all FTIR generated spectra.
3.1 Definitions—For definitions of terms relating to infrared
spectroscopy used in this test method, refer to Terminology
6.2 When the sample has increased baseline (soot >2.5 %)
E131. For definition of terms related to in-service oil condition
or interferent peak present, follow the optional procedure in
monitoring, refer to Practice D7418 and Terminology D4175.
Practice D7418 Section 11 depending on measurement accu-
racy needs.
3.2 machinery health, n—qualitative expression of the op-
erational status of a machine subcomponent, component, or
7. Apparatus
entire machine, used to communicate maintenance and opera-
tional recommendations or requirements in order to continue
7.1 Fourier transform infrared spectrometer equipped with
operation, schedule maintenance, or take immediate mainte-
sample cell, filter (optional) and pumping system (optional) as
nance action.
specified in Practice D7418.
7.2 FT-IR Spectral Acquisition Parameters—Set FT-IR
4. Summary of Test Method
spectral acquisition parameters according to instructions in
4.1 This test method uses FT-IR spectrometry to monitor
Pr
...

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: D7412 − 21 D7412 − 22
Standard 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
This standard is issued under the fixed designation D7412; 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 phosphate antiwear additives in in-service petroleum and hydrocarbon based lubricants
such as various types of engine oils, hydraulic oils, and other lubricants that are formulated for protection against wear. Typical
phosphate antiwear additives include zinc dialkyldithiophosphates, trialkyl phosphates, and triaryl phosphates.
1.2 This test method uses Fourier Transform Infrared (FT-IR) spectrometry for monitoring of phosphate antiwear additive
depletion in in-service petroleum and hydrocarbon based lubricants as a result of normal machinery operation. Monitoring the
depletion of phosphate antiwear additives in in-service lubricants can indicate unusual wear or severe operating conditions of the
machine. This test method is designed as a fast, simple spectroscopic check for monitoring of phosphate antiwear additives 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 phosphate antiwear additives in the oil.
1.3 Acquisition of FT-IR spectral data for measuring phosphate antiwear additives in in-service oil and lubricant samples is
described in Practice D7418. In this test method, measurement and data interpretation parameters for phosphate antiwear additives
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 phosphate antiwear additives in 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 centimeter).
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
D7412 – 18.D7412 – 21. DOI: 10.1520/D7412-21.10.1520/D7412-22.
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
D7412 − 22
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 changes in the level of phosphate antiwear
additives to equipment performance.
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)
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)
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
definition 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 levels of phosphate antiwear additives 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
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.
D7412 − 22
trend analysis or differential trend analysis described in Practice D7418, and the levels of phosphate antiwear additives are
measured using the peak height or area measurements described herein.
5. Significance and Use
5.1 Antiwear additives are commonly used in petroleum and hydrocarbon based lubricants to prevent machinery wear by forming
a chemical barrier activated by frictional heat. Antiwear additives that are phosphate based can be measured by FT-IR spectroscopy
using the phosphate absorption band. Initially, phosphate antiwear additives will decompose and form a protective film by binding
to metal surfaces and through oxidative mechanisms, and so a decrease in the level of phosphate antiwear additive relative to that
in the new oil is expected during normal machinery operation. Subsequently, significant depletion of phosphate antiwear additives
due to oxidation or hydrolysis can occur when the lubricant is subjected to high temperatures and high levels of moisture. This
usually occurs prior to the point where the oxidation of the lubricant begins to accelerate, making trending of phosphate antiwear
additives a useful indicator of the lubricant’s remaining in-service life. Monitoring of phosphate antiwear additive depletion 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), and nitration (Test Method D7624), which also assess elements of the oil’s condition,
see Refs (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 High levels of glycol and ester based additives, or contaminants, or both, can interfere with the When the sample has increased
baseline (soot >2.
...