ASTM D7415-22

Standard 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

SIGNIFICANCE AND USE
5.1 An increase in sulfate material can be an indicator of oil degradation caused by oxidation of sulfur in the oil and sulfur in fuel. It can also indicate the breakdown or oxidation of some key additives in the oil such as antiwear and extreme pressure additives as well as blow-by concerns. As oxidized sulfur from blow-by enters the lubricant, it will consume the overbase additive to generate sulfate by-products. Monitoring of sulfate by-products is therefore an important parameter in determining overall machinery health and in determining additive depletion 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), base number tests (Test Methods D974 and D4739), and other FT-IR oil analysis methods for nitration (Test Method D7624), oxidation (Test Method D7414), and additive depletion (Test Method D7412), which also assess elements of the oil’s condition, see Refs (1-6).
SCOPE
1.1 This test method covers monitoring sulfate by-products in in-service petroleum and hydrocarbon based diesel crankcase engine and motor oils that have a sulfur content of greater than 500 ppm. This test method should not be employed when low-sulfur fuels are used for combustion.  
1.2 This test method uses Fourier Transform Infrared (FT-IR) spectrometry for monitoring build-up of sulfate by-products in in-service petroleum and hydrocarbon based lubricants as a result of normal machinery operation. Sulfate by-products can result from the introduction of sulfur from combustion or from the oxidation of sulfur-containing base oil additives. This test method is designed as a fast, simple spectroscopic check for monitoring of sulfate by-products 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 sulfate by-products in the oil.  
1.3 Acquisition of FT-IR spectral data for measuring sulfate by-products in in-service oil and lubricant samples is described in Practice D7418. In this test method, measurement and data interpretation parameters for sulfate by-products 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 sulfate by-products 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).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 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 sulfate by-product changes 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...

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 D974-14e1 - Standard Test Method for Acid and Base Number by Color-Indicator Titration
• Effective Date: 01-Dec-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 E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• 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 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 D974-12 - Standard Test Method for Acid and Base Number by Color-Indicator Titration
• 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

Overview

ASTM D7415-22 is the standard test method for condition monitoring of sulfate by-products in in-service petroleum and hydrocarbon-based lubricants. This standard utilizes trend analysis through Fourier Transform Infrared (FT-IR) Spectrometry to detect and track the build-up of sulfate by-products in diesel crankcase engine and motor oils containing more than 500 ppm sulfur. By providing a fast, reliable spectroscopic method, ASTM D7415-22 aids in determining the operational health of machinery and the condition of the lubricants.

Monitoring sulfate by-products is critical because their accumulation can indicate oil degradation, sulfur oxidation, additive breakdown, and blow-by uptake, all of which directly impact machinery performance and lubricant lifespan.

Key Topics

• Condition Monitoring: The standard outlines procedures for monitoring sulfate by-products in oils during normal machine operation, helping identify oil degradation and additive depletion.
• FT-IR Spectrometry: This method uses FT-IR technology to analyze lubricant samples, leveraging both direct trend analysis and differential trend analysis for robust data interpretation.
• Trend Analysis: By trending sulfate by-product data over time, maintenance teams can identify patterns, assess machinery health, and establish maintenance intervals.
• Interference Factors: The standard notes that certain oil additives (detergents, dispersants, demulsifiers, overbase additives) and contaminants (esters, glycols, alcohols) can interfere with results. It is not suitable for oils based on esters or those with low-sulfur content due to measurement interference.
• Reporting and Data Interpretation: The procedure includes guidance on sampling intervals, baseline establishment, trend plotting, and data reporting, facilitating actionable maintenance decisions.

Applications

ASTM D7415-22 is widely applicable in industries where machinery and engines rely on petroleum or hydrocarbon-based lubricants. Practical uses include:

• Predictive Maintenance: Fleet operators and plant managers use the standard to monitor lubricant condition, detecting oil degradation before it leads to equipment failure.
• Oil Change Scheduling: By identifying changes in sulfate by-product levels, maintenance teams can optimize oil change intervals, reducing waste and operational costs.
• Additive Depletion Analysis: The method helps assess the rate of depletion of critical additives, enabling timely replenishment and extended equipment protection.
• Quality Control: Lubricant suppliers and laboratories use ASTM D7415-22 for in-service oil testing, supporting warranty claims, and ensuring ongoing lubricant performance.
• Comprehensive Machinery Health Assessment: This test is best used in conjunction with other oil analysis methods (e.g., wear metal analysis, viscosity testing, base number determination) to build a complete picture of equipment condition.

Related Standards

Several standards complement or reference ASTM D7415-22 in the field of oil analysis and lubricant testing:

• ASTM D7418: Practice for the set-up and operation of FT-IR spectrometers for in-service oil condition monitoring.
• ASTM D445: Method for determining the kinematic viscosity of lubricating oils.
• ASTM D5185: Procedure for multi-element determination in oils via ICP-AES, useful for wear metal analysis.
• ASTM D974 & D4739: Methods for measuring acid and base numbers in oils.
• ASTM D7414, D7412, D7624: Other FT-IR based condition monitoring methods targeting oxidation, additive depletion, and nitration in lubricants.

Keywords

ASTM D7415-22, FT-IR spectrometry, sulfate by-products, condition monitoring, lubricant analysis, petroleum-based lubricants, hydrocarbon oils, oil degradation, additive depletion, machinery health, trend analysis, in-service oil testing.

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: D7415 − 22
Standard 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
This standard is issued under the fixed designation D7415; 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* 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 sulfate by-products
1.4.1 For direct trend analysis, values are recorded directly
in in-service petroleum and hydrocarbon based diesel crank-
fromabsorptionspectraandreportedinunitsofabsorbanceper
case engine and motor oils that have a sulfur content of greater
0.1 mm pathlength.
than 500 ppm. This test method should not be employed when
1.4.2 For differential trend analysis, values are recorded
low-sulfur fuels are used for combustion.
from the differential spectra (spectrum obtained by subtraction
of the absorption spectrum of the reference oil from that of the
1.2 This test method uses Fourier Transform Infrared (FT-
in-service oil) and reported in units of 100*absorbance per
IR) spectrometry for monitoring build-up of sulfate by-
0.1 mm pathlength (or equivalently absorbance units per cen-
products in in-service petroleum and hydrocarbon based lubri-
timetre).
cants as a result of normal machinery operation. Sulfate
1.4.3 In either case, maintenance action limits should be
by-products can result from the introduction of sulfur from
determined through statistical analysis, history of the same or
combustion or from the oxidation of sulfur-containing base oil
similar equipment, round robin tests, or other methods in
additives. This test method is designed as a fast, simple
conjunction with the correlation of sulfate by-product changes
spectroscopic check for monitoring of sulfate by-products in
to equipment performance.
in-service petroleum and hydrocarbon based lubricants with
the objective of helping diagnose the operational condition of
NOTE 1—It is not the intent of this test method to establish or
the machine based on measuring the level of sulfate by- recommendnormal,cautionary,warning,oralertlimitsforanymachinery.
Suchlimitsshouldbeestablishedinconjunctionwithadviceandguidance
products in the oil.
from the machinery manufacturer and maintenance group.
1.3 Acquisition of FT-IR spectral data for measuring sulfate
1.5 This test method is for petroleum and hydrocarbon
by-products in in-service oil and lubricant samples is described
based lubricants and is not applicable for ester based oils,
in Practice D7418. In this test method, measurement and data
including polyol esters or phosphate esters.
interpretation parameters for sulfate by-products using both
1.6 The values stated in SI units are to be regarded as
directtrendanalysisanddifferential(spectralsubtraction)trend
standard. No other units of measurement are included in this
analysis are presented.
standard.
-1
1.4 This test method is based on trending of spectral
1.6.1 Exception—The unit for wave numbers is cm .
changes associated with sulfate by-products of in-service
1.7 This standard does not purport to address all of the
petroleum and hydrocarbon based lubricants. Warnings or
safety concerns, if any, associated with its use. It is the
alarm limits can be set on the basis of a fixed minimum value
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.8 This international standard was developed in accor-
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
dance with internationally recognized principles on standard-
Subcommittee D02.96.03 on FTIR Testing Practices and Techniques Related to
ization established in the Decision on Principles for the
In-Service Lubricants.
Current edition approved Oct. 1, 2022. Published October 2022. Originally
approved in 2009. Last previous edition approved in 2021 as D7415 – 21. DOI: The boldface numbers in parentheses refer to a list of references at the end of
10.1520/D7415-22. 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
D7415 − 22
Development of International Standards, Guides and Recom- 4. Summary of Test Method
mendations issued by the World Trade Organization Technical
4.1 This test method uses FT-IR spectrometry to monitor
Barriers to Trade (TBT) Committee.
sulfate by-product in in-service petroleum and hydrocarbon
based lubricants. The FT-IR spectra of in-service oil samples
2. Referenced Documents
are collected according to the protocol for either direct trend
2.1 ASTM Standards:
analysis or differential trend analysis described in Practice
D445 Test Method for Kinematic Viscosity of Transparent
D7418, and the levels of sulfate by-products are measured
and Opaque Liquids (and Calculation of Dynamic Viscos-
using the peak height or area measurements described herein.
ity)
5. Significance and Use
D974 Test Method for Acid and Base Number by Color-
Indicator Titration
5.1 An increase in sulfate material can be an indicator of oil
D2896 Test Method for Base Number of Petroleum Products
degradation caused by oxidation of sulfur in the oil and sulfur
by Potentiometric Perchloric Acid Titration
infuel.Itcanalsoindicatethebreakdownoroxidationofsome
D4175 Terminology Relating to Petroleum Products, Liquid
key additives in the oil such as antiwear and extreme pressure
Fuels, and Lubricants
additives as well as blow-by concerns.As oxidized sulfur from
D4739 Test Method for Base Number Determination by
blow-by enters the lubricant, it will consume the overbase
Potentiometric Hydrochloric Acid Titration
additive to generate sulfate by-products. Monitoring of sulfate
D5185 Test Method for Multielement Determination of
by-products is therefore an important parameter in determining
Used and Unused Lubricating Oils and Base Oils by
overall machinery health and in determining additive depletion
Inductively Coupled Plasma Atomic Emission Spectrom-
and should be considered in conjunction with data from other
etry (ICP-AES)
testssuchasatomicemission(AE)andatomicabsorption(AA)
D7412 Test Method for Condition Monitoring of Phosphate
spectroscopy for wear metal analysis (Test Method D5185),
Antiwear Additives in In-Service Petroleum and Hydro-
physical property tests (Test Methods D445 and D2896), base
carbon Based Lubricants byTrendAnalysis Using Fourier
numbertests(TestMethodsD974andD4739),andotherFT-IR
Transform Infrared (FT-IR) Spectrometry
oil analysis methods for nitration (Test Method D7624),
D7414 Test Method for Condition Monitoring of Oxidation
oxidation (Test Method D7414), and additive depletion (Test
in In-Service Petroleum and Hydrocarbon Based Lubri-
Method D7412), which also assess elements of the oil’s
cants byTrendAnalysis Using FourierTransform Infrared
condition, see Refs (1-6).
(FT-IR) Spectrometry
6. Interferences
D7418 Practice for Set-Up and Operation of Fourier Trans-
form Infrared (FT-IR) Spectrometers for In-Service Oil
6.1 Refer to Practice D7418 for a list of common interfer-
Condition Monitoring
ents affecting the quality of all FTIR generated spectra.
D7624 TestMethodforConditionMonitoringofNitrationin
6.2 When the sample has increased baseline (soot >2.5 %)
In-Service Petroleum and Hydrocarbon-Based Lubricants
or interferent peak present, follow the optional procedure in
by Trend Analysis Using Fourier Transform Infrared
Practice D7418 Section 11 depending on measurement accu-
(FT-IR) Spectrometry
racy needs.
E131 Terminology Relating to Molecular Spectroscopy
6.3 Oxidation by-products can be a major source of inter-
E177 Practice for Use of the Terms Precision and Bias in
ference in the measurement of sulfate by-products. When
ASTM Test Methods
oxidation by-products are present, the low levels of sulfate
E691 Practice for Conducting an Interlaboratory Study to
by-products associated with the use of low-sulfur fuels for
Determine the Precision of a Test Method
combustion cannot be adequately measured.
3. Terminology
7. Apparatus
3.1 Definitions—For definitions of terms relating to infrared
7.1 Fourier transform infrared spectrometer equipped with
spectroscopy used in this test method, refer to Terminology
sample cell, filter (optional) and pumping system (optional) as
E131. For definitions of terms related to in-service oil condi-
specified in Practice D7418.
tion monitoring, refer to Practice D7418 and Terminology
D4175. 7.2 FT-IR Spectral Acquisition Parameters—Set FT-IR
spectral acquisition parameters according to instructions in
3.2 machinery health, n—qualitative expr
...

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: D7415 − 21 D7415 − 22
Standard 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
This standard is issued under the fixed designation D7415; 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 sulfate by-products in in-service petroleum and hydrocarbon based diesel crankcase engine
and motor oils that have a sulfur content of greater than 500 ppm. This test method should not be employed when low-sulfur fuels
are used for combustion.
1.2 This test method uses Fourier Transform Infrared (FT-IR) spectrometry for monitoring build-up of sulfate by-products in
in-service petroleum and hydrocarbon based lubricants as a result of normal machinery operation. Sulfate by-products can result
from the introduction of sulfur from combustion or from the oxidation of sulfur-containing base oil additives. This test method is
designed as a fast, simple spectroscopic check for monitoring of sulfate by-products 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 sulfate
by-products in the oil.
1.3 Acquisition of FT-IR spectral data for measuring sulfate by-products in in-service oil and lubricant samples is described in
Practice D7418. In this test method, measurement and data interpretation parameters for sulfate by-products 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 sulfate by-products 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).
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
D7415 – 18.D7415 – 21. DOI: 10.1520/D7415-21.10.1520/D7415-22.
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
D7415 − 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 sulfate by-product changes 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)
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
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
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 sulfate by-product in in-service petroleum and hydrocarbon based
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.
D7415 − 22
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 sulfate by-products are measured using the peak height
or area measurements described herein.
5. Significance and Use
5.1 An increase in sulfate material can be an indicator of oil degradation caused by oxidation of sulfur in the oil and sulfur in fuel.
It can also indicate the breakdown or oxidation of some key additives in the oil such as antiwear and extreme pressure additives
as well as blow-by concerns. As oxidized sulfur from blow-by enters the lubricant, it will consume the overbase additive to
generate sulfate by-products. Monitoring of sulfate by-products is therefore an important parameter in determining overall
machinery health and in determining additive depletion 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), base number tests (Test Methods D974 and D4739), and other FT-IR oil analysis
methods for nitration (Test Method D7624), oxidation (Test Method D7414), 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,Refer to Practice D7418especially those containing detergents, dispersants, demulsifiers and
overbase additives, will interfere with the sulfate by-products measurement. for a list of common interferents affecting the quality
of all FTIR generated spectra.
6.2 Contaminants such as esters, polyols, glycols, and alcohols will also interfere with the When the sample has increased baseline
(soot >2.5 %) or interferent peak present, follow the optional procedure in Practice D7418measurement of sulfate by-
products. Section 11 depend
...