ASTM D8004-23

Standard Test Method for Fuel Dilution of In-Service Lubricants Using Surface Acoustic Wave Sensing

SIGNIFICANCE AND USE
5.1 This test method provides a means for a reliable field determination of fuel dilution that is quick and preparation-free. Results are obtained in approximately 1 min. Such a method is used, for example, at remote railroad depots where it is impractical to carry out a standard laboratory method for determination of fuel dilution, such as described in Test Method D7593, but it is a critical need to determine if fuel has contaminated the lubricant. If fuel has contaminated the lubricant, this is significantly detrimental to the machinery and it is typically serviced immediately. Further, the fuel can ignite at the high temperatures encountered in machinery lubricant paths.
SCOPE
1.1 This test method describes a means for determining the amount of fuel dilution present in an in-service lubricant. This is achieved by drawing into a surface acoustic wave (SAW) sensor vapor from the lubricant. Fuel vapor will be absorbed by the SAW sensor’s polymer coating. The amount of absorbance is then related to fuel content in the lubricant.  
1.2 The range of fuel dilution capable of being measured by the test method is from 0.1 % to 10.0 % by mass fuel dilution.  
1.3 This test method is specifically tailored to determining the fuel dilution of in-service lubricants, including newly utilized lubricants. The method is applicable to contamination with diesel, gasoline, and jet fuels.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 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.  See Section 9.  
1.6 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.

General Information

• Status: Published
• Publication Date: 30-Apr-2023
• ICS: 75.100 - Lubricants, industrial oils and related products
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.96.02 - Chemistry for the Evaluation of In-Service Lubricants

Relations

• Refers: ASTM D6708-24 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Mar-2024
• Refers: ASTM D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 15-Dec-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023
• Refers: ASTM E456-13a(2022)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM D6708-19 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-May-2019
• Refers: ASTM D6708-18 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Apr-2018
• Refers: ASTM E456-13A(2017)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Oct-2017
• Refers: ASTM E456-13A(2017)e3 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Oct-2017
• Refers: ASTM D6708-16a - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Apr-2016
• Refers: ASTM D6708-16 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Jan-2016
• Refers: ASTM D6708-15 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Jul-2015
• Refers: ASTM D7235-14 - Standard Guide for Establishing a Linear Correlation Relationship Between Analyzer and Primary Test Method Results Using Relevant ASTM Standard Practices
• Effective Date: 01-Dec-2014
• Refers: ASTM D7593-13 - Standard Test Method for Determination of Fuel Dilution for In-Service Engine Oils by Gas Chromatography
• Effective Date: 01-Dec-2013
• Refers: ASTM E456-13ae1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 15-Nov-2013
• Refers: ASTM E456-13ae3 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 15-Nov-2013

Overview

ASTM D8004-23 is the recognized standard test method for measuring fuel dilution in in-service lubricants using surface acoustic wave (SAW) sensing technology. Developed by ASTM International, this standard offers a quick, preparation-free solution for quantifying fuel contamination in lubricating oils used in operational machinery. With results available in approximately one minute, ASTM D8004-23 is particularly valuable for field use in locations such as remote railroad depots or sites where immediate lubricant assessment is essential and laboratory methods are impractical.

Key Topics

• Fuel Dilution Measurement: Determines fuel content in lubricants within a range of 0.1% to 10.0% by mass.
• Surface Acoustic Wave (SAW) Sensing Technology: Utilizes a polymer-coated piezoelectric sensor that absorbs fuel vapors from the lubricant’s headspace, correlating absorption to fuel concentration.
• Sample Handling:
  • Analysis can be performed on both in-service and newly utilized lubricants.
  • Compatible with diesel, gasoline, and jet fuel contaminants.
• Rapid Field Assessment:
  • Provides critical, on-the-spot results without extensive sample preparation.
  • Requires minimal equipment and short measurement times.
• Operational Guidance: Outlines requirements for sample temperatures, calibration, and handling to ensure accuracy and repeatability.
• Safety Considerations: Specifies user responsibility for health, safety, and environmental practices when handling fuel and lubricants.

Applications

ASTM D8004-23 is designed for practical, real-world utility in environments where rapid detection of fuel dilution is crucial to equipment maintenance and operational safety. Common applications include:

• Field Maintenance at Remote Sites: Enables immediate identification of fuel contamination in lubricants, supporting timely service decisions to prevent equipment damage or safety hazards.
• Industrial Equipment Monitoring: Used in industries such as transportation, construction, and energy, where machinery relies on lubricants free of fuel intrusion.
• Trend Analysis and Reliability: Data obtained can be trended per guides like ASTM D7669 and D7720 for ongoing equipment condition monitoring and predictive maintenance strategies.
• Contamination Diagnostics: Critical for preventing mechanical failure, as fuel-diluted lubricants can lead to reduced oil film strength and increased risk of ignition at high operating temperatures.

Related Standards

For comprehensive lubricant analysis, ASTM D8004-23 is closely linked with other international standards addressing sampling, testing, and data interpretation:

• ASTM D7593 – Test Method for Determination of Fuel Dilution in In-Service Engine Oils by Gas Chromatography
• ASTM D4057 – Practice for Manual Sampling of Petroleum and Petroleum Products
• ASTM D4175 – Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• ASTM D6708 – Practice for Statistical Assessment and Improvement of Agreement Between Test Methods
• ASTM D7235 – Guide for Correlation Relationship Between Analyzer and Primary Test Method Results
• ASTM D7669 – Guide for Practical Lubricant Condition Data Trend Analysis
• ASTM D7720 – Guide for Statistically Evaluating Measurand Alarm Limits When Using Oil Analysis

Conclusion

ASTM D8004-23 provides a critical solution for the quick and reliable measurement of fuel dilution in lubricants using advanced SAW sensing. Its field-ready approach is ideal for industries where immediate fuel contamination assessment guides maintenance actions, minimizes risk, and preserves equipment integrity. By referencing related ASTM standards, users can ensure complete and consistent lubricant analysis for optimized operational reliability and safety.

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: D8004 − 23
Standard Test Method for
Fuel Dilution of In-Service Lubricants Using Surface
Acoustic Wave Sensing
This standard is issued under the fixed designation D8004; 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* D4057 Practice for Manual Sampling of Petroleum and
Petroleum Products
1.1 This test method describes a means for determining the
D4175 Terminology Relating to Petroleum Products, Liquid
amount of fuel dilution present in an in-service lubricant. This
Fuels, and Lubricants
is achieved by drawing into a surface acoustic wave (SAW)
D6708 Practice for Statistical Assessment and Improvement
sensor vapor from the lubricant. Fuel vapor will be absorbed by
of Expected Agreement Between Two Test Methods that
the SAW sensor’s polymer coating. The amount of absorbance
Purport to Measure the Same Property of a Material
is then related to fuel content in the lubricant.
D7235 Guide for Establishing a Linear Correlation Relation-
1.2 The range of fuel dilution capable of being measured by
ship Between Analyzer and Primary Test Method Results
the test method is from 0.1 % to 10.0 % by mass fuel dilution.
Using Relevant ASTM Standard Practices
1.3 This test method is specifically tailored to determining D7593 Test Method for Determination of Fuel Dilution for
In-Service Engine Oils by Gas Chromatography
the fuel dilution of in-service lubricants, including newly
utilized lubricants. The method is applicable to contamination D7669 Guide for Practical Lubricant Condition Data Trend
Analysis
with diesel, gasoline, and jet fuels.
D7720 Guide for Statistically Evaluating Measurand Alarm
1.4 The values stated in SI units are to be regarded as
Limits when Using Oil Analysis to Monitor Equipment
standard. No other units of measurement are included in this
and Oil for Fitness and Contamination
standard.
3. Terminology
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3.1 Definitions:
responsibility of the user of this standard to establish appro-
3.1.1 For definitions of terms used in this test method, refer
priate safety, health, and environmental practices and deter-
to Terminology D4175.
mine the applicability of regulatory limitations prior to use.
3.2 Definitions of Terms Specific to This Standard:
See Section 9.
3.2.1 fuel dilution sample holder, n—a bottle that contains
1.6 This international standard was developed in accor-
the lubricant to be analyzed.
dance with internationally recognized principles on standard-
3.2.2 fuel dilution sample inlet, n—a tube that connects the
ization established in the Decision on Principles for the
sample to the SAW sensor.
Development of International Standards, Guides and Recom-
3.2.3 fuel dilution sample stand, n—mechanical device for
mendations issued by the World Trade Organization Technical
holding the bottle of lubricant in the SAW fuel dilution
Barriers to Trade (TBT) Committee.
apparatus in a way such that the headspace from the bottle is
2. Referenced Documents
directly fed into the SAW element.
2.1 ASTM Standards:
3.2.4 fuel dilution seal, n—a mechanism that seals the fuel
E456 Terminology Relating to Quality and Statistics dilution sample holder to the vapor path leading to the SAW
sensor.
This test method is under the jurisdiction of ASTM Committee D02 on
3.2.5 SAW fuel dilution apparatus, n—a device that mea-
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
sures fuel dilution using surface acoustic wave (SAW) tech-
Subcommittee D02.96.02 on Chemistry for the Evaluation of In-Service Lubricants.
nology. This is achieved by drawing vapor from the lubricant
Current edition approved May 1, 2023. Published May 2023. Originally
into a surface acoustic wave (SAW) sensor. The fuel dilution
approved in 2015. Last previous addition approved in 2015 as D8004 – 15. DOI:
10.1520/D8004-23.
apparatus measures the concentration of contaminating fuel
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
vapor present in the air “headspace” over the lubricant. The
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
fuel dilution apparatus assumes that this headspace fuel vapor
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. concentration is directly proportional to the fuel present in the
*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
D8004 − 23
oil. This relationship is based on Henry’s Law. As fuel 6. Interferences
contamination builds up, a vapor concentration will be estab-
6.1 Departures in temperature between the sample under
lished in the headspace that is directly proportional to the
test and the sample which was used in the calibration by more
concentration dissolved in the oil. The fuel dilution apparatus
than 2 °C will affect the precision of the results. This is due to
uses a SAW sensor to make these measurements.
the fact that the fuel vapor pressure is temperature dependent.
For example, if calibration was performed with the fuel
3.2.6 SAW sensor, n—consists of a piezoelectric substrate
standard at 20 °C and the measured samples that are at 30 °C,
that has an interdigitated electrode lithographically patterned
the fuel dilution determination would be approximately 50 %
on its surface. The surface of the SAW sensor has a polymer
high.
coating that is chosen to offer specific solubility to fuel vapors.
The mechanism of detection is a reversible absorption of the
6.2 Creating a standard using fresh, rather than aged, fuel
fuel component into the polymer. When this device is excited
will cause the method to underreport actual measured values.
by external RF (radio frequency) voltage, a synchronous
6.3 Possible interferences include the introduction of bio-
Rayleigh wave is generated on the surface of the device. When
diesel variations or other additives in the fuel after it has been
fuel contamination comes in contact with the SAW sensor
calibrated on the SAW fuel dilution meter. If the sample is
surface, it will absorb into the polymer coating. This absorption
calibrated with fuel containing the expected amount of bio-
into the polymer causes a mass change, which produces a
diesel or additive, no error in the measurement should occur. If
corresponding change in the amplitude and velocity of the
measured with an unexpected amount of biodiesel higher than
surface wave. When used in a self-resonant oscillator circuit,
that calibrated with, the apparent reading will be lower. This is
the change in Rayleigh wave velocity resulting from vapor
because the biodiesel is typically less volatile than the fuel
absorption into the polymer coating causes a corresponding
being measured. For example, if a calibration was performed
change in oscillator frequency. This change in frequency is the
on a 5.0 % fuel sample with no biodiesel, then a sample of that
basis of detection of the fuel dilution apparatus.
same fuel containing 10 % biodiesel (B10) is diluted into the
3.2.7 surface acoustic wave (SAW), n—a mechanical defor- lubricant at a 5.0 % level, the reading will be approximately
mation travelling on the surface of a material; such a defor- 4.5 %. Thus, unexpected additional amounts of biodiesel can
mation may be converted into electrical signals using a lead to false negative indications of fuel contamination if the
apparatus is not calibrated with that same fuel. Similarly,
piezoelectric material, which generates a voltage in response to
a mechanical deformation. unexpected lesser amounts of biodiesel can lead to false
positive indications of fuel content when the apparatus is not
calibrated with that fuel.
4. Summary of Test Method
6.4 Other interferences include the possibility of the cali-
4.1 A liquid sample is placed into the fuel dilution sample
bration not being performed with the source fuel and lubricant
holder of the SAW fuel dilution apparatus and fuel dilution
material under test. This can significantly reduce the precision
(percent by mass) is determined.
of the method.
4.2 The vapor headspace of the sample, equilibrated at room
6.5 Other interferences can arise from fuel dilution sample
temperature, is drawn into the SAW sensor by means of a
holders that are not completely dry or with a cleaning com-
diaphragm pump, which draws the vapor into the chamber of
pound residue.
the SAW sensor.
6.6 Samples that have very high water content (>1.0 % by
4.3 The SAW sensor registers the buildup of mass on its
mass) may also degrade the precision of the measurement.
polymer absorbent coating over a period of approximately one
minute.
7. Apparatus
4.4 Based on this mass buildup and a calibration, fuel
7.1 The SAW fuel dilution apparatus consists of the follow-
dilution (percent by mass) for the sample is determined.
ing components:
7.1.1 SAW Sensor Module, Fuel Dilution Sample Stand,
5. Significance and Use
Sample Inlet, and Seal—These components work in conjunc-
tion to extract a sealed vapor headspace from the sample being
5.1 This test method provides a means for a reliable field
analyzed, and gauge fuel contamination in the in-service
determination of fuel dilution that is quick and preparation-
lubricant sample.
free. Results are obtained in approximately 1 min. Such a
7.1.2 Fuel Dilution Sample Stand Holder—This is a dispos-
method is used, for example, at remote railroad depots where
able bottle into which the in-service lubricant is added and
it is impractical to carry out a standard laboratory method for
placed into the apparatus.
determination of fuel dilution, such as described in Test
Method D7593, but it is a critical need to determine if fuel has 7.2 Optional—A thermometer, for example a thermocouple,
contaminated the lubricant. If fuel has contaminated the which allows for the determination of the lubricant tempera-
lubricant, this is significantly detrimental to the machinery and ture. A thermometer is not required because users may elect to
it is typically serviced immediately. Further, the fuel can ignite calibrate the instrument each time before a series of
at the high temperatures encountered in machinery lubricant measurements, minimizing the temperature effects discussed in
paths. 6.1.
D8004 − 23
8. Reagents and Materials corresponding amount (2.65 g) of the fuel that is being tested
for is added to the bottle.
8.1 As-prepared Fuel Dilution Calibration Standards.
These are prepared from samples of the fuel and lubricant 12.2 It is critical that a calibration standard include a
under use. representative sample of the fuel to be detected, in addition to
representative lubricant itself. To ensure a representative cali-
8.2 Fuel Dilution Sample Holder, such as a pla
...

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: D8004 − 15 D8004 − 23
Standard Test Method for
Fuel Dilution of In-Service Lubricants Using Surface
Acoustic Wave Sensing
This standard is issued under the fixed designation D8004; 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 Scope*
1.1 This test method describes a means for determining the amount of fuel dilution present in an in-service lubricant. This is
achieved by drawing into a surface acoustic wave (SAW) sensor vapor from the lubricant. Fuel vapor will be absorbed by the SAW
sensor’s polymer coating. The amount of absorbance is then related to fuel content in the lubricant.
1.2 The range of fuel dilution capable of being measured by the test method is from 0.1 % to 10.0 % by mass fuel dilution.
1.3 This test method is specifically tailored to determining the fuel dilution of in-service lubricants, including newly utilized
lubricants. The method is applicable to contamination with diesel, gasoline, and jet fuels.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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 and healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use. See Section 9.
1.6 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:
E456 Terminology Relating to Quality and Statistics
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D6708 Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport
to Measure the Same Property of a Material
D7235 Guide for Establishing a Linear Correlation Relationship Between Analyzer and Primary Test Method Results Using
Relevant ASTM Standard Practices
D7593 Test Method for Determination of Fuel Dilution for In-Service Engine Oils by Gas Chromatography
D7669 Guide for Practical Lubricant Condition Data Trend Analysis
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
D02.96.02 on Chemistry for the Evaluation of In-Service Lubricants.
Current edition approved Oct. 1, 2015May 1, 2023. Published October 2015May 2023. Originally approved in 2015. Last previous addition approved in 2015 as
D8004 – 15. DOI: 10.1520/D8004-1510.1520/D8004-23.
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.
*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
D8004 − 23
D7720 Guide for Statistically Evaluating Measurand Alarm Limits when Using Oil Analysis to Monitor Equipment and Oil for
Fitness and Contamination
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, refer to Terminology D4175.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 fuel dilution sample holder, n—a bottle that contains the lubricant to be analyzed. For example, this may be a standard
125 mL bottle (see Fig. 1, example configuration A) or a standard 30 mL laboratory vial (see Fig. 2, example configuration B).
3.2.2 fuel dilution sample inlet, n—a tube that connects the sample to the SAW sensor.
3.2.3 fuel dilution sample stand, n—mechanical device for holding the bottle of lubricant in the SAW fuel dilution apparatus in
a way such that the headspace from the bottle is directly fed into the SAW element.
3.2.4 fuel dilution seal, n—a mechanism that seals the fuel dilution sample holder to the vapor path leading to the SAW sensor.
3.2.5 SAW fuel dilution apparatus, n—a device that measures fuel dilution using surface acoustic wave (SAW) technology. This
is achieved by drawing vapor from the lubricant into a surface acoustic wave (SAW) sensor. The fuel dilution apparatus measures
the concentration of contaminating fuel vapor present in the air “headspace” over the lubricant. The fuel dilution apparatus assumes
that this headspace fuel vapor concentration is directly proportional to the fuel present in the oil. This relationship is based on
Henry’s Law. As fuel contamination builds up, a vapor concentration will be established in the headspace that is directly
proportional to the concentration dissolved in the oil. The fuel dilution apparatus uses a SAW sensor to make these measurements.
3.2.6 SAW sensor, n—consists of a piezoelectric substrate that has an interdigitated electrode lithographically patterned on its
surface. The surface of the SAW sensor has a polymer coating that is chosen to offer specific solubility to fuel vapors. The
mechanism of detection is a reversible absorption of the fuel component into the polymer. When this device is excited by external
RF (radio frequency) voltage, a synchronous Rayleigh wave is generated on the surface of the device. When fuel contamination
comes in contact with the SAW sensor surface, it will absorb into the polymer coating. This absorption into the polymer causes
a mass change, which produces a corresponding change in the amplitude and velocity of the surface wave. When used in a
self-resonant oscillator circuit, the change in Rayleigh wave velocity resulting from vapor absorption into the polymer coating
causes a corresponding change in oscillator frequency. This change in frequency is the basis of detection of the fuel dilution
apparatus.
3.2.7 surface acoustic wave (SAW), n—a mechanical deformation travelling on the surface of a material; such a deformation may
be converted into electrical signals using a piezoelectric material, which generates a voltage in response to a mechanical
deformation.
4. Summary of Test Method
4.1 A liquid sample is placed into the fuel dilution sample holder (see Figs. 1 and 2) of the SAW fuel dilution apparatus and fuel
dilution (percent by mass) is determined.
4.2 The vapor headspace of the sample, equilibrated at room temperature, is drawn into the SAW sensor by means of a diaphragm
pump, which draws the vapor into the chamber of the SAW sensor.
4.3 The SAW sensor registers the buildup of mass on its polymer absorbent coating over a period of approximately one minute.
4.4 Based on this mass buildup and a calibration, fuel dilution (percent by mass) for the sample is determined.
5. Significance and Use
5.1 This test method provides a means for a reliable field determination of fuel dilution that is quick and preparation-free. Results
are obtained in approximately 1 min. Such a method is used, for example, at remote railroad depots where it is impractical to carry
D8004 − 23
out a standard laboratory method for determination of fuel dilution, such as described in Test Method D7593, but it is a critical
need to determine if fuel has contaminated the lubricant. If fuel has contaminated the lubricant, this is significantly detrimental to
the machinery and it is typically serviced immediately. Further, the fuel can ignite at the high temperatures encountered in
machinery lubricant paths.
6. Interferences
6.1 Departures in temperature between the sample under test and the sample which was used in the calibration by more than 2 °C
will affect the precision of the results. This is due to the fact that the fuel vapor pressure is temperature dependent. For example,
if calibration was performed with the fuel standard at 20 °C and the measured samples that are at 30 °C, the fuel dilution
determination would be approximately 50 % high.
6.2 Creating a standard using fresh, rather than aged, fuel will cause the method to underreport actual measured values.
6.3 Possible interferences include the introduction of biodiesel variations or other additives in the fuel after it has been calibrated
on the SAW fuel dilution meter. If the sample is calibrated with fuel containing the expected amount of biodiesel or additive, no
error in the measurement should occur. If measured with an unexpected amount of biodiesel higher than that calibrated with, the
apparent reading will be lower. This is because the biodiesel is typically less volatile than the fuel being measured. For example,
if a calibration was performed on a 5.0 % fuel sample with no biodiesel, then a sample of that same fuel containing 10 % biodiesel
(B10) is diluted into the lubricant at a 5.0 % level, the reading will be approximately 4.5 %. Thus, unexpected additional amounts
of biodiesel can lead to false negative indications of fuel contamination if the apparatus is not calibrated with that same fuel.
Similarly, unexpected lesser amounts of biodiesel can lead to false positive indications of fuel content when the apparatus is not
calibrated with that fuel.
6.4 Other interferences include the possibility of the calibration not being performed with the source fuel and lubricant material
under test. This can significantly reduce the precision of the method.
6.5 Other interferences can arise from fuel dilution sample holders that are not completely dry or with a cleaning compound
residue.
6.6 Samples that have very high water content (>1.0 % by mass) may also degrade the precision of the measurement.
7. Apparatus
7.1 The SAW fuel dilution apparatus (see Figs. 1 and 2) consists of the following components:
7.1.1 SAW Sensor Module, Fuel Dilution Sample Stand, Sample Inlet, and Seal—These components work in conjunction to extract
a sealed vapor headspace from the sample being analyzed, and gauge fuel contamination in the in-service lubricant sample.
7.1.2 Fuel Dilution Sample Stand Holder—This is a disposable bottle into which the in-service lubricant is added and placed into
the apparatus.
7.2 Optional—A thermometer, for example a thermocouple, which allows for the determination of the lubricant temperature. A
thermometer is not required because users may elect to calibrate the instrument each time before a series of measurements,
minimizing the temperature effects discussed in 6.1.
8. Reagents and Materials
8.1 As-prepared Fuel Dilution Calibration Standards. These are prepared from samples of the fuel and lubricant under use.
8.2 Fuel Dilution Sample Holder, such as a plastic bottle or laboratory vial.
8.2.1 If glassware is to be used as the fuel dilution sample holder, ensure that it is carefully cleaned and dried to avoid
interferences.
D8004 − 23
9. Hazards
9.1 Since pure fuel is mixed with lubricant during calibration, care should be taken to avoid any contact with electronic equipment
or spark sources to avoid fuel ignition.
9.2 Hazardous materials precautions, as appropriate, should be followed when handling both the fuel and lubricant under test.
9.3 Typical hazards considerations for electronic equipment should be followed in accordance with manufacturer’s instructions.
10. Sa
...