ASTM D7959-24

Standard Test Method for Chloride Content Determination of Aviation Turbine Fuels using Chloride Test Strip

SIGNIFICANCE AND USE
5.1 Chloride present in aviation turbine fuel can originate from refinery salt drier carryover or possibly from seawater contamination (for example, product transferred by barge). Elevated chloride levels have caused corrosive and abrasive wear of aircraft fuel control systems leading to engine failure.4
SCOPE
1.1 This test method covers a rapid means of determining chloride content of aviation turbine fuel. This methodology is applicable for chloride concentrations between 0 mg/L to 0.5 mg/L. This methodology will not detect chlorine originating from chlorinated organic compounds (that is, covalent bond).  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 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.  
1.4 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: 29-Feb-2024
• ICS: 71.040.40 - Chemical analysis
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.J0.05 - Fuel Cleanliness

Relations

• Replaces: ASTM D7959-19 - Standard Test Method for Chloride Content Determination of Aviation Turbine Fuels using Chloride Test Strip
• Effective Date: 01-Mar-2024
• Referred By: ASTM D1655-23a - Standard Specification for Aviation Turbine Fuels
• Effective Date: 01-Mar-2024

Overview

ASTM D7959-24 is the internationally recognized standard test method for determining the chloride content in aviation turbine fuels using a chloride test strip. Developed by ASTM International, this method provides a rapid and practical approach to assess potential chloride contamination, a significant concern in jet fuel quality control. Chloride in aviation fuels may originate from refinery salt drier carryover or seawater contamination, especially during transport by barge. Elevated chloride levels can lead to corrosive and abrasive wear on aircraft fuel control systems, posing risks to operational safety and engine performance.

This method covers detection of chloride concentrations from 0 mg/L to 0.5 mg/L and utilizes SI units exclusively. It is crucial to note that the method does not detect chlorine from covalently bonded organic chlorine compounds.

Key Topics

• Rapid Chloride Detection: The standard details a quick procedure relying on extraction and analysis using chloride test strips to determine the chloride content in aviation turbine fuels.
• Safety and Quality: Monitoring chloride levels helps prevent engine failures linked to corrosion and wear, supporting aviation safety and fuel quality assurance.
• Sample Requirements: The recommended sample size is 3 liters, and smaller samples may be used with adjusted calculations, though official results require the full sample volume.
• Usage Scope: The method is designed specifically for aviation turbine fuels and is not suitable for detecting organic chlorine compounds.
• SI Unit Compliance: All measurements and results are reported in SI units, aligning with international standardization practices.

Applications

ASTM D7959-24 is essential for:

• Aviation Fuel Quality Control: Routinely applied by fuel suppliers, airlines, and maintenance organizations to verify that jet fuel meets cleanliness and contamination limits.
• Refinery and Terminal Testing: Used to check for salt drier carryover or contamination during production, storage, and transportation of aviation fuels.
• Incident Investigation: Provides critical data in failure analysis and troubleshooting when fuel system corrosion or engine failure is suspected.
• Regulatory and Safety Compliance: Facilities meeting international standards can demonstrate adherence to best practices in aviation fuel management and safety protocols.
• Rapid On-Site Screening: Due to its simplicity and speed, this test method is well-suited for on-site field analysis as well as laboratory environments.

Related Standards

For a comprehensive approach to aviation fuel testing and petroleum quality management, consider referencing these related ASTM standards:

• ASTM D4175: Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants - Provides standardized terms used in ASTM D7959-24.
• ASTM D6300: Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants - Governs the statistical evaluation of test method precision.
• Other Jet Fuel Standards: ASTM D1655 (Specification for Aviation Turbine Fuels), ASTM D3241 (Thermal Oxidation Stability), and related fuel cleanliness standards.

Practical Value

Implementing ASTM D7959-24 supports:

• Improved Fuel Reliability: Preventing corrosive damage and costly operational issues in aircraft.
• Efficient Contamination Control: Easy and rapid assessment facilitates proactive maintenance and fuel handling decisions.
• Global Compliance: Aligns with international aviation safety requirements and trade regulations, assuring stakeholders of product integrity and quality.

Keywords: ASTM D7959-24, chloride content, aviation turbine fuel, jet fuel, fuel contamination, fuel quality, aviation safety, chloride test strip, refinery, seawater contamination, jet A, Jet A-1, petroleum standards.

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: D7959 − 24
Standard Test Method for
Chloride Content Determination of Aviation Turbine Fuels
using Chloride Test Strip
This standard is issued under the fixed designation D7959; 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* 2.2 ASTM Adjuncts:
Distillate Fuel Bar Chart
1.1 This test method covers a rapid means of determining
chloride content of aviation turbine fuel. This methodology is
3. Terminology
applicable for chloride concentrations between 0 mg ⁄L to
0.5 mg ⁄L. This methodology will not detect chlorine originat-
3.1 Definitions:
ing from chlorinated organic compounds (that is, covalent
3.1.1 For definitions of terms used in this test method, refer
bond).
to Terminology D4175.
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this 4. Summary of Test Method
standard.
4.1 A 3 L sample of aviation turbine fuel is extracted with
1.3 This standard does not purport to address all of the
pH 7 buffer solution by a magnetic stir plate and stir bar. The
safety concerns, if any, associated with its use. It is the
chloride in the aviation turbine fuel sample transfers to the
responsibility of the user of this standard to establish appro-
buffer solution. A portion of the aqueous extract solution is
priate safety, health, and environmental practices and deter-
then removed and analyzed with a chloride test strip. Silver
mine the applicability of regulatory limitations prior to use.
ions within the test strip combine with chloride ions in the
1.4 This international standard was developed in accor-
extract as it is drawn up by capillary action to form a white
dance with internationally recognized principles on standard-
column of silver chloride. The chloride concentration of the
ization established in the Decision on Principles for the
extract, determined by the height of the column, is then related
Development of International Standards, Guides and Recom-
back to the chloride content of the aviation turbine fuel sample.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
5. Significance and Use
2. Referenced Documents 5.1 Chloride present in aviation turbine fuel can originate
from refinery salt drier carryover or possibly from seawater
2.1 ASTM Standards:
contamination (for example, product transferred by barge).
D4175 Terminology Relating to Petroleum Products, Liquid
Elevated chloride levels have caused corrosive and abrasive
Fuels, and Lubricants
wear of aircraft fuel control systems leading to engine failure.
D6300 Practice for Determination of Precision and Bias
Data for Use in Test Methods for Petroleum Products,
6. Interferences
Liquid Fuels, and Lubricants
6.1 Some pH 7 buffer solution can contain trace levels of
chloride compounds and therefore produce a false positive
reading on the chloride test strip. Prior to using a new batch of
pH 7 buffer solution, a sample should be confirmed to produce
This test method is under the jurisdiction of ASTM Committee D02 on
no reading on the chloride test strip.
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.J0.05 on Fuel Cleanliness.
Current edition approved March 1, 2024. Published March 2024. Originally
approved in 2015. Last previous edition approved in 2019 as D7959 – 19. DOI:
10.1520/D7959-24. Available from ASTM International Headquarters. Order Adjunct No.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or ADJD417601. Original adjunct produced in 1991.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Guidelines for Sodium Chloride Contamination Troubleshooting and Decon-
Standards volume information, refer to the standard’s Document Summary page on tamination of Airframe and Engine Fuel Systems, International Air Transport
the ASTM website. Association, 2nd Ed., February 1998, pg. 1.
*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
D7959 − 24
6.2 The test strip will react with halides other than chloride 12.2 Add 3 L of the aviation turbine fuel test sample to a 4 L
(for example, bromide, iodide). The concentration of chloride beaker by filling and emptying a 1 L graduated cylinder three
in salt used in refinery salt driers (predominantly NaCl and times.
CaCl ) and in seawater, however, is in great excess compared
12.3 Remove the remaining fuel from the sample container.
to that of other halides.
12.4 Completely drain the sample container (discarding any
residual fuel) by means of one of the following methods.
7. Apparatus
12.4.1 If the sample container has a spout and can be
7.1 Magnetic Stir Plate and Stir Bar—The magnetic stir
effectively drained (see Fig. 1), drain upside down for 2 min,
plate shall be capable of producing the stirring energy de-
tilting and shaking occasionally to remove any residual fuel.
scribed in Section 12.11. A magnetic stir bar in the form of a
12.4.2 If the sample container does not have a spout and
cross or “starburst” approximately 32 mm by 32 mm has
cannot be effectively drained, tilt the sample container to the
proven to be more stable than the traditional bar shape. The stir
side or to a corner so that any residual fuel collects beneath the
bar shall have a chemically inert coating such as polytetrafluo-
sample container opening (see Fig. 2). Wait approximately
roethylene (PTFE).
2 min. Remove any residual fuel with a clean pipette. Wait an
7.2 Distillate Fuel Bar Chart. additional approximate 2 min and repeat (the same pipette may
be used).
8. Reagents and Materials
12.5 Add 5 mL pH 7 buffer solution by pipette to the now
8.1 Isooctane (2,2,4–trimethylpentane, CAS #540-84-1)— empty sample container.
Minimum ACS reagent grade purity.
12.6 Cap the sample container tightly and hand shake
8.2 pH 7 Buffer Solution—Some pH 7 buffer solution can vigorously for approximately 1 min. Try to have the pH 7
contain trace levels of chloride compounds and therefore buffer solution contact all inside surfaces of the container. The
produce a false positive reading on the chloride test strip. Prior use of a shaker table is not recommended since the buffer
to using a new batch of pH 7 buffer solution, a sample should solution will not contact all inside surfaces of the container.
be confirmed to produce no reading on the chloride test strip.
12.7 Transfer the contents to the 4 L beaker via one of the
following methods.
NOTE 1—Prior batches of Fisher Scientific pH 7 buffer solution, catalog
number SB108, have produced no reading on the chloride test strips.
12.7.1 If the sample container has a spout and can be
effectively drained, drain upside down for approximately 30 s,
8.3 Chloride Test Strips —The conversion of the dimen-
tilting and shaking occasionally to transfer any residual buffer
sionless test strip value to chloride concentration in mg/L
solution.
found on the test strip container varies slightly from one lot of
12.7.2 If the sample container does not have a spout and
chloride test strips to the next.
cannot be effectively drained, tilt the sample container to the
side or to a corner so that the buffer solution collects beneath
9. Hazards
the sample container opening. Tap the side or corner a few
9.1 If a combination heater and stir plate is to be used,
times lightly on a benchtop to encourage the buffer solution to
ensure the heater is off.
10. Sampling, Test Specimens, and Test Units
10.1 The sample should be obtained for testing in either a
1 gal or 5 L container.
10.2 Collect a sample of at least 3 L.
11. Preparation of Apparatus
11.1 Unless otherwise stated, all glassware should be
cleaned prior to use. No special cleaning or rinsing procedure
is required.
12. Procedure
12.1 Vigorously shake the sample container by hand for
approximately 15 s before analysis.
The sole source of supply of the apparatus (Chloride QuanTab (trademarked)
Test Strips, 30 – 600 mg/L) known to the committee at this time is Hach Company,
P.O. Box 389, Loveland, Colorado 80539-0389, http://www.hach.com. If you are
aware of alternative suppliers, please provide this information to ASTM Interna-
tional Headquarters. Your comments will receive careful consideration at a meeting
of the responsible technical committee, which you may attend. FIG. 1 Draining of Sample Container with a Spout
D7959 − 24
FIG. 2 Draining of Sample Container with No Spout
FIG. 3 Taping of Double-Sided Distillate Fuel Bar Chart to 4 L
Beaker
collect. Wait approximately 30 s. Transfer the buffer solution
with a clean, 20 mL (or larger) pipette. Wait an additional
approximate 30 s and repeat to ensure all the buffer solution is
delivered to the 4 L beaker. Set the pipette aside for later use;
do not clean. Lay the pipette down horizontally with no contact
to the tip so that any residual buffer solution is not lost.
12.8 Add 20 mL isooctane to the sample container with a
new, clean pipette.
...

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: D7959 − 19 D7959 − 24
Standard Test Method for
Chloride Content Determination of Aviation Turbine Fuels
using Chloride Test Strip
This standard is issued under the fixed designation D7959; 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 a rapid means of determining chloride content of aviation turbine fuel. This methodology is applicable
for chloride concentrations between 0 mg ⁄L to 0.5 mg ⁄L. This methodology will not detect chlorine originating from chlorinated
organic compounds (that is, covalent bond).
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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.
1.4 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:
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D6300 Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and
Lubricants
2.2 ASTM Adjuncts:
Distillate Fuel Bar Chart
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, refer to Terminology D4175.
4. Summary of Test Method
4.1 A 3 L sample of aviation turbine fuel is extracted with pH 7 buffer solution by a magnetic stir plate and stir bar. The chloride
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.J0.05 on Fuel Cleanliness.
Current edition approved May 1, 2019March 1, 2024. Published June 2019March 2024. Originally approved in 2015. Last previous edition approved in 20162019 as
D7959 – 16.D7959 – 19. DOI: 10.1520/D7959-19.10.1520/D7959-24.
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.
Available from ASTM International Headquarters. Order Adjunct No. ADJD417601. Original adjunct produced in 1991.
*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
D7959 − 24
in the aviation turbine fuel sample transfers to the buffer solution. A portion of the aqueous extract solution is then removed and
analyzed with a chloride test strip. Silver ions within the test strip combine with chloride ions in the extract as it is drawn up by
capillary action to form a white column of silver chloride. The chloride concentration of the extract, determined by the height of
the column, is then related back to the chloride content of the aviation turbine fuel sample.
5. Significance and Use
5.1 Chloride present in aviation turbine fuel can originate from refinery salt drier carryover or possibly from seawater
contamination (for example, product transferred by barge). Elevated chloride levels have caused corrosive and abrasive wear of
aircraft fuel control systems leading to engine failure.
6. Interferences
6.1 Some pH 7 buffer solution can contain trace levels of chloride compounds and therefore produce a false positive reading on
the chloride test strip. Prior to using a new batch of pH 7 buffer solution, a sample should be confirmed to produce no reading on
the chloride test strip.
6.2 The test strip will react with halides other than chloride (for example, bromide, iodide). The concentration of chloride in salt
used in refinery salt driers (predominantly NaCl and CaCl ) and in seawater, however, is in great excess compared to that of other
halides.
7. Apparatus
7.1 Magnetic Stir Plate and Stir Bar—The magnetic stir plate shall be capable of producing the stirring energy described in
Section 11.1112.11. A magnetic stir bar in the form of a cross or “starburst” approximately 32 mm by 32 mm has proven to be
more stable than the traditional bar shape. The stir bar shall have a chemically inert coating such as polytetrafluoroethylene (PTFE).
7.2 Distillate Fuel Bar Chart.
8. Reagents and Materials
8.1 Isooctane (2,2,4–trimethylpentane, CAS #540-84-1)—Minimum ACS reagent grade purity.
8.2 pH 7 Buffer Solution—Some pH 7 buffer solution can contain trace levels of chloride compounds and therefore produce a false
positive reading on the chloride test strip. Prior to using a new batch of pH 7 buffer solution, a sample should be confirmed to
produce no reading on the chloride test strip.
NOTE 1—Prior batches of Fisher Scientific pH 7 buffer solution, catalog number SB108, have produced no reading on the chloride test strips.
8.3 Chloride Test Strips —The conversion of the dimensionless test strip value to chloride concentration in mg/L found on the
test strip container varies slightly from one lot of chloride test strips to the next.
9. Hazards
9.1 If a combination heater and stir plate is to be used, ensure the heater is off.
10. Sampling, Test Specimens, and Test Units
10.1 The sample should be obtained for testing in either a 1 gal or 5 L container.
10.2 Collect a sample of at least 3 L.
Guidelines for Sodium Chloride Contamination Troubleshooting and Decontamination of Airframe and Engine Fuel Systems, International Air Transport Association,
2nd Ed., February 1998, pg. 1.
The sole source of supply of the apparatus (Chloride QuanTab (trademarked) Test Strips, 30 – 600 mg/L) known to the committee at this time is Hach Company, P.O.
Box 389, Loveland, Colorado 80539-0389, http://www.hach.com. If you are aware of alternative suppliers, please provide this information to ASTM International
Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend.
D7959 − 24
11. Preparation of Apparatus
11.1 Unless otherwise stated, all glassware should be cleaned prior to use. No special cleaning or rinsing procedure is required.
12. Procedure
12.1 Vigorously shake the sample container by hand for approximately 15 s before analysis.
12.2 Add 3 L of the aviation turbine fuel test sample to a 4 L beaker by filling and emptying a 1 L graduated cylinder three times.
12.3 Remove the remaining fuel from the sample container.
12.4 Completely drain the sample container (discarding any residual fuel) by means of one of the following methods.
12.4.1 If the sample container has a spout and can be effectively drained (see Fig. 1), drain upside down for 2 min, tilting and
shaking occasionally to remove any residual fuel.
12.4.2 If the sample container does not have a spout and cannot be effectively drained, tilt the sample container to the side or to
a corner so that any residual fuel collects beneath the sample container opening (see Fig. 2). Wait approximately 2 min. Remove
any residual fuel with a clean pipette. Wait an additional approximate 2 min and repeat (the same pipette may be used).
12.5 Add 5 mL pH 7 buffer solution by pipette to the now empty sample container.
12.6 Cap the sample container tightly and hand shake vigorously for approximately 1 min. Try to have the pH 7 buffer solution
contact all inside surfaces of the container. The use of a shaker table is not recommended since the buffer solution will not contact
all inside surfaces of the container.
12.7 Transfer the contents to the 4 L beaker via one of the following methods.
12.7.1 If the sample container has a spout and can be effectively drained, drain upside down for approximately 30 s, tilting and
shaking occasionally to transfer any residual buffer solution.
12.7.2 If the sample container does not have a spout and cannot be effectively drained, tilt the sample container to the side or to
FIG. 1 Draining of Sample Container with a Spout
D7959 − 24
FIG. 2 Draining of Sample Container with No Spout
a corner so that the buffer solution collects beneath the sample container opening. Tap the side or corner a few times lightly on
a benchtop to encourage the buffer solution to collect. Wait approximately 30 s. Transfer the buffer solution with a clean, 20 mL
(or larger) pipette. Wait an additional approximate 30 s and repeat to ensure all the buffer solution is delivered to the 4 L beaker.
Set the pipette aside for later use; do not clean. Lay the pipette down horizontally with no contact to the tip so that any residual
buffer solution is not lost.
12.8 Add 20 mL isooctane to the sample container with a new, clean pipette.
12.9 Cap the sample container tightly and hand shake vigorously for approximate
...