ASTM D6971-22
(Test Method)Standard Test Method for Measurement of Hindered Phenolic and Aromatic Amine Antioxidant Content in Non-zinc Turbine Oils by Linear Sweep Voltammetry
Standard Test Method for Measurement of Hindered Phenolic and Aromatic Amine Antioxidant Content in Non-zinc Turbine Oils by Linear Sweep Voltammetry
SIGNIFICANCE AND USE
5.1 The quantitative determination of hindered phenol and aromatic amine antioxidants in a new turbine oil measures the amount of these compounds that has been added to the oil as protection against oxidation. Beside phenols, turbine oils can be formulated with other antioxidants such as amines which can extend the oil life. In in-service oil, the determination measures the amount of original (hindered phenol and aromatic amine) antioxidants remaining after oxidation has reduced its initial concentration. This test method is not designed or intended to detect all of the antioxidant intermediates formed during the thermal and oxidative stressing of the oils, which are recognized as having some contribution to the remaining useful life of the in-service oil. Nor does it measure the overall stability of an oil, which is determined by the total contribution of all species present. Before making final judgment on the remaining useful life of the in-service oil, which might result in the replacement of the oil reservoir, it is advised to perform additional analytical techniques (as in accordance with Test Methods D6224 and D4378; see also Test Method D2272), having the capability of measuring remaining oxidative life of the in-service oil.
5.1.1 This test method is applicable to non-zinc type of turbine oils as defined by ISO 6743 Part 4, Table 1. These are refined mineral oils containing rust and oxidation inhibitors, but not antiwear additives.
5.2 The test is also suitable for manufacturing control and specification acceptance.
5.3 When a voltammetric analysis is obtained for a turbine oil inhibited with a typical synergistic mixture of hindered phenol and aromatic amine antioxidants, there is an increase in the current of the produced voltammogram between 8 s to 12 s (or 0.8 V to 1.2 V applied voltage) (see Note 1) for the aromatic amines, and an increase in the current of the produced voltammogram between 13 s and 16 s (or 1.3 V to 1.6 V applied voltage) (se...
SCOPE
1.1 This test method covers the voltammetric determination of hindered phenol and aromatic amine antioxidants in new or in-service type non-zinc turbine oils in concentrations from 0.0075 % by mass up to concentrations found in new oils by measuring the amount of current flow at a specified voltage in the produced voltammogram.
1.2 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.
1.3 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
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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: D6971 − 22
Standard Test Method for
Measurement of Hindered Phenolic and Aromatic Amine
Antioxidant Content in Non-zinc Turbine Oils by Linear
1
Sweep Voltammetry
This standard is issued under the fixed designation D6971; 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 Auxiliary Power Plant Equipment
D6810 Test Method for Measurement of Hindered Phenolic
1.1 This test method covers the voltammetric determination
Antioxidant Content in Non-Zinc Turbine Oils by Linear
of hindered phenol and aromatic amine antioxidants in new or
Sweep Voltammetry
in-service type non-zinc turbine oils in concentrations from
3
2.2 ISO Standards:
0.0075 % by mass up to concentrations found in new oils by
ISO 6743 Part 4, Lubricants, Industrial Oils, and Related
measuring the amount of current flow at a specified voltage in
Products
the produced voltammogram.
1.2 This standard does not purport to address all of the
3. Terminology
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 See Terminology D4175 for a more extensive list of
priate safety, health, and environmental practices and deter-
terms used in this test method.
mine the applicability of regulatory limitations prior to use.
3.1.2 electrolytic cell, n—an electrochemical cell in which
1.3 This international standard was developed in accor-
chemicalreactionsarecausedbyapplyinganexternalpotential
dance with internationally recognized principles on standard-
difference greater than, and opposite to, the galvanic electro-
ization established in the Decision on Principles for the
4
motive force of the cell. IUPAC
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
3.1.3 linear sweep voltammetry, n—a technique applied to
Barriers to Trade (TBT) Committee.
the monitoring of antioxidant additive content in lubricants,
where the current is detected as an applied potential is
2. Referenced Documents
increased linearly over a period of time.
2
2.1 ASTM Standards:
3.1.4 voltammogram, n—the plot of current versus voltage.
D1193 Specification for Reagent Water
D2272 Test Method for Oxidation Stability of Steam Tur-
4. Summary of Test Method
bine Oils by Rotating Pressure Vessel
4.1 A measured quantity of sample is dispensed into a vial
D4057 Practice for Manual Sampling of Petroleum and
containing a measured quantity of acetone based electrolyte
Petroleum Products
test solution and a layer of sand. When the vial is shaken, the
D4175 Terminology Relating to Petroleum Products, Liquid
hinderedphenolandaromaticamineantioxidantsandothertest
Fuels, and Lubricants
solution soluble oil components present in the sample are
D4378 Practice for In-Service Monitoring of Mineral Tur-
extracted into the test solution and the remaining droplets
bine Oils for Steam, Gas, and Combined Cycle Turbines
suspended in the test solution are agglomerated by the sand.
D6224 PracticeforIn-ServiceMonitoringofLubricatingOil
The sand/droplet suspension is allowed to settle out and the
hindered phenol and aromatic amine antioxidants dissolved in
1 the test solution are quantified by voltammetric analysis. The
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
results are calculated and reported as mass % of antioxidant or
Subcommittee D02.09.0C on Oxidation of Turbine Oils.
Current edition approved Nov. 1, 2022. Published November 2022. Originally
approved in 2004. Last previous edition approved in 2014 as D6971 – 09 (2014).
3
DOI: 10.1520/D6971-22. Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 4th Floor, New York, NY 10036, http://www.ansi.org.
4
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Inczedy,J.,Lengyel,T.,andUre,A.M.,Orange Book: IUPAC Compendium on
Standards volume information, refer to the standard’s Document Summary page on Analytical Nomenclature, Definitive Rules 1997, 3rd Edition, Blackwell Science,
the ASTM website. 1998.
*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
1
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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: D6971 − 09 (Reapproved 2014) D6971 − 22
Standard Test Method for
Measurement of Hindered Phenolic and Aromatic Amine
Antioxidant Content in Non-zinc Turbine Oils by Linear
1
Sweep Voltammetry
This standard is issued under the fixed designation D6971; 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 covers the voltammetric determination of hindered phenol and aromatic amine antioxidants in new or
in-service type non-zinc turbine oils in concentrations from 0.0075 0.0075 % by mass % up to concentrations found in new oils
by measuring the amount of current flow at a specified voltage in the produced voltammogram.
1.2 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.3 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
2.1 ASTM Standards:
D1193 Specification for Reagent Water
D2272 Test Method for Oxidation Stability of Steam Turbine Oils by Rotating Pressure Vessel
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D4378 Practice for In-Service Monitoring of Mineral Turbine Oils for Steam, Gas, and Combined Cycle Turbines
D6224 Practice for In-Service Monitoring of Lubricating Oil for Auxiliary Power Plant Equipment
D6810 Test Method for Measurement of Hindered Phenolic Antioxidant Content in Non-Zinc Turbine Oils by Linear Sweep
Voltammetry
3
2.2 ISO Standards:
ISO 6743 Part 4, Lubricants, Industrial Oils, and Related Products
3. Terminology
3.1 Definitions:
3.1.1 See Terminology D4175 for a more extensive list of terms used in this test method.
1
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
D02.09.0C on Oxidation of Turbine Oils.
Current edition approved May 1, 2014Nov. 1, 2022. Published July 2014November 2022. Originally approved in 2004. Last previous edition approved in 20092014 as
D6971 – 09.D6971 – 09 (2014). DOI: 10.1520/D6971-09R14.10.1520/D6971-22.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
*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
1
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D6971 − 22
NOTE 1—x-axis = time (seconds) and y-axis is current (arbitrary units). Top line in Fig. 1 is voltammogram of a fresh R&O turbine oil showing valley
indicators before and after antioxidant valleys.
FIG. 1 Aromatic Amine and Hindered Phenol Voltammetric Response in the Neutral Test Solution with Blank Response Zeroed
3.1.2 electrolytic cell, n—an electrochemical cell in which chemical reactions are caused by applying an external potential
4
difference greater than, and opposite to, the galvanic electromotive force of the cell. IUPAC
3.1.3 linear sweep voltammetry, n—a technique applied to the monitoring of antioxidant additive content in lubricants, where the
current is detected as an applied potential is increased linearly over a period of time.
3.1.4 voltammogram, n—the plot of current versus voltage.
4. Summary of Test Method
4.1 A measured quantity of sample is dispensed into a vial containing a measured quantity of acetone based electrolyte test
solution and a layer of sand. When the vial is shaken, the hindered phenol and aromatic amine antioxi
...
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