ASTM D6971-09
(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
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 D 6224 and D 4378; see also Test Method D 2272), having the capability of measuring remaining oxidative life of the in-service oil.
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.
The test is also suitable for manufacturing control and specification acceptance.
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 to 12 s (or 0.8 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 and 16 s (or 1.3 to 1.6 V applied voltage) (see Note 1) for the hindered...
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 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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D6971 − 09
StandardTest 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 3. Summary of Test Method
1.1 This test method covers the voltammetric determination
3.1 A measured quantity of sample is dispensed into a vial
of hindered phenol and aromatic amine antioxidants in new or
containing a measured quantity of acetone based electrolyte
in-service type non-zinc turbine oils in concentrations from
test solution and a layer of sand. When the vial is shaken, the
0.0075 mass % up to concentrations found in new oils by
hinderedphenolandaromaticamineantioxidantsandothertest
measuring the amount of current flow at a specified voltage in
solution soluble oil components present in the sample are
the produced voltammogram.
extracted into the test solution and the remaining droplets
1.2 This standard does not purport to address all of the
suspended in the test solution are agglomerated by the sand.
safety concerns, if any, associated with its use. It is the The sand/droplet suspension is allowed to settle out and the
responsibility of the user of this standard to establish appro-
hindered phenol and aromatic amine antioxidants dissolved in
priate safety and health practices and determine the applica-
the test solution are quantified by voltammetric analysis. The
bility of regulatory limitations prior to use.
results are calculated and reported as mass % of antioxidant or
as millimoles (mmol) of antioxidant per litre of sample for
2. Referenced Documents
prepared and fresh oils and as a percent remaining antioxidant
2
2.1 ASTM Standards:
for in-service oils.
D1193 Specification for Reagent Water
3.2 Voltammetric analysis is a technique that applies
D2272 Test Method for Oxidation Stability of Steam Tur-
electro-analytic methods wherein a sample to be analyzed is
bine Oils by Rotating Pressure Vessel
mixedwithanelectrolyteandatestsolution,andplacedwithin
D4057 Practice for Manual Sampling of Petroleum and
an electrolytic cell. Data is obtained by measuring the current
Petroleum Products
passing through the cell as a function of the potential applied,
D4378 Practice for In-Service Monitoring of Mineral Tur-
and test results are based upon current, voltage, and time
bine Oils for Steam and Gas Turbines
relationships at the cell electrodes. The cell consists of a fluid
D6224 PracticeforIn-ServiceMonitoringofLubricatingOil
container into which is mounted a small, easily polarized,
for Auxiliary Power Plant Equipment
working electrode, and a large, non-polarizable, reference
D6810 Test Method for Measurement of Hindered Phenolic
electrode. The reference electrode should be massive relative
Antioxidant Content in Non-Zinc Turbine Oils by Linear
totheworkingelectrodesothatitsbehaviorremainsessentially
Sweep Voltammetry
3
constant with the passage of small current; that is, it remains
2.2 ISO Standards:
unpolarized during the analysis period. Additional electrodes,
ISO 6743 Part 4, Lubricants, Industrial Oils, and Related
such as auxiliary electrodes, can be added to the electrode
Products
system to eliminate the effects of resistive drop for high
resistance test solutions. In performing a voltammetric
1
This test method is under the jurisdiction of ASTM Committee D02 on
analysis, the potential across the electrodes is varied linearly
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.09.0C on Oxidation of Turbine Oils. with time, and the resulting current is recorded as a function of
Current edition approved June 1, 2009. Published June 2009. Originally
the potential. As the increasing voltage is applied to the
approved in 2004. Last previous edition approved in 2004 as D6971–04. DOI:
prepared sample within the cell, the various additive species
10.1520/D6971-09.
2
under investigation within the oil are caused to electrochemi-
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
cally oxidize. The data recorded during this oxidation reaction
Standards volume information, refer to the standard’s Document Summary page on
can then be used to determine the remaining useful life of the
the ASTM website.
3 oil type. A typical current-potential curve produced during the
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ans
...
This document is not anASTM standard and is intended only to provide the user of anASTM 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.
An American National Standard
Designation:D6971–04 Designation:D6971–09
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 D 6971; 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 the voltammetric determination of hindered phenol and aromatic amine antioxidants in new or
usedin-service type non-zinc turbine oils in concentrations from 0.0075 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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
D 1193 Specification for Reagent Water
D 2272 Test Method for Oxidation Stability of Steam Turbine Engine Oils by Rotating Pressure Vessel
D 4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D 4378 Practice for In-Service Monitoring of Mineral Turbine Oils for Steam and Gas Turbines
D 6224 Practice for In-Service Monitoring of Lubricating Oil for Auxiliary Power Plant Equipment
D 6810 Test Method for Measurement of Hindered Phenolic Antioxidant Content In HLin Non-Zinc Turbine Oils by Linear
Sweep Voltammetry
3
2.2 ISO Standards: ISO6743 Part 4,
ISO 6743 Part 4, Lubricants, Industrial Oils, and Related Products
3. Summary of Test Method
3.1 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 antioxidants and other test solution
soluble oil components present in the sample are extracted into the test solution and the remaining droplets suspended in the test
solution are agglomerated by the sand. The sand/droplet suspension is allowed to settle out and the hindered phenol and aromatic
amine antioxidants dissolved in the test solution are quantified by voltammetric analysis. The results are calculated and reported
as mass % of antioxidant or as millimoles (mmol) of antioxidant per litre of sample for prepared and fresh oils and as a percent
remaining antioxidant for usedin-service oils.
3.2 Voltammetric analysis is a technique that applies electro-analytic methods wherein a sample to be analyzed is mixed with
an electrolyte and a solvent, test solution, and placed within an electrolytic cell. Data is obtained by measuring the current passing
through the cell as a function of the potential applied, and test results are based upon current, voltage, and time relationships at
the cell electrodes. The cell consists of a fluid container into which is mounted a small, easily polarized, working electrode, and
a large, non-polarizable, reference electrode. The reference electrode should be massive relative to the working electrode so that
its behavior remains essentially constant with the passage of small current; that is, it remains unpolarized during the analysis
period.Additional electrodes, such as auxiliary electrodes, can be added to the electrode system to eliminate the effects of resistive
drop for high resistance test solutions. In performing a voltammetric analysis, the potential across the electrodes is varied linearly
1
This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.09.0C
on Oxidation of Turbine Oils.
Current edition approved July 1, 2004. Published July 2004.
Current edition approved June 1, 2009. Published June 2009. Originally approved in 2004. Last previous edition approved in 2004 as D 6971–04.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM 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.or
...
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