ASTM D6810-13
(Test Method)Standard Test Method for Measurement of Hindered Phenolic Antioxidant Content in Non-Zinc Turbine Oils by Linear Sweep Voltammetry
Standard Test Method for Measurement of Hindered Phenolic Antioxidant Content in Non-Zinc Turbine Oils by Linear Sweep Voltammetry
SIGNIFICANCE AND USE
4.1 The quantitative determination of hindered phenol antioxidants in a new turbine oil measures the amount of this material 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 used oil, the determination measures the amount of original (phenolic) antioxidant remaining after oxidation have 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 used or 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 used oil, which might result in the replacement of the oil reservoir, it is advised to perform additional analytical techniques (in accordance with Practices D6224 and D4378), having the capability of measuring remaining oxidative life of the used oil.
4.1.1 This test method is applicable to non-zinc turbine oils. These are refined mineral oils containing rust and oxidation inhibitors, but not antiwear additives. This test method has not yet been established with sufficient precision for antiwear oils.
4.2 This test method is also suitable for manufacturing control and specification acceptance.
4.3 When a voltammetric analysis is obtained for a turbine oil inhibited with a typical hindered phenol antioxidant, there is an increase in the current of the produced voltammogram between 3-5 s (or 0.3 to 0.6 V applied voltage) (see Note 1) in the basic test solution (Fig. 1—x-axis 1 second = 0.1 V). Hindered phenol antioxidants detected by voltammetric analysis include, but are not limited to, 2,6-di-tert-butyl-4-methylphenol; 2,6-di-tert-butylphenol and 4,4'-methylenebi...
SCOPE
1.1 This test method covers the voltammetric determination of hindered phenol antioxidants in new or in-service non-zinc turbine oils in concentrations from 0.0075 weight % up to concentrations found in new oils by measuring the amount of current flow at a specified voltage in the produced voltammogram.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D6810 − 13
Standard Test Method for
Measurement of Hindered Phenolic Antioxidant Content in
1
Non-Zinc Turbine Oils by Linear Sweep Voltammetry
This standard is issued under the fixed designation D6810; 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
3.1 A measured quantity of sample is dispensed into a vial
1.1 This test method covers the voltammetric determination
containing a measured quantity of alcohol-based electrolyte
of hindered phenol antioxidants in new or in-service non-zinc
solution and containing a layer of sand. When the vial is
turbine oils in concentrations from 0.0075 weight % up to
shaken, the hindered phenol antioxidants and other solution
concentrations found in new oils by measuring the amount of
soluble oil components present in the sample are extracted into
current flow at a specified voltage in the produced voltammo-
the solution and the remaining droplets suspended in the
gram.
solution are agglomerated by the sand. The sand/droplet
1.2 The values stated in SI units are to be regarded as
suspension is allowed to settle out and the hindered phenol
standard. No other units of measurement are included in this
antioxidants dissolved in the solution are quantified by volta-
standard.
mmetric analysis. The results are calculated and reported as
weight percent of antioxidant or as millimoles (mmol) of
1.3 This standard does not purport to address all of the
antioxidant per litre of sample for prepared and fresh oils and
safety concerns, if any, associated with its use. It is the
as a percent remaining antioxidant for used oils.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
3.2 Voltammetric analysis is a technique that applies
bility of regulatory limitations prior to use.
electro-analytic methods when a sample to be analyzed is
mixed with an electrolyte and a solvent and placed within an
2. Referenced Documents
electrolytic cell. Data is obtained by measuring the current
2 passing through the cell as a function of the potential applied,
2.1 ASTM Standards:
and test results are based upon current, voltage and time
D1193 Specification for Reagent Water
relationships at the cell electrodes. The cell consists of a fluid
D4057 Practice for Manual Sampling of Petroleum and
container into which is mounted a small, easily polarized
Petroleum Products
working electrode, and a large nonpolarizable reference elec-
D4378 Practice for In-Service Monitoring of Mineral Tur-
trode.Thereferenceelectrodeshouldbemassiverelativetothe
bine Oils for Steam, Gas, and Combined Cycle Turbines
working electrode so that its behavior remains essentially
D6224 PracticeforIn-ServiceMonitoringofLubricatingOil
constant with the passage of small current; that is, it remains
for Auxiliary Power Plant Equipment
unpolarized during the analysis period. Additional electrodes,
D6447 Test Method for Hydroperoxide Number of Aviation
auxiliary electrodes, can be added to the electrode system to
Turbine Fuels by Voltammetric Analysis
eliminate the effects of resistive drop for high resistance
D6971 Test Method for Measurement of Hindered Phenolic
solutions. In performing a voltammetric analysis, the potential
and Aromatic Amine Antioxidant Content in Non-zinc
across the electrodes is varied linearly with time, and the
Turbine Oils by Linear Sweep Voltammetry
resulting current is recorded as a function of the potential. As
the increasing voltage is applied to the prepared sample within
the cell, the various additive species under investigation within
1
This test method is under the jurisdiction of ASTM Committee D02 on
the oil are caused to electrochemically oxidize. The data
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
recorded during this oxidation reaction can then be used to
Subcommittee D02.09.0C on Oxidation of Turbine Oils.
determine the remaining useful life of the oil type. A typical
Current edition approved May 1, 2013. Published May 2013. Originally
current-potential curve produced during the practice of the
approved in 2002. Last previous edition approved in 2007 as D6810-07. DOI:
10.1520/D6810-13.
voltammetric test can be seen by reference to Fig. 1. Initially,
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
the applied potential produces an electrochemical reaction
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
havingaratesoslowthatvirtuallynocurrentflowsthroughthe
Standards volume information, ref
...
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: D6810 − 07 D6810 − 13
Standard Test Method for
Measurement of Hindered Phenolic Antioxidant Content in
1
Non-Zinc Turbine Oils by Linear Sweep Voltammetry
This standard is issued under the fixed designation D6810; 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 antioxidants in new or in-service non-zinc
turbine oils in concentrations from 0.0075 weight % up to concentrations found in new oils by measuring the amount of current
flow at a specified voltage in the produced voltammogram.
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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
D1193 Specification for Reagent Water
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
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
D6447 Test Method for Hydroperoxide Number of Aviation Turbine Fuels by Voltammetric Analysis
D6971 Test Method for Measurement of Hindered Phenolic and Aromatic Amine Antioxidant Content in Non-zinc Turbine Oils
by Linear Sweep Voltammetry
3. Summary of Test Method
3.1 A measured quantity of sample is dispensed into a vial containing a measured quantity of alcohol-based electrolyte solution
and containing a layer of sand. When the vial is shaken, the hindered phenol antioxidants and other solution soluble oil components
present in the sample are extracted into the solution and the remaining droplets suspended in the solution are agglomerated by the
sand. The sand/droplet suspension is allowed to settle out and the hindered phenol antioxidants dissolved in the solution are
quantified by voltammetric analysis. The results are calculated and reported as weight percent of antioxidant or as millimoles
(mmol) of antioxidant per litre of sample for prepared and fresh oils and as a percent remaining antioxidant for used oils.
3.2 Voltammetric analysis is a technique that applies electro-analytic methods when a sample to be analyzed is mixed with an
electrolyte and a solvent 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 nonpolarizable
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, auxiliary electrodes, can be added to the electrode system to eliminate the effects of resistive drop for high resistance
solutions. In performing a voltammetric analysis, the potential across the electrodes is varied linearly with time, and the resulting
current is recorded as a function of the potential. As the increasing voltage is applied to the prepared sample within the cell, the
various additive species under investigation within the oil are caused to electrochemically oxidize. The data recorded during this
1
This test method is under the jurisdiction of ASTM 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, 2007May 1, 2013. Published August 2007May 2013. Originally approved in 2002. Last previous edition approved in 20022007 as
D6810-02.-07. DOI: 10.1520/D6810-07.10.1520/D6810-13.
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 th
...
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