ASTM D3635-13(2021)
(Test Method)Standard Test Method for Dissolved Copper In Electrical Insulating Oil By Atomic Absorption Spectrophotometry
Standard Test Method for Dissolved Copper In Electrical Insulating Oil By Atomic Absorption Spectrophotometry
SIGNIFICANCE AND USE
4.1 Electrical insulating oil may contain small amounts of dissolved metals derived either directly from the base oil or from contact with metals during refining or service. When copper is present, it acts as a catalyst in promoting oxidation of the oil. This test method is useful for research for new oils and to assess the condition of service-aged oils. Consideration should be given to the limits of detection outlined in the scope.
SCOPE
1.1 This test method covers the determination of copper in new or used electrical insulating oil of petroleum origin by atomic absorption spectrophotometry.
1.2 The lowest limit of detectability is primarily dependent upon the method of atomization, but also upon the energy source, the fuel and oxidant, and the degree of electrical expansion of the output signal. The lowest detectable concentration is usually considered to be equal to twice the maximum variation of the background. For flame atomization, the lower limit of detectability is generally in the order of 0.1 ppm or 0.1 mg/kg. For non-flame atomization, the lower limit of detectability is less than 0.01 ppm.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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.
1.5 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
Relations
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: D3635 − 13 (Reapproved 2021)
Standard Test Method for
Dissolved Copper In Electrical Insulating Oil By Atomic
Absorption Spectrophotometry
This standard is issued under the fixed designation D3635; 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 D3487 Specification for Mineral Insulating Oil Used in
Electrical Apparatus
1.1 This test method covers the determination of copper in
D5222 Specification for High Fire-Point Mineral Electrical
new or used electrical insulating oil of petroleum origin by
Insulating Oils
atomic absorption spectrophotometry.
1.2 The lowest limit of detectability is primarily dependent
3. Summary of Test Method
upon the method of atomization, but also upon the energy
3.1 The test specimen of oil is filtered and diluted with an
source, the fuel and oxidant, and the degree of electrical
appropriate organic solvent and analyzed in an atomic absorp-
expansion of the output signal. The lowest detectable concen-
tion spectrophotometer. Alternate procedures are provided for
tration is usually considered to be equal to twice the maximum
instruments employing flame and non-flame atomization. Con-
variation of the background. For flame atomization, the lower
centration is determined by means of calibration curves pre-
limit of detectability is generally in the order of 0.1 ppm or 0.1
pared from standard samples.
mg/kg. For non-flame atomization, the lower limit of detect-
ability is less than 0.01 ppm.
4. Significance and Use
1.3 The values stated in SI units are to be regarded as
4.1 Electrical insulating oil may contain small amounts of
standard. No other units of measurement are included in this
dissolved metals derived either directly from the base oil or
standard.
from contact with metals during refining or service. When
1.4 This standard does not purport to address all of the
copper is present, it acts as a catalyst in promoting oxidation of
safety concerns, if any, associated with its use. It is the
the oil. This test method is useful for research for new oils and
responsibility of the user of this standard to establish appro-
to assess the condition of service-aged oils. Consideration
priate safety, health, and environmental practices and deter-
should be given to the limits of detection outlined in the scope.
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor-
5. Apparatus
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
5.1 Volumetric flasks, 100-mL capacity.
Development of International Standards, Guides and Recom-
5.2 Membrane filter, 0.45 µm.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. 5.3 Burets, 5-mL and 50-mL capacity.
5.4 AtomicAbsorption Spectrophotometer —Theinstrument
2. Referenced Documents
shall have an atomizer, a spectral energy source, usually
2.1 ASTM Standards:
consisting of a copper hollow cathode lamp, a monochromator
D1193 Specification for Reagent Water
capable of isolating the desired line of radiation, an adjustable
slit, a photomultiplier tube or other photosensitive device as a
light measuring and amplifying device, and a read-out mecha-
nism for indicating the amount of absorbed radiation.
This test method is under the jurisdiction of ASTM Committee D27 on
Electrical Insulating Liquids and Gases and is the direct responsibility of Subcom-
Warning—Proper ventilation must be provided to remove
mittee D27.03 on Analytical Tests.
toxic metal vapors.
Current edition approved Dec. 1, 2021. Published January 2022. Originally
5.4.1 Instruments employing flame atomization require a
approved in 1977. Last previous edition approved in 2013 as D3635 – 13. DOI:
10.1520/D3635-13R21.
nebulizer assembly, burner head, and suitable pressure and
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
flow regulating devices to maintain constant oxidant and fuel
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
flow for the duration of the tests.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 5.4.1.1 Glass Syringe, 10-mL capacity.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3635 − 13 (2021)
5.4.2 Instruments employing non-flame atomization require copper are suspected in the new oil or the copper content is
a suitable pressure regulating device to maintain an inert simply unknown, refer to 8.4.1.5.
atmosphere. 8.2.2 Add to new oil aliquots of 10 µg/mLCu solution so as
5.4.2.1 Graphite Furnace with background correction. to obtain four standards containing additions of 0.0 µg⁄mL,
5.4.2.2 Output Device, Printer or Strip Chart Recorder (if 0.5 µg⁄mL, 1.0 µg⁄mL, and 3.0 µg/mL Cu; dilute each with
permanent record is required). MIBK to obtain an oil to ketone ratio of 10 % (V/V) as follows
5.4.2.3 Pipets, 1-µL and 5-µL. (Note 2):
Working 10 µg/mL Cu New Oil, mL MIBK, mL
5.5 Analytical Balance, capable of weighing to 0.0001 g.
Standard standard, mL
No. 1 (blank) 0.0 10.0 90
6. Reagents
No. 2 0.5 9.5 90
No. 3 1.0 9.0 90
6.1 Purity of Reagents—Use reagent grade chemicals in all
No. 4 3.0 7.0 90
tests.
NOTE 2—The new oil used to make these dilutions must be the same
6.2 Purity of Water—Unless otherwise indicated, references
new oil used to make the 10 µg/mL standard. Good transfers can be
towatershallbeunderstoodtomeanreagentwaterconforming
effected if a 50-mL buret is used for the new oil and a 5-mL buret is used
for the 10µ g/mL Cu standard. Do not transfer the solutions too rapidly.
to the requirements in Specification D1193 for Reagent Water,
Type 1.
8.2.3 Shake well after dilution with MIBK.
6.3 NitricAcid (1:2)—Addonevolumeofnitricacid(HNO
8.3 Preparation of Test Specimen:
sp gr 1.42) to two volumes of water.
8.3.1 Filter the test specimen using a 0.45 µm filter.
8.3.2 Using a 10-mL glass syringe, transfer 10 mL of the
6.4 New Oil—Unused oil of the same type as that being
filtered test specimen to a 100-mL volumetric flask. Dilute to
tested, such as oil meeting the requirements of Specification
volume with MIBK and shake well (Note 3).
D3487 or as described in Specification D5222.
NOTE 3—If a test specimen has a copper concentration greater than the
6.5 Methyl Isobutyl Ketone (MIBK).
range of the working standards, a more accurate result can be obtained by
6.6 Bis (1-phenyl-1, 3-butanediono) copper (II)—National
diluting a small aliquot of the test specimen with appropriate addition of
Institute of Standards and Technology Metallo-Organic Com- new oil and MIBK to keep the 10 % oil to ketone ratio and rerunning
against the working standards.
pound No. 1080.
8.4 Spectrophotometric Measurement:
6.7 Oxidant-Air, cleaned and dried through a suitable filter
8.4.1 Operate the atomic absorption spectrophotometer ac-
to remove oil, water, and other foreign substances.
cording to the manufacturer’s instructions for the determina-
6.8 Acetylene, atomic absorption grade (Note 1).
tion of copper with the following exceptions and additions:
6.9 Argon, commercial grade.
8.4.1.1 Set the auxiliary air at twice the aspirating air if this
is within the range of instrument parameters.
NOTE 1—Acetylene cylinders should be replaced when the pressure
8.4.1.2 For narrow slit burners, reduce flow as low as
reaches 700 kPa (;100 psi) to prevent acetone, always present, from
entering and damaging the burner head. possible while maintaining the flame on the burner head. For
three slit burners, reduce fuel flow as low as possible while
7. Preparation of Glassware
aspirating neat MIBK so that orange streaks rising from the
7.1 Wash all glassware thoroughly, rinse with HNO (1:2), rivet heads are still visible in the flame.
and then with distilled water. Dry thoroughly.
8.4.1.3 Adjust the aspiration rate for maximum absorbance
while burning No. 4 working standard.
8. Procedure A—Flame Atomization
8.4.1.4 Set the instrument at zero absorbance while burning
8.1 Preparation of Standard Copper Solution (500 ppm No. 1 working standard.
Cu): 8.4.1.5 Set the instrument at zero absorbance while burning
8.1.1 Dissolve 0.3030 g of NIST Standard No. 1080, bis methyl isobutyl ketone (MIBK). Plot a standard curve of
(1-phenyl-1, 3-butanediono) copper (II), according to instruc- absorbance versus copper concentration for standards
tions received with
...
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