ASTM D3635-01(2005)
(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
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 the standard. The values given in parentheses are for information only.
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. See for specific precautionary statements.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D3635 − 01(Reapproved 2005)
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 3. Summary of Test Method
3.1 The test specimen of oil is filtered and diluted with an
1.1 This test method covers the determination of copper in
appropriate organic solvent and analyzed in an atomic absorp-
new or used electrical insulating oil of petroleum origin by
tion spectrophotometer. Alternate procedures are provided for
atomic absorption spectrophotometry.
instruments employing flame and non-flame atomization. Con-
1.2 The lowest limit of detectability is primarily dependent
centration is determined by means of calibration curves pre-
upon the method of atomization, but also upon the energy
pared from standard samples.
source, the fuel and oxidant, and the degree of electrical
expansion of the output signal. The lowest detectable concen-
4. Significance and Use
tration is usually considered to be equal to twice the maximum
4.1 Electrical insulating oil may contain small amounts of
variation of the background. For flame atomization, the lower
dissolved metals derived either directly from the base oil or
limit of detectability is generally in the order of 0.1 ppm or 0.1
from contact with metals during refining or service. When
mg/kg. For non-flame atomization, the lower limit of detect-
copper is present, it acts as a catalyst in promoting oxidation of
ability is less than 0.01 ppm.
the oil. This test method is useful for research for new oils and
1.3 The values stated in SI units are to be regarded as
to assess the condition of service-aged oils. Consideration
standard. No other units of measurement are included in this
should be given to the limits of detection outlined in the scope.
standard.
5. Apparatus
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 5.1 Volumetric flasks, 100-mL capacity.
responsibility of the user of this standard to establish appro-
5.2 Membrane filter, 0.45 µm.
priate safety and health practices and determine the applica-
5.3 Burets, 5 and 50-mL capacity.
bility of regulatory limitations prior to use. See 5.4 for specific
precautionary statements. 5.4 AtomicAbsorption Spectrophotometer —Theinstrument
shall have an atomizer, a spectral energy source, usually
consisting of a copper hollow cathode lamp, a monochromator
2. Referenced Documents
capable of isolating the desired line of radiation, an adjustable
2.1 ASTM Standards:
slit, a photomultiplier tube or other photosensitive device as a
D1193 Specification for Reagent Water
light measuring and amplifying device, and a read-out mecha-
D3487 Specification for Mineral Insulating Oil Used in
nism for indicating the amount of absorbed radiation.
Electrical Apparatus
Warning—Proper ventilation must be provided to remove
D5222 Specification for High Fire-Point Mineral Electrical
toxic metal vapors.
Insulating Oils
5.4.1 Instruments employing flame atomization require a
nebulizer assembly, burner head, and suitable pressure and
flow regulating devices to maintain constant oxidant and fuel
This test method is under the jurisdiction of ASTM Committee D27 on
flow for the duration of the tests.
Electrical Insulating Liquids and Gasesand is the direct responsibility of Subcom-
5.4.1.1 Glass Syringe, 10-mL capacity.
mittee D27.03 on Analytical Tests.
5.4.2 Instruments employing non-flame atomization require
Current edition approved Oct. 1, 2005. Published November 2005. Originally
a suitable pressure regulating device to maintain an inert
approved in 1977. Last previous edition approved in 2001 as D3635 – 01. DOI:
10.1520/D3635-01R05.
atmosphere.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
5.4.2.1 Graphite Furnace with background correction.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.4.2.2 Output Device, Printer or Strip Chart Recorder (if
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. permanent record is required).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3635 − 01 (2005)
5.4.2.3 Pipets, 1 and 5-µL.
Working 10 µg/mL Cu New Oil, mL MIBK, mL
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-mLburet 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
3 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.
6.5 Methyl Isobutyl Ketone (MIBK). NOTE 3—If a test specimen has a copper concentration greater than the
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
rivet heads are still visible in the flame.
7.1 Wash all glassware thoroughly, rinse with HNO (1:2),
8.4.1.3 Adjust the aspiration rate for maximum absorbance
and then with distilled water. Dry thoroughly.
while burning No. 4 working standard.
8.4.1.4 Set the instrument at zero absorbance while burning
8. Procedure A—Flame Atomization
No. 1 working standard.
8.1 Preparation of Standard Copper Solution (500 ppm
8.4.1.5 Set the instrument at zero absorbance while burning
Cu):
methyl isobutyl ketone (MIBK). Plot a standard curve of
8.1.1 Dissolve 0.3030 g of NIST Standard No. 1080, bis
absorbance versus copper concentration for standards
(1-phenyl-1, 3-butanediono) copper (II), according to instruc-
Nos. 1–4. Extrapolate this curve to zero absorbance. The
tions received with the standard, and dilute to 100.0 6 0.1 g
absolute value of the copper concentration at zero absorbance
with new oil to make a 500 ppm standard copper solution.
(a negative number) provides an estimate of the copper
Shake well.
contained in the standard oil.
8.2 Preparation of Working Standards:
8.4.2 Run the standards and test specimen in the following
8.2.1 Dilute 2.00 g of the standard copper solution to 100
order: standards, test specimen,
...
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