ASTM D2668-96
(Test Method)Standard Test Method for 2,6-Ditertiary-Butyl Para Cresol and 2,6-Ditertiary-Butyl Phenol in Electrical Insulating Oil by Infrared Absorption
Standard Test Method for 2,6-Ditertiary-Butyl Para Cresol and 2,6-Ditertiary-Butyl Phenol in Electrical Insulating Oil by Infrared Absorption
SCOPE
1.1 This test method covers the determination of the weight percent of 2,6-ditertiary-butyl paracresol and 2,6-ditertiary-butyl phenol in new or used electrical insulating oil in concentrations up to 0.5% by recording the infrared spectrum of the oil at certain specific bands.
1.2 This standard does not purport to address all of the safety problems, 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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NOTICE: This standard has either been superseded and replaced by a new version or
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Designation: D 2668 – 96
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
2,6-Ditertiary-Butyl Para Cresol and 2,6-Ditertiary-Butyl
1
Phenol in Electrical Insulating Oil by Infrared Absorption
This standard is issued under the fixed designation D 2668; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope oil or when using a double-beam spectrophotometer, it has
been found convenient to obtain the spectrum between 2.5 μm
1.1 This test method covers the determination of the weight
−1 −1
(4000 cm ) and 2.9 μm (3450 cm ) because the instrument
percent of 2,6-ditertiary-butyl paracresol and 2,6-ditertiary-
is compensated for the presence of moisture and the band is not
butyl phenol in new or used electrical insulating oil in
influenced by intermolecular forces (associations). However,
concentrations up to 0.5 % by measuring its absorbance at the
when testing a highly oxidized oil or when using a single-beam
specified wavelengths in the infrared spectrum.
instrument better results may be obtained if the scan is made
1.2 This standard does not purport to address all of the
−1 −1
between 10.90 μm (918 cm ) and 14.00 μm (714 cm ).
safety concerns, if any, associated with its use. It is the
−1
3.4 Increased absorption at 11.63 μm (860 cm ) or 13.33
responsibility of the user of this standard to establish appro-
−1
μm (750 cm ) or both, will identify the inhibitor as 2,6-
priate safety and health practices and determine the applica-
ditertiary-butyl paracresol or 2,6-ditertiary-butyl phenol re-
bility of regulatory limitations prior to use.
spectively (Note 1).
2. Referenced Documents
−1
NOTE 1—The absorbance at 750 cm for 2,6-ditertiary-butyl phenol
−1
2.1 ASTM Standards:
and at 860 cm for 2,6-ditertiary-butyl paracresol for equal concentra-
D 923 Test Method for Sampling Electrical Insulating
tions will be in the approximate ratio of 2.6 to 1.
2
Liquids
4. Apparatus
D 2144 Test Methods for Examination of Electrical Insu-
2
4.1 With equipment description referring to compliance, the
lating Oils by Infrared Absorption
D 3487 Specification for Mineral-Insulating Oil Used in equipment shall be in accordance with Section 6 of Test
2
Methods D 2144.
Electrical Apparatus
5. Sampling
3. Significance and Use
5.1 Obtain the sample in accordance with Test Method
3.1 The quantitative determination of 2,6-ditertiary-butyl
D 923.
paracresol and 2,6-ditertiary-butyl phenol in a new electrical
insulating oil measures the amount of this material that has
6. Calibration and Standardization
been added to the oil as protection against oxidation. In a used
6.1 When the manufacturer of the oil is known and the base
oil it measures the amount remaining after oxidation products
oil is available, use it to prepare the standards. For oils of
have reduced its concentration. The test is also suitable for
unknown origin use base oils which meet the requirements of
manufacturing control and specification acceptance.
Specification D 3487. Some base oils may provide a better
3.2 When an infrared spectrum is obtained of an electrical
match than others and therefore it is desirable to have several
insulating oil inhibited with either of these compounds there is
available.
an increase in absorbance of the spectrum at several wave-
6.2 Prepare standards containing between 0.05 and 0.4
lengths (or wavenumbers). 2,6 ditertiary-butyl paracresol pro-
weight percent of 2,6-ditertiary-butyl paracresol or 2,6-
duces pronounced increases in absorbance at 2.72 μm (3680
−1 −1 ditertiary-butyl phenol dissolved in an uninhibited base oil.
cm ), and 11.63 μm (860 cm ). 2,6 ditertiary-butyl phenol
Obtain a spectrum, at the desired band, of each standard in
produces pronounced increases in absorbance at 2.72 μm (3680
−1 −1 accordance with Test Methods D 2144. Cells with a standard
cm ) and 13.33 μm (750 cm ).
path length of 0.3 to 1.0 mm are recommended. Other path
3.3 When making this test on other than a highly oxidized
lengths may be found more suitable for different instruments or
particular wave lengths. Other sample path lengths may be
1
used provided the instrument sensitivity can be adjusted to
This test method is under the jurisdiction of ASTM Committee D-27 on
Electrical Insulating Liquids and Gases and is the direct responsibility of Subcom-
compensate for this change. The dip in the curve for the
mittee D27.03 on Analytical Tests.
inhibited oil should provide a distinctive increase in the
Current edition approved D
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