Standard Test Method for 2,6-<i>di-tert</i>-Butyl-<i> p</i>-Cresol and 2,6-<ital>di-tert</ital>-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 measuring its absorbance at the specified wavelengths in the infrared spectrum.
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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09-Oct-2002
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ASTM D2668-02 - Standard Test Method for 2,6-<i>di-tert</i>-Butyl-<i> p</i>-Cresol and 2,6-<ital>di-tert</ital>-Butyl Phenol in Electrical Insulating Oil by Infrared Absorption
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D 2668–02
Standard Test Method for
2,6-di-tert-Butyl-p-Cresol and 2,6-di-tert-Butyl Phenol in Electrical
1
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.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope * 3.3 When making this test on other than a highly oxidized
oil or when using a double-beam spectrophotometer, it has
1.1 This test method covers the determination of the weight
been found convenient to obtain the spectrum between 2.5 µm
percent of 2,6-ditertiary-butyl paracresol and 2,6-ditertiary-
−1 −1
(4000cm )and2.9µm(3450cm )becausetheinstrumentis
butyl phenol in new or used electrical insulating oil in
compensated for the presence of moisture and the band is not
concentrations up to 0.5% by measuring its absorbance at the
influenced by intermolecular forces (associations). However,
specified wavelengths in the infrared spectrum.
whentestingahighlyoxidizedoilorwhenusingasingle-beam
1.2 This standard does not purport to address all of the
instrument better results may be obtained if the scan is made
safety concerns, if any, associated with its use. It is the
−1 −1
between 10.90 µm (918 cm ) and 14.00 µm (714 cm ).
responsibility of the user of this standard to establish appro-
−1
3.4 Increased absorption at 11.63 µm (860 cm ) or 13.33
priate safety and health practices and determine the applica-
−1
µm (750 cm ) or both, will identify the inhibitor as 2,6-
bility of regulatory limitations prior to use.
ditertiary-butyl paracresol or 2,6-ditertiary-butyl phenol re-
2. Referenced Documents
spectively (Note 1).
−1
2.1 ASTM Standards:
NOTE 1—The absorbance at 750 cm for 2,6-ditertiary-butyl phenol
−1
D 923 Test Method for Sampling Electrical Insulating
and at 860 cm for 2,6-ditertiary-butyl paracresol for equal concentra-
2
tions will be in the approximate ratio of 2.6 to 1.
Liquids
D 2144 Test Methods for Examination of Electrical Insu-
4. Apparatus
2
lating Oils by Infrared Absorption
4.1 Withequipmentdescriptionreferringtocompliance,the
D 3487 Specification for Mineral-Insulating Oil Used in
2
equipment shall be in accordance with Section 6 of Test
Electrical Apparatus
Methods D2144. Accordingly, the use of Fourier-transform
3. Significance and Use
rapid scan infrared spectrophotometers is permitted by refer-
ence to that test method.
3.1 The quantitative determination of 2,6-ditertiary-butyl
paracresol and 2,6-ditertiary-butyl phenol in a new electrical
5. Sampling
insulating oil measures the amount of this material that has
5.1 Obtain the sample in accordance with Test Method
been added to the oil as protection against oxidation. In a used
D923.
oil it measures the amount remaining after oxidation products
have reduced its concentration. The test is also suitable for
6. Calibration and Standardization
manufacturing control and specification acceptance.
6.1 When the manufacturer of the oil is known and the base
3.2 When an infrared spectrum is obtained of an electrical
oil is available, use it to prepare the standards. For oils of
insulating oil inhibited with either of these compounds there is
unknown origin, use base oils which meet the requirements of
an increase in absorbance of the spectrum at several wave-
Specification D3487. Some base oils may provide a better
lengths (or wavenumbers). 2,6 ditertiary-butyl paracresol pro-
match than others and therefore it is desirable to have several
duces pronounced increases in absorbance at 2.72 µm (3680
−1 −1
available.
cm ), and 11.63 µm (860 cm ). 2,6 ditertiary-butyl phenol
6.2 Prepare standards containing between 0.05 and 0.4
producespronouncedincreasesinabsorbanceat2.72µm(3680
−1 −1
weight percent of 2,6-ditertiary-butyl paracresol or 2,6-
cm ) and 13.33 µm (750 cm ).
ditertiary-butyl phenol dissolved in an uninhibited base oil.
Obtain a spectrum, at the desired band, of each standard in
1
This test method is under the jurisdiction of ASTM Committee D27 on
accordance with Test Methods D2144. Cells with a standard
Electrical Insulating Liquids and Gases and is the direct responsibility of Subcom-
path length of 0.3 to 1.0 mm are recommended. Other path
mittee D27.03 on Analytical Tests.
lengthsmaybefoundmoresuitablefordifferentinstrumentsor
Current edition approved Oct. 10, 2002. Published December 2002. Originally
published as D2668–67. Last previous edition D2668–96.
particular wave lengths. Other sample path lengths may be
2
Annual Book of ASTM Standards, Vol 10.03.
*A Summary of Changes section appears at the end of this standard.
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