Standard Historical Last Updated: Dec 31, 2010 Track Document
ASTM D2668-07

Standard Test Method for 2,6-di-tert-Butyl- p-Cresol and 2,6-di-tert-Butyl Phenol in Electrical Insulating Oil by Infrared Absorption

Standard Test Method for 2,6-di-tert-Butyl- p-Cresol and 2,6-di-tert-Butyl Phenol in Electrical Insulating Oil by Infrared Absorption D2668-07 ASTM|D2668-07|en-US Standard Test Method for 2,6-di-tert-Butyl- p-Cresol and 2,6-di-tert-Butyl Phenol in Electrical Insulating Oil by Infrared Absorption Standard new BOS Vol. 10.03 Committee D27
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Significance and Use

The quantitative determination of 2,6-ditertiary-butyl paracresol and 2,6-ditertiary-butyl phenol in a new electrical insulating oil measures the amount of this material that has been added to the oil as protection against oxidation. In a used oil it measures the amount remaining after oxidation has reduced its concentration. The test is also suitable for manufacturing control and specification acceptance.

When an infrared spectrum is obtained of an electrical insulating oil inhibited with either of these compounds there is an increase in absorbance of the spectrum at several wavelengths (or wavenumbers). 2,6 ditertiary-butyl paracresol produces pronounced increases in absorbance at 2.72 μm (3650 cm1), and 11.63 μm (860 cm1). 2,6 ditertiary-butyl phenol produces pronounced increases in absorbance at 2.72 μm (3650 cm1) and 13.42 μm (745 cm1).

When making this test on other than a highly oxidized oil or when using a double-beam spectrophotometer, it has been found convenient to obtain the spectrum between 2.5 μm (4000 cm1) and 2.9 μm (3450 cm1) because the instrument is compensated for the presence of moisture and the band is not influenced by intermolecular forces (associations). However, when testing a highly oxidized oil or when using a single-beam instrument better results may be obtained if the scan is made between 10.90 μm (918 cm1) and 14.00 μm (714 cm1).

Increased absorption at 11.63 μm (860 cm1) or 13.42 μm (745 cm1) or both, will identify the inhibitor as 2,6-ditertiary-butyl paracresol or 2,6-ditertiary-butyl phenol respectively (Note 1).

Note 1—The absorbance at 745 cm1 for 2,6-ditertiary-butyl phenol and at 860 cm1 for 2,6-ditertiary-butyl paracresol for equal concentrations will be in the approximate ratio of 2.6 to 1.

Scope

1.1 This test method covers the determination of the weight percent of 2,6-ditertiary-butyl paracresol (DBPC) and 2,6-ditertiary-butyl phenol (DBP) 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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Details
Book of Standards Volume: 10.03
Developed by Subcommittee: D27.03
Pages: 6
DOI: 10.1520/D2668-07
ICS Code: 29.040.10