ASTM D2668-2007(2013) 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《利用红外线吸收法测定电绝缘油中2 6-二叔丁基对.pdf
《ASTM D2668-2007(2013) 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《利用红外线吸收法测定电绝缘油中2 6-二叔丁基对.pdf》由会员分享,可在线阅读,更多相关《ASTM D2668-2007(2013) 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《利用红外线吸收法测定电绝缘油中2 6-二叔丁基对.pdf(6页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D2668 07 (Reapproved 2013)Standard Test Method for2,6-di-tert-Butyl- p-Cresol and 2,6-di-tert-Butyl Phenol inElectrical Insulating Oil by Infrared Absorption1This standard is issued under the fixed designation D2668; the number immediately following the designation indicates the year of
2、original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the weightperc
3、ent of 2,6-ditertiary-butyl paracresol (DBPC) and 2,6-ditertiary-butyl phenol (DBP) in new or used electrical insu-lating oil in concentrations up to 0.5 % by measuring itsabsorbance at the specified wavelengths in the infrared spec-trum.1.2 The values stated in SI units are to be regarded asstandar
4、d. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica
5、-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D923 Practices for Sampling Electrical Insulating LiquidsD2144 Practices for Examination of Electrical InsulatingOils by Infrared AbsorptionD3487 Specification for Mineral Insulating Oil Used inElectrical Appar
6、atus3. Significance and Use3.1 The quantitative determination of 2,6-ditertiary-butylparacresol and 2,6-ditertiary-butyl phenol in a new electricalinsulating oil measures the amount of this material that hasbeen added to the oil as protection against oxidation. In a usedoil it measures the amount re
7、maining after oxidation hasreduced its concentration. The test is also suitable for manu-facturing control and specification acceptance.3.2 When an infrared spectrum is obtained of an electricalinsulating oil inhibited with either of these compounds there isan increase in absorbance of the spectrum
8、at several wave-lengths (or wavenumbers). 2,6 ditertiary-butyl paracresol pro-duces pronounced increases in absorbance at 2.72 m (3650cm1), and 11.63 m (860 cm1). 2,6 ditertiary-butyl phenolproduces pronounced increases in absorbance at 2.72 m (3650cm1) and 13.42 m (745 cm1).3.3 When making this tes
9、t on other than a highly oxidizedoil or when using a double-beam spectrophotometer, it hasbeen found convenient to obtain the spectrum between 2.5 m(4000 cm1) and 2.9 m (3450 cm1) because the instrument iscompensated for the presence of moisture and the band is notinfluenced by intermolecular forces
10、 (associations). However,when testing a highly oxidized oil or when using a single-beaminstrument better results may be obtained if the scan is madebetween 10.90 m (918 cm1) and 14.00 m (714 cm1).3.4 Increased absorption at 11.63 m (860 cm1) or 13.42m (745 cm1) or both, will identify the inhibitor a
11、s 2,6-ditertiary-butyl paracresol or 2,6-ditertiary-butyl phenol re-spectively (Note 1).NOTE 1The absorbance at 745 cm1for 2,6-ditertiary-butyl phenoland at 860 cm1for 2,6-ditertiary-butyl paracresol for equal concentra-tions will be in the approximate ratio of 2.6 to 1.4. Apparatus4.1 With equipmen
12、t description referring to compliance, theequipment shall be in accordance with Section 6 of PracticesD2144. Accordingly, the use of Fourier-transform rapid scaninfrared (FTIR) spectrophotometers is permitted by referenceto that test method.5. Sampling5.1 Obtain the sample in accordance with Practic
13、es D923.6. Calibration and Standardization6.1 When the manufacturer of the oil is known and the baseoil is available, use it to prepare the standards. For oils ofunknown origin, use base oils which meet the requirements ofSpecification D3487. Some base oils may provide a bettermatch than others and
14、therefore it is desirable to have severalavailable.1This test method is under the jurisdiction of ASTM Committee D27 onElectrical Insulating Liquids and Gases and is the direct responsibility of Subcom-mittee D27.03 on Analytical Tests.Current edition approved Nov. 1, 2013. Published December 2013.
15、Originallyapproved in 1967. Last previous edition approved in 2007 as D2668 07. DOI:10.1520/D2668-07R13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standard
16、s Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16.2 Prepare standards containing between 0.05 and 0.4weight percent of 2,6-ditertiary-butyl paracresol or 2,6-ditertiary-butyl phenol dissolved
17、 in an uninhibited base oil.Alternatively, the range of prepared standards may be in-creased to 0.5 weight percent if certain oils to be investigatedare believed to contain greater amounts of inhibitor. Obtain aspectrum, at the desired band, of each standard in accordancewith Practices D2144. Cells
18、with a standard path length of 0.3to 1.0 mm are recommended. Other path lengths may be foundmore suitable for different instruments or particular wavelengths. Other sample path lengths may be used provided theinstrument sensitivity can be adjusted to compensate for thischange. The dip in the curve f
19、or the inhibited oil shouldprovide a distinctive increase in the absorbance at the criticalwavelength or frequency (Note 3). Repeat the procedure oneach of the standards making at least three scans on eachstandard. (See Note 2) Record all settings of the spectropho-tometer used in obtaining the resp
20、ective spectra (Note 4).NOTE 2The current method precision is based on manually deter-mined results where exactly three scans were determined for eachstandard. Newer instruments are capable of automatically performingscans much more rapidly, which can reduce the variability of resultsdetermined. In
21、such cases, it is recommended that the number of scans beincreased to statistically compensate for any outliers. Laboratories willneed to determine the minimum number of scans that should be used intheir instrument standardization and test specimen analyses to satisfy theirtesting needs.NOTE 3Where
22、desired, a chart having a non-linear wavelength scaleas the abscissa may be used.NOTE 4In making these tests, transmission-scaled charts may be used,but in this case special rulers and nomographs or logarithmic tables willbe necessary for determining the intensity measurements. Alternatively,instrum
23、ent software capable of recording all settings of the spectropho-tometer used in obtaining the respective spectra, may be used.6.3 The quantitative determination is made from the follow-ing equation which is derived from Beers law:Absorbance 5 A 2 Aowhere:Ao= absorbance units of base oil, andA = abs
24、orbance units of oil containing 2,6-ditertiary-butylparacresol or 2,6-ditertiary-butyl phenol.6.4 Manual Plotting Routine for Generating CalibrationCurveDesignate the point of maximum absorbance of theabsorbance band as Point A. Draw a tangent to the spectrumcurve and a second line through Point A p
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