1、Designation: D3635 01 (Reapproved 2005)D3635 13Standard Test Method forDissolved Copper In Electrical Insulating Oil By AtomicAbsorption Spectrophotometry1This standard is issued under the fixed designation D3635; the number immediately following the designation indicates the year oforiginal adoptio
2、n 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 copper in new or used electric
3、al insulating oil of petroleum origin by atomicabsorption 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 detec
4、table concentration is usuallyconsidered to be equal to twice the maximum variation of the background. For flame atomization, the lower limit of detectabilityis 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 v
5、alues stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriat
6、e safety and health practices and determine the applicability of regulatorylimitations prior to use. See 5.4 for specific precautionary statements.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD3487 Specification for Mineral Insulating Oil Used in Electrical Apparat
7、usD5222 Specification for High Fire-Point Mineral Electrical Insulating Oils3. Summary of Test Method3.1 The test specimen of oil is filtered and diluted with an appropriate organic solvent and analyzed in an atomic absorptionspectrophotometer. Alternate procedures are provided for instruments emplo
8、ying flame and non-flame atomization. Concentrationis determined by means of calibration curves prepared from standard samples.4. Significance and Use4.1 Electrical insulating oil may contain small amounts of dissolved metals derived either directly from the base oil or fromcontact with metals durin
9、g refining or service. When copper is present, it acts as a catalyst in promoting oxidation of the oil. Thistest method is useful for research for new oils and to assess the condition of service-aged oils. Consideration should be given tothe limits of detection outlined in the scope.5. Apparatus5.1
10、Volumetric flasks, 100-mL capacity.5.2 Membrane filter, 0.45 m.5.3 Burets, 5 and 50-mL capacity.1 This test method is under the jurisdiction of ASTM Committee D27 on Electrical Insulating Liquids and Gases and is the direct responsibility of Subcommittee D27.03on Analytical Tests.Current edition app
11、roved Oct. 1, 2005May 1, 2013. Published November 2005May 2013. Originally approved in 1977. Last previous edition approved in 20012005 asD3635 01.D3635 01(2005). DOI: 10.1520/D3635-01R05.10.1520/D3635-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Se
12、rvice at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previ
13、ous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM Int
14、ernational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.4 Atomic Absorption Spectrophotometer The instrument shall have an atomizer, a spectral energy source, usually consistingof a copper hollow cathode lamp, a monochromator capable of isolating the desired
15、 line of radiation, an adjustable slit, aphotomultiplier tube or other photosensitive device as a light measuring and amplifying device, and a read-out mechanism forindicating the amount of absorbed radiation. WarningProper ventilation must be provided to remove toxic metal vapors.5.4.1 Instruments
16、employing flame atomization require a nebulizer assembly, burner head, and suitable pressure and flowregulating devices to maintain constant oxidant and fuel flow for the duration of the tests.5.4.1.1 Glass Syringe, 10-mL capacity.5.4.2 Instruments employing non-flame atomization require a suitable
17、pressure regulating device to maintain an inertatmosphere.5.4.2.1 Graphite Furnace with background correction.5.4.2.2 Output Device, Printer or Strip Chart Recorder (if permanent record is required).5.4.2.3 Pipets, 1 and 5-L.5.5 Analytical Balance, capable of weighing to 0.0001 g.6. Reagents6.1 Puri
18、ty of ReagentsUse reagent grade chemicals in all tests.6.2 Purity of WaterUnless otherwise indicated, references to water shall be understood to mean reagent water conforming tothe requirements in Specification D1193 for Reagent Water, Type 1.6.3 Nitric Acid (1:2)Add one volume of nitric acid (HNO3
19、sp gr 1.42) to two volumes of water.6.4 New OilUnused oil of the same type as that being tested, such as oil meeting the requirements of Specification D3487or as described in Specification D5222.6.5 Methyl Isobutyl Ketone (MIBK).6.6 Bis (1-phenyl-1, 3-butanediono) copper (II)National Institute of St
20、andards and Technology Metallo-Organic CompoundNo. 1080.36.7 Oxidant-Air, cleaned and dried through a suitable filter to remove oil, water, and other foreign substances.6.8 Acetylene, atomic absorption grade (Note 1).6.9 Argon, commercial grade.NOTE 1Acetylene cylinders should be replaced when the p
21、ressure reaches 700 kPa (;100 psi) to prevent acetone, always present, from entering anddamaging the burner head.7. Preparation of Glassware7.1 Wash all glassware thoroughly, rinse with HNO3 (1:2), and then with distilled water. Dry thoroughly.8. Procedure AFlame Atomization8.1 Preparation of Standa
22、rd Copper Solution (500 ppm Cu):8.1.1 Dissolve 0.3030 g of NIST Standard No. 1080, bis (1-phenyl-1, 3-butanediono) copper (II), according to instructionsreceived with the standard, and dilute to 100.0 6 0.1 g with new oil to make a 500 ppm standard copper solution. Shake well.8.2 Preparation of Work
23、ing Standards:8.2.1 Dilute 2.00 g of the standard copper solution to 100 mL with new oil to give an intermediate standard containingapproximately 10 g/mL Cu. This working standard contains the 10 g/mL Cu added plus any copper present in the new oil usedto make the standard. If the copper content of
24、the new oil is not known, it must be determined. When detectable levels of copperare suspected in the new oil or the copper content is simply unknown, refer to 8.4.1.5.8.2.2 Add to new oil aliquots of 10 g/mL Cu solution so as to obtain four standards containing additions of 0.0, 0.5, 1.0, and3.0 g/
25、mL Cu; dilute each with MIBK to obtain an oil to ketone ratio of 10 % (V/V) as follows (Note 2):WorkingStandard10 g/mL Custandard, mLNew Oil, mL MIBK, mLNo. 1 (blank) 0.0 10.0 90No. 2 0.5 9.5 90No. 3 1.0 9.0 90No. 4 3.0 7.0 90NOTE 2The new oil used to make these dilutions must be the same new oil us
26、ed to make the 10 g/mL standard. Good transfers can be effected ifa 50-mL buret is used for the new oil and a 5-mL buret is used for the 10 g/mL Cu standard. Do not transfer the solutions too rapidly.8.2.3 Shake well after dilution with MIBK.3 Available from the Office of Standard Reference Material
27、s, U.S. Department of Commerce, National Institute of Standards and Technology, Washington, DC 20234.D3635 1328.3 Preparation of Test Specimen:8.3.1 Filter the test specimen using a 0.45 m filter.8.3.2 Using a 10-mL glass syringe, transfer 10 mL of the filtered test specimen to a 100-mL volumetric f
28、lask. Dilute to volumewith MIBK and shake well (Note 3).NOTE 3If a test specimen has a copper concentration greater than the range of the working standards, a more accurate result can be obtained bydiluting a small aliquot of the test specimen with appropriate addition of new oil and MIBK to keep th
29、e 10 % oil to ketone ratio and rerunning againstthe working standards.8.4 Spectrophotometric Measurement:8.4.1 Operate the atomic absorption spectrophotometer according to the manufacturers instructions for the determination ofcopper with the following exceptions and additions:8.4.1.1 Set the auxili
30、ary air at twice the aspirating air if this is within the range of instrument parameters.8.4.1.2 For narrow slit burners, reduce flow as low as possible while maintaining the flame on the burner head. For three slitburners, reduce fuel flow as low as possible while aspirating neat MIBK so that orang
31、e streaks rising from the rivet heads are stillvisible in the flame.8.4.1.3 Adjust the aspiration rate for maximum absorbance while burning No. 4 working standard.8.4.1.4 Set the instrument at zero absorbance while burning No. 1 working standard.8.4.1.5 Set the instrument at zero absorbance while bu
32、rning methyl isobutyl ketone (MIBK). Plot a standard curve of absorbanceversus copper concentration for standards Nos. 14. Extrapolate this curve to zero absorbance. The absolute value of the copperconcentration at zero absorbance (a negative number) provides an estimate of the copper contained in t
33、he standard oil.8.4.2 Run the standards and test specimen in the following order: standards, test specimen, standards, test specimen, andstandards.9. Calculation and Report9.1 Average the readings, and if the scale was expanded, divide the averages by the scale expansion factor and convert toabsorba
34、nces. Subtract the absorbance of the No. 1 working standard as a blank from the absorbances of the other standards andtest specimens and plot versus copper added.9.2 Calculate the copper concentration, in parts per million, as follows:Copper,ppm5Adwhere:A = copper concentration of the test specimen
35、solution determined from the concentration plot, g/mL andd = density of the test specimen, g/mL.9.3 Report the results to the nearest 0.1 ppm.10. Precision and Bias10.1 It is not possible to specify the precision of ProcedureAinTest Method D3635 for measuring dissolved copper in electricalinsulating
36、 oil because of the difficulty in arranging a round-robin test with a large-enough sample of participating laboratories.Attempts continue to be made to locate a laboratory capable of providing data from which the repeatability of this procedure canbe estimated.10.2 No information can be presented on
37、 the bias of Test Method D3635, ProcedureA, because no material having an acceptedreference value of copper in electrical insulating oil has been made available from a standards organization. Furthermore, theresponsible subcommittee has been unable as of yet to attract volunteers for an interlaborat
38、ory study.11. Procedure BNon-Flame Atomization11.1 Preparation of Standard Copper Solution (500 ppm Cu):11.1.1 Follow 8.1 in Procedure A.11.2 Preparation of Working Standards:11.2.1 Follow 8.2.1 in Procedure A.11.2.2 Add to new oil aliquots of the 10 g/mL Cu solution so as to obtain five intermediat
39、e standards containing additions of0.00, 0.05, 0.10, 0.50, and 1.00 g/mL copper, respectively. Dilute each with MIBK to obtain an oil to ketone ratio of 10 % (V/V)as follows (Note 2):WorkingStandard10 g/mL CuStandard, mL New Oil, mL MIBK, mLNo. 1 (blank) 0.00 10.0 90No. 2 0.05 9.95 90No. 3 0.10 9.90
40、 90No. 4 0.50 9.50 90No. 5 1.00 9.00 90D3635 13311.2.3 Shake the standard solutions well after dilution with MIBK.11.3 Preparation of Test Specimens:11.3.1 Prepare samples as indicated in 8.3 (Note 3).11.4 Set up the graphite furnace atomic absorption spectrophotometer for oil test specimens. A5-L s
41、ample size can be used forthe above standard solutions. Operate the spectrophotometer according to the manufacturers instructions with the followingexceptions and additions.11.4.1 The following decontamination (instrument blank) and test specimen run parameters have been found satisfactory.NOTE 4The
42、 temperatures achieved by control settings are only approximate and may vary with individual instruments.Decontamination RunCycle Control SettingDry cycle = 5 s, 150CAsh cycle = 10 s, 550CAtomize cycle = 4 s, 2500CTest Specimen RunCycle Control SettingDry cycle = 5 s, 150CAsh cycle = 10 s, 550CAtomi
43、ze cycle = 4 s, 2500C11.4.1.1 Record a decontamination run. If no signal is recorded above the noise level, make a run of the blank oil test specimen.If a signal is obtained on the decontamination run, repeat it. If a signal still persists, increase the atomize cycle temperature to2700C and repeat t
44、he run. If a signal still persists, refer to the instrument manual.11.4.2 Once a decontamination run has been obtained with no spurious signals, obtain triplicate absorbance values for eachstandard used.11.4.3 When an unknown test specimen signal is brought on scale according to the manufacturers re
45、commendation, obtaintriplicate absorbance values for each test specimen.12. Calculation and Report12.1 Plot the absorbance versus the copper added (g/mL) to the standards in 11.2. The negative value of the concentrationintercept represents the copper concentration in the new oil used to prepare thes
46、e standards and in the MIBK used to dilute them.12.2 Calculate the copper concentration in the test specimens as indicated in 9.2.12.3 Report the results to the nearest 0.01 ppm.13. Precision and Bias13.1 It is not possible to specify the precision of Procedure B inTest Method D3635 for measuring di
47、ssolved copper in electricalinsulating oil because of the difficulty in arranging a round-robin test with a large enough sample of participating laboratories. Anestimate of the repeatability has been developed based on data supplied by a single laboratory. These data are presented inAppendix X1. The
48、se results suggest that the 95 % repeatability limit for copper content is 8.5 % of the test result or approximately1 ppb, when the mean copper level is 10 ppb.13.2 No information can be presented on the bias of Test Method D3635, Procedure B, because no material having an acceptedreference value of
49、 copper in electrical insulating oil has been made available from a standards organization. Furthermore, theresponsible subcommittee has been unable to attract enough volunteers for a valid interlaboratory study.14. Keywords14.1 atomic absorption; copper; electrical insulating oil; spectroscopyD3635 134APPENDIX(Nonmandatory Information)X1. REPEATABILITY DATA ESTIMATE FOR A SINGLE LABORATORY TEST SERIES OF ANALYSESX1.1 Data are given from a single laboratory for the measurement of the copper content of two oil samples used as quality co
