1、 INTERNATIONAL STANDARD IECCEINORME INTERNATIONALE62021-2First editionPremire dition2007-05Insulating liquids Determination of acidity Part 2: Colourimetric titration Liquides isolants Dtermination de lacidit Partie 2: Titrage colorimtrique Reference number Numro de rfrence IEC/CEI 62021-2:2007 THIS
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14、 Email: csciec.ch Tl.: +41 22 919 02 11 Fax: +41 22 919 03 00 INTERNATIONAL STANDARD IECCEINORME INTERNATIONALE62021-2First editionPremire dition2007-05Insulating liquids Determination of acidity Part 2: Colourimetric titration Liquides isolants Dtermination de lacidit Partie 2: Titrage colorimtriqu
15、e For price, see current cataloguePour prix, voir catalogue en vigueur PRICE CODE CODE PRIX P Commission Electrotechnique InternationaleInternational Electrotechnical Commission 2 62021-2 IEC:2007 CONTENTS FOREWORD.3 INTRODUCTION.5 1 Scope.6 2 Normative references .6 3 Terms and definitions .7 4 Pri
16、nciple .7 5 Reagents7 5.1 Titration reagent7 5.2 Titration solvent.8 5.3 Potassium hydrogen phthalate, primary standard 8 5.4 Standard hydrochloric acid solution .8 5.5 Alkali Blue 6B indicator solution 8 5.6 Cobalt nitrate solution .8 6 Apparatus.8 6.1 Titration vessel8 6.2 Stirrer8 6.3 Burette 8 7
17、 Sampling 8 8 Procedure 9 8.1 Standardization of alcoholic potassium hydroxide solution.9 8.2 Blank titration 9 8.3 Sample titration .10 9 Calculation of results10 10 Precision 10 10.1 Repeatability .10 10.2 Reproducibility 11 11 Report 11 Annex A (informative) Determination of acidity in electrical
18、 insulating oils by photometric titration 12 Figure A.1 Molecular structure of para-naphtolbenzein indicator in (I) acidic media and (II) basic media 15 Figure A.2 UV spectra of para-naphthol-benzein indicator in toluene/2-propanol/water solution in (a) acidic media, (b) basic media .16 62021-2 IEC:
19、2007 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ INSULATING LIQUIDS DETERMINATION OF ACIDITY Part 2: Colourimetric titration FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC Nati
20、onal Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publi
21、cly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governm
22、ental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of IEC on
23、technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested IEC National Committees. 3) IEC Publications have the form of recommendations for international use and are accepted
24、by IEC National Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user. 4) In order to promote international u
25、niformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications. Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
26、 5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment declared to be in conformity with an IEC Publication. 6) All users should ensure that they have the latest edition of this publication. 7) No liability shall attach to IEC or its direc
27、tors, employees, servants or agents including individual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising
28、 out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications. 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is dra
29、wn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 62021-2 has been prepared by IEC technical committee 10: Fluids for electrotechnica
30、l applications. The text of this standard is based on the following documents: FDIS Report on voting 10/692/FDIS 10/696/RVD Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accorda
31、nce with the ISO/IEC Directives, Part 2. 4 62021-2 IEC:2007 A list of all parts of IEC 62021 series, under the general title Insulating liquids Determination of acidity can be found on the IEC website. The committee has decided that the contents of this publication will remain unchanged until the ma
32、intenance result date indicated on the IEC web site under “http:/webstore.iec.ch“ in the data related to the specific publication. At this date, the publication will be reconfirmed; withdrawn; replaced by a revised edition, or amended. 62021-2 IEC:2007 5 INTRODUCTION The standardized method given in
33、 IEC 62021-1 is a method for measurement of acidity in used and unused mineral oil and is a potentiometric titration requiring special instrumentation for measurement of acidity. Historically, acidity of insulating oil was measured by colourimetric titration as described in IEC 60296, 1982 edition.
34、With the revision of IEC 60296, the colourimetric titration was deleted as that method used high volumes of sample and solvent, generating undesirable volumes of waste. However, there is still a market requirement for having colourimetric titration as many labs use this method. Health and safety Thi
35、s International Standard does not purport to address all the safety problems associated with its use. It is the responsibility of the user of the Standard to establish appropriate health and safety practices and determine the applicability of regulatory limitations prior to use. The mineral oils whi
36、ch are the subject of this standard should be handled with due regard to personal hygiene. Direct contact with eyes may cause slight irritation. In the case of eye contact, irrigation with copious quantities of clean running water should be carried out and medical advice sought. Some of the tests sp
37、ecified in this standard involve the use of processes that could lead to a hazardous situation. Attention is drawn to the relevant standard for guidance. This standard involves mineral oils, chemicals and used sample containers. The disposal of these items should be carried out in accordance with cu
38、rrent national legislation with regard to the impact on the environment. Every precaution should be taken to prevent the release into the environment of mineral oil. 6 62021-2 IEC:2007 INSULATING LIQUIDS DETERMINATION OF ACIDITY Part 2: Colourimetric titration 1 Scope This part of IEC 62021 describe
39、s a procedure for determination of the acidity of unused and used electrical mineral insulating oils. NOTE 1 In unused and used mineral insulating oils, the constituents that may be considered to have acidic characteristics include organic acids, phenolic compounds, some oxidation products, resins,
40、organometallic salts and additives. The method may be used to indicate relative changes that occur in a mineral insulating oil during use under oxidizing conditions that may or may not be shown by other properties of the resulting mineral oil. The acidity can be used in the quality control of unused
41、 mineral oil. As a variety of oxidation products present in used mineral oil contribute to acidity and these products vary widely in their corrosion properties, the test cannot be used to predict corrosiveness of a mineral oil under service conditions. NOTE 2 The acidity results obtained by this tes
42、t method may or may not be numerically the same as those obtained by potentiometric methods, but they are generally of the same magnitude. The potentiometric method uses an endpoint at pH 11,3 to ensure titration of all species, whereas the colourimetric methods uses an indicator changing colour at
43、approximately pH 9,5. This may lead to slightly higher results for oils with acidities above 0,3 mg KOH/g oil when using the potentiometric method. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition
44、 cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60475: Method of sampling liquid dielectrics IEC 60567: Oil-filled electrical equipment Sampling of gases and of oil for analysis of free and dissolved gases Guidance ISO 572
45、5: Accuracy (trueness and precision) of measurement methods and results ISO 6619: Petroleum products and lubricants Neutralization number Potentiometric titration method 62021-2 IEC:2007 7 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 acidi
46、ty quantity of base, expressed in milligrams of potassium hydroxide per gram of sample, required to titrate colourimetrically a test portion in a specified solvent to the neutralization point of Alkali Blue 6B 3.2 unused oil mineral insulating oil that has not been used in, or been in contact with e
47、lectrical equipment 4 Principle The test portion is dissolved in a specified solvent and titrated colourimetrically with alcoholic potassium hydroxide to a specified colour using Alkali Blue 6B indicator. 5 Reagents Only reagents of recognized analytical grade and de-ionized water or water of equiva
48、lent purity shall be used. 5.1 Titration reagent Standard alcoholic solution 0,05 mol/l potassium hydroxide. Add 3,0 g of potassium hydroxide to 1 000 ml 10 ml of 2-propanol. Boil gently for 10 min to effect solution. Cool and stopper the flask. Allow the solution to stand in the dark for 2 days and
49、 then filter the supernatant liquid through a 5 m membrane filter. Store in a suitable amber glass bottle. The concentration of this solution is approximately 0,05 mol/l and shall be standardized as described in 8.1. For periodic tests on equipment in service, faster titration may be achieved by the use of 0,1 mol/l potassium hydroxide by agreement between the laboratory and
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