1、BSI Standards PublicationInsulating liquids Determination of acidityPart 3: Test methods for non mineral insulating oilsBS EN 62021-3:2014National forewordThis British Standard is the UK implementation of EN 62021-3:2014. It isidentical to IEC 62021-3:2014.The UK participation in its preparation was
2、 entrusted to TechnicalCommittee GEL/10, Fluids for electrotechnical applications.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisions ofa contract. Users are responsible for its cor
3、rect application. The British Standards Institution 2014.Published by BSI Standards Limited 2014ISBN 978 0 580 76280 2ICS 29.040.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strate
4、gy Committee on 30 November 2014.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARDBS EN 62021-3:2014EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 62021-3 November 2014 ICS 29.040.10 English Version Insulating liquids - Determination of acidity - Part 3: Test met
5、hods for non mineral insulating oils (IEC 62021-3:2014) Liquides isolants - Dtermination de lacidit - Partie 3: Mthode dessai pour les huiles non minrales isolantes (CEI 62021-3:2014) Isolierflssigkeiten - Bestimmung des Suregehaltes - Teil 3: Prfverfahren fr Isolierle auf Nichtminerallbasis (IEC 62
6、021-3:2014) This European Standard was approved by CENELEC on 2014-04-23. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibl
7、iographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the re
8、sponsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Fi
9、nland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. European Committee for Ele
10、ctrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2014 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
11、 Ref. No. EN 62021-3:2014 E BS EN 62021-3:2014EN 62021-3:2014 - 2 - Foreword The text of document 10/936/FDIS, future edition 1 of IEC 62021-3, prepared by IEC TC 10 “Fluids for electrotechnical applications“ was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN 62021-3:2014.
12、The following dates are fixed: latest date by which the document has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2015-05-14 latest date by which the national standards conflicting with the document have to be withdrawn (dow) 2017-04-23
13、 Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CENELEC and/or CEN shall not be held responsible for identifying any or all such patent rights. Endorsement notice The text of the International Standard IEC 62021-3:2014 was approv
14、ed by CENELEC as a European Standard without any modification. BS EN 62021-3:2014- 3 - EN 62021-3:2014 Annex ZA (normative) Normative references to international publications with their corresponding European publications The following documents, in whole or in part, are normatively referenced in th
15、is document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. NOTE 1 When an International Publication has been modified by common modifications, i
16、ndicated by (mod), the relevant EN/HD applies. NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here: www.cenelec.eu Publication Year Title EN/HD Year IEC 60475 - Method of sampling insulating liquids EN 60475 - ISO 5725 series Accuracy
17、 (trueness and precision) of measurement methods and results - series ISO 6619 - Petroleum products and lubricants; neutralization number; potentiometric titration method - - BS EN 62021-3:2014 2 IEC 62021-3:2014 IEC 2014 CONTENTS INTRODUCTION . 6 1 Scope 7 2 Normative references 7 3 Terms and defin
18、itions 7 4 Method A: Automatic potentiometric titration 8 4.1 Principle 8 4.2 Reagents and auxiliary products 8 Reagents 8 4.2.1Titration reagent . 8 4.2.2Titration solvent 8 4.2.3Potassium hydrogen phthalate, primary standard 9 4.2.4Reference electrode electrolyte 9 4.2.5Aqueous buffer solutions 9
19、4.2.6Glass electrode cleaning solution . 9 4.2.74.3 Apparatus 9 Potentiometric titration apparatus . 9 4.3.1Glass indicator electrode 9 4.3.2Reference electrode . 10 4.3.3Stirrer . 10 4.3.4Titration vessel . 10 4.3.5Titration stand 10 4.3.64.4 Sampling 10 4.5 Preparation and maintenance of electrode
20、 system . 10 Preparation . 10 4.5.1Maintenance . 10 4.5.24.6 Calibration . 11 Calibration of pH titrimeter 11 4.6.1Settings for the potentiometric instrument . 11 4.6.24.7 Procedure 12 General 12 4.7.1Standardization of alcoholic potassium hydroxide solution 12 4.7.2Blank titration . 13 4.7.3Sample
21、titration 13 4.7.44.8 Calculation of result . 14 4.9 Precision 14 Repeatability 14 4.9.1Reproducibility 14 4.9.24.10 Report 15 5 Method B: Colourimetric titration 15 5.1 Principle 15 5.2 Reagents . 15 General 15 5.2.1Titration reagent . 15 5.2.2Titration solvent 16 5.2.3Potassium hydrogen phthalate,
22、 primary standard 16 5.2.4BS EN 62021-3:2014IEC 62021-3:2014 IEC 2014 3 Standard hydrochloric acid solution 16 5.2.5Alkali blue 6B indicator solution 16 5.2.6Cobalt nitrate solution . 16 5.2.75.3 Apparatus 16 Titration vessel . 16 5.3.1Stirrer . 16 5.3.2Burette . 16 5.3.35.4 Sampling 16 5.5 Procedur
23、e 17 General 17 5.5.1Standardization of alcoholic potassium hydroxide solution 17 5.5.2Blank titration . 17 5.5.3Sample titration 18 5.5.45.6 Calculation of result . 18 5.7 Precision 18 Repeatability 18 5.7.1Reproducibility 19 5.7.25.8 Report 19 (informative) Determination of acidity in non-mineral
24、electrical insulating oils Annex Aby photometric titration . 20 A.1 Principle 20 A.2 Reagents and solvents . 20 A.3 Preparation of titration solutions and solvents 20 A.3.1 Potassium hydroxide alcoholic solution (0,01 mol/l) 20 A.3.2 Potassium hydrogen phthalate solution (0,01 mol/l) 20 A.3.3 Titrat
25、ion solvent 21 A.4 Apparatus 21 A.4.1 Volumetric titrator . 21 A.4.2 Titration vessel . 21 A.4.3 Titration stand 21 A.4.4 Stirrer . 21 A.4.5 Recorder/printer . 21 A.4.6 Photometric sensor . 21 A.5 Sampling 22 A.6 Procedure 22 A.6.1 Preparation and maintenance of the titration system . 22 A.6.2 Deter
26、mination of acidity of the titration solvent (blank titration) . 22 A.6.3 Determination of molarity of the potassium hydroxide alcoholic solution (0,01 mol/l) 22 A.6.4 Titration of soluble acidity in the oil sample. 23 A.7 Calculation of result . 23 A.8 Report 23 Figure 1 Potentiometric titration cu
27、rve 12 Figure A.1 Molecular structure of para-naphtholbenzein indicator in a) acidic media and b) basic media . 24 Figure A.2 UV spectra of para-naphtholbenzein indicator in toluene/2-propanol/water solution in acidic media (curve a) and basic media (curve b) . 24 BS EN 62021-3:2014 6 IEC 62021-3:20
28、14 IEC 2014 INTRODUCTION Health and safety This 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
29、limitations prior to use. The insulating liquids which are the subject of this standard should be handled with due regard to personal hygiene. Direct contact with the eyes may cause slight irritation. In the case of eye contact, irrigation with copious quantities of clean running water should be car
30、ried out and medical advice sought. Some of the procedures referenced in this standard involve the use of processes that could lead to a hazardous situation. Attention is drawn to the relevant standard for guidance. Environment This standard involves non-mineral insulating oils, chemicals, used samp
31、le containers and fluid-contaminated solids. The disposal of these items should be carried out according to local regulations with regard to their impact on the environment. Every precaution should be taken to prevent the release into the environment of these oils. BS EN 62021-3:2014IEC 62021-3:2014
32、 IEC 2014 7 INSULATING LIQUIDS DETERMINATION OF ACIDITY Part 3: Test methods for non-mineral insulating oils 1 Scope This part of IEC 62021 describes two procedures for the determination of the acidity of unused and used electrical non-mineral insulating oils. Method A is potentiometric titration an
33、d Method B is colourimetric titration. NOTE 1 In unused and used non-mineral insulating oils, the constituents that may be considered to have acidic characteristics include organic acids, phenolic compounds, some oxidation products, resins, organometallic salts and additives. The method may be used
34、to indicate relative changes that occur in non-mineral insulating oil during use under oxidizing conditions regardless of the colour or other properties of the resulting non-mineral oil. The acidity can be used in the quality control of unused non-mineral insulating oil. As a variety of oxidation pr
35、oducts present in used non-mineral insulating oil contribute to acidity and these products vary widely in their corrosion properties, the test cannot be used to predict corrosiveness of non-mineral insulating oil under service conditions. NOTE 2 The acidity results obtained by potentiometric test me
36、thod may or may not be numerically the same as those obtained by colourimetric methods, but they are generally of the same magnitude. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated
37、references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60475, Method of sampling insulating liquids ISO 5725 (all parts), Accuracy (trueness and precision) of measurement methods and results ISO 6619,
38、Petroleum products and lubricants Neutralization number Potentiometric titration method 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 acidity quantity of base, expressed in milligrams of potassium hydroxide per gram of sample, required to t
39、itrate potentiometrically or colourimetrically a test portion in a specified solvent to the end point 3.2 non-mineral insulating oil insulating liquid, not derived from petroleum crudes BS EN 62021-3:2014 8 IEC 62021-3:2014 IEC 2014 3.3 unused oil non-mineral insulating oil that has not been used in
40、, or been in contact with, electrical equipment 4 Method A: Automatic potentiometric titration 4.1 Principle Any acid-base titration may be conducted potentiometrically. The test portion of the insulating fluid is dissolved in solvent and titrated potentiometrically with alcoholic potassium hydroxid
41、e using a glass-indicating electrode and a reference electrode. The potential difference (which can be expressed as pH after calibration) is measured after the successive addition of known increments of alcoholic potassium hydroxide. Where a strong point of inflection is detected from the first deri
42、vative of the titration curve, this should be used as the end point. If only a weak inflection point is present, the potential difference corresponding to pH of 11,5 has been found more reproducible and less instrument-dependent. 4.2 Reagents and auxiliary products Reagents 4.2.1Only reagents of rec
43、ognized analytical grade and de-ionized water or water of equivalent purity shall be used. Titration reagent 4.2.2Standard alcoholic solution between 0,01 mol/l and 0,05 mol/l potassium hydroxide (KOH). EXAMPLE Preparation of 0,01 mol/l potassium hydroxide in 2-propanol. Add 0,6 g of potassium hydro
44、xide 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 then filter the supernatant liquid through a 5 m membrane filter. Store in a suitable amber glass bottle. The concentration of this solu
45、tion is approximately 0,01 mol/l and shall be standardized as described in 4.7.2. Store in such a manner that the solution is protected from atmospheric carbon dioxide by means of a guard tube containing soda-lime absorbent and in such a way that it does not come into contact with cork, rubber or sa
46、ponifiable stopcock grease. Commercial alcoholic potassium hydroxide solution may be used, if necessary diluting to 0,01 mol/l with 2-propanol. This shall be standardized as described in 4.7.2. NOTE 1 For oils with high acidity, which may give an extended titration time, it may be helpful to carry o
47、ut a pre-test using 0,1 mol/l potassium hydroxide titrant to determine a suitable titrant concentration. NOTE 2 For periodic tests on equipment in service, faster titration may be achieved by the use of 0,05 or 0,1 mol/l potassium hydroxide by agreement between the laboratory and the equipment owner
48、, although this may result in poorer precision and detection limit. Titration solvent 4.2.3The titration solvent is as follows: BS EN 62021-3:2014IEC 62021-3:2014 IEC 2014 9 2-propanol (isopropanol, IPA), pure. 2-propanol is the preferred solvent. It should be noted that the use of other solvents mi
49、ght change the dissociation potential and thus the neutralisation point. Potassium hydrogen phthalate, primary standard 4.2.4This should be dried before use for 2 h at 105 C. A 0,1 mol/l solution of hydrochloric acid in de-ionized water, prepared as in ISO 6619, may be used. Other acids may be used, e.g. benzoic acid, provided they are certified against a primary standard. Reference electrode electrolyte 4.2.5Prepare a solution of potassium chloride in de-ionized water, or lithium chloride in etha
