1、BRITISH STANDARD BS EN 60814:1998 IEC 60814:1997 Insulating liquids Oil-impregnated paper and pressboard Determination of water by automatic coulometric Karl Fischer titration The European Standard EN 60814:1997 has the status of a British Standard ICS 29.035.40BSEN 60814:1998 This British Standard,
2、 having been prepared under the directionof the Electrotechnical Sector Board, was published underthe authority of the Standards Board and comes intoeffect on 15 February 1998 BSI 04-1999 ISBN 0 580 29356 4 National foreword This British Standard is the English language version of EN 60814:1997. It
3、is identical with IEC60814:1997. It supersedes BS 6725:1986 (1991) which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee GEL/10, Fluids for electrotechnical applications, which has the responsibility to: aid enquirers to understand the text; present to the
4、responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained
5、on request to its secretary. From 1 January 1997, all IEC publications have the number 60000 added to the old number. For instance, IEC 27-1 has been renumbered as IEC 60027-1. For a period of time during the change over from one numbering system to the other, publications may contain identifiers fr
6、om both systems. Cross-references Attention is drawn to the fact that CEN and CENELEC Standards normally include an annex which lists normative references to international publications with their corresponding European publications. The British Standards which implement these international or Europe
7、an publications may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract.
8、 Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theEN title page, pages 2 to 18, an
9、inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date CommentsBSEN 60814:1998 BSI 04-1999 i Contents
10、Page National foreword Inside front cover Foreword 2 Text of EN 60814 3ii blankEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN60814 October1997 ICS29.035.40 Supersedes HD487 S1:1987 Descriptors: Electric insulating materials, liquid electrical insulating materials, insulating oils, paper, paper
11、boards, chemical analysis, determination of content, water, Karl Fischer method, coulometric methods English version Insulating liquids Oil-impregnated paper and pressboardDetermination of water by automatic coulometric KarlFischer titration (IEC 60814:1997) Isolants liquides Cartons et papiers impr
12、gns dhuile Dtermination de la teneur en eau par titrage coulomtrique deKarlFischer automatique (CEI 60814:1997) Isolierflssigkeiten limprgniertes Papierund limprgnierter Presspan Bestimmung von Wasser durch automatischecoulometrische Karl-Fischer-Titration (IEC 60814:1997) This European Standard was
13、 approved by CENELEC on 1997-10-01. 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 bibliographical references concerning such
14、 national standards may be obtained on application to the Central Secretariat 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 responsibility of a CENELEC member into its own la
15、nguage and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden,
16、 Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1997 CENELEC All rights of exploitation in any fo
17、rm and by any means reserved worldwide for CENELEC members. Ref. No. EN60814:1997 EEN60814:1997 BSI 04-1999 2 Foreword The text of document 10/406/FDIS, future edition 2 of IEC 60814, prepared by IEC TC10, Fluids for electrotechnical applications, was submitted to the IEC-CENELEC parallel vote and w
18、as approved by CENELEC as EN60814 on 1997-10-01. This European Standard supersedes HD 487 S1:1987. The following dates were fixed: Annexes designated “normative” are part of the body of the standard. Annexes designated “informative” are given for information only. In this standard, Annex ZA is norma
19、tive and Annex A is informative. Annex ZA has been added by CENELEC. Endorsement notice The text of the International Standard IEC60814:1997 was approved by CENELEC as a European Standard without any modification. Contents Page Foreword 2 1 General 3 1.1 Scope 3 1.2 Normative references 3 2 Direct t
20、itration for low viscosity liquids 3 2.1 Field of application 3 2.2 Chemistry 3 2.3 Apparatus 4 2.4 Reagents and auxiliary materials 5 2.5 Preparation of the apparatus 5 2.6 Sampling methods 5 2.7 Procedure 6 2.8 Calculation of the result 6 2.9 Report 6 Page 2.10 Precision 6 3 Evaporative stripping
21、method for highviscosity liquids 7 3.1 Field of application 7 3.2 Outline of the method 7 3.3 Apparatus and reagents 7 3.4 Procedure 7 3.5 Calculation of water content 8 3.6 Report 8 4 Determination of water in oil-impregnatedpaper and pressboard 8 4.1 Field of application 8 4.2 Determination of wat
22、er after previous extraction with methanol 8 4.3 Determination by direct titration 9 4.4 Evaporative stripping method 10 Annex A (informative) Method for sampling of oil-impregnatedpaper and pressboard 17 Annex ZA (normative) Normative references tointernational publications with their corresponding
23、 European publications Inside back cover Figure 1 Block diagram of automatic titrator 12 Figure 2 Suitable titration vessel assembly 13 Figure 3 Block diagram of automatic titratorandevaporation stripping unit 14 Figure 4 Evaporator glass vessel with heater 15 Figure 5 Methanol container and extract
24、iontube 16 latest date by which the ENhas to be implemented at national level by publication of an identical national standard or by endorsement (dop) 1998-07-01 latest date by which the national standards conflicting with the EN haveto be withdrawn (dow) 1998-07-01EN60814:1997 BSI 04-1999 3 1 Gener
25、al 1.1 Scope This International Standard describes methods for the determination of water in insulating liquids and in oil-impregnated cellulosic insulation with coulometrically generated Karl Fischer reagent. The method in clause 2 is applicable to water concentrations above2mg/kg in liquids having
26、 viscosity of less than100mm 2 /s at40C. The test method in clause 3, where water is extracted by means of a nitrogen stream, is the preferred method for insulating liquids of viscosity higher than100mm 2 /s. Clause 4 describes methods for the determination of water content in oil-impregnated paper
27、and pressboard over the range0,1 % to20% by mass. 1.2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All normative do
28、cuments are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. Members of IEC and ISO maintain registers of currently valid International St
29、andards. IEC 60475:1974, Method of sampling liquid dielectrics. IEC 60567:1992, Guide for the sampling of gases and of oil from oil-filled electrical equipment and for the analysis of free and dissolved gases. ISO 595-1:1986, Reusable all-glass or metal-and-glass syringes for medical use Part 1: Dim
30、ensions. ISO 595-2:1987, Reusable all-glass or metal-and-glass syringes for medical use Part 2: Design, performance requirements and tests. 2 Direct titration for low viscosity liquids 2.1 Field of application This method is applicable to water concentrations above2mg/kg in liquids having viscosity
31、up to100mm 2 /s at40C. The precision data given in2.10 apply only to new liquids. NOTE 1For liquids in service, the accuracy of the method may be affected by the presence of contaminants and degradation products. NOTE 2The method has been designed to be particularly suitable to hydrocarbon and ester
32、 liquids. With other liquids, particularly silicone fluids, methanol free reagents must be used. 2.2 Chemistry The reactions occurring in a Karl Fischer titration are known to be complex, but are essentially of water with iodine, sulphur dioxide, an organic base and an alcohol in an organic solvent.
33、 The original Karl Fischer reagent used pyridine and methanol, and the reactions may be expressed as: Other base-alcohol combinations are possible and may be necessary for titrations on some insulating liquids. In coulometric Karl Fischer titration, the sample is mixed with a base/alcohol solution o
34、f iodide ion and sulphur dioxide. Iodine is generated electrolytically and reacts with water in a similar way to that shown in reactions (1) and (2). Iodine is generated in proportion to the quantity of electricity according to Faradays law, as shown by the following reaction: H 2 O + I 2+ SO 2+ 3C
35、5 H 5 N F 2C 5 H 5 N.HI + C 5 H 5 N.SO 3 (1) C 5 H 5 N.SO 3+ CH 3 OH F C 5 H 5 NH.SO 4 .CH 3 (2) 2 I 2 e F I 2 (3)EN60814:1997 4 BSI 04-1999 One mole of iodine reacts with one mole of water stoichiometrically as shown in reactions (1) so that 1mg of water is equivalent to10,72C (number of coulombs).
36、 Based on this principle it is possible to determine the amount of water directly from the quantity of electricity (number of coulombs) required for the electrolysis. 2.3 Apparatus 2.3.1 Principle of operation The titration vessel has the configuration of an electrolysis cell with two compartments c
37、onnected by a porous diaphragm. The anodic compartment contains the mixture of reagent-solvent and sample (anodic solution), the cathodic compartment (generator assembly) contains anhydrous reagent (cathodic solution). On both sides of the diaphragm are located the electrolysis electrodes. NOTETitra
38、tors without the porous diaphragm may be used. Iodine generated by the electrolysis, as shown in reaction (3), reacts with the water in a similar way to the Karl Fischer reactions (1) and (2). The end-point of the reaction is detected by a pair of platinum electrodes immersed in the anodic solution.
39、 At the end of the titration, excess iodine depolarizes the dual platinum electrodes, giving a change in the current/voltage ratio which is used to activate the end-point indicator and to stop the current integrator. The current integrator integrates the current consumed during the electrolysis, cal
40、culates the water equivalent according to Faradays law, and finally displays it in micrograms of water. 2.3.2 Description of the apparatus Commercial coulometric Karl Fischer titrators use proprietary circuitry. The following description of one suitable form of apparatus is given for illustrative pu
41、rposes only. The block diagram shown in Figure 1 illustrates the apparatus and includes the components detailed below. 2.3.2.1 Titration vessel assembly An example of a suitable titration vessel assembly is shown in Figure 2. However, the changes in instrument technology are such that radically diff
42、erent designs may become available which comply with the technical requirements of this standard. The exemplified apparatus consists of: a flanged glass reaction vessel a) with sample injection plug b) and drain cock c) (optional); a polytetrafluoroethylene lid d), flanged to match the titration ves
43、sel, with three holes to receive the electrodes and drying tube; a generator assembly (combined electrolysis cell) e) consisting of a glass tube closed at its lower end by a diaphragm and equipped with platinum electrodes on each side of the diaphragm; NOTEThe diaphragm may consist of ion exchange m
44、embrane, fritted disc, ceramic filter or other system to prevent diffusion of both solutions, while allowing enough current for electrolysis. detector electrodes: dual platinum electrodes for measurement of potential or current f); a polytetrafluoroethylene coated stirrer bar g); drying tubes h) to
45、protect the titration vessel and the generator assembly from atmospheric moisture; silicone rubber septa to seal the injection port. It is recommended that crosscuts should be made in the septa before use, to enable blunt, square-ended needles to be used for sample injection see 2.4.2 d). Septa shou
46、ld be replaced as required to prevent air leakage as indicated by excessive instrument drift. 2.3.2.2 Detection circuit DC constant voltage or a.c. constant current is supplied to the detector electrodes (dual platinum measuring electrodes) so that the end-point may be detected from the change of th
47、e polarized current or voltage. 2.3.2.3 Current regulator circuit This circuit controls the electrolysis according to the signal from the detector circuit. 2.3.2.4 DC power supply DC power supply for electrolysis.EN60814:1997 BSI 04-1999 5 2.3.2.5 End-point indicator Indicates when the end-point has
48、 been reached. 2.3.2.6 Current integrator Measures the quantity of electricity consumed by the electrolysis cell during the titration, then calculates and displays the quantity of water, in micrograms, corresponding to it. NOTESome instruments have built-in calculation facilities, and display the wa
49、ter concentration for a specific sample quantity. 2.3.2.7 Electromagnetic stirrer Electromagnetic stirrer, capable of maintaining a constant speed sufficient to ensure adequate dispersion. (The content of the titration vessel will not in general be a single phase, since most insulating liquids are not completely miscible with the reagent liquids.) 2.4 Reagents and auxiliary materials WARNING Certain reagents may be detrimental to health and must be handled with proper care. 2.4.1 Reagents Prepared reage
