1、BRITISH STANDARD 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 29.035.40 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRI
2、Gm LAW BS EN 60814 : 1998 IEC 60814 : 1997 - STD-BSI BS EN bBLLI-ENGL 1998 m 1b2LibbS Ob3b5 722 m Amd. No. BS EN 60814 : 1998 Date Text affected This British Standard, having been prepared under the direction of the Electrotechnicai Sector Board, was published under the authority of the Standards Bo
3、ard and comes into effect on 15 February 1998 National foreword This British Standard is the English language version of EN 60814 : 1997. It is identical with IEC 60814 : 1997. It supersedes BS 6725 : 1986 (1991) which is withdram The UK participation in its preparation was entrusted to Technical Co
4、mmittee GEMO, Fluids for eleclxotechnicd applications, which has the responsibility to: - aid enquirers to understand the text; - present to the responsible internationallEuropean committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; - monitor re
5、lated international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained 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 ren
6、umbered as IEC 60027-1. For a period of time during the change over from one numbering system to the other, publications may contain identifiers from both systems. Cross-references Attention is drawn to the fact that CEN and CENELEC Standards normally include an annex which lists nonnative reference
7、s to international publications with their corresponding European publications. The British Standards which implement these jnkrnaiional or European publications may be found in the BSI Standards Catalogue under the section entitled International Standards Correspondence Index, or by using the Find
8、facility of the BSI Standards Electronic Catalogue. 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, the EN title page, pages 2 to 23, a blank page, an inside back cover and a
9、back cover. Amendments issued since publication O BSI 1998 ISBN O 680 29366 4 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 60814 October 1997 CS 29.035.40 Supersedes HO 487 S1: 1987 Descriptors: Electric insulating materials, liquid electrlcal insulating materials. insulating oils, paper, pa
10、perboards, chemical analysis, determination of content, water, Karl Fischer method, coulometric methods English version Insulating liquids - Oil-impregnated paper and pressboard Determination of water by automatic coulometric Karl Fischer titration (IEC 608 1 4: 1 997) Isolants liquides - Cartons et
11、 papiers imprgns dhuile - Determination de la teneur en eau par titrage coulomtrique de Karl Fischer automatique (CE1 6081 4: 1997) Karl-Fischer-Titration Isolierflssig keiten - limprgniertes Papier und limprgnierter Presspan Bestimmung von Wasser durch automatische coulometrische (IEC 60814:1997) T
12、his European Standard was approved by CENELEC on 1997-1 0-01. CENELEC members are bound to comply with the CENICENELEC 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 bibliographicai
13、references concerning such national standards may be obtained on application to the Central Secretariat or KO any CENELEC member. This European Standard exists in three official versions (English, French, Germant. A version in any other language made by translation under the responsibility of a CENE
14、LEC member into its own language 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, Rance, Germany, Greece, Iceland, Ireland. Italy, Luxembourg, Netherlands, Norway,
15、 Ponugal, Spain, Sweden, 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, 8 - 7050 Brussels a : 997 CENELEC - All
16、rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 60814:1997 E Page 2 EN 60814 : 1997 Foreword The text of document 10/406/FDIS, future edition 2 of IEC 608 14, prepared by IEC TC 1 O, Fluids for electrotechnical applications, was submitted to th
17、e IEC-CENELEC parallel vote and was approved by CENELEC as EN 60814 on 1997-10-01. This European Standard supersedes HD 487 S1:1987. The following dates were fixed: - latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsemen
18、t (dop) 1998-07-01 - latest date by which the national standards conflicting with the EN have to be withdrawn (daw) 1998-07-01 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 normative
19、 and annex A is informative. Annex ZA has been added by CENELEC. Endorsement notice The text of the International Standard IEC 6081 4: 1997 was approved by CENELEC as a European Standard without any modification. Page 3 EN 60814 : 1997 CONTENTS Clause 1 General . 1.1 scope 1.2 Normative references 2
20、 Direc titration for low viscosity liquids 2.1 Field of application 2.2 Chemistry 2.3 Apparatus 2.4 Reagents and auxiliary materials 2.5 Preparation of the apparatus . 2.6 Sampling methods 2.7 Procedure 2.8 Calculation of the result . 2.9 Report . 2.10 Precision . 3 Evaporative stripping method for
21、high viscosity liquids 3.1 Field of application 3.2 Outline of the method 3.3 Apparatus and reagents 3.4 Procedure 3.5 Calculation of water content 3.6 Report . 4 Determination of water in oil-impregnated paper and pressboard . 4.1 Field of application 4.2 Determination of water after previous extra
22、ction with methanol . 4.3 Determination by direct titration . 4.4 Evaporative stripping method Figures 1 Block diagram of automatic titrator . 2 Suitable titration vessel assembly 3 Block diagram of automatic titrator and evaporation stripping unit 4 Evaporator glass vessel with heater . 5 Methanol
23、container and extraction tube . Annexes A . Method for sampling of oil-impregnated paper and pressboard . Dublications with their COrreSDOndinQ EuroDean Dublications . ZA (normative) Normative references to international Page 4 4 4 4 4 5 5 7 7 7 8 8 8 9 9 9 9 9 10 IO 10 11 11 11 12 13 15 16 17 18 19
24、 20 23 Page 4 EN 60814 : 1997 INSULATING LIQUIDS - OIL-IMPREGNATED PAPER AND PRESSBOARD - DETERMINATION OF WATER BY AUTOMATIC COULOMETRIC KARL FISCHER TITRATION 1 General 1.1 Scope This International Standard describes methods for the. determination of water in insulating liquids and in oil-impregna
25、ted cellulosic insulation with coulometrically generated Karl Fischer reagent. The method in clause 2 is applicable to water concentrations above 2 mg/kg in liquids having viscosity of less than 100 mm /s at 40 OC. The test method in clause 3, where water is extracted by means of 2 nitrogen stream,
26、is the preferred method for insulating liquids of viscosity higher than 100 mm /s. Clause 4 describes methods for the determination of water content in oil-impregnated paper and pressboard over the range 0,l % to 20 % by mass. 1.2 Normative references The following normative documents contain provis
27、ions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this International Standard are encouraged to investiga
28、te the possibility of applying the most recent editions of the normative documents indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. IEC 60475: 1974, Method of sampling liquid dielectrics IEC 60567: 1992, Guide for the sampling of gases and of oil
29、 from oil-filled electrical equipment and for the analysis of free and dissolved gases IS0 595-1: 1986, Reusable all-glass or metal-and-glass syringes for medical use - Part 1: Dimensions IS0 595-2: 1987, Reusable all-glass or metal-and-glass syringes for medical use - Pari 2: Design, performance re
30、quirements and tests 2 Direct titration for low viscosity liquids 2.1 Field of application This meth$d is applicable to water concentrations above 2 mg/kg in liquids having viscosity up to 100 mm /s at 40 “C. The precision data given in 2.10 apply only to new liquids. NOTES 1 For liquids in service,
31、 the accuracy of the method may be affected by the presence of contaminants and degradation products. 2 The method has been designed to be particularly suitable to hydrocarbon and ester liquids. With other liquids, particularly silicone fluids, methanol free reagents must be used. STD-BSI BS EN bO81
32、4-ENGL 1998 Lb24bb9 Ub83b70 09T Page 5 EN 60814 : 1997 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. The original Karl Fischer reagent used py
33、ridine and methanol, and the reactions may be expressed as: HZO + I, + SO, + 3C5HSN + PC,H,N.HI + C,H,N.SO, (1) 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
34、solution of 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: 2 I- 2 e I,
35、(3) One mole of iodine reacts with one mole of water stoichiometrically as shown in reactions (1) so that 1 mg of water is equivalent to 10,72 C (number of coulombs). Based on this principle it is possible to determine the amount of water directly from the quantity of electricity (number of coulombs
36、) required for the electrolysis. 2.3 Apparatus - 2.3.1 Principle of operation I The titration vessel has the configuration of an electrolysis cell with two compartments connected by a porous diaphragm. The anodic compartment contains the mixture of reagent- solvent and sample (anodic solution), the
37、cathodic compartment (generator assembly) contains anhydrous reagent (cathodic solution). On both sides of the diaphragm are located the electrolysis electrodes. NOTE -Titrators without the porous diaphragm may be used. Iodine generated by the electrolysis, as shown in reaction (3), reacts with the
38、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. At the end of the titration, excess iodine depolarizes the dual platinum electrodes, giving a change in the current/voltage ra
39、tio 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, calculates the water equivalent according to Faradays law, and finally displays it in micrograms of water. 2.3.2 Description of th
40、e apparatus Commercial coulometric Karl Fischer titrators use proprietary circuitry. The following description of one suitable form of apparatus is given for illustrative purposes only. The block diagram shown in figure 1 illustrates the apparatus and includes the components detailed below. Page 6 E
41、N 60814 : 1997 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 different designs may become available which comply with the technical requirements of this standard. The ex
42、emplified 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 vessel, with three holes to receive the electrodes and drying tube; - a generator assembly (combine
43、d 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; NOTE - The diaphragm may consist of ion exchange membrane, fritted disc, ceramic filter or other system to prevent diffusion of both solutio
44、ns, while allowing enough current for electrolysis. - detector electrodes: dual platinum electrodes for measurement of potential or current (f); - a polytetrafluoroethylene coated stirrer bar (9); - drying tubes (h) to protect the titration vessel and the generator assembly from atmospheric moisture
45、; - 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 should be replaced as required to prevent air leakage as indicated by excessive in
46、strument 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 the polarized current or voltage. 2.3.2.3 Current regulator circuit This circuit
47、 controls the electrolysis according to the signal from the detector circuit. 2.3.2.4 DC power supply DC power supply for electrolysis. 2.3.2.5 End-point indicator Indicates when the end-point has been reached. 2.3.2.6 Current integrator Measures the quantity of electricity consumed by the electroly
48、sis cell during the titration, then calculates and displays the quantity of water, in micrograms, corresponding to it. NOTE - Some instruments sample quantity. have built-in calculation facilities, and display the water concentration for a specific 2.3.2.7 Electromagnetic stirrer Electromagnetic sti
49、rrer, 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.) Page 7 EN 60814 : 1997 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 reagents are commercially available, but care is needed that the reagent is suitable for the particular type of instrument used and the in
