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BRITISH STANDARD Common test methods for cables under fire conditions Ð Tests on gases evolved during combustion of materials from cables Ð Part 2-3: Procedures Ð Determination of degree of acidity of gases for cables by determination of the weighted average of pH and conductivity The European Standard EN 50267-2-3:1998 has the status of a British Standard ICS 13.220.40; 29.060.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BS EN 50267-2-3:1999 BS EN 50267-2-3:1999 National foreword This British Standard is the English language version of EN 50267-2-3:1998 When combined with BS EN 50267-1, it supersedes BS 6425-2:1993 which is withdrawn The UK participation in its preparation was entrusted by Technical Committee GEL/20, Electric cables, to Subcommittee GEL/20/3, Insulation and sheath, which has the responsibility to: Ð aid enquirers to understand the text; Ð present to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; Ð monitor related international and European developments and promulgate them in the UK A list of organizations represented on this subcommittee can be obtained on request to its secretary Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled ªInternational Standards Correspondence Indexº, or by using the ªFindº facility of the BSI Standards Electronic Catalogue A British Standard does not purport to include all the necessary provisions of a contract 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, the EN title page, pages to 6, an inside back cover and a back cover The BSI copyright notice displayed in this document indicates when the document was last issued This British Standard, having been prepared under the direction of the Electrotechnical Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 September 1999 BSI 09-1999 ISBN 580 32735 Amendments issued since publication Amd No Date Comments EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM EN 50267-2-3 June 1998 ICS 13.220.40; 29.060.20 Partly supersedes HD 602 S1:1992 Descriptors: electrical installation, electric cables, fire tests, combustion tests, combustion products, burning gases, corrosive gases, determination, acidity, measurements, pH, conductivity, testing conditions, procedure English version Common test methods for cables under fire conditions — Tests on gases evolved during combustion of materials from cables — Part 2-3: Procedures — Determination of degree of acidity of gases for cables by determination of the weighted average of pH and conductivity Méthodes d’essai communes aux câbles soumis au feu — Essais sur les gaz émis lors de la combustion d’un matériau prélevé sur un câble — Partie 2-3: Procédures — Détermination de l’acidité des gaz des câbles par une mesure de la moyenne pondérée du pH et de la conductivité Allgemeine Prüfverfahren für das Verhalten von Kabeln und isolierten Leitungen im Brandfall — Prüfung der bei der Verbrennung der Werkstoffe von Kabeln und isolierten Leitungen entstehenden Gase — Teil 2-3: Prüfverfahren — Bestimmung des Grades der Azidität der wesentlichen Werkstoffe von Kabeln durch die Bestimmung eines gewichteten Mittelwertes von pH-Wert und Leitfähigkeit This European Standard was approved by CENELEC on 1998-04-01 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 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 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, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels © 1998 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC national members Ref No EN 50267-2-3:1998 E Page EN 50267-2-3:1998 Foreword This European Standard was prepared by the Technical Committee CENELEC TC20, Electric cables When used in conjunction with EN 50267-1, this European Standard supersedes HD 602 S1:1992 Significant technical differences are: a) limits for water quality are introduced; b) requirements are given in an informative annex, as recommendations only The text of the draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC as EN 50267-2-3 on 1998-04-01 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 endorsement (dop) 1999-03-01 latest date by which national standards conflicting with the EN have to be withdrawn (dow) 2000-03-01 Annexes designated "normative" are part of the body of the standard Annexes designated "informative" are given for information only In this standard annex A is informative There is no normative annex Contents Page Scope Normative references Definitions Test apparatus Test method and procedure 5.1 General principle 5.2 Samples and conditioning 5.3 Test pieces 5.4 Procedure 5.5 Determination of the pH value and conductivity Expression of the results 6.1 Mean value 6.2 Weighted values Annex A (informative) Performance requirements 3 3 3 4 4 4 © BSI 09-1999 Page EN 50267-2-3:1998 Scope EN 50267-2-3 specifies the test method and procedure for the determination of the degree of acidity of gases evolved during the combustion of electric or optical cables by determination of the weighted average of pH and conductivity of the constituent materials NOTE The relevant cable standard should indicate which materials from the cable should be tested Normative references This European Standard incorporates by dated or undated reference, provisions from other publications These normative references are cited at the appropriate places in the text and the publications are listed hereafter For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision For undated references the latest edition of the publication referred to applies EN 50267-1, Common test methods for cables under fire conditions — Tests on gases evolved during the combustion of materials from cables — Part 1: Test apparatus EN 60695-4, Fire hazard testing — Part 4: Terminology concerning fire tests NOTE IEC 60695 is in the course of re-numbering its parts and sections This will also affect the equivalent ENs Definitions For the purposes of EN 50267-2-3 the following definition applies The definition is taken from EN 60695-4 ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ 3.1 combustion exothermic reaction of a substance with an oxidizer with emission of effluent, generally accompanied by flames and/or glowing and/or emission of smoke Test apparatus The apparatus used shall be that specified in EN 50267-1 together with the following measuring instruments: — analytical balance of an accuracy of ±0,1 mg; — pH meter to an accuracy of ±0,02, equipped with a suitable pH electrode; — conductivity measuring device with a range 10 µS/mm to 10² µS/mm and a suitable electrode; — timer -2 Test method and procedure 5.1 General principle A pre-determined quantity of the test material is burned in a tube furnace The evolved gases are trapped by bubbling through wash bottles filled with distilled or demineralized water Each wash bottle shall contain approximately 450 ml of distilled or demineralized water with the following properties: pH 6,5 ± 1,0; conductivity ≤ 0,5 µS/mm The acidity is measured by determination of pH value The conductivity of the solution is also measured © BSI 09-1999 Page EN 50267-2-3:1998 5.2 Samples and conditioning Representative samples of the materials of the cable to be tested shall be taken The samples shall be stored for at least 16 h at a temperature of (23 ± 2) °C and a relative humidity of (50 ± 5) % 5.3 Test pieces A test piece shall consist of (1 000 ± 5) mg of each material to be tested taken from the representative sample The test piece shall be cut into a number of smaller pieces 5.4 Procedure The test pieces, which shall be weighed to an accuracy of mg, shall be put into a combustion boat They shall be evenly distributed on the bottom of the boat -1 The air flow shall be adjusted by means of a needle valve at (0,015 7D²) l·h ±10 % and kept constant during the test NOTE It is recommended that the air flow is not started until immediately prior to the commencement of the test The temperature value shall be measured by a thermocouple suitably protected against corrosion and placed inside the tube The boat containing the test pieces shall be quickly inserted into the effective zone of the tube and the timer shall be started The combustion boat shall be placed in such a way that the distance between the boat and the exit end of the effective heating zone is ≥ 300 mm; the temperature measured at the position of the boat shall be not less than 935 °C The temperature measured at a position 300 mm from the boat in the direction of the air flow shall be not less than 900 °C ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ The combustion procedure under the air flow condition shall be continued for 30 in the furnace NOTE The operator should take precautions, i.e the wearing of eye protection and suitable protective clothing, because certain materials ignite quickly, and can cause “blow-back” of hot gases Care should also be taken to avoid over-pressurization of the system, and to allow for venting of exhaust gases After the test, and before determination of the pH and conductivity, the contents of both bottles shall be aggregated in a volumetric flask and made up to 000 ml using water with the properties given in 5.1 NOTE After removing the combustion boat, the tube has to be cleaned throughout its length by calcination at 950 °C 5.5 Determination of the pH value and conductivity 5.5.1 Calibration of the pH meter The pH meter shall be calibrated as proposed by the instrument supplier 5.5.2 Determination of the pH value and conductivity of the solution The pH value of the solution shall be determined at room temperature The pH value shall be read by using the automatic temperature compensation, usually integral with the instrument Conductivity measurements shall be performed in accordance with the test procedures as prescribed by the supplier Expression of the results 6.1 Mean value For each material, three test determinations shall be undertaken Calculate the mean value, standard deviation and coefficient of variation © BSI 09-1999 Page EN 50267-2-3:1998 If the coefficient of variation expressed in per cent is higher than 5, a further three tests on this material are required and the mean value, standard deviation and coefficient of variation should be recalculated using the six values 6.2 Weighted values Using the mean values for each material determined from 6.1, the assessment of the pH and conductivity of fire gases expected to be evolved by a combination of materials found in a specified cable under similar test conditions may be estimated as follows 6.2.1 pH Measure the weight wi ,of each non-metallic material, i, per unit length of cable / The weighted value of pH, pH , is calculated as follows: pH / = log10 Σi wi Σi wi x 10 where x is the pH of each non-metallic material, i 6.2.2 Conductivity Measure the weight, wi, of each non-metallic material, i, per unit length of cable / ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ The weighted value of conductivity, c , is calculated as follows: c /= S i c ×wi S i wi where c is the conductivity of each non-metallic material, i © BSI 09-1999 Page EN 50267-2-3:1998 Annex A (informative) Performance requirements No requirements for conformity are included in this standard The method specified in this standard is intended for type testing of specific cables Where no requirements are specified in the particular cable specification, and where the cable is described as “zero halogen” or “halogen-free” it is recommended that the following requirements should be met a) The weighted pH value, as determined in 6.2.1, should not be less than 4.3, when related to l of water b) The weighted value of conductivity, as determined in 6.2.2, should not exceed 10 µS/mm when related to l of water In case of dispute over the conductivity value, such as may occur if the recommended value is exceeded even though the test shows compliance with the recommended pH value, alternative methods of investigation should be agreed between interested parties ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ © BSI 09-1999 Page EN 50267-2-3:1998 ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ blank © BSI 09-1999 BS EN 50267-2-3:1999 BSI 389 Chiswick High Road London W4 4AL | | | | | 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