BRITISH STANDARD

Common test methods for cables under fire conditions - Tests on

The European Standard EN 50267-2-2:1998 has the status of a British Standard

BS EN 50267-2-2:1999

ICs 13.220.40: 29.060.20

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ST3=BSI ES EN 5-2b7-2-2-EKGL 3999 U lb2Ybb4 0777483 733

direction of the Electrotechnical h d . No. Date Sector Committee, was published under the authority of the Standards Committee and comes into effect on 16 September 1999

BS EN 50267-2-2:1999

Comments

National foreword This British Standard is the English language version of EN 50267-2-2:1999.

The UK participation in its preparation was entrusted by Technical Committee GEMO, Electric cables, to Subcommittee GEI20/3, Insulation and sheath, which has the responsibility to:

- aid enquirers to understand the text;

- present to the responsible European committee any enquiries on the

- monitor related international and European developments and promulgate

interpretation, or proposals for change, and keep the UK interests informed;

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 Standarch 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. 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 2 to 5 and a back cover.

The BSI copyright notice displayed in this document indicates when the document was last issued.

O BSI 041999 I l

ISBN O 680 32734 6

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EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM

EN 50267-2-2

June 1998

ICs 13.220.40; 29.060.20

Descriptors: elecical installation, electrical cables, fire tests, combustion tests, combustion products, burning gases, corrosive gases, determination, acidity, measurements, pH conductivity, testing, conditions, procedures

English version

Common test methods for cables under fire conditions - Tests on gases evolved during combustion of materials from cables -

Part 2-2: Procedures - Determination of degree of acidity of gases for materials by materials by measuring pH and conductivity

Mthodes dessai communes aux cbles soumis au feu - Essais sur les gaz mis lors de la combustion dun matriau prlev sur un cble - Partie 2-2: Procdures -Dtermination de lacidit des gaz des matriaux par une mesure du pH et de la conductivit

Allgemeine Prfverfahren fr das Verhalten von Kabeln und isolierten Leitungen im Brandfall -Prfung der bei der Verbrennung der Werkstoffe von Kabeln und isolierten Leitungen entstehenden Gase - Teil 2-2: Prfverfahren - Bestimmung des Grades der Aziditt von Gasen bei Werkstoffen durch pH-Wert und LeiWgkeit

This European Standard was approved by CENELEC on 1998 04.01. CENELEC members are bound to comply with the CENKENELEC 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 oficial 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

Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B-1050 Brussels

O 1998 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC national members Ref. No. EN 50267-2-2: 1998 E

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Page 2 EN 50267-2-2: 1998

Fore wo rd

This European Standard was prepared by the Technical Committee CENELEC TC20, Electric Cables.

The text of the draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC as EN 50267-2-2 on 1998-04-0 1.

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) 2000-03-0 1

Annexes designated "nonnative" 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

Foreword 1 Scope 2 Normative references 3 Definition 4 Test apparatus 5 Test method and procedure 5 . I General principle 5.2 Samples and conditioning 5.3 Test pieces 5.4 Procedure 5.5 Determination of pH and conductivity 6 Expression of the results Annex A (informative) Performance requirements

Page

2 3 3 3 3 3 3 4 4 4 4 4 5

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Page 3 EN 50267-2-2 : 1998

1 Scope

EN 50267-2-2 specifies the test method and procedure for the detemination of the degree of acidity of gases evolved during the combustion of materials taken from electric or optical cables by measuring pH and conductivity.

NOTE The relevant cable standard should indicate which materials from the cable should be tested.

2 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 underfire conditions - Tests on gases evolved during the cornbusrion of materialsfrom cables. Part 1: Tesr apparum.

EN 60695-4, Fire Hazard testing - Part 4: Terminology concemingfire tests.

NOTE IEC 60695 is in the course of re-numbering its parts and sections. This will also affect the equivalent ENS.

3 Definition

For the purposes of EN 50267-2-2 the following definition applies. The definition is taken from EN 60695-4.

3.1 combustion exothermic reaction of a substance with an oxidizer with emission of effluent, generally accompanied by flames andor glowing and/or emission of smoke

4 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 *O, 1 mg; - pH meter to an accuracy of *0,02, equipped with a suitable pH electrode; - Conductivity measuring device with a range l o 2 pS/mm to lo2 pS/mm and a suitable electrode; - timer.

5 Test method and procedure

5.1 General principle

A pre-determined quantity of the test material is burned in a tube h a c e . The evolved gases are trapped by bubbling through wash bottles filled with distilled or demineralized water. Each wash bottle shall contain approximately 450 mi of distilled or demineralized water with the following properties:

pH 6,5 f 1,O; conductivity I 0,5pS/mm.

The acidity is measured by determination of pH value. The conductivity of the solution is also measured.

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Page 4 EN 50267-2-2 : 1998

5.2 Samples and conditioning

Representative samples of the material to be tested shall be taken. The samples shall be stored for at least 16 h at a temperature of (23 i 2) OC and a relative humidity of (50 f 5) %.

5.3 Test pieces

A test piece shall consist of (1 O00 f 5) mg of the 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 1 mg, shall be put into a combustion boat. They shall be evenly distributed on the bottom of the boat.

The air flow shall be adjusted by means of a needle valve at (0,015 702) 1.h-I I10 % and kept constant during the test.

NOTE 1 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 2300 mm; the temperature measured at the position of the boat shall be not less than 935 OC. The temperature measured at a position 300 mm fiom the boat in the direction of the air flow shall be not less than 900 "C.

The combustion procedure under the air flow condition shall be continued for 30 min in the furnace.

NOTE 2 The operator should take precautions, .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-pressurisation 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 1 O00 mi using water with the properties given in 5.1.

NOTE 3 AAer removing the combustion boat, the tube has to be cleaned throughout its length by calcination at 950 OC.

5.5 Determination of the pH value and conductivity

5.5.1 Calibration of thepH 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.

6 Expression of the results

Two test determinations shall be undertaken on each non-metallic individual material to be tested.

The test is considered to be passed if both the pH value of each sample of the material is not less than the specified value and the conductivity does not exceed the specified value.

If one sample fails, the test determination shall be repeated on two further samples of the relevant material. Both repeat samples shall comply with specified limit values.

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Page 5 EN 50267-2-2: 1998

Annex A (informative) Performance requirements

No requirements for conformity are included in this standard.

The method specified in this standard is intended for testing of individual materials used in cable construction. The use of this method will enable the requirements for individual materials of a cable construction to be stated in the appropriate cable specification.

Where no requirements are specified in the particular cable specification, and where the cable is described as zero halogen or halogen-he it is recommended that at least both the following requirements should be met for each of the individual materials of a cable constniction.

a) The pH value as determined in 6, should not be less than 4,3, when related to one litre of water.

b) The conductivity value as determined in 6, should not exceed 10 pS/mm, when related to one litre 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.

O BSI 09-1999

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BS EN 50267-2-2:1999

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