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50267-2-3:1999
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
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
Trang 2This 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 0 580 32735 3
BS EN 50267-2-3:1999
Amendments issued since publication
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English language version of EN 50267-2-3:1998 When combined with BS EN 50267-1, it supersedes BS 6425-2:1993 which is withdrawn The UK participation in its preparation was entrusted by Technical Committee GEL/20, Electric cables, to Subcommittee GEL/20/3, Insulation and sheath, which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 2 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
Trang 3EUROPEAN STANDARD EN 50267-2-3 NORME EUROPÉENNE
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
Trang 4Page 2
EN 50267-2-3:1998
© BSI 09-1999
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
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
Trang 5Page 3
EN 50267-2-3:1998
© BSI 09-1999
1 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.
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 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.
3 Definitions
For the purposes of EN 50267-2-3 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
and/or 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 ±0,1 mg;
— pH meter to an accuracy of ±0,02, equipped with a suitable pH electrode;
— conductivity measuring device with a range 10-2 µS/mm to 10² µS/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 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
Trang 6Page 4
EN 50267-2-3:1998
© BSI 09-1999
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 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 7D²) l·h-1 ±10 % 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 ≥ 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
The combustion procedure under the air flow condition shall be continued for 30 min in the furnace
NOTE 2 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 1 000 ml using water with the properties given in 5.1.
NOTE 3 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
6 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
Trang 7Page 5
EN 50267-2-3:1998
© BSI 09-1999
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:
Σ
Σ 10
log
= pH
x 10
/
w
w
i i
i i
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.
The weighted value of conductivity, c/, is calculated as follows:
w
w c c
i
i i
S
S
=
where c is the conductivity of each non-metallic material, i.
Trang 8Page 6
EN 50267-2-3:1998
© BSI 09-1999
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 1 l of
water
b) The weighted value of conductivity, as determined in 6.2.2, should not exceed 10 µS/mm when
related to 1 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
Trang 9Page 7
EN 50267-2-3:1998
© BSI 09-1999
blank
Trang 10BS EN
50267-2-3:1999
BSI
389 Chiswick High Road
London
W4 4AL
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