BRITISH STANDARD BS EN 50290-2-24: 2002+A1:2008 Incorporating corrigendum January 2011 Communication cables — Part 2-24: Common design rules and construction — PE sheathing ICS 29.035.20; 33.120.01 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BS EN 50290-2-24:2002+A1:2008 National foreword This British Standard is the UK implementation of EN 50290-2-24:2002+A1:2008 It supersedes BS EN 50290-2-24:2002 which is withdrawn The start and finish of text introduced or altered by amendment is indicated in the text by tags Tags indicating changes to CENELEC text carry the number of the CENELEC amendment For example, text altered by CENELEC amendment A1 is indicated by !" The UK participation in its preparation was entrusted by Technical Committee EPL/46, Cables, wires and waveguides, RF connectors and accessories for communication and signalling, to Subcommittee EPL/46/1, Communication cables A list of organizations represented on this subcommittee can be obtained on request to its secretary This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application Compliance with a British Standard cannot confer immunity from legal obligations This British Standard was published under the authority of the Standards Policy and Strategy Committee on 15 April 2002 Amendments /corrigenda issued since publication © BSI 2011 ISBN 978 580 74255 Date Comments 30 April 2009 Implementation of CENELEC amendment A1:2008 31 January 2011 Correction to identifier on EN title page EUROPEAN STANDARD EN 50290-2-24:2002+A1 NORME EUROPÉENNE EUROPÄISCHE NORM October 2008 ICS 29.035.20; 33.120.10 Supersedes HD 624.4 S1:1996 English version Communication cables Part 2-24: Common design rules and construction – PE sheathing Câbles de communication Partie 2-24: Règles de conception communes et construction – Polyéthylène pour gainage Kommunikationskabel Teil 2-24: Gemeinsame Regeln für Entwicklung und Konstruktion – PE-Mantelmischungen This European Standard was approved by CENELEC on 2001-11-01 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, Malta, 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 © 2002 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members Ref No EN 50290-2-24:2002 E BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 -2- Foreword This European Standard was prepared by a joint working group of the Technical Committees CENELEC TC 46X, Communication cables, and CENELEC TC 86A, Optical fibres and optical fibre cables The text of the draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC as EN 50290-2-24 on 2001-11-01 This European Standard supersedes HD 624.4 S1:1996 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) 2002-08-01 – latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2004-08-01 Annexes designated "normative" are part of the body of the standard In this standard, annexes A, B and C are normative This European Standard has been prepared under the European Mandate M/212 given to CENELEC by the European Commission and the European Free Trade Association _ Foreword to amendment A1 This amendment was prepared by a Joint Working Group of the Technical Committees CENELEC TC 46X, Communication cables, and CENELEC TC 86A, Optical fibres and optical fibre cables The text of the draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC as amendment A1 to EN 50290-2-24:2002 on 2008-11-01 The purpose of this amendment is to align EN 50290-2-24:2002 with new grades available The following dates were fixed: – – latest date by which the amendment has to be implemented at national level by publication of an identical standard or by endorsement (dop) 2009-11-01 latest date by which the national standards conflicting with the amendment have to be withdrawn (dow) 2011-11-01 -3- BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 Scope This Part 2-24 of EN 50290 gives specific requirements for PE sheathing compounds used in communication cables It is to be read in conjunction with Part 2-20 of EN 50290 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 (including amendments) EN 60811-1-1:1995 Insulating and sheathing materials of electric and optical cables - Common test methods Part 1-1: General application - Measurement of thickness and overall dimensions - Tests for determining the mechanical properties (IEC 60811-1-1:1993) EN 60811-1-2:1995 Insulating and sheathing materials of electric cables - Common test methods Part 1-2: General application Thermal ageing methods (IEC 60811-1-2:1985 + corr May 1986 + A1:1989) EN 60811-1-3:1995 Insulating and sheathing materials of electric and optical cables - Common test methods Part 1-3: General application - Methods for determining the density - Water absorption tests - Shrinkage test (IEC 60811-1-3:1993) EN 60811-1-4:1995 Insulating and sheathing materials of electric and optical cables - Common test methods Part 1-4: General application - Tests at low temperature (IEC 60811-1-4:1985 + corr May 1986 + A1:1993) EN 60811-4-1:1995 Insulating and sheathing materials of electric cables - Common test methods - - Part 4: Methods specific to polyethylene and polypropylene compounds - Section 1: Resistance to environmental stress cracking - Wrapping test after thermal ageing in air - Measurement of the melt flow index - Carbon black and/or mineral content measurement in PE (IEC 60811-4-1:1985) EN 60811-4-2:1999 Insulating and sheathing materials of electric and optical fibre cables Common test methods - - Part 4: Methods specific to polyethylene and polypropylene compounds Section 2: Tensile strength and elongation at break after pre-conditioning - Wrapping test after thermal ageing in air Measurement of mass increase – Long - term stability test - Test method for copper - catalysed oxidative degradation (IEC 60811-4-2:1990, mod.) Requirements In case of specific applications, additional performances could be needed Relevant test methods and requirements shall be included in the detail specifications of the cables BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 -4- Table – Black PE sheathing compound ! Characteristics Test method a Unit Grades (see Note 1) LD MD HD LLD °C 70 80 80 80 EN 60811-1-3, Clause g/cm³ < 0,930 ≥ 0,930 ≤ 0,940 > 0,940 < 0,930 EN 60811-4-1, Clause 10 g/10 ≤ 0,4 ≤ 2,0 ≤ 2,0 ≤ 3,0 Maximum rated temperature at cable for which the compound can be used Density (without carbon black) Melt flow index (see Note 2) Mechanical characteristics 4.1 In state of delivery Tensile strength – median, MPa 10 18 18 16 Elongation at break – median, % 300 300 300 500 °C 100 ± 100 ± 100 ± 100 ± h 24 x 10 24 x 10 24 x 10 24 x 10 % 300 300 300 500 mm 200 200 200 200 °C c c c c h c c c c % c c c c 4.2 a a After ageing EN 60811-1-1, 9.2 EN 60811-1-2, 8.1 Ageing conditions – temperature – duration Elongation at break – median, Shrinkage b EN 60811-1-3, Clause 11 Test conditions – sample length (if not otherwise specified) – temperature – duration Result to be obtained – shrinkage, max " BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 -5- Table – Black PE sheathing compound (continued) ! Characteristics Test method a Unit Grades (see Note 1) LD Performance after pre-conditioning (for sheath in direct contact with filling compound) °C – duration Result to be obtained Tensile strength – median, Elongation at break – median, d Carbon black content Carbon black dispersion Stress cracking (see Note 3) EN 60811-4-1, Clause 11 d d HD LLD Annex A Test conditions – temperature MD Annex B EN 60811-4-1, Clause 8, Procedure B 60/70 ± 60/70 ± 60/70 ± 60/70 ± h x 24 x 24 x 24 x 24 MPa 10 18 18 16 % 300 300 300 500 % 2,5 ± 0,5 2,5 ± 0,5 2,5 ± 0,5 2,5 ± 0,5 To meet To meet To meet To meet > 000 h > 000 h > 000 h > 000 h NOTE In order to differentiate LD from LLD-Polyethylene the melting point according to ISO 11357-3 e can be measured The melting point of LD is < 120 °C and of LLD is ≥ 120 °C NOTE If required, MFI may be measured on sheath with other values to be specified NOTE Stress cracking test on raw material may not be sufficient to guarantee a stress cracking performance on finished product Therefore an additional test has to be performed either on complete cable or on a piece of sheath taken from complete cable, in accordance with the test methods described in Annex C a To be given by the supplier b For special application c In the relevant cable specification d For inner sheath applications, non-black PE compounds can be used, then items 7, 8, may not apply e ISO 11357-3, Plastics – Differential scanning calorimetry (DSC) – Part 3: Determination of temperature and enthalpy of melting and crystallization " BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 -6- Table – Coloured PE sheathing compounds ! Characteristics Maximum rated temperature at cable for which the compound can be used Density Melt flow index (see Note 2) Mechanical characteristics 4.1 In state of delivery Tensile strength – median, a a Test method After ageing MD HD LLD °C 70 80 80 80 EN 60811-1-3, Clause g/cm³ < 0,930 ≥ 0,930 ≤ 0,940 > 0,940 < 0,930 EN 60811-4-1, Clause 10 g/10 ≤ 0,4 ≤ 2,0 ≤ 2,0 ≤ 3,0 MPa 10 18 18 16 % 300 300 300 500 °C 100 ± 100 ± 100 ± 100 ± h 24 x 10 24 x 10 24 x 10 24 x 10 % 300 300 300 500 mm 200 200 200 200 °C c c c c h c c c c % c c c c EN 60811-1-1, 9.2 EN 60811-1-2, 8.1 Ageing conditions – temperature – duration Elongation at break – median, Shrinkage b Grades (see Note 1) LD Elongation at break – median, 4.2 a Unit EN 60811-1-3, Clause 11 Test conditions – sample length (if not otherwise specified) – temperature – duration Result to be obtained – shrinkage, max " BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 -7- Table – Coloured PE sheathing compounds (continued) ! Characteristics Test method a Unit Grades (see Note 1) LD Performance after pre-conditioning (for sheath in direct contact with filling compound) °C – duration Result to be obtained Tensile strength – median, Elongation at break – median, Stress cracking (see Note 3) HD LLD Annex A Test conditions – temperature MD EN 60811-4-1, Clause 8, Procedure B 60/70 ± 60/70 ± 60/70 ± 60/70 ± h x 24 x 24 x 24 x 24 MPa 10 18 18 16 % 300 300 300 500 > 000 h > 000 h > 000 h > 000 h NOTE In order to differentiate LD from LLD-Polyethylene the melting point according to ISO 11357-3 d can be measured The melting point of LD is < 120 °C and of LLD is ≥ 120 °C NOTE If required, MFI may be measured on sheath with other values to be specified NOTE Stress cracking test on raw material may not be sufficient to guarantee a stress cracking performance on finished product Therefore an additional test has to be performed either on complete cable or on a piece of sheath taken from complete cable, in accordance with the test methods described in Annex C a To be given by the supplier b For special application c In the relevant cable specification d ISO 11357-3, Plastics – Differential scanning calorimetry (DSC) – Part 3: Determination of temperature and enthalpy of melting and crystallization Guidance to use: Natural or coloured polyolefin cable sheaths, containing conventional antioxidant stabilisers degrade rapidly when subjected to natural daylight weathering through photocatalysed oxidation (actinic degradation) Degradation is manifested by discolouration of the sheath followed immediately by loss of mechanical properties and spontaneous cracking This ageing process is accelerated in situations where the sheath is physically stressed, for example at sharp bends Under temperate European climates failure can occur within two years of exposure Ageing will not only occur on installed cables but also on cables stored externally on drums or reels where the cables have been inadequately protected from solar radiation Ultraviolet stabilisation systems may be incorporated in the sheath compound to extend the induction period before the onset of failure Such systems will permit prolonged external storage of cables but their performance does not approach that of conventional sheaths containing a minimum of % of carbon black Consequently they are unsuitable for external use where long service lives are required, especially where the cable will be installed in exacting climatic conditions such as aerial cables " BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 -8- Annex A (normative) Performances after pre-conditioning To perform the test, use EN 60811-4-2 with the following modifications1: Scope - Second paragraph Replace " elongation at break " by " tensile strength and elongation at break " Pre-conditioning Replace the existing title by the following new title: Conditioning Elongation at break after pre-conditioning Replace the existing title and text of this clause by the following new title and text: Tensile strength and elongation at break after pre-conditioning 8.1 General This text is intended for filled cables for polyolefin insulations with a wall thickness of more than 0,8 mm and for polyolefin sheaths in direct contact with filling compound 8.2 Pre-conditioning procedure A sample of complete cable of sufficient length shall be pre-conditioned in air (i.e suspended in an oven) The duration of the test and the temperature of the air maintained continuously shall be as follows: - x 24 h at 60 °C for filling compound having a nominal drop-point above 50 °C and up to an including 70 °C - x 24 h at 70 °C for filling compound having a nominal drop-point above 70 °C After pre-conditioning, the cable sample shall be left at ambient temperature for at least 16 h without being exposed to direct sunlight Then the sheath and cores to be tested shall be taken from the cable and shall be cleaned by suitable means 8.3 Tensile strength and elongation tests after pre-conditioning Tensile strength and/or elongation tests, with respect to requirements in the cable standard, on test pieces according to 8.2 shall be performed in accordance with clause of EN 60811-1-1 without any further ageing treatment 1) The modifications listed are intended for revision of EN 60811-4-2 (IEC 60811-4-2) BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 - 10 - Annex B (normative) 2) Test methods for the assessment of carbon black dispersion in polyethylene using a microscope B.1 Introduction The methods below describe procedures for assessing the uniformity of dispersion of carbon black in a compound or extrusion B.2 Scope These methods describe procedures for assessing the carbon black dispersion in polyethylene using a microscope Procedure A is primarily intended for use with polyethylene compounds but may be used for extrusions Procedure B is intended for use with polyethylene extrusions or moundings only B.3 Principle Procedure A A small sample of the material is squeezed into a thin layer 20 mm to 30 mm thick between two microscope slides heated to either 170 °C to 210 °C, or a higher temperature if specified in the material specification The pressed sample is examined microscopically by transmitted light The frequency and size distribution of particles and agglomerates is measured and graded by comparison with Table B.1 The uniformity of dispersion is assessed by comparison with the photomicrographs of Table B.2 Procedure B A microtome section of the material, 10 mm to 20 mm thick, is examined as per procedure A B.4 Apparatus The following apparatus is required B.4.1 Hot plate Capable of being controlled at the required temperature B.4.2 Microscope slides B.4.3 Microscope Calibrated and capable of at least X 200 magnification The circular field of view at X 100 magnification shall be 0,7 mm ± 0,07 mm 2) Based on ISO document at draft stage, as ISO/DIS 18553 - 11 - BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 B.4.4 Microtome B.5 Procedure B.5.1 Preparation of specimens Procedure A Place two of the clean microscope slides on the hotplate maintained at 170 °C to 210 °C, or other higher temperature, as specified in the material specification Choose six separate granules of compound, or six separate parts of an extruded article, to be as representative as possible of the whole batch Cut a specimen of approximate mass 0,2 mg from the interior of each granule or part Place the six specimens on one of the hot microscope slides so that each one is approximately equidistant from its neighbour(s) and from adjacent edge(s) of the slide Place the second slide over the first, and press the specimens out by applying even pressure for minute to minutes to the whole area of the face of the upper slide Exert an amount of pressure for a period necessary for each specimen to be pressed out to a thickness of between 20 mm and 30 mm After the specimens have been placed on the slide, the latter shall in no case remain on the hotplate for more than minutes Remove the slide from the hotplate and allow it to cool NOTE Shims of metal or some other suitable material may be used to achieve the required specimen thickness and uniformity of thickness Procedure B Cut six microtome sections of thickness between 10 mm and 20 mm each approximately of mass 0,25 mg, from different parts of the extrusion or moulding B.5.2 Assessment of dispersion Agglomerates Examine the six specimens in turn under the microscope under transmitted light with a magnification of at least X 100 For each specimen examine the agglomerates checking that they are really pigment by varying the light intensity and using transmitted and reflected light if possible Measure and record the largest dimension of each agglomerate, ignoring those less than mm Rate according to the size categories given in Table B.1 Examine the whole of the specimen NOTE If larger sample sizes are used to prepare the specimens the number of for a 1,25 mg sample mass For some pigments no particles or agglomerates greater than mm may be visible, hence a grading of is obtained from Table B.1 Appearance Examine each of the specimens in turn under the microscope under transmitted light at a magnification X 100 ± 10 Compare each specimen with the micrographs in the Table B.2 for uniformity of appearance taking into account smears and streaks BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 - 12 - B.6 Expression of results B.6.1 Grading of agglomerates Using Table B.1, determine the highest grade for each sample Calculate the arithmetic mean of the six gradings obtained, and express the result to a single decimal point, rounded up to its higher value (see the examples given in Table B.3) B.6.2 Rating of appearance Express the appearance as the highest comparative rating with the photomicrographs in Table B.2 B.7 Requirements The mean agglomerate grading shall not be greater than 4,0 The appearance rating shall not be worse than photomicrograph C2 BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 - 13 Table B.1 (normative) - Grading table for agglomerates Dimensions (m) to 11 21 31 41 51 61 71 81 91 101 111 121 131 141 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 Grades 0 0,5 1 £3 + 1,5 £6 + £3 + £ 12 + £6 + £3 + 2,5 > 12 + £ 12 + £6 + £3 + > 12 + £ 12 + £6 + £3 + > 12 + £ 12 + £6 + £3 + > 12 + £ 12 + £6 + £3 + > 12 + £ 12 + £6 + £3 + > 12 + £ 12 + £6 + £3 + < 12 + £ 12 + £6 + £3 + > 12 + £ 12 + £6 + £3 + > 12 + £ 12 + £6 + £3 + > 12 + £ 12 + £6 + £3 3,5 4,5 5,5 6,5 0 0 0 0 NOTE mm corresponds to 0,7 spc mm under a magnification of 100; similarly 60 mm corresponds to spc mm under a magnification of 100 0 0 + BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 - 14 - Table B.2 (normative) - Photomicrographs for rating the appearance of dispersions - 15 - BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 - 16 - Table B.3 (informative) - Examples of grading of agglomerates Table B.3.1 - Example Dimension samples (mm) to 10 11 21 31 41 51 61 Sample Sample 20 30 40 50 60 70 Grade 2,0 Grade 2,5 Grade 3,0 Sample 14 Grading for the sample Sample 2 Grade 2,5 Sample Grade 3,0 Sample Grade 3,5 12 Incidence of agglomerates by size Table B.3.1 shows the number of agglomerates, classed by size, in each sample Gradings: (2,0 + 2,5 + 3,0 + 2,5 + 3,0 + 3,5) / = 2,75 Hence the mean grade = 2,8 BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 - 17 - Table B.3 (informative) - Examples of grading of agglomerates (Cont’d) Table B.3.2 - Example Dimension samples (mm) to 10 11 21 31 41 51 20 30 40 50 60 Sample Sample Grade 3,0 Sample Grade 2,5 Sample 19 Grade 2,5 Sample 19 Sample Table B.3.2 shows the number of agglomerates, classed by size, in each sample (3,0 + 3,0 + 2,5 + 2,5 + 3,0 + 3,0) / = 2,8333 Hence the mean grading = 2,9 Grade 3,0 Grade 3,0 Incidence of agglomerates by size Gradings: Grading of the sample Grade 3,0 BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 - 18 - Annex C (normative) Resistance to environmental stress cracking on cable sheath C.1 Purpose The purpose of this annex is to describe methods to evaluate the resistance to stress cracking of the polyethylene cable jackets C.2 Method A - Test on complete cable C.2.1 General This test method is applicable for all sizes of cable A test specimen comprising a length of cable is submitted both to a constant deformation and to a surfaceactive liquid heated at 50 °C C.2.2 Apparatus C.2.2.1 Metallic half-circular bends whose diameter is 12 times the cable diameter C.2.2.2 A climatic circulating air oven whose dimensions are sufficient to accept bends with test specimens to be tested The temperature shall be regulated (70 ± 1) °C C.2.2.3 Surface-active liquid whose volume is sufficient and regulated (50 ± 1) °C The surface-active liquid used is an aqueous solution containing % of polyethanol-nonyl-phenol (Igepal CO-630 or Antarox CO-630 or equivalent) This reagent is bio-degradable, the bath shall be regenerated after a maximum 10 days of use C.2.3 Specimen Test specimens shall constitute cable lengths whose dimensions comply with the relevant bend diameter These specimens shall form a semi-circle and shall be secured on the mandrel with metallic clamps or polyamide bonds, located at the end of the bend A minimum length of one metre, for each cable, consisting of one or several specimens, shall be tested C.2.4 Procedure C.2.4.1 The bent cable on the mandrel is placed in the climatic oven for hours; at a temperature of (70 ± 2) °C C.2.4.2 The cable and the mandrel are then removed from the oven and kept at ambient temperature for a minimum duration of hours C.2.4.3 The specimen is removed from the mandrel, straightened and then bent in the reverse direction on the same mandrel C.2.4.4 The specimen and the mandrel are then immersed in the bath of surface-actve liquid, heated to (50 ± 2) °C for 72 hours - 19 - BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 C.2.5 Evaluation of results Examination for presence of cracks, with normal or corrected vision without magnification C.2.6 Test report The test report shall mention - the type of cable; - the cable diameter; - the diameter of the bend used; - the number of specimens tested and their length; - any other observations; - the result obtained C.3 method B - Test on pieces of sheath C.3.1 General This method can be used for cable diameter greater than 10 mm and sheath thickness greater than 1,6 mm C.3.2 Apparatus C.3.2.1 An apparatus to achieve test pieces with two smooth and parallel surfaces by cutting C.3.2.2 Electrically heated air oven C.3.2.3 Clean, sharp, undamaged blanking die with blanking press suitable for cutting test pieces (38,0 ± 2,5) mm x (13,0 ± 0,8) mm or other suitable devices In case of sheath thickness greater than 2,0 mm the sample thickness must be reduced by suitable means to the value specified in C.3.3 C.3.2.4 Dial gauge, with spherical measuring inset (ball-diameter: at least mm) pressure of 0,3 N to 1,5 N C.3.2.5 Notching device as in Figure C.1 with blades as in Figure C.2 C.3.2.6 Bending clamp assembly as in Figure C.3 with vice or other suitable device ensuring the symmetrical closing of the clamping jaws C.3.2.7 Transfer tool assembly as in Figure C.4 for shifting in one operation the bent test piece(s) from the bending clamp to the brass channel C.3.2.8 Brass channel specimen holder as in Figure C.5 for accommodating ten bent test pieces C.3.2.9 Hard glass test tubes 200 mm x 32 mm for accommodating the brass channel specimen holder with the bent test specimens The tubes are plugged by suitable aluminium foil wrapped corks (see Figure C.6) C.3.2.10 Reagent: 10 % aqueous solution of Igepal CO-630 or Antarox CO-630 or equivalent reagent The reagent shall be used only once C.3.2.11 A heated container of sufficient size and depth to accept racks which will hold the filled test tubes (Figure C.6) The temperature shall be maintained at (50 ± 0,5) °C by means of suitable equipment The thermal capacity shall be high enough to ensure that the temperature does not drop below 49 °C even when the test tubes are inserted BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 - 20 - C.3.3 Samples Examination of the PE cable sheaths The surfaces shall not show any swellings, dents or holes The apparatus as in C.3.2.1 is used to prepare strips with two parallel surfaces from the cable sheath The samples should be taken in direction of the cable axis and approximately in the middle of the test piece, with a thickness of 1,8 mm, and from these strips 10 test pieces are prepared as in C.3.2.3 The thickness of these test pieces, measured using the dial gauge as in C.3.2.4, shall be (1,8 ± 0,2) mm The surfaces of the test pieces shall be at right angles to each other, as oblique edges can lead to erroneous results The test pieces are kept in a straight condition for at least 16 hours in the oven as in C.3.2.2 at a temperature of (70 ± 2) °C and then cooled to room temperature C.3.4 Procedure Shortly before placing into the reagent, each of the test pieces shall be given a notch in the middle of the test piece surface (Figure C.7) using the notching devices as in C.3.2.5 The notch depth shall be 0,30 mm to 0,40 mm NOTE The blade shall be neither dull nor damaged and, therefore, shall be replaced as required Even under favourable conditions it should not be used for more than 100 notches Ten test pieces are then placed , with the notch up, in the bending clamp as in C.3.2.6 The clamp is closed for 30 s to 35 s by means of a vice or a motor-driven arbor press at a constant speed The bent test pieces are lifted with the transfer tool as in C.3.2.7 from the bending clamp and placed in the brass channel as in C.3.2.8 If some test pieces are riding too high in the holder they shall be forced down by manual pressure The holder is inserted in a tube as in C.3.2.9, to 10 after the test pieces have been bent The test tube is filled with the appropriate reagent as in C.3.2.10 until all the test pieces are covered by the liquid, and shall be closed by a cork The filled test tube shall be placed immediately in a rack in the heated container as in C.3.2.11 Care shall be taken that the test pieces not touch the test tube during the test The moment of insertion in the heated container shall be noted The holder with the test tubes and the test pieces shall be maintained for 48 hours in the heated container at (50 ± 2) °C C.3.5 Evaluation of results After removal from the heated container, the 10 test pieces are examined for cracks with normal or corrected vision without magnification The test is considered as passed when none of ten test pieces shows a crack If only one test piece fails, the test shall be repeated with 10 new test pieces from the cable sheath Then only the test pieces of the repeated test will be considered The test is considered as passed if no test piece fails NOTE In general the stress cracks originate perpendiculary from the notch - 21 - The blade is made of “Gem” as in Figure C.2 Insert test specimen Front clamp Rear clamp Guide bar Screw BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 BS EN 50290-2-24:2002+A1:2008 EN 50290-2-24:2002+A1:2008 - 22 - Channel internal width dimension Test tube with inserted brass channel specimen holder containing ten test specimens blank BS EN 50290-2-24: 2002+A1:2008 British Standards Institution (BSI) BSI is the independent national body responsible for preparing British Standards It presents the UK view on standards in Europe and at the international level It is incorporated by Royal Charter Revisions British Standards are updated by amendment or revision Users of British Standards should make sure that they possess the latest amendments or editions It is the constant aim of BSI to improve the quality of our products and services We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover Tel: +44 (0)20 8996 9000 Fax: +44 (0)20 8996 7400 BSI offers members an individual updating service called PLUS which ensures that subscribers automatically receive the latest editions of standards Buying standards Orders for all BSI, international and foreign standards publications should be addressed to Customer Services Tel: +44 (0)20 8996 9001 Fax: +44 (0)20 8996 7001 Email: orders@bsigroup.com You may also buy directly using a debit/credit card from the BSI Shop on the Website http://www.bsigroup.com/shop In response to orders for international standards, it is BSI policy to supply the BSI implementation of those that have been published as British Standards, unless otherwise requested Information on standards BSI provides a wide range of information on national, European and international standards through its Library and its Technical Help to Exporters Service Various BSI electronic information services are also available which give details on all its products and services Contact the Information Centre Tel: +44 (0)20 8996 7111 Fax: +44 (0)20 8996 7048 Email: info@bsigroup.com Subscribing members of BSI are kept up to date with standards developments and receive substantial discounts on the purchase price of standards For details of these and other benefits contact Membership Administration Tel: +44 (0)20 8996 7002 Fax: +44 (0)20 8996 7001 Email: membership@bsigroup.com Information regarding online access to British Standards via British Standards Online can be found at http://www.bsigroup.com/BSOL Further information about BSI is available on the BSI website at http://www.bsigroup.com Copyright BSI Group Headquarters 389 Chiswick High Road, London W4 4AL, UK Tel +44 (0)20 8996 9001 Fax +44 (0)20 8996 7001 www.bsigroup.com/standards Copyright subsists in all BSI publications BSI also holds the copyright, in the UK, of the publications of the international standardization bodies Except as permitted under the Copyright, Designs and Patents Act 1988 no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means – electronic, photocopying, recording or otherwise – without prior written permission from BSI This does not preclude the free use, in the course of implementing the standard, of necessary details such as symbols, and size, type or grade designations If these details are to be used for any other purpose than implementation then the prior written permission of BSI must be obtained Details and advice can be obtained from the Copyright & Licensing Manager Tel: +44 (0)20 8996 7070 Email: copyright@bsigroup.com