Detail of GB/T 18380.33-2022

Introduction of GB/T 18380.33-2022

Tests on electric and optical fibre cables under fire conditions—Part 33: Test for vertical flame spread of vertically-mounted bunched wires or cables—Category A 1 Scope This document covers test methods of category A for the assessment of vertical flame spread inhibition ability of vertically-mounted bunched wires or cables, or optical fibre cables, under defined conditions. This document relates to electric or optical fibre cable test pieces mounted on the test steel ladder to achieve a nominal total volume of non-metallic material of 7 L/m. The flame application time is 40 min. Electric and optical fibre cables are mounted in the front of the ladder, with a standard or wide ladder being used for electric cables having a conductor with the cross-section greater than 35 mm2 according to the number of test pieces required, and a standard ladder for cables having a conductor with the cross-section of 35 mm2 and smaller. The category A is intended for general use where high volumes of non-metallic material are required to be evaluated. The test is intended for type approval testing. The requirements for the selection of electric and optical fibre cables for testing are given in Annex A. The flame spread is measured as the extent of damage of the electric and optical fibre cable test sample. This procedure may be used to demonstrate the electric and optical fibre cable’s ability to limit flame spread. A recommended performance requirement is given in Annex B. Note: For the purposes of this document, the term "wire or cable" covers all insulated metallic conductor cables used for the conveyance of energy or signals. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.   IEC 60332-3-10 Tests on electric and optical fibre cables under fire conditions—Part 3-10: Test for vertical flame spread of vertically-mounted bunched wires or cables—Apparatus Note: GB/T 18380.31-2022 Tests on electric and optical fibre cables under fire conditions—Part 31: Test for vertical flame spread of vertically-mounted bunched wires or cables—Apparatus (IEC 60332-3-10: 2018, IDT) IEC 60811-606 Electric and optical fibre cables—Test methods for non-metallic materials—Part 606: Physical tests—Methods for determining the density 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 ignition source source of energy that initiates combustion [Source: ISO 13943: 2017, 3.219] 3.2 char carbonaceous residue resulting from pyrolysis or incomplete combustion [Source: ISO 13943: 2017, 3.47] 3.3 flame spread propagation of a flame front [Source: ISO 13943: 2017, 3.168] 4 Test apparatus 4.1 General The apparatus specified in IEC 60332-3-10 shall be used. 4.2 Ignition source The ignition source shall be one or two ribbon-type propane gas burners as specified in IEC 60332-3-10. A single burner shall be used with the standard ladder and two burners with the wide ladder.   5 Test procedure 5.1 Test sample The test sample shall comprise a number of test pieces of the electric and optical fibre cable with the same length, each having a minimum length of 3.5m. The total number of test pieces shall be that number required to provide a nominal total volume of non-metallic material of 7 L/m of test sample. The test sample shall be selected within the range specified in Annex A. The electric or optical fibre cable test pieces forming the test sample shall be conditioned at a temperature of (20 ± 10)°C for at least 16h before commencing the test. The test pieces shall be dry. 5.2 Determination of the number of test pieces In order to calculate the appropriate number of test pieces, it is necessary to determine the volume per meter of non-metallic material of one test piece. A length of electric and optical fibre cable which shall be not less than 0.3m long is carefully cut to ensure that the surfaces are at right angles to the cable axis, thus enabling precise measurements of its length. The density of each non-metallic material (including cellular material) shall be measured in an appropriate way, for example according to IEC 60811-606, in order to obtain values expressed to the second decimal place. Each non-metallic material Ci shall be removed from the test piece and weighed. Any non-metallic material making up less than 5% of the total non-metallic mass of the test piece shall be assumed to have a density of 1 kg/dm3. Where semi-conducting screens cannot be removed from the insulating material, the components may be considered as one for the purpose of measuring their mass and density. The volume Vi (L/m) of each non-metallic material Ci is calculated as follows: where, Mi——the mass of the material Ci, kg; ρi——the density of the material Ci, kg/dm3; l——the length of the test piece of the electric and optical fibre cable, m. The total volume, V, of the non-metallic materials contained in per meter of electric and optical fibre cable is equal to the sum of the individual volumes V1, V2, etc. The number of test pieces to be mounted is obtained by taking the closest integer (0.5 and above corresponding to 1) of the ratio of the volume per meter specified in 5.1 and the total volume, V, of non-metallic material per meter of cable, subject to a minimum number of two test pieces.

Contents of GB/T 18380.33-2022

Foreword i Introduction iii 1 Scope 2 Normative references 3 Terms and definitions 4 Test apparatus 5 Test procedure 6 Evaluation of test results 7 Performance requirements 8 Retest procedure 9 Test report Annex A (Normative) Guidance on electric and optical fibre cable selection for type approval testing Annex B (Informative) Recommended performance requirements Bibliography