Vertical bracket flame spread test for cables and fiber optic cables

1. Calculate the required number of specimens N=(4/D)+0.33, D is the average outside diameter of the cable under test, and the results are rounded up. Cut a sufficient number of specimens, each 2.44 m long. 2. Fixed specimens: with a cross-sectional area of not more than 2.1 mm² of steel or copper wire, the ends of the specimens and the middle of the two equally spaced bundled in the bracket cross-file, the spacing between the specimens is half the diameter of the specimen, all specimens should be distributed in the middle of the bracket within 150 mm, after the completion of the bundle of all tests to be at the same level. 3. Install the bracket: install the bracket on the base of the bracket and push the torch to a position (75±5) mm from the surface of the specimen. 4. Ignition: Turn on the device power, propane valve, confirm the propane flow rate is set to (13.2 ± 0.48) L/min, air flow rate is set to (76.8 ± 4.8) L/min. Open the middle of the test device propane and air switch and exhaust switch, press the reset button to ignite the torch for 20 minutes to continuously burn the specimen. 5. Carbonation height measurement: After the flame on the sample is completely extinguished, the height of the damaged specimen is measured from the bottom of the bracket.