According to statistics from the World Safety Supervision Administration, 90% of fires are caused by wires and cables. With the development of economy and society, higher and higher requirements are put forward for the properties of wire and cable such as flame retardant, fire resistance, low smoke and halogen-free. When the wire and cable products are short-circuited or contacted with fire, the insulation or sheath may be burned, In many strict fire prevention occasions (such as coal mines, ships, subways, etc.) It is required that in the event of burning of the wire and cable products used, the flame should not spread, and it should be able to extinguish itself within a certain time and length, which is called non-flammability.
| ● | Test Room | The vertical burning test machine’s test room is 300mm wide x 1200mm high x 450mm deep |
| ● | Burning Torch | 1kW Burner Nozzle (According to GB/T5169.14-2007/IEC60695-11-2:2003 standard), Height of the blue flame core is 50 ~ 60mm, and the total flame height is 170 ~ 190mm. |
| ● | Gas Source | Using high-purity 95% technical grade propane gas |
| ● | Test Samples | 600 ±25mm｜Flammability Test machine for a Single Insulated Cable |
| ● | Specimen Holder | The distance between the lower edge of the upper bracket and the upper edge of the lower bracket of the two horizontal brackets is 550mm |
| ● | Fire Flame Time | 0.1-999.9 seconds continuous setting, The flame can continuously burn the sample within the set time |
| ● | Torch Installation Location | The blue flame contact point is 475mm away from the lower edge of the horizontal upper bracket, and the torch is at an angle of 45 degrees to the vertical axis of the sample |
| ● | Control Function | Manual or Automatic Available |
| ● | Gas Flow Range | 100 ~ 1000mL/min｜IEC 60332-1-2 | Electrical Cable Flammability Test |
| ● | Air Flow Range | 1 ~ 10L/min｜Vertical Burning Test Equipment for Wire and cable EN 50265-1 |
| ● | Pressure Gauge | Pressue with 0 ~ 0.75kpa Range Adjustment |
| ● | Ignition Method | High Pressure Auto Ignition，AC220V, 50Hz, 60Hz, 1 Phase |
In some occasions, If the product does not have this function, it will cause very serious consequences. Products that require non-flammable properties generally use polyvinyl chloride, neoprene and butylamine polyvinyl chloride compounds as insulation and sheathing materials. When these materials are burned, chlorine gas will be released to play a flame retardant role. Sometimes in order to enhance the effect of flame retardant, a certain flame retardant is also added. The combustion tests include the following 8 types:
| It is used to evaluate the ability to suppress the spread of flames in the state of bundled simulation in high-risk occasions, and to study the smoking characteristics of the wire and cable industry and cables with low flame retardancy. It can be applied to UL1685, IEC 60332 and EN 50266-2001. | Bundle Combustion Test |
| It is used to simulate the ability of wires and cables to delay the spread of flames in general situations, and can be applied to vertical burning tests of wires and cables such as IEC 60332, UL1581-2003, GB/T19666, etc. | Vertical Combustion Test of Single Wire and Cable |
| It is used to simulate and detect the refractory delay characteristics of refractory cables in the case of electric combustion, which is a test method that requires the maintenance of line integrity when burning under flame conditions, and can be applied to IEC 60331, EN 50200-2001 and GB/T 19216 and other refractory combustion test standards. | Refractory Combustion Test |
| Is in the oxygen and nitrogen mixture gas stream, the determination of just maintain the minimum oxygen concentration (oxygen index) required when the specimen is just maintained smooth combustion, expressed in terms of the volume percentage of the required oxygen, suitable for the test of the combustion performance of rubber, plastics, fibers, foam plastics and various solids, as a means of identifying the flame retardancy of polymers, is to judge the difficulty of the material in contact with the flame in the air is very effective and evaluate the level of combustion performance of an effective method, suitable for GB/T2406-98, ASTM D2863, ISO 4589 test standard. | Oxygen Index Test |
| Cable combustion smoke density test can be used to study the determination of smoke density of cables or optical cables burning under specific conditions, suitable for IEC61034 and other combustion smoke density test standards. | Cable Combustion Smoke Density Test |
| It can be used for the wire and cable industry to research and produce cable insulation material sheaths and other materials for halo acid gas content determination, suitable for GB/T17650 and other standard conditions under the determination of halo acid gas content. | Hydrogen Chloride and Acidity Testing |
| Under the protection of nitrogen, the specimen is analyzed by high temperature decomposition, which can be used for the determination of carbon black and mineral filler content in polyethylene, and is suitable for the test of carbon black content under standard conditions such as GB/T2951.8. | Carbon Black Content Test |
| It is used to determine the toxicity index of material combustion products, and is suitable for test standards such as NES 713 toxicity index. | Toxicity Index Test |
Error Analysis And Description of The Test Results of Vertical Combustion of a Single Wire And Cable: The current single insulated wire and cable vertical combustion test method implementation standard is IEC 60332-1-2, in the standard of the test conditions are specified in detail: including specimen treatment, test temperature, specimen installation, the position of the blowtorch, the angle of the blowplight and the specimen, the fire time to ask, etc. Including test devices are also clearly defined in the IEC 60332-1-2 standard. Now China’s cable companies and related testing institutions are using the above standards to implement. According to the provisions of the standard and the statistical analysis of a large number of test data, it can be concluded that some of the test conditions in the test will have a greater impact on the test results. Here is a brief analysis and discussion of several of them:
| ● | The standard stipulates that the ignition source shall comply with the provisions of IEC 60695-11-2, in particular the method of approval of the test flame. In order to make the test results have good reproducibility and comparability, specific provisions should be made in the test conditions for the factors that affect the propagation of the flame on the cable. Although the flow rate of combustible gases and air and the height of the flame are clearly defined in the standard. However, in the test, it was found that the difference in test results was largely due to the difference in flame intensity. In the test, not only to meet the standard requirements of the temperature can meet the requirements, but must reach a certain heat value, in order to truly assess the flame retardancy of the cable. The flow rate of combustible gases, air flow, flame height, etc. specified in the standard are only the basic requirements for achieving combustion power, but no clear method is proposed for the calibration and measurement of blowtorch power. Therefore, it is imperative to clarify the requirements and measurement methods of the combustion power of the blowtorch lamp. | Combustion Power |
| ● | The flame retardant performance of the cable depends on the flame retardancy of various flame retardants in the material formulation, especially the self-extinguishing nature directly affects the flame retardant effect of the cable. The current assessment index of the flame retardancy of the material is the oxygen index, and the level of the oxygen index can be used as an indicator to measure the flame retardant performance of the material. However, we tend to ignore the “temperature index”. That is, the temperature at which the flame retardant material can burn on its own at a certain temperature. This shows. The oxygen index of the material will be subject to obvious changes in temperature, which is why nuclear power cables need to test the oxygen index of the insulating material at different temperatures to assess whether the change in flame retardant performance of the insulation material at different temperatures is within the acceptable range. Therefore, the test should be carried out strictly according to the temperature specified in the standard. Of course, in the conventional environment of the test, due to the small change in ambient temperature, there will be no obvious impact on its flame retardancy. But even so, in order to eliminate the influence of the test temperature on the test results, the test temperature requirements are also specified in the standard. | Test Temperature |
| ● | The production of cables requires the combination and sequence of multiple processes in a row, and there may be mixtures such as oil contamination attached to the surface of the cable during the production process. Such adhesions may have a combustion-assisting effect during the test, which may cause the test results to deviate from normal indicators. Therefore, the specimen surface should be carefully inspected before the test, and the attachments on the specimen surface should be removed in time. To ensure the correctness of the test results. In particular, the irradiation cross-linked cable has a greater impact, in the irradiation crosslinking process due to the penetration of the electron beam caused by the cable temperature in a short period of time, some of the surface precipitation of oil substances, if the irradiation after a short period of time direct combustion test, will have a significant impact on the test results, so it is recommended that the irradiated cable should be treated after irradiation, and then the combustion test. | Surface Treatment of the Specimen |
| ● | Due to the flame retardant material added a large number of flame retardants, so the extruder heating and cooling system put forward higher requirements, if the extrusion temperature is too low will cause the extrusion pressure is too large, the extrusion surface is not smooth, if the extrusion temperature is too high, will cause the decomposition of the flame retardant, affecting the flame retardant performance of the cable, therefore, for the production of flame retardant materials, in order to avoid the temperature is too high to cause the flame retardant to decompose, the breech and screw must be cooled, and the extruder temperature must be controlled at ± 2 °C. | Heating and Cooling of The Extrusion Process |
| ● | According to the requirements of the standard, the ignition source should use technical grade propane with a purity of more than 95% for fire. For the purity of propane is not less than 95%, in reality, most of the laboratories can not meet the requirements, because many laboratories use gas source is bottled petroleum liquefied gas, although the average combustion heat of petroleum liquefied gas and the combustion heat of propane is not very large, but in the test we can not determine the composition of petroleum liquefied gas and its combustion test value, so it is impossible to ensure that the test can meet the requirements of the test regulations. In order to make the test more comparable, a combustion source with a certain combustion heat value that meets the requirements of the standard should be used. | Ignition Source |
| ● | The test standard specifies the gas flow, flame height, etc., but does not make any provisions on the treatment and calibration of the surface of the blowtorch lamp. In long-term tests, due to the natural aging of the blowtorch device will lead to the carbonization of the blowtorch surface, this carbonization will have a great impact on the test results, so this requires that there must be an effective method to determine and calibrate the specific value of the blowtorch combustion power. | Blowtorch Unit |
| IEC 60332-1-2 | Tests on Electric and Optical Fibre Cables Under Fire Conditions – Part 1-2: Test for Vertical Flame Propagation for a Single Insulated Wire or Cable – Procedure for 1 Kw Pre-Mixed Flame |
| IEC60332-1-3 | Tests on Electric and Optical Fibre Cables Under Fire Conditions – Part 1-3: Test for Vertical Flame Propagation for a Single Insulated Wire or Cable – Procedure for Determination of Flaming Droplets/Particles |
| IEC 60332-2-1 | Tests on Electric and Optical Fibre Cables Under Fire Conditions – Part 2-1: Test for Vertical Flame Propagation for a Single Small Insulated Wire or Cable – Apparatus |
| IEC 60332-2-2 | Tests on Electric and Optical Fibre Cables Under Fire Conditions – Part 2-2: Test for Vertical Flame Propagation for a Single Small Insulated Wire or Cable – Procedure for Diffusion Flame |
| EN 50265-1 | Common Test Methods for Cables Under Fire Conditions – Test for Resistance to Vertical Flame Propagation for a Single Insulated Conductor or Cable – Part 1:Apparatus |
| IEC 60695-11-2 | Fire Hazard Testing – Part 11-2: Test Flames – 1 kW Pre-Mixed Flame – Apparatus, Confirmatory Test Arrangement and Guidance |
Single Wire and Cable Burning Test Methods for IEC 60332-1-2 Standard: Samples Prepare: The sample should be a wire and cable with a length of (600 ± 25) mm. Before the burning test, all samples should be treated at (23±5)℃ and relative humidity (50±20)% for at least 16 hours. If the surface of the wire and cable is coated with paint or varnish, the sample should be placed at a temperature of (60 ± 2) ℃ for 4 hours, and then the above treatment is carried out.
1. Placing the instrument in a suitable place enables the upper exhaust system behind the standard fume hood to smoothly release harmful gases to the outside. 2. Connect the instrument to the air compressor source, liquefied gas or propane source. 3. Connect the gas pipe and the compressed air pipe to the gas inlet of the box (the thick one is gas, and the thin one is compressed air), and check the airway interface to prevent air leakage. 4. Install the connecting wire, turn on the power switch, and set the relevant experimental parameters: Set the flame application time according to the experimental standard
5. The choice of flame time: For tests on non-circular cables (such as flat structures), the circumference of the cable should be measured and converted into a circular equivalent diameter. ● Diameter of the Sample ≤ 25 mm → Burn Time 60 ±2 Seconds ● Diameter of the Sample 25 ≤ 50 mm → Burn Time 120 ±2 Seconds ● Diameter of the Sample 50 ≤ 75 mm → Burn Time 240 ±2 Seconds ● Diameter of the Sample ＞75 mm → Burn Time 480 ±2 Seconds
6. Fix the test sample on the sample holder (there is a stainless steel sheet on each of the upper and lower beams, and the sample is fixed between the beam and the stainless steel sheet, and then pressed with screws). 7. Press the gas button to connect the compressed air and gas, pull out the knob of the pressure regulating valve, turn the knob to the right to increase the air pressure, adjust the air pressure to 0.1MPa, then turn up the gas flow meter, and press the ignition button to light the book light.
Note: Turn on the power supply, temperature switch, start the ignition button, make the gas lamp burn, adjust the flow rate of the gas flowmeter (≥650ml/min), and the flow rate of the air flowmeter (≥10L/min) to make the height of the blue inner cone that produces the flame The height of the outer flame is 50-60mm, the height of the outer flame is 170-190mm, and the time required to observe the thermocouple from 100°C-700°C is 40-50 seconds, which is regarded as qualified flame intensity. If it fails, adjust the ratio of gas and air until it meets the standard Require
8. Adjust the flame that meets the requirements by adjusting the gas flow meter and air flow meter. 9. Check the flame intensity, and place the thermocouple and bracket relative to the gas burner according to the regulations.
10. Flame Approval Method 1 or 2 (1) The height of the inner cone of the blue flame is 50 ~ 60mm, and the height of the outer flame is 170-190mm. (2) The diameter of the copper block is 9mm, the weight of the hole before embedding the thermocouple is 10g, and the 0.5mm thermocouple is embedded, and the temperature of the copper block is measured from 100±2°C to 700±3°C, and the average time of three times is 45±5 seconds
11. Press the start button, the Bunsen burner will automatically tilt 45° and move to the pattern position. 12. When the flame time is up, the Bunsen burner will automatically return to the vertical position. 13. After the Bunsen burner returns, the afterburning time will be automatically counted. When the flame of the sample continues to burn, press the timer button to stop the afterburning time. 14. After 6 consecutive tests, the system will automatically jump out of the save interface. If the 6 tests are not completed, you can click the save button to save the data. 15. At the end of the test, the components are reset, the gas source is turned off, and the power supply is turned off. Turn on the exhaust fan switch to exhaust the harmful gas to the outside.
