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Research Fire - Cables

Research on fire spread of cables, thermal radiation effects, and functional performance. Conducted as EU project, basis for Euroclasses, available as a book. Improvement of tests, modeling studies, composite model development. Testing setups and results discussed in detail.

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Research Fire - Cables

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  1. Research Fire - Cables Patrick van Hees

  2. Content • Cables • Fire spread of cables • Functional performance • Thermal radiation effects • Temperature effect • Modelling • Optical cables (Jonathan) • Modelling fire - Evacation

  3. Fire spread of cables – FIPEC project • Data base with real scale cables. • Data base of small scale tests • Conducted as EU project • Basis for Euroclasses • Models for material and cable prediction cables • Published as a book • Available www.interscience.com

  4. Four levels of tests Improvement of tests if necessary Modelling or correlation studies between the different levels of testing Real scale model Cable test model Composite model

  5. Choice of Horizontal Set-up for Data Base • Closed configuration • 40-100-300 kW sand box burner • 3 trays with 4 m of cables • Mounting with spacing

  6. Choice of Vertical Set-up for Data base testing • Semi - Closed configuration (corner) • 40-100-300 kW sand box burner • 1 ladder with 4 m of cables • Mounting with spacing

  7. Full scale testing • based on IEC 332.3 (60332.3) test • HRR and Smoke measurements included • sensitivity study to improve IEC 332.3 test • data base tests on selected cables • Test used for Euroclasses

  8. Summary Sensitivity Mounting • Spacing is more severe than non spacing for larger diameters • Spaced bundles are more severe for smaller cables • Increasing loading by more layers does NOT make the test more severe by definition • Mounting is a DOMINATING factor in the flame spread of cables

  9. Cone calorimeter testing • development of a test procedure for cables and cable materials • cable materials were tested as composites and as single materials • data base tests on selected cables

  10. Functional performance • Combined multi-physics problem • Electrical properties • Heat transfer (radiation, convection, conduction) • Chemical decomposition • Mechanical behavior • Cables with fire spread classes do not by definition have a performance class

  11. Performance of cables subject to thermal radiation Worked performed together with Petra Andersson SP Available as an SP report

  12. Test method - The cone calorimeter

  13. Conclusions • The approach used in this project in finding a critical thermal radiation levels was succesfull • For the data cables there seems to be a critical level of about 9 kW/m² below which no short circuit occurs. A critical dose principle can be used (integrated value of exposure)

  14. Performance of Cables Subjected to Elevated Temperatures Work conducted together with Petra Andersson SP Available as SP report

  15. Performance of Cables Subjected to Elevated Temperatures

  16. Performance of Cables Subjected to Elevated Temperatures • Test methods available for functional performance tests • Fullscale test t.ex. Din 4102, UL 2196 etc. • Smallscale IEC 60331-11 och 12, EN 50200, 50362

  17. Performance of Cables Subjected to Elevated Temperatures

  18. Performance of Cables Subjected to Elevated Temperatures

  19. Performance of Cables Subjected to Elevated Temperatures - Goal Obtain test data and Development of a model Requirements for the model: • Easy to use • Fast • No special computer program • Safe side

  20. Test Set-up Furnace with two cables: One life cable One cable for temperature measurement

  21. Results

  22. Analyticalsolution of heat conduction • Introduce dimensionless variables • Heat conduction, cylindrical coordinates, constant surrounding temperature • Especially for the centre of the cable and terminated after first term 

  23. Validation of model

  24. Outcome • Simple analytical model with certain assumptions • Model has been applied in FDS CFD software and taken over by NRC for their safety assessments. (THIEF Model) • Validated by NRC USA • Validated by Japanese nuclear industry • Model has been used for prediction activation of detection cables based on temperature activation by LTH

  25. Further validation – THIEF model FDS Test to investigate if detection cables based on a melting insulation could be modelled in FDS (THIEF model) Test set-up in lab environment

  26. THIEF modell validation experiment 10 kW burner. 2 detection cables installed 3 experiments:

  27. THIEF Model FDS simulations • Density, thickness and sheet material were input to FDS • Calculation model 1.66 x 1.2 x 2.25 m • Calculation grid of 1 cm.

  28. SIMULATION OF CRITICAL EVACUATION CONDITIONS FOR FIRE SCENARIOS INVOLVING CABLES AND COMPARISON OF DIFFERENT CABLES Patrick van Hees & Daniel Nilsson Lund University – Department of Fire Safety Engineering

  29. Layout of the procedure

  30. Choice of the building

  31. Tenability assessment Based on 450 occupants

  32. Conclusions • Flame spread properties are not equal to functional performance • Moutning is important for flame spread • Functional performance for cables can be modelled for copper cables • Modelling of evacuation and fire spread is possible

  33. http://www.brand.lth.se

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