The information provided in this report will support a more realistic assessment of fires in electrical enclosures and the overall impact of material composition on key burning be￾haviors of interest to fire safety scientists and engineers. Beyond the direct observations and experimental measurements obtained for this specific test configuration, this study also offers a comprehensive set of validation data for computational fluid dynamics (CFD) simulations of large scale fire growth due to flame spread over the surface of combustible solids. The design and expected impact of the next phase of this study (including how it in￾tegrates with these full-scale measurements) is concisely summarized in the Future Work section, below.

1. Introduction 1

2. Experimental 8

2.1. Test Configuration/Apparatus 8

2.2. Materials 11

2.3. Instrumentation 14

      2.3.1. Video and Photographs 14

      2.3.2. Heat Release Rate and Species Yields 14

      2.3.3. Heat Flux 15

2.4. Ignition Source 20

2.5. Test Procedure 35

3. Results and Discussion 38

3.1. Burning Behavior, Heat Release Rate, and Wall Flame Heat Flux 38

      3.1.1. PMMA - poly(methyl methacrylate) 38

      3.1.2. ABS, poly(acrylonitrile butadiene styrene) 51

      3.1.3. GPO-1, fiberglass-reinforced polyester laminate 56

      3.1.4. GPO-3, fiberglass-reinforced polyester laminate (Redboard: improved arc- and flame-resistance) 61

      3.1.5. HDPE, high density polyethylene 63

      3.1.6. HIPS, high impact polystyrene 65

      3.1.7. OSB, oriented strand board 72

      3.1.8. PBT, poly(butylene terepthalate) 79

      3.1.9. PMMA-PVC alloy (Kydex) 81

      3.1.10. Polyiso, polyisocyanurate foam 84

      3.1.11. POM-GF, glass-fiber reinforced poly(oxymethylene) 90

      3.1.12. PVC, poly(vinyl chloride) 95

      3.1.13. SIS Wire, switchboard wire 97

      3.1.14. Western Red Cedar 100

      3.1.15. XLPE, cross-linked polyethylene foam 105

      3.1.16. XPS, extruded polystyrene foam 109

3.2. Scaling of Flame Heat Flux Data During Fully-Involved Burning 114

3.3. Radiative Fraction of Total Wall Flame Heat Flux, q_rad(%) 116

3.4. Heat Release and Product Yields 123

4. Conclusions and Future Work 130

4.1. Summary of Results 130

4.2. Fire Size (Heat Release Rate, HRR) 132

4.3. Heat Transfer 134

4.4. Species Yields 136

4.5. Future Work 137

References 138

Appendices 147

A. Material Manufacturer and Distributor Information 148

B. Uncertainty of Measurements 150

B.1. Heat Release Rate 151

B.2. Heat Flux Measurements 152

      B.2.1. Total Heat Flux to Panel Walls 153

      B.2.2. Radiation Heat Flux to Panel Walls 154

      B.2.3. Radiative Fraction of Total Heat Flux to Panel Walls 155

      B.2.4. Radiative Heat Flux Away From Panel Walls 155

B.3. Species Yields, Y_CO, Y_CO_2, and Y_soot 156

B.4. Sensor Location 158

C. Test-Specific Experimental Results: Measurement Data and Sample Behavior 159

C.1. ABS - Poly(acrylonitrile butadiene styrene) 159

C.2. GPO-1 - Fiberglass-Reinforced Polyester laminate (limited arc- and flame￾resistance) 174

C.3. HDPE - High Density Polyethylene 191

C.4. HIPS - High Impact Polystyrene 193

C.5. OSB - Oriented Strand Board 219

C.6. PBT - Poly(Butylene Terepthalate) 237

C.7. PMMA - Poly(Methyl Methacrylate) 239

C.8. PMMA-PVC alloy (Kydex) 264

C.9. Polyiso - Polyisocyanurate Foam 270

C.10. POM-GF - Poly(Oxymethylene) reinforced with chopped Glass Fibers 292

C.11. PVC - Polyvinyl Chloride 310

C.12. GPO-3 (Redboard) - Fiberglass-Reinforced Polyester laminate (limited arc￾and flame-resistance) 319

C.13. Western Red Cedar 325

C.14. SIS Wire - Switchboard Wire 348

C.15. XLPE Foam - Cross-linked Polyethylene Foam 353

C.16. XPS Foam - Extruded Polystyrene Foam 374

List of Tables

Table 1. Materials Tested 13

Table 2. Burner flame heat flux along the centerline of panel walls, Preliminary Burner Configuration 32

Table 3. Burner flame heat flux along the centerline of panel walls, Final Burner Con￾figuration 33

Table 4. Spatially-resolved measurements of burner flame heat flux during steady flaming; Final Burner Configuration, Tests 7-66 34

Table 5. Timing of burner shutoff (propane flow) and shield application in XLPE foam tests 106

Table 6. Tabulated values of constants used to scale flame heat flux data 14

Table 7. Tabulated values of radiative and total flame heat flux 122

Table 8. Tabulated values of fire size, growth rate, and energy release 125

Table 9. Tabulated values of soot, residue, and gaseous species yields 128

List of Figures

Fig. 1. Photographs of electrical enclosures typically found near the main control room in a Nuclear Power Plant 8

Fig. 2. Photograph of a series of electrical enclosures in a Nuclear Power Plant 9

Fig. 3. Schematic of the NIST/NRC Parallel Panel Apparatus 11

Fig. 4. Representative behavior of laminar wall flames supported by six common commodity plastics 12

Fig. 5. Photograph of GPO-1 prior to testing 17

Fig. 6. Time-resolved measurements of burner heat release rate and centerline heat flux 23

Fig. 7. Time-resolved and steady-state measurements of burner flame heat flux (along the centerline of panels) 25

Fig. 8. Impact of flame attachment to panel walls on measured flame heat flux (uni￾form flaming) 26

Fig. 9. Impact of flame attachment to panel walls on measured flame heat flux (non￾uniform flaming) 26

Fig. 10. Propane burner behavior in its final configuration 29

Fig. 11. Spatially-resolved measurements of burner flame heat flux 30

Fig. 12. Height-resolved measurements of centerline burner flame heat flux and schemat￾ics of burner fill in two configurations 33

Fig. 13. Measured heat release rate during parallel panel experiments on PMMA 40

Fig. 14. Fire behavior of PMMA slabs during parallel panel experiments 41

Fig. 15. Centerline heat flux time/HRR history, PMMA 44

Fig. 16. Centerline heat flux time history, PMMA 46

Fig. 17. Centerline heat flux time history, PMMA 47

Fig. 18. Vertical profiles of heat flux, PMMA 49

Fig. 19. Representative images of fire growth, PMMA 50

Fig. 20. Fire behavior of ABS slabs during parallel panel experiments 52

Fig. 21. Measured heat release rate during parallel panel experiments on ABS 53

Fig. 22. Centerline heat flux time history, ABS 54

Fig. 23. Vertical profiles of heat flux, ABS 55

Fig. 24. Representative images of fire growth, ABS 55

Fig. 25. Fire behavior of GPO-1 slabs during parallel panel experiments 57

Fig. 26. Measured heat release rate during parallel panel experiments on GPO-1 58

Fig. 27. Centerline heat flux time history, GPO-1 59

Fig. 28. Vertical profiles of heat flux, GPO-1 60

Fig. 29. Representative images of fire growth, GPO-1 60

Fig. 30. Fire behavior of GPO-3 (Redboard) slabs during parallel panel experiments 61

Fig. 31. Measured heat release rate during parallel panel experiments on GPO-3 (Red￾board) 62

Fig. 32. Fire behavior of HDPE slabs burning in parallel panel configuration 64

Fig. 33. Measured heat release rate of HDPE slabs burning in parallel panel configu￾ration 64

Fig. 34. Fire behavior of HIPS slabs burning in parallel panel configuration 66

Fig. 35. Measured heat release rate of HIPS slabs burning in parallel panel configuration 67

Fig. 36. Centerline heat flux time history, HIPS 68

Fig. 37. Vertical profiles of heat flux, HIPS 68

Fig. 38. Representative images of fire growth, HIPS 69

Fig. 39. Comparison of fire growth rate and flame heat flux measurements for HIPS burning in the parallel panel or single panel configurations 71

Fig. 40. Fire behavior of OSB panels during parallel panel experiments 74

Fig. 41. Measured heat release rate during parallel panel experiments on OSB 75

Fig. 42. Centerline heat flux time history, OSB 76

Fig. 43. Vertical profiles of heat flux, OSB 77

Fig. 44. Representative images of fire growth, OSB 78

Fig. 45. Fire behavior of PBT slabs burning in parallel panel configuration 79

Fig. 46. Measured heat release rate of HIPS slabs burning in parallel panel configuration 80

Fig. 47. Fire behavior of PMMA-PVC slabs during parallel panel experiments 82

Fig. 48. Measured heat release rate of PMMA-PVC slabs burning in parallel panel con￾figuration 83

Fig. 49. Polyiso samples prior to and shortly after ignition in parallel panel tests 86

Fig. 50. Measured heat release rate of polyisocyanurate foam samples burning in par￾allel panel configuration 87

Fig. 51. Peak fire size on polyiso samples of three thickness (13 mm, 25 mm, and 51 mm) 88

Fig. 52. Remaining sample residue on polyiso of three different thickness (13 mm, 25 mm, and 51 mm) 89

Fig. 53. Representative images of fire growth, POM-GF 92

Fig. 54. Measured heat release rate of POM-GF slabs burning in parallel panel config￾uration 93

Fig. 55. Centerline heat flux time history, POM-GF 93

Fig. 56. Vertical profiles of heat flux, POM-GF 94

Fig. 57. Fire behavior of PVC slabs during parallel panel experiments 95

Fig. 58. Measured heat release rate of PVC slabs burning in parallel panel configuration 96

Fig. 59. Centerline heat flux time history, PVC 96

Fig. 60. Fire behavior of SIS Wire during parallel panel experiments 98

Fig. 61. Measured heat release rate of SIS Wire burning in parallel panel configuration 99

Fig. 62. Centerline heat flux time history, SIS wire. 99

Fig. 63. Fire behavior of Western Red Cedar panels during parallel panel experiments 101

Fig. 64. Measured heat release rate during parallel panel experiments on Western Red Cedar 102

Fig. 65. Centerline heat flux time history, Western Red Cedar 103

Fig. 66. Vertical profiles of heat flux, Western Red Cedar 103

Fig. 67. Representative images of fire growth, Western Red Cedar 104

Fig. 68. Representative images of fire growth, XLPE4 107

Fig. 69. Measured heat release rate of polyiso slabs burning in parallel panel configu￾ration 107

Fig. 70. Burner flame structure at sample ignition in XLPE2 tests 108

Fig. 71. Representative images of fire growth, XPS 110

Fig. 72. Measured heat release rate of XPS foam slabs burning in parallel panel con￾figuration 113

Fig. 73. Heat flux data collapsed into a single function of HRR and height 115

Fig. 74. Photograph of radiation shield removal while ABS burns at Q˙ = 2 MW 116

Fig. 75. Total and radiation heat flux, OSB 117

Fig. 76. Radiative fraction of total wall flame heat flux measured at multiple heights 118

Fig. 77. Radiative fraction of total wall flame heat flux measured at multiple HRR 119

Fig. 78. Representative images of flame structure of each material at Q˙ = 400 kW 131

Fig. 79. Representative flame structure of selected materials at peak HRR 132

Fig. 80. Time-resolved HRR of each material 133

Fig. 81. Flame structure and vertical profiles of heat flux at Q˙ = 120 kW to Q˙ = 2800 kW (PMMA) 134

Fig. 82.Vertical profiles of heat flux (ABS, HIPS, and PMMA) 135

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