PREDICTING LARGE-SCALE FIRE PERFORMANCE FROM SMALL- SCALE FIRE TEST DATA

Transcription

1 PREDICTING LARGE-SCALE FIRE PERFORMANCE FROM SMALL- SCALE FIRE TEST DATA Marcelo M. Hirschler * And Marc L. Janssens ** * GBH International ** Univ. North Charlotte

2 OVERALL OUTLINE Predictive Procedures: * Models * Correlations * Pass/Fail Small-Scale Fire Tests Large-Scale Fire Tests Products Applications

3 Predictive Procedures Models Calculate Results Based on Theories and Equations Correlations Can Predict Relative Fire Performance and Perhaps Test Results Pass/Fail Procedures Can Assess Whether Products are Likely to Meet Certain Criteria, e.g. Flashover

4 Flashover Temperature/Products Growth Time Fully-developed Fire Decay

5 Self-Propagating Fire Products May be Unacceptable and Yet Not Lead to Flashover This Can Happen if Product Fails Certain Regulatory Pass/Fail Criteria This Can Happen if Product Leads to Self-Propagating Fire Self-Propagating Fire is Fire that Doesn t Cease Burning Without External Input

6 Large-Scale Fire Test Methods

7 Interior Wall and Ceiling Finish: ROOM/CORNER TEST STANDARDS NFPA 265 NFPA 286 ISO 9705

8 ROOM/CORNER TEST STANDARDS Basic Test Apparatus

9 ROOM/CORNER TEST STANDARDS Details & Measurements

10 ROOM/CORNER TEST STANDARDS NFPA x 12 x 8 ft room with type X gypsum walls 30 x 90 in. door opening in front wall 12 x 12 in. propane gas burner, 12 in. off floor Burner at 2 in. standoff from back & side walls 40 kw first 5 min, 150 kw next 10 min Only back and side walls lined Ceiling thermocouples are present Flashover is primary endpoint

11 ROOM/CORNER TEST STANDARDS NFPA x 12 x 8 ft room with type X gypsum walls 30 x 90 in. door opening in front wall 12 x 12 in. propane gas burner, 12 in. off floor Burner in contact with back and side walls 40 kw first 5 min, 160 kw next 10 min Only back and side walls lined Ceiling thermocouples are present Acceptance criteria in codes include smoke production

12 ROOM/CORNER TEST STANDARDS ISO x 2.4 x 3.6 m room with calcium silicate or concrete walls 0.8 x 2 m door opening in front wall 0.17 x 0.17 m propane gas burner, 0.17 m off floor Burner in contact with back and side walls 100 kw first 10 min, 300 kw next 10 min Back wall, side walls, and ceiling lined No ceiling thermocouples Criteria for Marine Fire Restricting Materials based on heat release and smoke production

13 ISO 9705 Test (1) Fully Lined Room Prior to Test

14 ISO 9705 Test (2) Start of 100 kw Exposure

15 ISO 9705 Test (3) Prior to Flashover

16 ISO 9705 Test (4) After Termination

17 Upholstery Items PRODUCT TEST STANDARDS ASTM E 1537/CA TB 133 ASTM E 1590/CA TB 129 CBUF Test Protocol ASTM E 1822

18 Key Test Measurements Heat Release: RHR & THR Smoke Release: RSR & TSR Mass Loss of Item Room Temperature Room Visibility

19 Furniture Test Details ASTM E 1537/NFPA 266/UL 1056 Gas 19 kw (13 L/min) 80 s Impinges on Item from Top/Front Furniture or Mock-up Needed Everything Else Like Room-Corner Tests

20 Mattress Test Details ASTM E 1590/NFPA 267/UL 1895 Gas 18 kw (12 L/min) 180 s Impinges on Item from Front Actual Mattress Needed Everything Else Like Room/Corner Tests

21 CBUF Test Details European Test Gas 30 kw (19.5 L/min) 120 s Impinges on Item from Top/Front Furniture or Mattresses Everything Else Like Room-Corner Tests

22 Stacking Chair Test Details ASTM E 1822 Gas 18 kw (12 L/min) 180 s Impinges on Item from Front 5 Stacked Chairs Needed Everything Else Like Room/Corner Tests

23 Furniture Pass/Fail Criteria Chairs: CA TB 133 & NFPA 101/IFC Mattresses: CA TB 129 & NFPA 101/IFC Stacking Chairs: NFPA 301 All Criteria Based on RHR and THR Depend on Occupancy

24 Cables: VERTICAL TRAY STANDARDS ASTM D 5424/ D 5537 UL 1685 & CSA FT4 w/rhr FIPEC Test Protocol IEC Modified

25 Vertical Cable Tray Test

26 ASTM D 5424/D5537 Cable Tray Test: Front

27 ASTM D 5424/D 5537 Cable Tray Test: Back

28 CSA FT4 Cable Tray Test: Burner and Tray

29 IEC or FIPEC Cable Tray Test

30 Fire Source Input to Tests 20 kw or 70,000 BTU/hr

31 Cables Pass/Fail Criteria UL 1685: RHR, flame spread, smoke CSA FT4: flame spread and smoke IEC : flame spread FIPEC: RHR, THR, flame spread & smoke (classes under development)

32 Pipe Insulation Draft NFPA 274: Vertical Pipe Chase Use in Plenums Input: 20 kw (3 min), 70 kw (7 min) Criteria: RHR, THR, flame spread & smoke (standard under development)

33 Pipe Chase Fire Test Pipe Chase - dimensions are interior dimensions

34

35 Transportation Applications Same Tests & Techniques Can be Used: Aircraft Trains Buses Ships Cars

36 Small-Scale Scale Fire Test Methods: RHR

37 Small-Scale Scale Test Methods Useful for Predictions Cone Calorimeter: ASTM E 1354 or NFPA 271 or ISO 5660 OSU Calorimeter: ASTM E 906 FM Calorimeter: ASTM E 2058 or NFPA 287 or FM Global Tests

38 Cone Calorimeter

39 OSU Calorimeter

40 FM Calorimeter

41 A Survey of Methods to Predict Performance of Wall Linings in the Room/Corner Test

42 INTRODUCTION Room/corner tests have been used for more than two decades to assess the fire performance of linings Several standard protocols are now available Standards are specified in codes and regulations Textile Linings (Codes) NFPA 265 All Other Interior Finish (Codes) NFPA 286 Fire Restricting Materials (IMO High Speed Craft) ISO 9705 Development of predictive methods is motivated by high cost for testing and sample size

43 Physical Phenomena

44 ROOM/CORNER FIRE GROWTH Flame Spread Modes

45 ROOM/CORNER FIRE GROWTH Ignition of Initially Heated Area

46 ROOM/CORNER FIRE GROWTH Flames Spread to Ceiling

47 ROOM/CORNER FIRE GROWTH Flames Spread to End of Wall

48 LITERATURE SURVEY 16 methods found Distinction can be made between 3 types of methods Simulation models: predict room environment and fire growth Analytical methods: predict fire growth Statistical correlations: predict particular aspect of fire growth such as the time to flashover The extent of validation varies widely

49 Simulation Models (1 of 2) Steckler (1983) OSU (Smith and Satija, 1983) Karlsson ( ) Quintiere (1993) Janssens (1995) variation of Quintiere model Wade (1996) variation of Quintiere model

50 Simulation Models (2 of 2) Opstad (1995) Yan (1996) HAI (1999) SwRI (1999) variation of Quintiere model WPI (1999)

51 Steckler Model (NBS) Described in NBSIR (1983) Based on conceptual framework developed by Quintiere Two-zone room environment Only considers lateral flame spread and does not address upward and wind-aided spread Accounts for oxygen vitiation effects on burning rate No validation

52 OSU Model Described by Smith and Satija Many revisions were published subsequently Critical review by Janssens Two-zone room environment Considers ceiling jet Upward flame spread algorithms based on data from OSU calorimeter (ASTM E 906) Lateral flame spread based on OSU data No separation between physics and numerics

53 Karlsson Model (Lund, Sweden) Described in detail in Karlsson s Ph.D. thesis (1992) Two-zone room environment with layer interface fixed at soffit Only considers upward and downward flame spread Upward flame spread based on RHR and ignition data from Cone Calorimeter (ASTM E 1354, ISO 5660) Downward spread based on LIFT data (ASTM E 1321) Model used to develop power law correlations between flashover time and flammability properties downward spread not relevant for lined ceiling

54 Karlsson Model/Inequality Described by Karlsson (1994) Based on cone data, 50 kw/m^2 3 critical parameters: (a) Exponential Decay Factor (Lambda) (b) Equivalent Time to Ignition (Tau) (c) Peak RHR Cone RHR curve must be fitted Inequality predicts whether Self-Propagating Fire is likely to occur

55 Regions of Flame Front Acceleration - Bjorn Karlsson Model Lambda Tau lbd tau=(1+sqrta)^2 lbd tau=(1-sqrta)^2 lbd tau=a a: K Pk RHR

56 Example of a Fire Retarded Textile Wallcovering 50 kw/m^2 - Karlsson Analysis RHR (kw/m^2) Time (s) Data Fitted

57 Example of an Unpainted Gypsum Wall Karlsson Analysis - 50 kw/m^ RHR (kw/m^2) time (s) Data Fitted

58 Example of Car Interior Molding Karlsson Analysis - 40 kw/m^ RHR (kw/m^2) time (s) Data Fitted

59 Example of Vinyl Lining Karlsson Analysis - 50 kw/m^ RHR (kw/m^2) time (s) Fitted Data

60 Quintiere Model (1 of 2) One-zone room environment T g based on modified MQH correlation Uniform T s based on 1-D heat conduction Considers all spread mechanisms Wind-aided spread based on cone calorimeter data Opposed-flow spread based on LIFT data Accounts for burnout Validation for wide range of materials and different standard room/corner test scenarios

61 Quintiere Model (2 of 2)

62 Variations of Quintiere Model Janssens (AF&PA, DC) Includes burner flame geometry and heat flux calculations Revised procedures to obtain ignition, flame spread, and heat release properties from cone calorimeter and LIFT Validated with NFPA 286 & ISO 9705 wood data Wade (BRANZ, New Zealand) Incorporates spread algorithms in two-zone room fire model Uses Janssens ignition and flame spread properties

63 CFD-Based Models CFD grid in gas phase defines wall grid No explicit consideration of flame spread modes LIFT flame spread data are not needed Opstad (SINTEF, Norway, 1995) Extension of KAMELEON code developed at SINTEF Ignition and heat release rate based on cone data Yan (Lund, Sweden, 1996) Ignition and heat release rate based on pyrolysis submodel

64 US Coast Guard Models Three models were developed to simulate ISO 9705 tests on marine composites conducted at SwRI SwRI model (Janssens and Dillon) Based on Janssens version of Quintiere model Revised heat release and add smoke production calculations WPI model (Dembsey and Barnett) Based on Mitler s flame spread algorithms and CFAST HAI model (Beyler et al.) Extension of corner fire model developed by HAI for US Navy SwRI model gives the most consistent predictions

65 Analytical Methods Room effects are fixed single test scenario All methods require only cone data Magnusson (Lund, Sweden, 1984) Assumes exponential heat release rate curve in room test Requires ignition temperature measurements Validation: ISO 9705 and 1/3 scale room data for 13 materials Wickström and Göransson (SP, Sweden, 1992) Single cone calorimeter test needed Applied to ISO 9705, but modified for larger room Validation: ISO 9705 and large room for 11 EUREFIC materials Dietenberger (FPL, WI, 1998) measurements dynamics

66 Statistical Correlations Östman (Trätek, Sweden) Flashover time correlation Smoke SEA correlations Based on Swedish ISO 9705 test data for 13 materials Quintiere (University of Maryland, MD) Critical b-parameter for accelerating upward flame spread " t b = 0.01 q 1 t Originally developed for ISO 9705 Later modified for NFPA 265 and NFPA 286 ig b

67 Quintiere Modified b Flammability Parameter EPS foam tflashover (s) Polyurethane foam b NFPA 265 Protocol NFPA 286 Protocol

68 DISCUSSION Extensive validation shows that Quintiere s model, in original or modified form provides good predictions for a wide range of materials and different scenarios The b-parameter concept is a useful screening tool Additional modification by Dillon et al. follows, and is applied to actual data

69 Dillon Janssens - Hirschler Developed tools for predicting performance of materials in room/corner tests NFPA 265 & NFPA 286 Cone 50 kw/m² 36 Materials investigated Predicted likelihood of flashover (19 materials) No flashover (17 materials) Peak heat release rate Smoke production

70 Wall and Ceiling Linings NFPA 265 required by US codes for textile wall coverings: No Flashover NFPA 286 required by US codes for other interior finish: No Flashover and TSR < 1,000 m²

71 What Does the Cone Calorimeter Do? The cone calorimeter measures:! Heat release rate! Total heat released! Effective heat of combustion (all measurements done by the oxygen consumption principle)

72 What Does the Cone Calorimeter Do? The calorimeter also measures:! Mass loss rate! Time to ignition! Specific extinction area (i.e. smoke), and! Optionally, CO/CO 2 production

73 Schematic of Cone Calorimeter in Concept

74 Cone Calorimeter Sample Exposure:! Radiant heat fluxes from a conical heater! Exposure values range from 0 to 100 kw/m 2! Horizontal Orientation

75 Materials Database 6 sets of materials 36 materials. Room/corner test: NFPA 265 fi 11 materials. NFPA 286 fi 25 materials. Cone Calorimeter: all materials 50 kw/m² Horizontal 6 materials tested vertically

76 Occurrence of Flashover Most important factor in Room-Corner tests Time to flashover based on cone data. Flashover unlikely if t flashover > 900 s Correlation based on a wind-aided flame spread analysis by Cleary and Quintiere: b = 0.01 HRR avg 1 b > 0 indicates likelihood of flashover. t b for many materials not presented. t ig t b

77 Occurrence of Flashover RHR ( ) ( ( ) t t = RHR exp λ t t ig peak ig RHR represented as an exponentially decaying function of time, with l determined by matching to RHR 180

78 Occurrence of Flashover Fit Decay Coefficient 500 HRR (kw/m²) Time (s)

79 Likelihood of Flashover b =.01 HRR 1 λ t ig

80 Likelihood of Flashover 1200 Time to Flashover (s) No Flashover PU Foam EPS Foam NFPA 265 Protocol b NFPA 286 Protocol

81 Time to Flashover Materials reach flashover within 2 minutes of burner increase. No correlation developed for t flashover.

82 Peak Heat Release Rate Materials that do not reach flashover. 17 materials HRR peak approximation: Peak HRR from 50 kw/m² Area in contact with burner Exposed sample area: A = 2 D H flame Flame height at 50% intermittency: NFPA 265 fi 150 kw fi H flame = 1.71 m NFPA 286 fi 160 kw fi H flame = 1.79 m

83 Peak RHR Correlation 500 Predicted Peak HRR (kw) Measured Peak HRR (kw) NFPA 265 Protocol NFPA 286 Protocol

84 Revised RHR peak Correlation Extended burning area. Requires t ig from Cone (13 materials). Area ignites t ig seconds after burner increase. Taller flame Based on RHR of burning area Heated section ignites t ig seconds later At 2 t ig the RHR is a sum of the two areas RHR peak depends on rate of exponential decay Provides a reasonable, conservative correlation

85 Revised Pk RHR Correlation 500 Predicted Peak HRR (kw) Measured Peak HRR (kw) NFPA 265 Protocol NFPA 286 Protocol

86 Total Smoke Release Based on the TSR measured in the cone: TSR = A Room TSR Cone TSR Cone based on measured cone properties: TSR Cone = THR HOC Relies on an estimate of the burning area. Area assumed to be 4 m² 1/6 of total wall surface σ

87 Total Smoke Release Correlation Cone Calorimeter TSR (m²/m²) m² 4 m² 8 m² Room Test TSR (m²) NFPA 265 Protocol NFPA 286 Protocol

88 Interior Finish Predictions Data for 36 materials obtained from 6 studies Method to estimate NFPA 265 & 286 room/corner test performance was successful Cone data at 50 kw/m². Modified Quintiere b parameter provides reasonable estimation of the likelihood of flashover. Based of exponential decay factor l. Discrepancies for low-density foams.

89 Successful Predictions Using Dillon et al. Model Peak RHR conservatively estimated From RHR peak measured in the cone Area of material exposed to burner flames Limited wind-aided flame propagation Conservative estimate of Total Smoke Release From TSR in the cone Assuming an area of 4 m²

90 Cable Tray Tests

91 CSA FT4 20 Flux Total cables tested: 21, with 7 Failures All Failures: Cone Pk RHR > 200 kw/m^2 11 of 14 Passes: Cone Pk RHR < 200 kw/m^2 3 of 14 Passes: Cone Pk RHR: Safe Errors

92 FIPEC Cable Test & 50 If Pk RHR 150 kw/m^2 & SMOGRA 10: 88% Correct Predictions on Smoke 95% Safe Predictions on Smoke 2 of 43 Cables with Unsafe Errors

93 Cable Tray Predictions Using cone calorimeter data CSA & UL 1685 results can be predicted by Correlations FIPEC test results can be predicted by Pass/Fail methods

94 Furniture Predictions Using Cone Calorimeter Data Chair & Mattress test results can be predicted by Correlations, occasionally Chair & Mattress test results can be predicted by Pass/Fail Methods, often

95 Cable Tray or Furniture Predictions (Correlations or Pass/Fail) Using cone calorimeter data Self-Propagating Fires can be predicted, often Furniture Flashover can be predicted, usually

96 Transportation Environments Aircraft predictions use OSU Calorimeter Surface Mass Transportation predictions can use the same techniques as other rooms Cars: Self-Propagating Fires are being predicted based on cone tests

97 Conclusions Prediction Techniques Exist and Can be Successful Work on Interior Finish, Furniture and Cables to Various Extents Flashover or Self Propagating Fires Can Be Predicted, Often There is Much More Work to be Done