There has never been a test on a plastic tote!There were plastic totes insidethe warehouse.In-rack has been suggested as a solution… - Increasing suppression for all materials requires a method of almost literally removing all Oxygen. Some warehouses might as well be built underwater.
Mentoin environmental impacts of warehoues fires as well – such as in Sweden….
Discuss how each of these plays a role in
“Both Factory Mutual and NFPA realize that their generic classification schemes are more valuable for providing a preliminary indication of relative flammability than a firm irrefutable determination.” – Zalosh pg. 131i.e. A highly hazardous material may only be moderately hazardous in Europe, and vice versa.
Approach to classify commodities starts with laboratory tests on single commodities, then mid-scale tests on mixed commodities, and eventually full-scale validation. Once full scale validation is accomplished, only laboratory tests will be required in the future.
Mf is the mass loss rate per unit area per unit time, all other variables are constants in this case. They depend on the properties of air and the material.
Xp is the pyrolysis height, and the flame height is found using phi.
This does depend on densityDifferent density papers lightweight heavywheight in 13 and how this is effected.
Conce Calorimeter single sheet cardboard test (identical to single sheet polystyrene & polystyrene backed cardboard tests)
Cone calorimiter tests were conducted on single-cell setups, double-cell setups (as shown above), as well as individual materials.Data will be showed later individually for cardboard, polystyrene, and mixed setups.
One small piece of a big project.To get to a point to accurate equations to calculate in the design phase this is what we have to go through.
2009 sfpe san diego - a fundamental approach towards fire hazard classification 4.0
Presenter: Michael Gollner UC San DiegoWork sponsored by Schirmer Engineering, an AON Global Company 1
CollaborationTheory & Data Analysis Forman Williams Michael Gollner UC San Diego UC San DiegoSmall-Scale Testing Ali Rangwala Kris Overholt Cecelia Florit WPI WPI WPI/University of Marsielle, France Jonathan Perricone Schirmer EngineeringCorporate Sponsor 2
Presentation Overview Current Commodity Classification Limitations A Fundamental Approach Towards Classification Upward Turbulent Fire Propagation Theory Nondimensional Parameters Experimental Approach Conclusion and Future Recommendations 3
Recent Loss Case Example 2007 – Tupperware storage warehouse fire* 15,392m2 warehouse burned 24 hours to extinguish fire Sprinklers met state & local requirements including NFPA 13 Significant property losses have Once plastic became involved occurred in the United States as fire was uncontrollable recent as 2007 as a result of such shortcomings. Building was a total loss (Photo: Georgetown Country Fire, Dept., Hemingway, SC) *The Problem with Big, NFPA Journal, March/April 2009 4
Recent Loss History 2006 – Fire destroys warehouse, vehicles at UPS facility* 2002 – Storage Warehouse Fire Phoenix, Az.+ 2001 – Supermarket Fire in Phoenix, Az.‡ 1998 – Warehouse fire in Tempe, Az.‡ 1996 – Lowes store fire in Albany, Ga.‡ *Arizona News briefs. Fire destroys warehouse, vehicles at UPS facility. Newspaper. Mar. 28, 2006. +Duval, R. F. Fire Investiagtion Report - Storage Warehouse - Phoenix, AZ. Quincy, MA : National Fire Protection Association, 2002. §Duval, R. F. and Foley, S. N. Fire Investigation: Supermarket Fire, Phoenix Arizona, March 14, 2001. Quncy, MA : National Fire Protection Association, 2002. ‡Harrington, J. L. Lessons Learned from Understanding Warehouse Fires. Fire Protection Engineering. Winter, 2006. 5
Aspects of Material Flammability Ignition Fire Growth Burning Intensity Extinction/Suppression Generation of Smoke & Toxic Compounds 7
Warehouse Fire Protection Model*Zalosh, R. G., Industrial Fire ProtectionEngineering. John Wiley and Sons, 2003 8
Current Commodity Classification Current classification methods use ranking scheme (Class I-IV, Group A-C Plastics) based upon the free-burning heat-release rate of a given fuel Intermediate-scale measurements of this parameter are used as the cornerstone for fire suppression design in modern storage facilities The sprinkler industry identifies a database of full-scale fire tests as validation for this approach There is a lack of detailed measurements associated with performance analysis of these tests. Full-scale fire tests are typically judged in terms of pass/fail with great significance attached to subjective observations 9
Current Commodity Classification NFPA and FM Global recognize their classification schemes at the very best can only provide a preliminary indication of relative flammability* These results can be misleading and dangerous! European (CEN) standards classify commodities into 4 groups much like NFPA 13, but there are contradictions between these categories* Repeatability cannot even be explored - extensive large- scale testing is too expensive* *Zalosh, R. G., Industrial Fire Protection Engineering. John Wiley and Sons, 2003 10
A Fundamental Approach Towards Classification 11
Why have a fundamental approach? Fire scenarios will become more predictable Scientifically verifiable results from testing Moves towards guaranteed protection because the worst case fire conditions and suppression or extinction requirements can be better estimated 12
Our ApproachCurrent Research Large/Full Scale Intermediate Modeling Scale Testing (Proof of (Proof of concept) Small Scale Testing concept) Commodity type classification Cone Calorimeter testing Engineering Approach to Commodity Classification 13
Stage 1 – Laminar Case Boundary layer B is a function of: 1. Corrugated board Buoyant Plume Plume Radiative + Convective Heat Transfer Commodity Excess Combusting Plume Flame Radiative + Pyrolyzate Convective Heat Transfer Pyrolysis Zone flame XF mF (~ 20 to 25 cm Laminar XP Flame Propagation)• Flame height <25 cm Y-axis• Unrealistic in fire situation Corrugated board• Study important because provides physical understanding of the problem 15
Stage 2 – Turbulent Case Buoyant Plume Plume Radiative + Boundary layer Convective Heat Transfer B is a function of: 1. Corrugated board Combusting Plume 2. Commodity pyrolysis vapor Flame Radiative + Convective Heat Transfer Excess Pyrolyzate Commodity mF Pyrolysis XP XF (Turbulent flame height >25 cm) Zone• Flame height >25 cm flame• Realistic fire situation• Cardboard still intact Y-axis Corrugated board 16
Buoyant Plume Plume Radiative + Convective Heat Transfer Stage 3 – Mixed Case Combusting Plume Flame Radiative + B is a function of: fla Convective Heat Transfer (from pool and wall fire) 1. Corrugated board me 2. Commodity pyrolysis vapor 3. Commodity Excess Pyrolyzate Commodity XF Boundary layer Corrugated Solid/Liquid board m F Pool fire Pyrolysis Zone• Flame height >25 cm• Realistic fire situation m F Pyrolysis• Cardboard breaks Zone Y-axis Commodity leakage 17
Theory •The B-number is a ratio that compares a summation of the various impetuses (i.e. heat of combustion) for burning to a summation of the various resistances (i.e. heat of vaporization) to the process. “Thermodynamic Efficiency” •It can be described in relation to a mass-loss rate of a commodity which can be measured in a laboratory  •Solving for B and using several other well-known heat transfer relations a formula for estimating an average B-number based on mass loss is  Kanury, A. M. An Introduction to Combustion Phenomena. s.l. : Gordon & Breach Science Publishers, Inc, 1977. M.J. Gollner, T. Hetrick, A. S. Rangwala, J. Perricone, and F. A. Williams. Controlling Parameters Involved in the Burning ofStandard Storage Commodities: A fundamental approach towards fire hazard classification. 6th U.S. National CombustionMeeting, 2009.
Flame Height Theory •Using theory given by Annamali & Silbulkin , the expected flame height for a vertically oriented material can be found by using a B- number and constant material and air properties [1,2] •A procedure to perform this calculation is found in reference  Overholt, K., Gollner, M.J., Rangwala, A.S. Characterizing flammability of corrugated cardboard using acone calorimeter. 6th US National Combustion Meeting of the Combustion Institute. May, 2009. Annamalai, K. and Sibulkin, M. Flame spread over combustible surfaces for laminar flow systems. Part I & II:Excess fuel and heat flux. 1979, Combust. Sci. Tech., vol. 19, pp. 167-183. 19
Cone Calorimeter ResultsFlame heights measured in thesmall-scale cone calorimetertests are compared to thepredicted flame heightscalculated by A&S model. Theshaded area represents theflame heights from the conetests. The dashed line shows thepredicted flame heights fromthe model using an average B-number from 2 cardboard tests.The dark circles represent thepredicted flame heights fromprevious literature (0.8)Overholt, K., Gollner, M.J., Rangwala, A.S. Characterizing flammability of corrugated cardboard using a conecalorimeter. 6th US National Combustion Meeting of the Combustion Institute. May, 2009. 20
Cone Calorimeter ResultsFlame heights from FMexperiments are compared topredicted flame heightscalculated by the A&S model.The shaded area represents theflame heights from the FMtests. The dashed line shows thepredicted flame ehgiths fromthe model using an average Bnumber from the 4 cardboardtests. The dark circles representflame heights using a B-numberfrom previous literature (0.8).Overholt, K., Gollner, M.J., Rangwala, A.S. Characterizing flammability of corrugated cardboard using a conecalorimeter. 6th US National Combustion Meeting of the Combustion Institute. May, 2009. 21
Commodity Test Results Measured vs. Predicted Flame Heights 150 B=1.26 B=0.7 B=1.41 Predicted flame height from Group-AFlame Height (cm) Region with plastic commodity Transition cardboard region using A&S data. 100 front face burning •Blue dotted lines are predicted flame heights 50 Region with cardboard & •Red x’s denote measured PS burning flame heights 0 0 50 100 150 200 Time (s) 22
Nondimensionalization Nondimensionalization is the removal of units from a mathematical equation by a suitable substitution of variables This technique can simplify and parameterize problems where measured units are involved Useful in scaling analyses (small-scale to full-scale) For Example: Reynolds number is a nondimensional parameter 24
Parameters ClassifyingFlammability*Here only the B-number, HRP, and LOI are nondimensional 25
Parameters Involved in Study Fire Propagation Fire Propagation Index (FPI) Ignition Critical Heat Flux (CHF) Burning Rate B-number A nondimensional form will allow useful scaling analyses of these parameters 26
Fire Propagation Index Fire propagation Index, FPI is proportional to the square root of the flame spread velocity FPI is nondimensionalized by the regression velocity, VR of the material: qfHg VR FPI is expressed as a nondimensional parameter of the form FPI FPI FPI * qfHg / VR 27
Calculations of FPI* VR Material FPI [(m/s)1/2] FPI* [m/s.10-5]Polymethylmethacrylate 31 3.2 5.5(PMMA)Polypropyelene (PP) 32 3.7 5.3Polystyrene (PS) 34 4.2 5.2Polyethylene (PE) 28 3.2 4.9Polycarbonate (PC) 14 1.4 3.7Wood Slab (Doug Fir) 14 4.1 2.2Polyvinylchloride (PVC) 7 1.5 1.8 * Data for calculations taken from SFPE Handbook of Fire Protection Engineering, Fourth Edition. 28
Critical Heat Flux The Critical Heat Flux is the minimum flux applied to a material that will cause it to ignite [W/m2] CHF can be nondimensionalized by means of a maximum heat-release rate, HRR [W/ m2] of the commodity CHF CHF * HRR 29
The B-number Spalding’s B-number, or Mass Transfer Number Derived directly from governing equations for combustion Dimensionless ratio that compares a summation of the various impetuses (i.e. heat of combustion) for burning to a summation of the various resistances (i.e. heat of vaporization to the process. “Thermodynamic Efficiency” B-number can be found experimentally from burning rate* h mf ln(B 1) Cg*Kanury, A. M., Introduction to Combustion Phenomena. Gordon and Breach Science Publishers, New York. 1975 30
Nondimensional Parameters Non-Dimensional FPI used to quantify flame spread FPI FPI = Fire Propagation Index FPI* ρ = Flame Density qfHg / ∆Hg = Heat of gasification qf‘’ = Feedback flux Non-Dimensional Flux to quantify heating flux from the burning commodity CHF CHF * CHF = Critical Heat Flux (flux which will cause material to HRR ignite) HRR = Average heat-release rate of material H f YO , Cg (T TB ) B-number to characterize burning rateB CHF = Critical Heat Flux (flux which will cause L C l (TB TR ) material to ignite) HRR = Average heat-release rate of material 31
Experimental Setup- Cone TestsOverholt, K., Gollner, M.J., Rangwala, A.S. Characterizing flammability of corrugated cardboard using a conecalorimeter. 6th US National Combustion Meeting of the Combustion Institute. May, 2009. 33
Experimental Setup- Cone Tests 34 *Cone calorimiter work conducted by K. Overholt, WPI
Cone Testing 35 *Cone calorimeter work conducted by K. Overholt, WPI
Experimental Setup: Small-Scale Test Class III CommodityGroup-A Plastic Commodity Standard Group-A Plastic Commodity Polystyrene cups in compartmented cardboard carton 36
Picture of Experimental SetupWPI, Summer 2008 TC wires Heat flux sensors Back View Front View 37
Flame Spread – Small Scale Front View Front View 38
Flame Spread – Small Scale Extent of commodity participation Side View of Spreading Flame 39
Cone Calorimeter Results Average B numbers found Cardboard: B ≈ 1.78 Polystyrene (PS): B ≈ 2.76 Cardboard with PS Backing: B ≈ 4.41 Values are preliminary data Cardboard values approximately double previously reported values When used to predict flame heights, B-number values for cardboard match test data 42
Commodity Test Results 30 s 92 s 100 s 132 s 150 s Front Face of Cardboard Plateau PS Cups & Cardboard Burning Burning
Commodity Test Results m f PS cups burning (g/m2s)Measured mass loss 1rate during the Packing material Extinctionexperiments. After 0.8 (cardboard)120s the PS cupsstarted burning and 0.6 Front face of cardboardtest was terminated. burning 0.4 0.2 0 0 20 40 60 80 100 120 140 160 Time from Ignition [s] 44
Commodity Results – Mass Loss Mass Loss Rate, Test 1 Mass Loss Rate, Test 2 0.016 0.016 Mass Loss Rate [kg/m2] Mass Loss Rate [kg/m2] 0.014 0.014 0.012 0.012 0.01 0.01 0.008 0.008 0.006 0.006 0.004 0.004 0.002 0.002 0 0 0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140 160 180 200 Time from Ignition, [s] Time from Ignition, [s] Mass Loss Rate, Test 3 Mass Loss Rate, Test 4 0.018 0.018 0.016 0.016 Mass Loss Rate [kg/m2] Mass Loss Rate [kg/m2] 0.014 0.014 0.012 0.012 0.01 0.01 0.008 0.008 0.006 0.006 0.004 0.004 0.002 0.002 0 0 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 160 180 45 Time from Ignition, [s] Time from Ignition, [s]
Commodity Results – Mass Loss B-number, Test 1 B-number, Test 2 5 5 4.5 4.5 4 4 3.5 3.5 3 3 B B 2.5 2.5 2 Average B 2 1.5 1.5 1 1 0.5 0.5 0 0 0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140 160 180 200 Time from Ignition, [s] Time from Ignition, [s] B-number, Test 3 B-number, Test 4 5 5 4.5 4.5 4 4 3.5 3.5 3 3 B B 2.5 2.5 2 2 1.5 1.5 1 1 0.5 0.5 0 0 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 160 180 Time from Ignition, [s] Time from Ignition, [s] 46
Commodity Test – MeasuredValues Test 1 Test 2 Test 3 Test 4Average MLR (g/s): 2.97 3.88 2.54 4.15 Average B number: 0.60 0.82 1.33 1.26Median B number: 0.31 0.51 1.01 0.47 StdDev for B: 0.64 0.87 2.59 1.94 Average B- number 1.2595 47
Warehouse Fire Protection Model*Zalosh, R. G., Industrial Fire ProtectionEngineering. John Wiley and Sons, 2003 49
Conclusions A new method of hazard ranking is introduced in this study based on nondimensional parameters: B, FPI*, and CHF* In a warehouse setting, where the burning rate is the dominant fire hazard, the B-number may appropriately classify the hazard of a grouped commodity – especially if we can correlate FPI* and CHF* with B These parameters can be determined by small-scale laboratory tests The B-number can be calculated by the Cone Calorimeter and/or grouped commodity tests FPI* can be determined using current testing methods by incorporating parameters already measurable on the NIST LIFT apparatus CHF* could possibly be determined by testing of a single grouped warehouse commodity 50
Conclusions These parameters are nondimensional and in preliminary tests show good correlations to full-scale test data The economic advantage of predicting full-scale performance with small-scale experiments may be an impetus for a significant evolution in the field of fire protection engineering. 51