The first and largely experimental part of a research program on flammability characteristics of upholstered furniture has been completed with full-scale tests in an extensively instrumented burn-out room as main element. The results indicate that fire response parameters vary within a large range with choice of filling, interlining and fabric material. Selection of performance criteria may cause difficulties, as parameters like heat release and smoke potential fluctuate strongly during the fire process. A second part of the program will be directed towards measurement of heat release by oxygen consumption methods, more detailed smoke and gas analysis measurements and use of mathematical simulation procedures

Andersson, Berit

Magnusson, Sven Erik

English

Lund University Publications

LUND UNIVERSITYPO Box 117221 00 Lund+46 46-222 00 00Fire Behaviour of Upholstered Furniture - An Experimental StudyAndersson, Berit; Magnusson, Sven Erik1982Link to publicationCitation for published version (APA):Andersson, B., & Magnusson, S. E. (1982). Fire Behaviour of Upholstered Furniture - An Experimental Study.(LUTVDG/TVBB--3005--SE; Vol. 3005). Division of Building Fire Safety and Technology, Lund Institute ofTechnology.Total number of authors:2General rightsUnless other specific re-use rights are stated the following general rights apply:Copyright and moral rights for the publications made accessible in the public portal are retained by the authorsand/or other copyright owners and it is a condition of accessing publications that users recognise and abide by thelegal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private studyor research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portalRead more about Creative commons licenses: https://creativecommons.org/licenses/Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will removeaccess to the work immediately and investigate your claim.LUND INST ITUTE OF TECHNOLOGY . LUND SWEDEN DIV IS ION OF BUILDING FIRE SAFETY AND TECHNOLOGY REPORT L U m G / ( M B  -3005)  BERIT  ANDERSSON - SVEN ER1 K MAGNUSSON F I R E  BEHAVIOUR OF UPHOLSTERED FURNITURE - AN EXPERIMENTAL STUDY Presented at "Interflarn 82", held at University of Surrey, Guildford, March 30 - April 1 ,  1982 LUND 1982 FIRE BEHAVIOUR OF UPHOLSTERED FURNITURE - AN EXPERIMENTAL STUDY B. Andersson, S E Magnusson Introduction The goal of the project "Fire behaviour of upholstered fur- niture - an experimental study" was to study in full scale a number of combinations of fabric, interliner and filling material with regard to ignitability, burning intensity, generation of smoke and production of toxic gases. The possibility of classifying the product after conducting tests in reduced scale was also investigated. The experiments were performed during 1 9 7 8  and 1 9 7 9 .  A comp- rehensive report has been written in Swedish [ l ] ,  Experiments in reduced scale Materials - - - - - - - - The project comprised 53 experiments in reduced scale with different combinations of fabric, interliner and filling material. 14 different fabrics with varying fibre content, e.g. cotton, wool, viscose, acrylic and different mixtures of these fibres were used. The interliners were of three designs: fire-retardant treated polyurethane foam, felt of novaloid fibres and modified neoprene foam. Three filling materials were tested; one standard polyurethane, one high resilie,nt polyurethane and one flame-retardant treated stan- dard polyurethane. Two densities were used, 25 kg/m3 for backs and 35 kg/m3 for seats. The experiments in reduced scale were performed with a testing rig designed according to DD 58:1978 [ 2 1 ,  the original propo- sal for a British ignitability standard. The seat and back cushions were 0.5 m X 0.5 m with a thickness of 0.075 m. The test configuration is outlined by Fig. 1. During the experiments,measurements were taken of temperatures, smoke production and mass burning rates. The locations of the thermocouples, the photocell, the loadcell and the bi-direc- tional probe are indicated in Fig. 1. All experiments were also well photodocumented. The ignition source was a wooden crib weighing 10 g or 40 g. The small crib was first applied and if this source failed to ignite the tested combination, the bigger crib was used. The crib design was accorsing to-.:?T Fire 007 [31 and the sgall crib was one fourth of the big one. @ phorocell 0 thermocouple D hi-directional probe Figure 1 Test configuration for experiments in reduced scale Test results The experiments indicate that ignitability can be considerably decreased either by using an interliner between the fabric and the filling material or by careful choise of the fabric. In experiments with fabric fibres of acrylic, viscose and cotton, ignition is achieved with the 10 g crib in combination with the three filling materials used. This is also valid for fibre blends with less than 50% wool content. If these covers are improved with an interliner the 40 g crib is needed to ignite the combinations. When a fabric with more than 50% wool is combined with the filling materials, the 40 g crib is necessary to get ignition. These results are in conformity with the ex- perience obtained in other investigations [4, 5, 61. The results from the reduced scale tests also show that the rate of fire spread across the piece of furniture is strongly dependent on the fabric (and existing interliner). There is great need for a testing method which explicitly and in small scale gives information on this important fire risk characte- ristic. The total amount of smoke produced during an experi- ment is given as D (*-m3), Fig. 2, for combinations with tot m the same fabric but varying filling materials. For a defini- tion of the parameter Dtot, see Rasbash [ 7 1 .  dE ' 101  h 1500 1000 500 0 Fabr i c  Standard Flameretardant Highres i l ien t  C o ~ b i n a t i o n  with oolyure thane  0 polyurethane t r e a t e d  standard j n t e r l i n e r  polyurethane 5 6 7 0 Q 10 11 13 1L 15 16 17 l0 19 20 21 2 2  2L 25 26 Acry l i c  Viscose Viscose ' Polypropylen Wool FR- Wool Cotton t r e a t e d  Figure 2 The total amount of smoke produced during experi- ments in reduced scale From the results it is evident that combinations with flame- retardant treated standard polyurethane generate more smoke than other combinations. Combinations with interliners pro- duce in most cases small amounts of smoke. Experiments in full scale Materials - - - - - - - - - 1 1  full-scale experiments were conducted with combinations of 3 different fabrics, 3 interliners and 3 filling materials. The combinations are described in Table 1. Test Fabric Interliner Filling material NO. Acrylic Acrylic Acrylic W001 Acrylic Wool 61%, viscose 39% Wool 61%, viscose 39% Wool 61%, viscose 39% Wool 61 % ,  viscose 39% Wool 61%, viscose 39% Wool 61 %, viscose 39% Fire-retardant treated poly- urethane Modified neo- prene foam Felt of nova- loid fibres Standard polyurethane Standard polyurethane Flame-retardant treat- ed standard polyure- thane Standard polyurethane Standard polyurethane Standard polyurethane High-resilient poly- urethane Flame-retardant treat- ed standard polyure- thane Standard polyurethane Standard polyurethane Standard polyurethane Table 1 Combinations tested in the full-scale experiments TeHt-confisu~atinn-ar!G-i11st~umentaLi11n The full-scale tests were conducted in a room of 15 cm thick lightweight concrete with the internal dimensions 2.4 m x 3.6 m and a height of 2.4 m. A doorway 0.8 m x 2.0 m was situated on one of the short sides of the room. The room was designed and instrumented according to ASTM recommendations [81. Temperatures were measured on 35 locations in the test room; just under the ceiling and along one vertical profile in the middle of the room and one in the doorway. Heat flux measurements were taken in several locations. The tested piece of furniture was placed on a weighing platform to facilitate a determination of the mass burning rate. The gas flows out of and in to the room were measeured with 7-14 bi-directional probes. The optical density of the combustion products was measured with a vertical light path in the door- way. To get reproducible fire scenarios and clearly defined and measurable reactions to variations in the main parameter, i.e. material selection, the test furniture was a full-scale mock-up model of a sofa for three ?ersons, ?esiqned with loose cushions on a steel frame. A liquid fuel burner with a heat output of 20-30 kW was used as ignition source. The test results show that the rate of fire spread is strongly dependent on the surface material. The presence of an inter- liner highly influences the rate of fire spread across the piece of furniture, as was also evident in the experiments in reduced scale. One conclusion is that the rate of fire spread is just as important for the development of a fire as the mass burning rate, and that choice of fabric determines not only ignitability but also to a large extent the total fire growth process. Rate of heat release The rate of heat release is an important parameter for the development and spread of a fire. With the instrumentation used in the reported experiments, two ways of calculating the rate of heat release are possible: 1) integration of the product of gas flow rate and gas tempe- rature in the gas stream out of the room 2) the product of mass burning rate and an effective heat of combustion (AH for the combustion products. ef f To illustrate results, Fig. 3 presents time curves of the rate of heat release for the experiments 5 and 8. Both methods men- tioned above have been used to calculate the rate of heat re- lease. Two different values, indicative of possible upper and lower bounds, of the effective heat of combustion were applied. The theoretical heat of combustion for polyurethane is approxi- mately 28.7 MJ/kg [g]. For combustion in a fully ventilated room about 65% of the heat is released and this gives a AHeff of 18.7 MJ/kg. Values for the effective heat of combustion as low as 10.9 MJ/kg have been reported [IOI. The curves for rate of heat release in Fig. 3 show that the maximum effect released is 1400 kW during experiment 5 and 580 kW during experiment 8. The time after ignition for these heat release rates were 4 and 22 minutes, respectively. The figures indicate the improvements of the fire growth and heat release characteristics of upholstered furniture that can be achieved within present technological knowledge. Figure 3 Time curves of the rate of heat release for experi- ments a) 5 and b) 8 It should be noted that in method 2 no correction is made for losses caused by conduction into surrounding surfaces nor for losses caused by radiation through the doorway. Production of smoke Smoke potential, or mass optical density, was measured in the two types of tests as well as the total smoke production. The main conclusion was that the mass optical density parameter is varying strongly during the fire process and is, thus, no meaningful parameter characterizing the material of a product with respect to smoke hazard. On the other hand, the results indicate a positive correlation with regard to total smoke production between the two test methods. It must be emphasized that the number of tests with the same material combination is too small to allow any firm conclusions. As an example of the results, Fig. 4 gives, for five different material combinations, the total, accumulated smoke production Dtot as a function of time. In accordance with the terminology used in 171 ,  Dtot is expressed as (dB/m) .m3, where the first factor expresses light attenuation as decibel per meter of light path through the outflowing smoke, and the second one expresses the total flow of combustion products (smoke). Fig. 4 clearly illustrates the influence of material selection on the rate of smoke production. Risk analysis Risk for human injury in case of an unwanted fire depends on the combination of exposure time and -level for a number of hazard components: heat, smoke or toxic gas concentration, heat fluxes. In order to summarize the test results, Table 2 gives the time available for escape or evacuation out of the room of fire origin; that is the minimum time for a specified hazard component to reach untenable conditions inside or in the opening of the test compartment. Figure 4 The rate of smoke production for the experiments 5, 6 ,  7 ,  8 ,  and 1 1  The headings of the table should be self-explanatory; blood concentration of COHb is computed by the equation given in 1111.  The heat flux level 2.5 kw/m2 is indicative of burn injury 7 of unprotected human skin and the level 20 kW/rnU to the flash-over phenomena. U 0 0 ri LA m - m > > m 0 0 4  U a rc b.4 aJ 0 E E O  -d rl H - W ld d m d m d m 0 m C 4 E N m 0 LA C .d E  N m 0 v-. C .ri E  N m 0 m C 4 E  N LA Present and future work The test series reported in this paper was a pilot one. Al- though the instrumentation used in the test was of an exten- sive character, it became clear that a reliable assessment of rate of heat release, smoke and toxic qas qeneration de- manded measurement techniques, which, in some aspects, shoule be changed. It also became apparent that a successful %athe- matical simulation 05 the fire growth process required input data that was lacking. Especially, there is a need for flame spread data obtained in small-scale laboratory testing. A second test series has been carried out during %arch 1982, comprising both mattresses and upholstered furniture. Tests will be carried out both in the room and in open, free-burn- ing configuration. In both cases, rate of heat release will be measured by oxygen consumption. A correlation will be sought Setween natural room fire data (full-scale and reduced, one-third scale), laboratory test data (flame spread, rcte of heat release and smoke generation) and mathematical siaulation results from the Harvard Computer Fire Code [ 1 2 ,  131. Conclusion The first and largely experimental part of a research program on flammability characteristics of upholstered furniture has been completed with full-scale tests in an extensively instru- mented burn-out room as main element. The results indicate that fire response parameters vary within a large range with choice of filling, interlining and fabric material. Selection of performance criteria may cause difficulties, as parameters like heat release and smoke potential fluctuate strongly during the fire process. A second part of the program will be directed towards measure- ment of heat release by oxygen consumption methods, more de- tailed smoke and gas analysis measurements and use of mathema- tical simulation procedures. Acknowledgement The study,summarized in this paper,was jointly financed by government, through the National Swedish Board for Technical Development and the Foundation for Research of the Wood Working Industries and by industry, represented through the Swedish Plastic Federation. It has, as a part of a larger joint fire research program in the pre-flashover area, been carried out in co-operation with the Division of Fire Techno- logy of the Swedish National Testing Institute. References Andersson, B. and Magnusson, S.E., Brand i stoppmobler - en experimentell studie (Fire behaviour of upholstered furniture - an experimental study),Lund Institute of Technology, Department of Structural Mechanics, Report No. R80-4 British Standards Institution, Draft for Development, Test for the ignitablity of upholstered seating, DD58:1978 Nordtest Method NT Fire 007, Floorings; Resistability to spreading fire and smoke development Woolley, W.D. et al, The ignition and burning characteris- tics of fabric covered foams, Fire Safety Journal, Vol. 2, 1979/80 Schultz, B., Provning av antandlighet hos kombinationer av mobeltyger, mellanskikt och stoppningsmaterial, del I (Test of ignitability of combinations of fabrics, inter- liners and filling materials, Part I), TFB 78002 FR, 1978-07-24 Schultz, B., Provning av antandlighet hos kombinationer av mobeltyger, mellanskikt och stoppningsmaterial, del I1 (Test of ignitability of combinations of fabrics, inter- liners and filling materials, Part II), TFB 79001 FR, 1979-06-29 Rasbash, D.J. and Pratt, B.T., Estimation of smoke pro- duced in fires, Fire Safety Journal, Vol. 2, 1979/80 ASTM, Recommended Practice for Room Fire Tests, Working Document, ASTM E-39.10.01, Task Group 4, April 1976 9 Mitler, H . E . ,  The physical basis for the Harvard Computer Fire Code, Home Fire Project Technical Report No. 34, October 1978 10 Kung, H-C., Residential sprinkler-protection study, Fac- tory Mutual Research Center, Serial No. 22442, November 1975 1 1  Babrauskas, V . ,  Combustion of mattresses exposed to flam- ing ignition sources, NBSIR 77-1290, Center for Fire Re- search, National Bureau of Standards, September 1977 12 Rocket, J.A., Modelinq of NBS Mattress Tests with the Harvard Fire Code, Center for Fire Research, National Bureau of Standards, August 1981 13 Mitler, H.E. and Emmons, H.W., Documentation for CFC V, the fifth Harvard Computer Fire Code, Division of Applied Sciences, Harvard Universi.ty, Home Fire Project Technical Report No. 45, October 1981 

Fire Behaviour of Upholstered Furniture - An Experimental Study

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Fire Behaviour of Upholstered Furniture - An Experimental Study

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