Comparison of cone and OSU calorimetric techniques to assess the flammability behaviour of fabrics used for aircraft interiors

Two test methods for measuring the heat release rate, HRR have been compared on fabric composites used for aircraft interior materials as side‐wall panels. These methods are based on the principles of direct measurement of the convective and radiant heat by thermopiles using an Ohio State University (OSU) calorimeter, and oxygen consumption using a cone calorimeter. It has been observed when tested by standard procedures, cone results at 35 kW/m² incident heat flux do not correlate with OSU results at the same heat flux. This is because in the cone calorimeter, the sample is mounted horizontally whereas the OSU calorimetric method requires vertical sampling with exposure to a vertical radiant panel. A further difference between the two techniques is the ignition source—in the cone it is spark ignition, whereas in the OSU it is flame ignition; hence, samples in the OSU calorimeter ignite more easily compared to those in the cone under the same incident heat fluxes. However, in this paper we demonstrate that cone calorimetric exposure at 50 kW/m² heat flux gives similar peak heat release results as the 35 kW/m² heat flux of OSU calorimeter, but significantly different average and total heat release values over a 2 min period. The performance differences associated with these two techniques are also discussed. Moreover, the effects of structure, i.e. type of fibres used in warp/weft direction and design of fabric are also analysed with respect to heat release behaviour and their correlation discussed. Copyright © 2005 John Wiley & Sons, Ltd.     

The Accumulation of Flammable Gases in Cone Calorimeter Tests is Responsible for Flash Ignition of Wool and Cotton Samples

In this paper a possible explanation is presented for the differences found between the fire behaviour of materials in small-scale cone calorimeter tests and the large-scale furniture calorimeter. The results obtained with cone calorimeter/FTIR equipment at 35 kW m⁻² will show that the early flash ignitions of typical materials like cotton and wool are due to the liberation of flammable gases during the pyrolysis phase and the typical ignition situation on the cone calorimeter, that is, the presence of a sparking igniter above the sample. This fast flash ignition and the early heat release behaviour on the cone calorimeter may be in contradiction to the early fire growth in other fire tests where the ignition conditions are clearly different from pyrolysis circumstances, that is, ignition via a burning newspaper, match, gas flame, etc.     

Effects of variations in incident heat flux when using cone calorimeter test data for prediction of full‐scale heat release rates of polyurethane foam

The development of methods to predict full‐scale fire behaviour using small‐scale test data is of great interest to the fire community. This study evaluated the ability of one model, originally developed during the European Combustion Behaviour of Upholstered Furniture (CBUF) project, to predict heat release rates. Polyurethane foam specimens were tested in the furniture calorimeter using both centre and edge ignition locations. Input data were obtained using cone calorimeter tests and infrared video‐based flame area measurements. Two particular issues were investigated: how variations in incident heat flux in cone calorimeter tests impact heat release rate predictions, and the ability of the model to predict results for different foam thicknesses. Heat release rate predictions showed good agreement with experimental results, particularly during the growth phase of the fire. The model was more successful in predicting results for edge ignition tests than for centre ignition tests and in predicting results for thinner foams. Results indicated that because of sensitivity of the burning behaviour to foam specimen geometry and ignition location, a single incident heat flux could not be specified for generating input for the CBUF model. Potential methods to determine appropriate cone calorimeter input for various geometries and ignition locations are discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

Effect of curprous oxide in combination with molybdenum trioxide on smoke suppression in rigid poly(vinyl chloride)

Further investigation of the synergistic effect of smoke suppression between cuprous oxide and molybdenum trioxide in rigid poly(vinyl chloride) (PVC) was carried out by using a cone calorimeter (cone) at a high incident heat flux of 50 kW m^?2. Experimental data derived from the cone calorimeter indicated that binary mixtures of Cu₂O and MoO₃ clearly showed the synergistic effect in reducing smoke by decreasing total smoke production (TSP), average specific extinction area (av‐SEA), and smoke production rate (SPR). This result is in good agreement with that obtained from the NBS smoke chamber. However, the combustion process of rigid PVC could clearly be seen from the heat release rate (HRR), curve, SPR, and fire degradation obtained from the cone test, which could not be determined from the NBS smoke chamber. It was also found that the binary mixture showed the synergistic effect by increasing was also found that the binary mixture showed the synergistic effect by increasing char residue and reducing the fire degradation of the PVC backbone at a high incident heat flux of 50 kW.m^?2. All experimental data well supported the early cross‐linking mechanism of the PVC backbone mentioned in the literature and were consistent with the fire degradation behavior obtained from the cone calorimeter.     

Ignition performance of new and used motor vehicle upholstery fabrics

This paper examines the standards for fire safety in transport systems and in particular the test method for the flammability of materials within passenger compartments of motor vehicles. The paper compares data from ignition tests conducted in the cone calorimeter and the FIST apparatus with tests conducted using the FMVSS 302 horizontal flame spread apparatus. Ten materials were selected as representative of those used as seat coverings of private and commercial passenger vehicles. The time to ignition of new and used materials subject to exposure heat fluxes between 20 kW/m² and 40 kW/m² was measured. The results from the ignition tests were analysed using thermally thick and thermally thin theoretical models. The critical heat flux for sustained piloted ignition was determined from the time to ignition data using the thermally thin approach. Derived ignition temperatures from both the thermally thick and thermally thin methods were compared with measurements using a thermocouple attached to the back surface of materials in selected tests. The flame spread rates in the FMVSS 302 apparatus were determined and a comparison was made between the performance of the materials in the flame spread apparatus, the cone calorimeter and the FIST. The results suggests that a critical heat flux criterion could be used to provide an equivalent pass/fail performance requirement to that specified by the horizontal flame spread test although further testing is needed to support this. Copyright © 2004 John Wiley & Sons, Ltd.     

Controlled-atmosphere cone calorimeter studies of silicones

A controlled-atmosphere cone calorimeter was used to investigate the burning of a silicone fluid and two silicone elastomers. The silicone materials were tested at 50 kW/m² incident heat flux in environments containing 15–30% oxygen. The test results were compared with a high molecular weight hydrocarbon fluid and an ethylene propylene rubber in terms of time to ignition, peak heat release rate and total heat released, carbon monoxide yield and carbon monoxide production rate, and smoke production and smoke production rate. The data from this study show that when materials burn in oxygen-enriched, normal, and vitiated atmospheres, silicone-based materials have a comparatively low peak heat release rate, total heat released, average CO production rate, and average smoke production rate as compared with organic-based materials. The smoke production and smoke production rate of silicone elastomers can be significantly reduced by adding appropriate smoke suppressants and additives. © 1997 John Wiley & Sons, Ltd.     

Thermal and chemical analysis of flammability and combustibility of fir wood in cone calorimeter coupled to FTIR apparatus

This paper deals with the thermal degradation of fir wood in a cone calorimeter under well‐ventilated atmosphere used with a piloted ignition. The thermal and chemical sample decompositions were studied with heat fluxes varying from 15 to 60 kW m^?2. With the cone calorimeter results and equations found in literature, the significant parameters of fir wood sample flammability and combustibility were deduced from ignition time (t_ig), mass loss and gas analysis. These parameters are thermal response parameter, critical heat flux, ignition surface temperature, thermal thickness, mass loss rate, thermal inertia, effective heat of combustion, heat release rate, heat of gasification and others. Moreover, during each experiment, the main gaseous species emissions were continuously and simultaneously monitored. Furthermore, the solid degradation and combustion process for fir wood were described in details. Experimental results from cone calorimeter were compared with data found in literature, and generally, a quite good accordance was found between the both sets of results. Copyright © 2013 John Wiley & Sons, Ltd.     

The rapid mass calorimeter: A route to high throughput fire testing

The rapid mass calorimeter based on reduced‐size specimens is proposed for accelerated fire testing and put up for discussion, particularly for flame retarded polymeric materials. A mass loss calorimeter is combined with a semiautomatic sample changer. Experiments on specimens of reduced size were conducted on poly(methyl methacrylate), poly(propylene), polyamide 66, poly(ether ether ketone), and pine sapwood square samples with edge lengths of 100, 75, 50, 25, 20, and 10 mm. Specimens of 20 × 20 mm² were selected to achieve a crucial reduction in specimen size and a measuring protocol developed. A total of 71 different polymeric materials were investigated in the rapid mass calorimeter and cone calorimeter for comparison and several materials with different heat release rate characteristics in the pyrolysis combustion flow calorimeter to test this additional screening method as well. The important fire properties obtained in the rapid mass calorimeter show reasonable correlation with the cone calorimeter results but also with the oxygen index. All in all, the rapid mass calorimeter produces reliable and meaningful results and, despite acceleration and size reduction, still allows for a certain degree of burning behavior interpretation. Material savings of 96% and time savings of around 60%‐70% are achieved compared to measure cone calorimeter.     

Experimental investigation and numerical modelling of the fire performance for epoxy resin carbon fibre composites of variable thicknesses

This paper applies a unique integrated approach to determine the flammability properties of a composite material (epoxy with carbon fibre) and compares its fire behaviour at two different thicknesses (2.1 and 4.2 mm) by performing small scale (thermo‐gravimetric analysis (TGA)/Fourier transform infrared radiation) and meso‐scale tests (cone calorimeter). For small‐scale tests, experiments were conducted in nitrogen using TGA coupled to gas analysis by Fourier transform infrared radiation. These results allow the determination of thermal stability, main degradation temperature and main gaseous emissions released during the thermal degradation. For meso‐scale tests, experiments were carried out using a cone calorimeter with sample dimensions of 100 × 100 mm at five heat fluxes (30, 40, 50, 60 and 70 kW/m²). The results show that the ignition time increases with an increase in the thickness of the material. Relative hazard classification of the fire performance of the current composites has also been compared with other materials using parameters obtained elsewhere. In addition, the effective ignition, thermal and pyrolysis properties obtained from the ignition and mass loss rate experiments for the 4.2‐mm thick samples were used in a numerical model for pyrolysis to predict well ignition times, back‐surface temperatures and mass pyrolysis rates for all heat fluxes as well as for the 2.1‐mm thick samples. Note that the ignition temperature obtained in the cone agrees with the main degradation temperature in the TGA. The flammability properties deduced here can be used to predict the heat release rate for real fire situations using CFD modelling. Copyright © 2016 John Wiley & Sons, Ltd.     

Effects of retainer frame,irradiance level and specimen thickness on cone calorimeter test results

The effects of retainer frame use, irradiance level and specimen thickness were studied as the second phase work of a round robin project on the cone calorimeter. The project was conducted in support of various U.S. building code groups, developing a system to determine the degrees of combustibility of building materials. The results of the second phase and a comparison with the corresponding round robin results conducted at 75 kW/m² according to the Board for the Coordination of the Model Codes (BCMC) protocol, are presented here. For most of the materials, no significant differences in parameters measured in the cone calorimeter were found when the retainer frame was not used, versus when the retainer frame was used. The irradiance of 50 kW/m² compared with 75 kW/m² produced significantly longer ignition times (with one exception) and lower heat‐release‐related variables as expected. The exception was gypsum board, for which heat release related values were usually higher at 50 kW/m² than at 75 kW/m². The specimen thickness effect could not be studied adequately due to the small number of tests conducted. A significant thickness effect was shown for the heat‐release‐related variables but not for time to ignition. The effect, however, was opposite for polyurethane foam in comparison with cellulosic materials. Copyright © 2004 John Wiley & Sons, Ltd.     

Heat release and classification of fire retardant wood products

A comparison is presented of cone calorimeter heat release data between fire retardant treated and untreated wood products. The test results show significant differences between these two groups. The parameters included in the comparison are time to ignition, rate of heat release (peak and average values) and total heat release. The wood-based products were also tested in different small-scale national standard fire tests and in the full-scale room fire test. Fire retardant wood products achieve an improved classification both in present national systems and in possible new systems based on the cone calorimeter and the room fire test.     

Evaluation of passenger train car materials in the cone calorimeter

Recent advances in fire test methods and hazard analysis techniques make it useful to re‐examine passenger train fire safety requirements. The use of test methods based on heat release rate (HRR), incorporated with fire modelling and hazard analysis, could permit the assessment of potential hazards under realistic fire conditions. The results of research directed at the evaluation of passenger train car interior materials in the cone calorimeter are presented. These measurements provide data necessary for fire modelling as well as quantitative data that can be used to evaluate the performance of component materials and assemblies. The cone calorimeter test data were also compared with test data resulting from individual bench‐test methods specified in the FRA fire safety guidelines. The majority of the tested materials which meet the current FRA guidelines show comparable performance in the cone calorimeter. Copyright © 1999 John Wiley & Sons, Ltd.     

Thermal degradation of epoxy resin/carbon fiber composites: Influence of carbon fiber fraction on the fire reaction properties and on the gaseous species release

The thermal degradation of epoxy resin/carbon fiber composites has been performed in ISO 5660 standard cone calorimeter using a piloted ignition. Two kinds of composites that differ by their volume fractions in carbon fiber (56 and 59 vol.%) were tested in this study. The cone calorimeter irradiance level was increased up to 75 kW m^?2 to characterize the carbon fiber volume fraction influence on the composite thermal degradation. Thus, main flammability and combustibility parameters were determined and calculated such as mass loss, mass loss rate, ignition time, thermal response parameter, ignition temperature, thermal inertia, and heat of gasification. As a result, all the characteristic parameters for the thermal resistance of composites were decreased when the carbon fiber volume fraction increased. Moreover, the main gaseous products (such as NO, CO, CO₂, HCN, H₂O, and lightweight hydrocarbons) emitted as well as the oxygen consumption during the composite thermal decomposition were also quantified simultaneously with a portable gas analyzer and a Fourier transform infrared spectrometer. The main species emission yields calculated from the gas analysis results increased slightly when the carbon fiber volume fraction was increased in the initial sample. The epoxy composite was represented as a sooty material with a significant production of soot particles during the combustion process. Furthermore, heat release rate, total heat release, and effective heat of combustion were calculated by using the oxygen consumption calorimetry technique. The results obtained showed that a small increasing of composite carbon fiber amount induced a sharp decrease of heat release rate and total heat release. Copyright © 2014 John Wiley & Sons, Ltd.     

Fire safety of thermoplastic polyurethane based on pyromellitic dianhydride

In this paper, pyromellitic dianhydride (PMDA) was firstly used as fire safety agent for thermoplastic polyurethane (TPU). And, the fire safety improvement of PMDA in TPU was intensively investigated by limiting oxygen index (LOI), smoke density test (SDT), cone calorimeter test, and thermogravimetric/infrared spectroscopy, respectively. It has been found that PMDA could significantly improve the ignition level, and the LOI value increase to 28.5% when 8.0 wt% PMDA was incorporated into TPU; PMDA also could effectively suppress the smoke production and heat release during the combustion process. The peak heat release rate and total smoke release of the sample with 8.0 wt% PMDA were decreased by 68% and 22% compared with pure TPU in cone calorimeter test. The thermogravimetric/infrared spectroscopy results showed that PMDA could improve the thermal stability of TPU composites at high temperature and increased the release of CO₂, H₂O, and so on. All results confirmed that PMDA would have a good prospect in reducing the fire hazard of TPU.     

Development of fire‐retarded materials—Interpretation of cone calorimeter data

There is little consensus within the fire science community on interpretation of cone calorimeter data, but there is a significant need to screen new flammability modified materials using the cone calorimeter. This article is the result of several discussions aiming to provide guidance in the use and interpretation of cone calorimetry for those directly involved with such measurements. This guidance is essentially empirical, and is not intended to replace the comprehensive scientific studies that already exist. The guidance discusses the fire scenario with respect to applied heat flux, length scale, temperature, ventilation, anaerobic pyrolysis and set‐up represented by the cone calorimeter. The fire properties measured in the cone calorimeter are discussed, including heat release rate and its peak, the mass loss and char yield, effective heat of combustion and combustion efficiency, time to ignition and CO and smoke production together with deduced quantities such as FIGRA and MARHE. Special comments are made on the use of the cone calorimeter relating to sample thickness, textiles, foams and intumescent materials, and the distance of the cone heater from the sample surface. Finally, the relationship between cone calorimetry data and other tests is discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

An assessment of PVC smoke

The conventional test method for evaluating the potential of a material to produce smoke in a real fire is the NBS Smoke Density Chamber. However there are major problems with this approach. These include foremost the fact that its results do not correlate with those of real fires. Furthermore, materials that melt and drip are able to achieve a favorable, but misleading, evaluation because a significant fraction of the sample escapes the burning process. Another problem is that the test takes no account of the role the rate or extent of material burning plays in controlling the smoke density in a real fire situation. The physical problems are solved by material smoke production evaluation techniques based on measurements from the Cone Calorimeter rate of heat release apparatus, which has been developed by the National Bureau of Standards. A smoke parameter has been developed, calculated from cone calorimeter measurements, which reflects the smoke hazard of a real fire. The smoke evolution characteristics for a series of rigid thermoplastic materials have been measured using the cone calorimeter and the smoke parameter concept. The results demonstrate that due to its tendency to resist ignition and to burn very slowly, PVC would produce very little smoke in a real fire situation. Of the 15 materials tested, the expected real fire smoke performance characteristics of PVC were superior to those of all other materials except one.     

Fire performance studies on glass-reinforced plastic laminates

Polyester, epoxy and phenolic glass-reinforced laminates were compared in terms of their fire properties in the cone calorimeter. The presence of a gel coat on the polyester and epoxy products had some effect, mainly in the FR grades. The FR polyester with a brominated flame retardant showed a marked decrease in rate of heat release and in rate of smoke production. Aluminium hydroxide (commonly called alumina trihydrate of ATH) caused a significant delay in ignition time for the epoxy product and some reduction in rate of heat release but rate of smoke release was still relatively high. Phenolic laminates showed a long ignition time and relatively low rate of heat release (RHR). The peak RHR was further reduced by the presence of aluminium hydroxide and by changing the type of glass reinforcement. The influence of thickness was explored for a series of phenolic laminates in both cone calorimeter and the International Maritime Organization (IMO) surface flammability test. Ignition delay time was significantly affected and the cone calorimeter results showed that the shape of the RHR curve was also changed as the thickness increased. However, the heat release measurements in the IMO test were not sensitive enough to pick up the differences in this property. The type of substrate under the laminate significantly altered the burning rate but this may have been because they were not glued or mechanically fixed.     

Flammability testing of pure and flame retardant-treated cotton fabrics

A Controlled-atomosphere cone calorimeter was used to investigate the burning of pure and flame retardant-treated cotton fabrics. The condensed-phase flame retardants used were Morguard (containing ammonium dihydrogen phosphate and diammonium hydrogen phoisphate) and Nochar (containing ammonium sulfate and a sodium salt). The fabrics were tested at 25 kW m^?2 incident heat flux in environments containing 15–30% oxygen. The flame retardants increased the time to ignition, residue yield, and CO and CO₂ yields. The flame retardants decreased the peak and average mass loss rates, the peak and average heat release rates, the effective heat of combustion at peak heat release rate, and the propensity to flashover. The effect of oxygen concentration on the burning of pure and flame retardant-treated cotton fabrics has also been investigated. The flame retardants had better performance when the treated fabrics burned in the lower oxyge concentrations. The result of this study indicate that the controlled-atmosphere cone calorimeter is a good tool for studying the effect of flame retardant and oxygen concentration on the burning of materials.     

Enhancement of fire retardancy properties of glass fibre–reinforced polyesters composites

This paper presents the results of an experimental investigation on the fire retardancy properties of glass fibre–reinforced polyester (GFRP) composites with bisphenol‐A vinylester and isophthalic polyester as matrices and low electrical conductivity E‐glass fibres as reinforcement. The fire protection systems tested were alumina trihydrate (ATH), decabromodiphenyl ether (DBDE), and antimony trioxide (Sb₂O₃). A mass loss cone calorimeter was used to obtain the properties of heat release rate (HRR), peak HRR, total heat released, total mass loss, time to ignition, and time of combustion. Moreover, limiting oxygen index (LOI), UL‐94, and glow‐wire tests were also performed. The fire tests were carried out in order to investigate if the combination of ATH and DBDE could have “additive,” “antagonistic,” or “synergistic” effects on the flame retardant properties of the GFRP studied in this work. In addition, the influence of the ATH content variation on flame retardant properties was also evaluated. The results indicate that the sole addition of ATH at 47.7 phr could lead to the complete inhibition of the composites ignition, while the materials containing DBDE exhibit ignition and flame propagation in the cone calorimeter test.     

Evaluation of thermal fire hazard of 10 polymeric building materials and proposing a classification method based on cone calorimeter results

The use of polymeric building materials has been grown in many countries of Middle East in recent years. However, there are only a few fire testing laboratories in this region. Therefore, development of a method for controlling the reaction to fire of materials with bench scale tests is necessary. Providing a framework for classification of thermal fire hazard of materials based on bench scale heat release rate results was attempted. The fire behavior of 10 polymeric building materials was tested with cone calorimeter. The relationship between reaction to fire variables and physical properties of tested samples was examined. The thermal fire hazards of materials were assessed using methods presented by different researchers and with Conetools software. The results revealed that time to ignition, peak rate of heat release, and total heat release are essential variables for determining the fire hazard of materials. A classification method is proposed, which can be used in building codes in countries where the full‐scale test facilities are not available. The method also can be used for quality control purpose and evaluation of fire behavior of materials in bench scale by manufacturers. An example of potential requirements for interior finishes for some occupancy types is also presented. Copyright © 2013 John Wiley & Sons, Ltd.