Smoke data from the Cone Calorimeter for comparison with the room fire test

Smoke production in the full–scale room fire test ISO 9705 (Commonly referred to as the Room Corner Test) and in the Cone Calorimeter ISO 5660 has been analysed for three sets of building products comprising a total of 28 products. The smoke production may be critical for the fire classification of surface products since some products produce large amounts of smoke in the room fire test even if they do not reach flashover within 20 min. Several smoke parameters in the Cone Calorimeter and the room fire test have been analysed. Good correlations have been obtained when the products are divided into two groups: products with more than 10 min to flashover in the room fire test and those with less than 10 min. These two time categories correspond to the two heat output levels in the room fire test: 100 kW for the first 10 min and then 300 kW up to 20 min. For products with more than 10 min to flashover the average rate of smoke production and the total smoke production seem to be useful parameters for predictions of smoke release in the room fire test. Both parameters have good correlations between data from the Cone Calorimeter and the room fire test. For products with less than 10 min to flashover no parameter seems to give useful predictions. For all products evaluated together, the correlations are not so good, but the same regression lines as for products with more than 10 min might be used as a first rough estimate. In this case the total smoke production in the Cone Calorimeter could be used to estimate the total smoke production in the room fire test for different building products, independent of their estimated time to flashover. It is suggested that the average rate of smoke production and the total smoke production from the Cone Calorimeter is reported in addition to the mass-based specific extinction area. This will be helpful in predicting smoke release in the room fire test and will also make the data on smoke release analogous to those on heat release.     

Thermal analysis of polymer ignition

Gas phase criteria for the onset of flaming combustion of solids in fires are used to locate a critical temperature T_cr in a nonisothermal analysis (TA) experiment that corresponds to the surface temperature of the solid at ignition in a fire test, T_ign. This critical TA temperature occurs at low conversion of solid to gaseous fuel so it is independent of the heating rate in the test or the thermal decomposition reaction model. However, T_cr depends on the thermal properties of the polymer and the conditions of the fire test in which the gas phase criteria were measured. Nonisothermal analysis data in nitrogen and air were obtained for 20 polymers by thermogravimetric analysis and microscale combustion calorimetry. The critical temperatures T_crs obtained from TA experiments compared favorably with analytic results for a simple polymer ignition model and finite element simulations and were in qualitative agreement with ignition temperatures measured in standardized fire tests.     

Empirical prediction of smoke production in the ISO Room Corner Fire Test by use of ISO Cone Calorimeter Fire Test data

The combustion conditions in the ISO Room Corner Fire Test make it possible to predict full scale smoke production by use of prediction models and bench scale fire test data procured by the ISO Cone Calorimeter Fire Test. The full scale smoke production is governed by the type of material burning only if the rate of heat release is less than 400–600 kW. For higher rates of heat release, the smoke production is more governed by the combustion conditions. The influence of the combustion conditions on the full scale smoke production reduces the possibilities of smoke prediction to materials causing flashover within 10 min in the ISO Room Corner Fire Test. The smoke to heat ratio S_Q (m²MJ) was used to compare smoke production between the scales. In general, the comparison revealed that the smoke yield was significantly less in full scale than in bench scale, especially for the plastics. Plastics do yield more smoke than wood based materials in both scales, but the differences in full scale are not as extreme as indicated by the bench scale smoke data. No simple correlations between the scales seem to exist. Multiple regression studies on empirical smoke prediction models show that bench scale fire parameters can be used to predict full scale fire performance. A quite accurate empirical smoke prediction model is presented for the group of materials which caused flashover within 10 min. The model predicts the full scale rate of smoke production at a rate of heat release of 400 kW. The presented results might be used to assess the fire safety hazard of visible smoke, but benchmarks of smoke hazard do not seem to exist. Thus further studies and agreement on safety levels and principles are needed for general visibility analysis concerning fire safety engineering purposes. Copyright © 1999 John Wiley & Sons, Ltd.     

Study on flashover in a single chamber lined with combustible materials

With the theories of fire dynamics and relevant parameters of combustible lining materials, a predicted model of hot gas layer temperature during pre‐flashover stage of enclosure fires was established, and the effects of lining materials on the likelihood of flashover were theoretically analyzed. By using common commercial lining materials, such as wall papers, foam plastics, wood‐based panels, and fabric‐upholstered wall panel, the phenomenon of flashover was reproduced in a small‐scale firebox of 1/4 sizes of ISO 9705 test chamber. By comparing the theoretical results with experimental data, the equation predicting the hot gas layer of quasi‐steady enclosure fires was gained; an indicator I_FO to reflect overall the hazards of flashover and to classify flashover fires was proposed, and its application was initially studied. The study results can be helpful to explain further and overall the effects of lining materials on enclosure fires and can be used to guide the prevention of flashover by choosing appropriate interior decoration materials. Copyright © 2012 John Wiley & Sons, Ltd.     

Correlation between cone calorimeter data and time to flashover in the room fire test

Correlations based on linear regressions between data as time to ignition and heat release in the cone calorimeter and time to flashover in the room fire test have been developed. They are a further development of an earlier approach which has been modified and extended to a wider range of surface linings. The correlations apply so far only to surface linings on both walls and ceilings. When the density of the linings as a simplified measure of the thermal inertia is included, the correlations are improved significantly. The new correlations are based on data readily available from the cone calorimeter test at one heat flux level, 50 kWm^?2. The correlation coefficient for the basic relationship, including the density of the linings, is now 0.98 when applied to the 13 linings investigated earlier. This is slightly better than the previous study, in which the best correlation coefficient was 0.96. When applied to 28 linings, the correlation coefficient remains about the same (0.97). Very similar regression equations have been obtained when analysing only 13 products and all 28. This is a strong indication of the general predictive capacity of this approach. The inclusion of other data such as thickness of linings or mass loss during fire does not improve the correlation coefficients. The approach is quite straightforward and simple. However, it has provided a useful prediction which is also valid for an extended range of linings.     

Experimental study on fire hazard of typical curtain materials in ISO 9705 fire test room

Curtain materials are commonly used as decoration, shade, or screen. They are flammable and are usually across a large part of a room, leading to the risk of a high fire hazard. Once ignited, the upward fire spread would accelerate the fire development in an enclosure. In this paper, fire hazard of three typical curtain materials with different pleat rates were tested in an ISO 9705 fire test room. Fire parameters such as temperature field, flame spread rate, heat release rate (HRR), and emitted gases, and the influences of pleat rate and cotton content on flame spread rate were investigated. The correlation between flame spread rate and HRR was discussed. The results show that the upward flame spread has an accelerating rate, and an inverted‐triangle burning area would emerge during the combustion. Some horizontal fibrillar structures appear in this burning area. Pleat rate and cotton content have considerable influence on the curtain fire behavior. The flame spread rate shows a linear response to HRR at the early stage. In addition, a function between average flame spread rate and pleat rate for engineering estimation is proposed, and a linear relationship between HRR/m_CO and m/m_CO has been obtained. The study results provide valuable reference to building fire simulation and safety design. Copyright © 2011 John Wiley & Sons, Ltd.     

A correlation for predicting smoke layer temperature in a room adjacent to a room involved in a pre‐flashover fire

Advanced fire modelling software have been developed and improved during the last couple of decays and these kinds of software have been shown to be valuable tools for fire safety engineers. However, the advances made have not replaced the need for simple hand‐calculation methods. Simple hand‐calculations methods can be used to obtain a first estimate of, for example, smoke layer temperatures in a performance‐based design or to help an engineer determine if it is necessary to perform a detailed computational fluid dynamics calculation, but the current hand‐calculations methods are limited. The current methods can for example only predict smoke gas temperatures in the fire room. A correlation that could predict temperatures in an adjacent space would be useful in performance‐based design when, for example, evaluating the conditions for evacuees or sensitive equipment in an adjacent space to the room of fire origin. In this paper, a correlation for predicting gas temperatures in a room adjacent to a room involved in a pre‐flashover fire is developed. The correlation is derived from results from computer simulations and the external validity is studied by comparing results from the correlation with full‐scale test data. Copyright © 2012 John Wiley & Sons, Ltd.     

Improved flashover performance and tracking resistance of silicone rubber by direct fluorination

Silicone rubber (SIR) samples are fluorinated using a F₂/N₂ mixture at different temperatures. Physicochemical characteristics are analyzed by attenuated total reflection infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. Basic properties of the fluorinated surface layers are investigated, and the intrinsic alternating current (AC) flashover performance and tracking resistance of the surface fluorinated samples are evaluated. The flashover test results indicate that the fluorination leads to an improvement in AC flashover performance of the SIR material, as a result of the competition between the favorable effect of the increase in surface conduction and the adverse effect of a likely increase in surface layer permittivity. The increase in AC flashover voltage is associated with the voltage-increasing mode of the flashover test. The flashover test results also show an improved tracking resistance of the SIR material by the fluorination, and the improvement is especially significant for the fluorinated surface layer that has less cleavage of Si C bonds or a good compactness as well as a large thickness. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48556.     

Thermal stability and mechanical properties of room temperature vulcanized silicone rubbers

Based on much of the importance of RTV on the field of self-cleaning application for its nontoxic, tasteless, and thermal stability, the effects of D₄-SiO₂ on mechanical properties, Al(OH)₃ and decabromodiphenyl oxide ethyl(DBDPE) on flame retardant property of RTV matrix were investigated firstly. Then, a new kind of complex fire retardants was compounded. The morphology of additives and fracture appearance of composites were demonstrated by SEM. The hot property of RTV-based composites was outlined by TG. It is found that D₄-SiO₂/Al(OH)₃/DBDPE/Sb₂O₃/RTV composites were of better comprehensive performances in mechanical property, hot property, fire resistance property, and insulating property, which presented tear 26.73 kN/m of strength, 279.8% of elongation at break, 2.81 MPa of tensile strength, FV-0 at the level of flame retardant property, 46 of Oxygen index (OI) 3.03 × 10¹⁵ Ωm of Volume electric resistivity, the range of decomposition temperature was 370°C to 650°C, and the percentage of remain weight was 26.4%. Those properties was acquired on the condition of 11 wt % D₄-SiO₂ + 20 wt % Al(OH)₃ + 15 wt % DBDPE+ Sb₂O₃ at the amount of 3.0 wt % to 3.7 wt %. This investigation leads the authors to a conclusion that D₄-SiO₂/Al(OH)₃/DBDPE/Sb₂O₃ is a kind of better combination modifier than anyone kind of which in comprehensive properties for RTV. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Fire effluent component yields from room‐scale fire tests

Estimation of the time available for escape (ASET) in the event of a fire is a principal component in fire hazard or risk assessment. Valid data on the yields of toxic smoke components from bench‐scale apparatus is essential to accurate ASET calculations. This paper presents a methodology for obtaining pre‐flashover and post‐flashover toxicant yields from room‐scale fire tests. The data are to be used for comparison with bench‐scale data for the same combustibles: a sofa, bookcases, and electric power cable. Each was burned in a room with a long adjacent corridor. The yields of CO₂, CO, HCl, HCN, and soot were determined. Other toxicants (NO₂, formaldehyde, and acrolein), whose concentrations were below the detection limits, were of limited importance relative to the detected toxicants. The uncertainty values were comparable to those estimated for calculations used to determine ASET and were sufficiently small to determine whether a bench‐scale apparatus is producing results that are similar to the real‐scale results here. The use of Fourier transform infrared spectroscopy was useful for obtaining toxicant concentration data; however, its operation and interpretation are not routine. The losses of CO, HCN, and HCl along the corridor were dependent on the combustible. Copyright © 2009 John Wiley & Sons, Ltd.     

A two‐step method for predicting time to flashover in room corner test fires using cone calorimeter data

A method to predict time to flashover in ISO 9705 room corner fire tests based on cone calorimeter data is proposed in this paper. The method involves classification of materials and estimation of time to flashover as two steps in sequence. In the first step, the investigated material is classified into discriminating material groups. In the second step, the time to flashover is calculated with a derived formula for the corresponding material group, which contains material density, time to ignition and heat release rate collected from small‐scale experiments. Compared with two existing models, the proposed method has improved the prediction precisions in both the time to flashover and classification of material categories for a wide range of materials. Copyright © 2012 John Wiley & Sons, Ltd.     

Improving Thermal Stability and Electrical Insulation of Gamma‐Irradiated Silicone Rubber Nanocomposites

Room temperature vulcanized silicone rubber (RTVSR) nanocomposites were prepared by mixing of surface‐modified montmorillonite nanoclay or nano fumed silica, or both of them with RTVSR to improve thermal stability, electrical insulation, and flame retardant. Their tensile strength, elongation, swelling, and solubility properties at different doses of gamma radiation were investigated to study the effect of gamma radiation on the properties of the nanocomposites. The thermal stability, flammability properties, and volume resistivity of the nanocomposites were also investigated. The nanocomposite which containing fumed silica has the best thermal, mechanical properties, electrical insulation and fire retardancy. The thermal characteristics, namely, T_onset, T_10%, T_comp, and T_max, of the nanocomposite sample containing fumed silica were 22, 23, 13, and 11 °C higher than those of the blank, respectively. The tensile strength (TS) increased when the radiation dose was increased up to 100 kGy, but elongation, swelling, and solubility decreased when the radiation dose was increased up to 150 kGy. It can be generally concluded that the nanocomposites containing fumed silica and irradiated to 100 kGy are characterized by having outstanding mechanical, thermal, fire retardant, and electrical insulation properties and hence, they may have wide industrial applications as good thermal and electrical insulating materials. J. VINYL ADDIT. TECHNOL., 26:354–361, 2020. © 2019 Society of Plastics Engineers     

The generation of CO in bench-scale fire tests and the prediction for real-scale fires

Carbon monoxide (CO) is the single most important factor associated with deaths in fires; thus, predictions of CO developed in fires is an essential aspect of fire quantification. It is considered crucial to have correct CO prediction methods for post-flashover fire stages, since, in the United States at least, the majority of fire deaths are associated with fires which have gone to flashover. In this paper it is shown that the yiels of CO observed in real-scale fires are generally not related to either the chemical nature of the material being burned nor to the yield observed for the same material in bench-scale testing. Instead, the generation of CO in real-scale fires is determined largely according to the oxygen available for combustion, with thermal conditions of the fire plume also playing a significant role. This behavior is in sharp contrast to many other material fire properties, including yields of gases such as CO₂ and HCI, which can be predicated for real-scale fires from bench-scale results. Finally, results from various studies completed thus far indicate how effective prediction of real-scale CO yields may be accomplished. While bench-scale measurements are not necessary to predict real-scale CO, bench-scale toxic potency measurements can be in error if the CO component in them does not reflect on the real-scale CO yield. Thus, a method is developed whereby the bench-scale toxic potency measurements can be computationally corected to better approximate the toxic potencies measured in real-scale, post-flashover room fires. These techniques will, undobtedly, be further refined as additional experimental results become available.     

Studies of fundamental physical–chemical mechanisms and processes of flame extinguishing by powder aerosols

Theoretical and experimental studies on mechanisms of interaction of the fire‐extinguishing aerosol with flame are carried out. The factors of heterogeneous inhibition of flame free radicals (O, OH, H, CH_x) on a crystal surface of inorganic salts being the basic components of fire‐extinguishing powders and aerosols are measured using laboratory equipment. The semi‐empirical calculations by methods of quantum chemistry for heterogeneous and homogeneous inhibition reactions of burning are executed. The thermal mechanism for fire extinguishing is evaluated. The universal mechanism of influence on flame of a crystal surface of a fire‐extinguishing powder particle is offered. Copyright © 2007 John Wiley & Sons, Ltd.     

Measurement of thermal properties of polyaniline/metal from room temperature to 170°C

The heat transfer through polyaniline (PANI) mixed with metals (manganese and iron) is studied by measuring its effective thermal conductivity (λ_e) and effective thermal diffusivity (χ_e) from room temperature to 170°C at normal pressure. Simultaneous measurements of the λ_e and χ_e values of samples A (100% Fe), B (50% Fe and 50% Mn), and C (100% Mn) of the PANI mixtures with different percentages of Fe and Mn are carried out using the transient plane source technique. It is observed that the λ_e and χ_e of the above samples are almost independent of the temperature in a range of temperatures. However, maximum values for the λ_e and χ_e are found for sample A at ～140°C, sample B at ～130°C, and sample C at ～120°C. An empirical relationship deduced from a polynomial fit of the experimental data is established for the temperature dependence of the λ_e and χ_e values of these samples. Reasonably good agreement is obtained between the theoretically predicted results and the experimental data. This behavior is explained on the basis of bond formation between the metals (Fe and Mn) and nitrogen of the PANI matrix. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 430–435, 2003     

Studies of the combined effects of some important factors on the likelihood of flashover

Among those factors that affect the likelihood of flashover in enclosure fires, the thermal inertia of lining materials, ventilation factor of door openings, heat release rate of fuel, and internal dimensions of the enclosure are the most important. The effects of the four factors are related, so it is very necessary to study their combined effects. In the present study, based on analyzing the approximate heat balance on the control volume similar to that in the MQH method, a dimensional relationship was derived that facilitates the estimation of pre‐flashover temperatures, which is used in the popular guidance literature as the key parameters for practical methods of predicting flashover. By correlating a vast amount of data gained in both small‐scale and large‐scale enclosure fire experiments, an important equation was obtained, which can embody explicitly and quantitatively the combined effects of the four important factors on the likelihood of flashover. According to the temperature criteria of 600°C identifying flashover, a new ‘combined method of predicting flashover’ was put forward. The validity of the method was verified in small‐scale experiments, and the results showed that it could be applied to predict well whether flashover occurs in enclosure fires or not. Copyright © 2010 John Wiley & Sons, Ltd.     

Study of the relationship between thermal insulation behavior and microstructure of a fire‐resistant gel containing silica during heating

Adding a transparent gel containing silica between 2 sheets of glass could improve the fire resistance of laminated glazing by its thermal intumescent behavior at high temperature. In this study, a custom fire test shows that the glazing reaches the highest thermal insulation rating of 40 minutes when the molar ratio of SiO₂ and Na₂O in the gel is 4.0, but above this ratio, the thermal insulation rating of the glazing decreases with the increasing silica content. Thermal and scanning electron microscopic analyses have been used to investigate the thermal behavior and microstructure of the residual layer, respectively. The results indicate that, although the high silica content is responsible for the high amount of residue that is essential in the formation of a protection barrier between fire‐exposed and unexposed sides of the glass, it is not the only factor that resulted in the improved thermal insulation of the glazing.     

Metal‐coordinated epoxy polymers with suppressed combustibility. Preparation technology,thermal degradation,and combustibility test of new epoxy‐amine polymers containing the curing agent with chelated copper(II) carbonate

The diethylenetriamine chelate complex of copper(II) carbonate—DETA‐CuCO₃ (a fire retardant hardener of epoxy resins)—and the CuCO₃‐containing epoxy‐amine polymers—DGEBA/DETA‐CuCO₃(6), DGEBA/DETA‐CuCO₃(12), DGEBA/DETA‐CuCO₃(40), and DGEBA/DETA‐CuCO₃(80) with suppressed combustibility—have been obtained in the DETA‐DGEBA‐CuCO₃ system (DETA and DGEBA are diethylenetriamine and bisphenol A diglycidyl ether, respectively). The DETA‐CuCO₃ chelate complex was characterized by X‐ray powder diffraction, infrared spectra, and thermal analysis. The thermal gravimetric analysis results have revealed that thermal destruction of DETA‐CuCO₃ was finished at 400°С, and the maximal temperature of the combustion gases amounted to 520°С. The thermal behavior and combustibility of the CuCO₃‐containing epoxy‐amine polymers were studied using thermal analysis and “Ceramic tube” (CT) method. Thermal gravimetric analysis confirms that incorporation of the DETA‐CuCO₃ into DGEBA appreciably heightens the thermal stability and antiflammability of the CuCO₃‐containing epoxy‐amine polymers. Results of CT measurement reveal that maximal temperature of the combustion gases under burning of the DGEBA/DETA‐CuCO₃(12) sample in comparison with unmodified epoxy‐amine polymer (DGEBA/DETA) is lowered on 219°С and the loss of weight is decreased on 20.5 wt%. According to ASTM 635‐14, ASTM D2863‐13, and ASTM D1929‐16, the flame propagation rate, limiting oxygen index, and temperatures of ignition and self‐ignition have been measured for the elaborated polymer samples.     

Preparation and properties of polyurethane/montmorillonite nanocomposites cured under room temperature

The polyurethane/C₁₆C₁₈‐MMT (the montmorillonite modified with cetyloctadecyldimethyl ammonium bromide) nanocomposites were synthesized by intercalative polymerization and cured under room temperature. The d‐spacing and the dispersion of the C₁₆C₁₈‐MMT in the nanocomposites were measured by X‐ray Diffraction (XRD) and Transmission Electron Microscope (TEM). The mechanical and thermal properties of the nanocomposites were measured by Universal Testing System, Electric Anti‐fold Instrument, Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC). It was found out that introducing C₁₆C₁₈‐montmorillonite (MMT) in the polyurethane (PU) displayed good mechanical properties and thermal stability. Rheology behavior in liquid state showed that the addition of the C₁₆C₁₈‐MMT to PU resulted in low gel time and high viscosity. POLYM. COMPOS. 27:470–474, 2006. © 2006 Society of Plastics Engineers.     

Mechanical tailoring of dislocation densities in SrTiO3 at room temperature

Dislocation-tuned functional properties such as electrical conductivity, thermal conductivity, and ferroelectric properties in oxides are attracting increasing research interest. A prerequisite for harvesting these functional properties in oxides requires successful introduction and control of dislocation density and arrangement without forming cracks, which is a great challenge due to their brittle nature. Here, we report a simple method to mechanically tailor the dislocation densities in single-crystal perovskite SrTiO₃. By using a millimeter-sized Brinell indenter, dislocation densities from ∼10¹⁰ to ∼10¹³ m⁻² are achieved by increasing the number of indenting cycles. Depending on tip radius and indenting load, large and crack-free plastic zones over hundreds of micrometers are created. The dislocation multiplication mechanisms are discussed, and the work hardening in the plastic zone is evaluated by micro-hardness measurement as a function of dislocation density. This simple approach opens many new opportunities in the area of dislocation-tuned functional and mechanical studies.