Surface temperature at ignition of wooden based slabs (original) (raw)
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Ignition of Wood-Based Boards by Radiant Heat
Forests
Particleboards (PB) and oriented strand boards (OSB) are commonly used materials in building structures or building interiors. The surface of boards may hence become directly exposed to fire or radiant heat. The aim of this paper is to evaluate the behaviour of uncoated particleboards and OSB exposed to radiant heat. The following ignition parameters were used to observe the process of particleboard and OSB ignition: heat flux intensity (from 43 to 50 kW.m-2) and ignition temperature. The time-to-ignition and mass loss of particleboards and OSB with thicknesses of 12, 15 and 18 mm were monitored and compared. The experiments were conducted on a modified device in accordance with ISO 5657: 1997. Results confirmed thermal degradation of samples. Heat flux had a significant effect on mass loss (burning rate) and time-to-ignition. OSB had higher ignition time than particleboards and the thermal degradation of OSB started later, i.e., at a higher temperature than that of particleboards, ...
Ignition of wood-based materials by thermal radiation
International Journal on Engineering Performance-Based Fire Codes, 2006
Ignition is the initial stage of burning the materials. Consequent flame spread over the materials, heat release rate, fire spread across the rooms, and other issues for building fires all depend on that. Ignition of cellulose materials is commonly classified as smoldering or glowing ignition (self-heating ignition) and flaming ignition including piloted and spontaneous ignition. Numerous studies on this topic were reported in the literature. A review on ignition of wood will be reported in this paper. Ignition temperature, critical mass flux of volatiles, time to ignition, critical heat flux and critical heat release were measured experimentally and applied as key ignition criteria for theoretical analysis. Quantitative study on modeling smoldering ignition of cellulosic materials is not yet well understood. As experimental data is inadequate, this part is only briefly discussed. Models of flaming ignition were well developed from those well validating experimental data. However, most of the flaming ignition models of wood were only on the solid phase. Gas phase phenomena during ignition should be further examined for developing flaming ignition models.
International Journal on Engineering Performance-Based Fire Codes, 2002
It is necessary to study the fire behaviour of plywood as the material is widely used for partitioning places into rooms. For example, most of the karaoke boxes built six years ago are made of plywood boards. In this paper, studies on burning behaviour of plywood samples by a cone calorimeter are reported. From the results, ignition time and time to first peak for different incident heat fluxes and samples thickness are discussed. It is observed from this study that shorter ignition time was found under higher heat flux, even for thicker plywood samples. For example, by increasing the heat flux from 20 kWm-2 to 50 kWm-2 on plywood of 6 mm thick under ambient condition, the ignition time reduced from 191 s to 13 s. The ignition time decreased from 191 s to 152 s when the thickness of plywood sample was increased from 6 mm to 18 mm.
Experimental tools applied to the ignition study of spruce wood under cone calorimeter
Journal of Physics: Conference Series, 2018
Wood-based materials, which are more and more used in building construction, are often characterized by normative tests using the cone calorimeter. The ignition time and temperature, the mass loss rate or heat release rate are the most current measurements performed. The sample ignition can vary according to a large number of variables (humidity, density, scale sample, experimental conditions). The auto ignition phenomenon has been studied so far but opinions concerning the involved physical processes remain controversial. The purpose of the present work is to improve the study of thermal degradation of wood under cone calorimeter thanks to a dedicated experimental set up. This set up includes mainly, an infrared camera, enabling an accurate surface temperature measurement and a fast visible camera (3000 fps), used to highlight the "auto" ignition phenomenon. Surface temperature and mass loss rate evolution are presented for different heat flux expositions. The fast visible camera pictures showed an ignition piloted by the coil. The ignition occurs only above 55 kW.m-2. When this external heat flux was sufficiently low, it was possible to observe the transition between pyrolysis solely and smouldering combustion for a sample surface temperature around 400 ° C.
Assessing fire behaviour of common building materials with a cone calorimeter
International Journal on Architectural Science, 2004
Fire behaviour of selected samples of building materials including wood and plastic materials such as polyvinyl chloride (PVC) and poly(methyl methacrylate) (PMMA) commonly used in the market were assessed. Both thermal aspects and smoke toxicity were studied by testing the samples of wood, PVC and PMMA in a cone calorimeter. PVC was found to be very toxic as it has the smallest value of smoke potency. Not much smoke was given out in testing wood with a cone calorimeter. PMMA has a higher value of smoke potency, appeared to be not so toxic. A flashover heat flux at floor level of 20 kWm-2 was applied. It was found that under such heat flux, both wood and PMMA were ignited, but PVC was very difficult to ignite. Therefore, the thermal effects of burning PVC by an accidental fire would not be so bad. However, when the heat flux was increased to 50 kWm-2 , smoke would give problems upon ignition of the materials.
2016
Maple plywood samples were heated in an oven at 180°C to a residual weight of 70%, 50%, and 30 % of the virgin weight. The virgin plywood and the thermally pretreated samples were tested in a cone calorimeter over the range of 6 to 15 kW/m2 without the use of an ignitor. Tests were conducted until smoldering/glowing combustion was observed or for eight hours if ignition was not observed. The extent of thermal pretreatment of the plywood had no measurable effect on the minimum heat flux for smoldering ignition. At heat fluxes above the minimum for ignition, ignition times were reduced for thermally pretreated samples relative to virgin wood. This is consistent with the thermal pretreatment achieving the charring required as the first step in smoldering ignition and the reduction in thermal inertia resulting from charring. Samples of the virgin and pretreated wood were subjected to thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The chemical kinetics anal...
On the Thermal Ignition of Combustible Materials
Formulas are derived for the time to achieve the ignition temperature as a function of the incident heat flux and the various thermophysical material parameters for thermally thick, thermally thin and thermally intermediate solid combustibles. Predictions are compared with recent experimental data for various natural wood species and wood products, and to previous data for wood and thermoplastics. The correlations are excellent when (1) the physical parameters used as the axes of the plots are chosen consistent with those of the theoretical formulas and (2) the experiments and the materials do not violate any of the restrictions imposed by the theory. From these plots it is easy to estimate the minimum heat flux for ignition, which is of great importance both in practice and for making theoretical predictions.
Fire Safety Journal, 2001
This paper experimentally and theoretically examines the ignition of 50 mm thick samples of wood in the Cone Calorimeter. Four species of wood were exposed to a range of incident heat fluxes up to 75 kW/m 2 with their grain oriented either parallel or perpendicular to the incident heat flux. The time to ignition measurements obtained from the Cone Calorimeter were used to derive characteristic properties of the materials. These properties were used as input to a one-dimensional integral model that describes the transient pyrolysis of a semi-infinite charring solid subject to a constant radiant heat flux.
International Journal on Engineering Performance-Based Fire Codes, 2005
Fire behaviour of timber partition materials were assessed in a room calorimeter with size following ISO 9705. Fourteen full-scale burning tests on timber materials used in the local industry with and without paint, wallpaper, fiberglass and fire retardant were carried out. The heat release rate, surface temperature of materials, upper layer gas temperature, floor heat flux and time to flashover were recorded. Flame spreading over the materials was observed. Results are useful for comparing the flame spreading behaviour of different surfacing and insulating materials with and without fire retardants. It is observed that materials with rapid flame spreading rate might not necessarily give a shorter time to flashover. The performance of fire retardant depends on the substrate and the orientation of the materials.
Assessment of fire behaviour of timber partition materials with a room calorimeter
International Journal on Engineering Performance-Based Fire Codes, 2007
Fire behaviour of timber partition materials were assessed in a room calorimeter with size following ISO 9705. Fourteen full-scale burning tests on timber materials used in the local industry with and without paint, wallpaper, fiberglass and fire retardant were carried out. The heat release rate, surface temperature of materials, upper layer gas temperature, floor heat flux and time to flashover were recorded. Flame spreading over the materials was observed. Results are useful for comparing the flame spreading behaviour of different surfacing and insulating material with and without fire retardants. It is observed that materials with rapid flame spreading rate might not necessarily give a shorter time to flashover. The performance of fire retardant depends on the substrate and the orientation of the materials.