Flame Spread Over Two Extruded Insulation Material Foam Slabs Side By Side

Fire is the combustion phenomenon that out of control in the space and time. According the evolution process of the building fire, it can be divided into the solid fuel pyrolysis initial stage, flame spread development stage, combustion stable stage, and the flame slowly extinguished stage. Flame spread of solid combustible is one of important subprocedures in initial and development stage in fire which determine the whole fire speed and combustion intensity, and thus have been the focus of many researchers in the last decades. As the city of complicated layout, the form of fire occurs, development is diversified, especially the heat preservation material which is widely used in high-rise building external wall material, but its parallel fire burning spread behavior is seldom paid attention by researchers. When an external fire source or heat radiation onto the material, pyrolysis reaction will happen after absorbing heat flux, then the flammable gas diffuse to the ambient environment and mixed with air at the surface of slab which combustion reaction take place when up to a certain concentration of chemical reaction. Because of its unique thermal material properties, the material appears a large number of melting due to the heat flux. The molten material will be out of the burning zone when it interfere with environmental loads wind or gravitational force, slide to combustion zone to form a new fire origin, and then form a parallel fire burning flame spread. It has designed eight serices two fire fire spread experiments for XPS (extruded polystyrene insulation board) with the varying separation distance based on the homemade portable fire test bench, theoretical research was carried out on the basis of fire spread experiments and established the corresponding two fire spread theoretical model, specific content as follows:The separation distance of the two material plate side by side which ranging from0.5cm to to∞cm was controlled by the movable experiment device, the oo cm is supposed to single plate experiment. Linear light two pieces of material plate at the same time, measure mass loss rate with electronic balance, shoot the migration of the flame spread process with DV, and test the heat flux distribution with High temperature heat flow meter.The Findings as flowers:in the wide area (d≥2cm), the logarithmic of flame height and mass loss rate shows a linear relationship, but in the narrow area (d<2 cm), due to the environmental air flow is not simple controlled by buoyant, so there is no linear relationship. For both the vertical and horizontal flame spread rate of two fire burning, the rates of flame spread and mass loss both offered upgrade firstly than descending latter tendency by separation distance, and its value significantly greater than single fire in the narrow area. In vertical experiments, there is a little difference that the extreme point in the curve of flame spread rate moves right to the x-direction relative to the mass loss rate. Theoretical calculate the convection coefficient in prolysis/preheated region and then flame spread rate. According to the theoretical analysis the formula of flame spread rate theoretically, arrived at a conclusion that the flame spread is controlled by the varied convection coefficient, finally account for the offset of extreme point and similar tendency of flame spread and mass loss rate.