RESEARCH ON THE INFLUENCE OF FIRE PARAMETERS ON THE HEATING OF ORIENTED-STAINLESS STEEL BOARDS

Abstract

Problem. Wood is a common building material and the basis for OSB boards – three-layer composites of pressed chips and synthetic resins. At the same time, their significant disadvantage is flammability: wood ignition begins at 240–270 °C, and self-ignition – at 350–450 °C. This work investigates the influence of heat flux intensity and standard fire temperature regime on heating OSB boards to the ignition temperature. The aim of the article is a study of the effect of OSB/3 board thickness on fire hazard indicators, in particular flame spread and flammability group. Research methods. The work uses the method of mathematical modeling of heat transfer processes in flat structures using the differential equation of heat conduction and boundary conditions of the second and third kind. Results. Based on the conducted research, it was found that the time to reach the ignition temperature or self-ignition of the OSB board will depend on the intensity of the heat flux density that hits the surface of the board. At an intensity of the heat flux density from 1 to 5 kW, this change will be for thicknesses from 10 to 30 mm. For a thickness of 30 mm and more, the time to reach the ignition temperature or self-ignition will be virtually unchanged. For an intensity of the heat flux density from 8 kW and more, the time to reach the ignition temperature or self-ignition will not depend on the thickness of the board. Under the influence of a standard temperature regime of fire, the ignition time of the OSB board will depend on its thickness. If the time to reach a temperature of 240…270 °С for a 10 mm thick plate is 160–198 s, then for a 1 000 mm thick plate this time will be 52–70 s, and for a 2 000 mm thick plate – 36–47 s. This is explained by the fact that wood has a relatively low thermal conductivity coefficient and at small thicknesses the heat manages to pass through the plate and dissipate into the environment. At a greater thickness of the plate, the heat accumulates in the structure and does not have time to pass quickly through the plate, so the heating process accelerates. Conclusion. Based on the conducted research, it was found that the heating time of the OSB plate surface will vary depending on the influence of different heat flux intensities. The thickness of the OSB plate will also affect the heating time, but only within the limits of up to 30 mm at an intensity of up to 5 kW/m2. At a heat flux intensity of 5 kW/m2, the thickness of the structure will not affect the time to reach the ignition temperature. Under the influence of the standard temperature regime of fire, increasing the thickness of the OSB plate will reduce the heating time to the ignition temperature.