Self-heating and Spontaneous Ignition of Fibreboard Insulating Panels

Abstract

In recent years, several fires in Canada have been attributed to spontaneous ignition in insulating fibreboard panels. To investigate this claim, critical temperatures for the spontaneous ignition of 75, 190 and 305 mm cubes of fibreboard were measured in small-scale laboratory tests. Employing the Frank-Kamenetskii theory, it was then determined that the critical temperature for spontaneous ignition of 1.2 m cubical pallet of fibreboard is 104∞C and for a tractor trailer full of fibreboard is 89∞C. A test in which a dry, 305 mm cube of fibreboard was placed in a humid environment showed that absorption of water vapour by fibreboard is exothermic. For large quantities of fibreboard, such as found in tractor trailers and railway cars, adiabatic conditions may prevail near the centre of the load so that absorption of water vapour can result in centre temperatures in the order of 100∞C. This is sufficiently hot that oxidation within the load will commence and may result in spontaneous combustion. Recommendations on how spontaneous combustion can be avoided during the storage and transport of fibreboard panel products are also presented.