Flame heights and charring in a particleboard cavity under varying cavity widths and sample heights

Flame spread through ventilation cavities in timber facades is a serious fire safety concern in tall buildings. In this study, flame behaviour inside a particleboard cavity, resembling the ventilation cavity in a façade system, was investigated. Experiments were conducted with particleboard on one side and an inert panel on the other, for six cavity widths from 10 cm to 25 cm. Variation in flame height, mass loss, temperature along the height of the cavity and gas velocity above the cavity were quantified. These quantities were found to increase as cavity width was reduced. 3D scans of the sample surface were conducted after the experiment to quantify the charred volume. Deeper charring was observed when cavity width was reduced. Most of the charring was found to occur from ∼ 15 cm to ∼ 60 cm above the base of the sample. Flame heights for particleboard samples showed a significant variation during each experimental run, while for inert samples the flame height was more stable. A significant change in flame and char behaviour was observed when the cavity width was reduced from 15 cm to 10 cm. Flame heights, gas velocity, maximum char depth and char volume increased when the particleboard sample height was increased.