Flammability of tropical forest litter with and without fire retardant

This work presents a comprehensive study on the flammability of typical tropical broad-leaf forest litter using bench-scale cone calorimetry. For comparison, similar tests are conducted on native pine forest litter. The tests are carried out for the litter bed densities ranging from 25 to 75 kg/m3 in standard and perforated walled sample holders. Tests are also carried out on forest litter treated with fire retardant, Ammonium Poly Phosphate(APP). The broad-leaf tropical litter ignites earlier and burns longer than pine litter but with lower heat release rates. Smouldering combustion, which ensues after flaming combustion, is also longer for the tropical litter. The heat release rate decreases with increase in bed density; however, it increases especially at low litter bed densities, when sample holder walls are made porous. These effects are less drastic for the tropical litter. The heat release rate for tropical litter exhibits sporadic peaks not observed in pine litter. In contrast, forest litter treated with fire retardant has reduced flame duration in porous holders compared to tests in standard holders, and the heat release rate may be lower for high bed densities. Critical heat flux is higher for the untreated tropical litter, but with APP treatment, it is higher pine litter.