Asphyxiant yields from common polymers in under-ventilated fires in the large instrumented fire enclosure (LIFE)

Abstract

Polymer pellets have been burned in 12 large scale tests in under-ventilated conditions in a 2.5 m3 fire enclosure with attached corridor. The polymers investigated were low density polyethylene (LDPE), polymethyl methacrylate (PMMA), polystyrene (PS), and polyamide 6.6 (PA6.6). The enclosure, based on a scaled-down ISO 9705 room attached to a horizontally divided corridor, has been designed to replicate under-ventilated burning in enclosure fires, while allowing the equivalence ratio to be determined. This provides a more robust, alternative verification of equivalence ratio, based on measured air flow, than the phi meter used in other reported work. Comparison between the yields of carbon monoxide (CO), carbon dioxide (CO2) and hydrogen cyanide (HCN), with values from the same materials from a bench-scale test together with generically similar materials, shows very good agreement, demonstrating the ability of bench-scale apparatuses, such as the steady state tube furnace (ISO 19700) and the fire propagation apparatus (ISO 12136) to replicate the high toxic yields of under-ventilated combustion. Depending on the material, CO yields between 0.1 and 0.25 g/g were obtained for under-ventilated flaming of the four polymers, alongside HCN yields of 0.01–0.02 g/g for PA6.6