A study of the fire behaviour of polypropylene letter trays

Abstract

AbstractA study of the fire behaviour of polypropylene plastics trays being considered for letter handling has been carried out. Various ignition sources and configurations of trays (both empty and filled with letters) were examined. In particular, stacks of trays contained in large steel‐mesh unit load devices (ULDs), protected by automatic sprinklers, were ignited and the progress of the fires, release of heat and smoke, and sprinkler activation recorded. It was found that, when examined singly or in stacks in scenarios which might be encountered in sorting areas and post offices, the trays made from fire‐retardant plastics were more difficult to ignite and took longer to become involved in fire than those made from standard grade plastics. The benefits of this slower build‐up fire with the retarded plastics formulation were reduced to some extent by the greater amounts of smoke released by the burning of the retarded plastics. For stacks of ULDs filled with trays, typical of a scenario in a mail exchange, the fire‐retardant plastics gave significant benefits in terms of life safety and fire damage to the trays and mail.