Detailed study of distribution patterns of polycyclic aromatic hydrocarbons and isocyanates under different fire conditions

摘要

This study has examined the distribution patterns between gas phase and particle phase of some chemical compounds produced in fires. It has also addressed the question of the distribution of individual particle-associated species between the different size-ranges of particles. The chemical compounds studied and discussed in this paper are polycyclic aromatic hydrocarbons (PAHs), and isocyanates. The steady-state tube furnace, ISO/TS 19700, was chosen as the physical fire model in order to study the production of particles from different types of fire exposure, that is, oxidative pyrolysis, well-ventilated flaming fires and under-ventilated flaming post-flashover fires. Two materials were chosen for investigation, a poly vinyl chloride (PVC) carpet and a wood board. The particle production from the two materials investigated varied concerning both the amounts produced and the particle size distributions. The analysis of PAHs showed that volatile PAHs were generally dominant. However, when the toxicity of the individual species was taken into account, the relative importance between volatile and particle-associated PAHs shifted the dominance to particle-bound PAH for both materials. The substantial degradation in the tests of the low polyurethane content of the PVC carpet, and the (4,4'-methylenediphenyl diisocyanate)-based binder in the wood board resulted in no or very small amount of quantifiable dnsocyanates.