Clogging of industrial pleated high efficiency particulate air (HEPA) filters in the event of fire

The IRSN and AREVA NC are currently conducting a common interest fire research programme with the aim, among other things, of improving knowledge of clogging of high efficiency particulate air (HEPA) filters and developing an empirical model for clogging of such filters by combustion aerosols. This model must – insofar as possible – be independent of the nature of the fuel and be able to be integrated in a calculation code covering the interaction between the ventilation and the fire. This paper discusses the influence of various “direct” factors such as the filtration velocity, the mass of deposited aerosol per filter area, the diameter and morphology of the combustion particles, the condensate content of the aerosols, and “indirect” factors such as the air flow feeding the fire and its oxygen content, which influence the evolution of the aeraulic resistance of a clogged filter.