Use of metallic filters to prevent the degradation of HEPA filters in case of vapour release

S. Bourrous*, M. Barrault, A. Brunisso, INRS Institut National de Recherche et de Sécurité, France

Most of the industrial activities dealing with hazardous matter, such as nuclear industry use glass fibres HEPA filter to prevent the release of any airborne pollution in the environment. This technology, used for many decades is well known and its limitations in terms of particle holding capacity / mechanical resistance is either balanced by the use of pre-filtration systems such as inertial devices (cyclones, impactors …) or less efficient fibrous filters (Charvet et al. 2018). In the specific context of the nuclear energy production cycle, purification of the exhaust air needs to be ensured even in incidental context with vapour release. In this context, fibrous filters exposed to liquid aerosol present a quick an important pressure drop increase (Charvet et al. 2010) leading, in certain cases, to a break of the filters and the release of contaminants. If the purification process could be affected or inefficient, a static confinement of the contaminated areas should be applied. This needs to be done without any use of mechanic/electronic device in order to ensure the reliability of the system.

In this context, the important pressure drop increase of a metallic filter could be used to break the ventilation and to prevent contamination release. In this context, the maximal pressure drop depends on the efficiency/structure of the filter media. In this work, 4 different metallic filter medium, with different filtration efficiencies, and fibrous structure (fibre diameters, packing density layered structure) previously loaded with a solid aerosol simulating a contaminant (fluorescein soda) have been exposed to a water aerosol. The pressure drop

Session: G15 - Filter Medium Design
Day: 24 October 2019
Time: 10:45 - 12:00 h

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