HIGH SECURITY FILTRATION SYSTEM FOR PROTECTING BUILDINGS FROM AIRBORNE CHEMICAL, BIOLOGICAL, AND RADIOLOGICAL HAZARDS

摘要

Buildings are vulnerable to airborne chemical, biological or radiological (CBR) hazards. Toxic agents released in a building or into an air intake would spread rapidly throughout the building via ventilation system. Efficient filtration is one of the few measures that can be implemented in advance to reduce the consequences of an intentional CBR agent release. However, due to their high pressure drop, large space requirements and high initial and operating costs the present high efficiency filter systems consisting of a HEPA filter followed by an impregnated activated carbon bed are not practical solutions for existing buildings. The aim of this study was to improve the security of building occupants by developing a novel low pressure drop protective filtration system for continuous removal of both particulate and gaseous toxic agents from the supply air. The protective filter consists of electrically enhanced particle filter to remove liquid and solid toxic aerosols combined with a chemical filter to remove gas phase agents. The performance of the high security filter was measured in laboratory tests and compared with conventional filters. The results showed that the new filter provides high removal efficiency for particulate (>99.97% @ 0.3μm size) and gaseous contaminants at a much lower pressure drop than present solutions. With the aid of the new filtration system, protection against toxic agents can be flexibly and cost-efficiently increased in specific high-risk areas in a building without extensive modifications to the ventilation system. The side benefits of the improved filtration include healthier indoor air quality, increased building cleanliness, and limited effects from accidental releases of toxic chemicals.