NWI has developed a multi-pronged approach to help increase the available capacity of filters that can be used as MERV 13 or higher but with a lower pressure drop. The target is a pressure drop of 65 Pascals or lower for a 24x24x2 inch filter tested at a flow rate of 1968 CFM.
Goal 1: Enhance NWI’s fibrillated spunbond technology previously used for facemasks by altering its structure and controlling consolidation to lower its pressure drop to 65 Pascals at a flow rate of 1968 CFM. The spunbond process offers a significantly higher throughput. NWI’s pilot facility can produce as much as 200,000 meters per week.
Goal 2: Create staple carded nonwovens by using similar fibers as produced on the spunbond line. The structure will be consolidated by thermal bonding and/or needle punching to allow a much lower pressure drop. Two structures will be formed. The first will be a pleatable structure with a weight of 50 to 75 g/m2. Another will be one inch thick and can be die-cut and inserted in the filter housing without the need for pleating. The weight will be ~300 to 350 g/m2. This filter will be a depth filter and can offer better filtration compared to its pleated counterpart.
Goal 3: Determine best microscale (fiber-level) and macroscale (pleat-level) geometries for the nonwovens generated under goals 1 and 2.
Successful completion of this research will lead to new classes of high efficiency filter media capable of capturing viruses that can be deployed in existing infrastructure to mitigate the spread of the virus through the air.
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North Carolina State University