WPT Nonwovens recently expanded our air filter nonwoven production capabilities through an investment in an air through bond production equipment in Beaver Dam, KY. This investment has allowed it to develop new material that meet the requirements of MERV 8 and MERV 10 air filter materials.
MERV (minimum efficiency reporting value) is a measure of air filter performance. Ratings are determined by performance in tests designed by The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). To achieve a MERV 8 rating, a filter must trap more than 70% of particles between 3 and 10 microns in size. The requirements for MERV 10 are quite a bit more challenging. The material must trap more than 85% of particles in the three to 10 micron range and must capture 50-65% of particles measuring between one and three microns.
The permeability of a nonwoven material depends on two factors: the diameter and length of the individual fibers and the size of the pores between them. It takes precise control over these variables to produce nonwoven filter material that consistently meets MERV ratings.