High efficiency air filter

Claim 1

A high efficiency type filter suitable for filtering foreign matter from a gaseous medium comprising a filter medium of microdiameter filtering material, said filter having a plurality of filter socks, each sock comprising a pair of opposed substantially coextensive side walls forming major filtering areas, said side walls being joined togeTher to form an openended enclosure adapted to receive a flow of gaseous medium to be filtered through said side walls, said side walls being joined together along a plane generally parallel to the principal flow direction of a gaseous medium in said sock to form a first pair of substantially similar pockets having a common entrance in said sock at said open end, said side walls being joined together from a first point removed from said open end along a substantial portion of the length of said side walls to a second point spaced from the other end of said sock opposite said open end, said side walls being further joined together on either side of the first line of joinder along a plane generally parallel thereto from a third point located between said first and second points to a fourth point located at said other end of said sock to form a further pair of substantially similar pockets on either side of the first line of joinder.