PYRAMIDAL SHAPED FILTER CONE AND MATCHING SURFACE

摘要

A filtering device including a filter receptacle and a filter element, the inner supporting faces of said filter receptacle and the outer supported faces of said filter element having the shape of identical equilateral triangles forming a pyramid having a quadratic cross-section. Blanks for forming filter elements of the above set forth type consisting of one-piece blanks of filter material composed of four equilateral triangles of identical size. Finally, processes of producing filter elements by first forming rows of blanks and then folding such blanks into pyramid-shaped filter elements and securing the free edges of the folded blanks to each other so as to maintain the filter elements in finished folded condition.