Additional flow filter

A filter comprising a pleated main filter element having a plurality of pleats in a closed loop having an outer perimeter defined by a plurality of outer pleat tips, and an inner perimeter defined by a plurality of inner pleat tips, said loop having a hollow interior extending along a given axis, wherein fluid to be filtered flows through said main filter element from an upstream dirty side to a downstream clean side, and flows axially in said hollow interior, said main filter element having first and second axial ends, said first axial end being open and providing an axial flow exit passage therethrough, a safety filter element in said hollow interior downstream of said main filter element and having first and second axial ends, said first axial end of said safety filter element being adjacent said first axial end of said main filter element, said first axial end of said safety filter element being open and providing an axial flow exit passage therethrough, said safety filter element being tapered along said axis from a wider radial width at said first axial end to a narrower radial width at said second axial end, to provide lateral clearance of said second axial end of said safety filter element within said hollow interior at said second axial end of said main filter element to facilitate lateral rocking back and forth of said second end of said main filter element to facilitate removal of the latter without removing said safety filter element during servicing.

A fluid filter comprising a housing extending axially along an axis, a pleated main filter element having a plurality of pleats in a closed loop having an outer perimeter defined by a plurality of outer pleat tips, and an inner perimeter defined by a plurality of inner pleat tips, said loop having a hollow interior extending along said axis, wherein fluid to be filtered flows through said main filter element from an upstream dirty side to a downstream clean side, said pleats forming wall segments extending in serpentine manner between said inner and outer pleat tips, said wall segments extending axially between upstream and downstream ends, said wall segments defining axial flow channels therebetween, said upstream ends of said wall segments being alternately sealed to each other to define a first set of flow channels open at their upstream ends, and a second set of flow channels interdigitated with said first set of flow channels and closed at said upstream ends, said downstream ends of said wall segments being alternately sealed to each other such that said first set of flow channels have closed downstream ends, and said second set of flow channels have open downstream ends, such that fluid flows substantially directly axially through said main filter element, through said open upstream ends of said first set of flow channels then through said wall segments then through said open downstream ends of said second set of flow channels, a safety filter element in said housing downstream of said main filter element.