Abstract: The present invention comprises a fluid filter element which has a hollow perforate cylindrical supporting core. A relatively fine filter media of substantial cross section is spirally wound about the supporting core with adjacent layers spaced from each other and with the fine filter media accommodating fluid flow for filtering in both a radial and circumferential direction through the cross section and with free access through the cross section to the supporting core. In substantially the same manner, a relatively coarse filter media of substantial cross section is disposed in the space between the layers of fine filter media and with the coarse filter media exiting at the supporting core, the coarse filter media accommodating fluid flow for filtering in both a radial and circumferential direction through the cross section and with free access through the cross section to the supporting core.

Abstract: A filter element is formed by spirally winding at least two layers of filter material about a central, perforate supporting core. The layers include a relatively fine porous filter material and a relatively coarse porous filter material. The layers may be formed from blankets of material, or one or both layers may be pleated. The fine filter material extends beyond the edge of the coarse filter material to overlie and close the longitudinal ends of the layers of the coarse material. Fluid to be filtered passes radially through the element until it encounters a clogged or plugged area. The fluid will then take a circumferential spiral route until it again finds an open area of the filter and can pass radially toward the core.