Abstract: A filtering device comprising a cylindrical housing having an upper open end and a lower closed end, an outer annular pleated filter element located within the housing adjacent the wall of the housing and an inner pleated filter element mounted concentrically within the outer filter element, the inner filter element being provided with a central open area, a disk extending across the open end of the housing and having inlet openings communicating with the upper end of the outer filter element, a barrier for preventing the outer pleat edges of the inner filter element from penetrating into the spaces between the inner pleat edges of the outer filter element, the disk having an outlet which communicates with the inner filter element, whereby dirty oil can flow through the inlet openings into outer triangularly shaped spaces in the outer annular filter element downwardly to the lower end of the housing and into the annular open area, from the open annular area into inner triangularly shaped spaces of the inner f

Abstract: The invention is a filter including a housing within which are positioned annular, concentrically mounted filter elements that are folded in opposite helical pleats so that the inside pleats of the outer filter element touch the outer pleats of the inner filter element in a crisscross fashion. Being positioned in this manner, the filter elements support each other and form channels between them through which filtered material passes before exiting the filter. The invention also including a housing within which is positioned pairs of annular filter elements consecutively numbered with capped ends for selective fluid passage between the inner surface of the odd elements and the outer surface of the even elements.