A reinforced top cover structure for a chemical filter includes a cover member made of injection molded plastic material and covering a metal-made core board mounted with multiple positioning pillars. Each positioning pillar has an upper section extending upwardly from a top surface of the core board, a middle section connected to the upper section and extending through a corresponding one of multiple positioning holes in the core board, and a lower positioning part connected to the middle section and extending downwardly from the bottom surface of the core board. The core board has an annular peripheral surface formed with multiple notches. The cover member has an outer peripheral surface surrounding the annular peripheral surface of the core board and formed with multiple engaging grooves that correspond respectively to the notches in position.

A spin-on filter assembly with replaceable coreless element comprises: a reusable spin-on housing including a filter bowl having sealing structure on a bottom of the filter bowl and a sealing structure on a top of the filter bowl; a center support tube integral with the filter bowl and including a perforated tube and an upper portion having an threaded coupling allowing for the filter assembly to threaded into position and an exterior sealing structure; and a replaceable coreless filter element mounted on the central support tube within the filter bowl and having filter media, a lower sealing structure configured to engage with the sealing structure on the bottom of the filter bowl and an upper sealing structure configured to engage with the exterior sealing structure on the center support tube.

A filter system may include a housing, a filter element, and a separate positioning mechanism. The housing may include an opening, a function carrier, a drain opening, and a radially protruding contour. The filter element may include a first end disc, a second end disk, and a filter material disposed between the first end disk and the second end disk. The first end disk may include at least one of a radially projecting contour and an inwardly projecting recess. The second end disk may include a central opening and an eccentrically projecting locking pin. The central opening may be adapted to interact with the function carrier. The positioning mechanism may have a body with a first recess and at least one second recess, which may be configured to facilitate positioning and aligning the filter element in the housing such that the locking pin engages in the drain opening.