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: Disclosed is a hub ring for a filter wherein a supporting member having a plurality of supporting portions is interposed between a pair of keep plates, a supporting plate for a filter wherein a plurality of wave portions extending substantially in the circumferential direction are arranged in the radial direction, and methods for manufacturing these members. The hub ring has a great opening ratio to achieve a low pressure loss property and causes substantially no residence of polymer, and the hub ring can be manufactured at a low cost. The supporting plate has high pressure resistance, low-pressure loss property, good directivity of polymer flow and excellent polymer mixing effect, and it is suitable for use as a retainer disposed inside of a filter.