| 摘要 |
The specification discloses improvements in axial flow filters of the type having filter elements constructed of spirally wound tissue layers and having planar fluid entry and exit surfaces located at their opposite axial ends. Entry and exit filtration stages are provided in the form of annular webs of filter media covering the entry and exit surfaces the filter elements to provide additional filtration of fluid entering and exiting the elements. The filter media comprising the entry filtration stage is specially adapted for distributing the flow evenly across the entry surfaces of the filter element to minimize the formation of bypass flow channels between the tissue layers, and for plugging any bypass flow channels that form to effect a distribution of the flow to areas on the entry surfaces where bypass flow channels do not exist. The filter media comprising the exit filtration stage is maintained against the fluid exit surface and sealed thereto so that fluid passing out of the fluid exit surface cannot bypass the filter media.
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