| 摘要 |
A filter structure, typically for in ground use on perforated pipes, in which a tubular knit fabric is used, thus providing the elasticity inherent in a knit construction, but the yarns of the fabric are napped or suaded, cutting filaments from them. The filaments extend across the stitch opening, reducing the micron size rating of the filter without the need to use more and costly yarn. Preferably the filaments are cut from additional laid-in yarns while leaving the base or ground structure of the fabric intact and hence unweakened. The napping or suading can be on the inside or outside of the filter fabric. The filter can be used for gases as well as liquids and can be on flat sheets as well as in tubular form.
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