Filter and method of filtering a fluid

Abstract

A filter including alternating layers of filter medium and diffusion medium. The filter provides optimum distribution of fluid over the filtering medium, a reduced pressure drop and an increased filter life, without a reduction in filter rating. The diffusion medium has a first plane of spaced-apart, substantially parallel strands defining first longitudinal passages having a first height dimension and a first width dimension, and a second plane of spaced-apart, substantially parallel strands defining second longitudinal passages having a second height dimension and a second width dimension. The strands of the second plane of the diffusion medium are oriented in a non-parallel manner with respect to the strands of the first plane, such that the first and the second planes define lateral openings having side dimensions. The first and the second longitudinal passages include at least one dimension that is smaller than any of the side dimensions of the lateral openings. At least a portion of the layers of filter medium have bypass apertures, wherein such portion defines at least one pre-qualifying filter medium layer.

Description

[0001] The present application claims priority to U.S. provisional patent application Ser. No. 60 / 103,233, filed Oct. 5, 1998, the disclosure of which is incorporated herein by reference.BACKGROUND OF THE DISCLOSURE[0002] 1. Technical Field[0003] The present disclosure relates, in general, to a filter, a method of making a filter and a method of filtering a fluid.[0004] More particularly, the present disclosure relates to a filter having alternating layers of non-filtering diffusion medium and filter medium. Some of the layers of the filter medium are provided with bypass apertures, while the remaining layers do not include bypass apertures so that they act as qualifying layers for the filter. Filters according to the present disclosure have been found to provide improved fluid distribution over the filter medium, reduced pressure drop and increased filter life, without a reduction in filter rating.[0005] 2. Discussion of Background Disclosures[0006] In general, a filter assembly is...

AI Technical Summary

Benefits of technology

[0014] Filters of the type disclosed herein demonstrate superior fluid distribution over the filter medium contained therein, and an optimum use of the filter medium. Filters according to the present disclosure, therefore, have an increased life and a lower pressure drop without a reduction in filter rating, and provide more cost effective filtering.

[0056] The advantageous performance described above for Test Cartridges 3 and 4 is confirmed by visual inspection. Upon dissection of the Test Cartridge 3 after testing, the filter medium 16 displayed contaminant loading to a radial depth from the outermost layer 24 of about fifty percent (50%) of the filter 14. In comparison, only the outermost layer of filter medium displayed contaminant loading in Test Cartridge 1. Thus, the combination of the diffusion medium 20 and the bypass apertures 18 as described for Test Cartridges 3 and 4 provides a synergetic effect that was not to be expected based upon the performances of Test Cartridges 1 and 2 possessing either non-filtering diffusion medium or bypass apertures, respectively, but not both.

Problems solved by technology

When a depth filter cartridge mimics a surface filter and collects contaminants in primarily one layer, the results are an inefficient distribution of fluid over the filter medium, a higher pressure drop for fluid passing through the filter and a lower flow rate capability for the filter.

Such filters also tend to have a shorter useful life, and thus must be replaced more often.

The Drori filter elements fail to optimally enhance fluid flow while providing extended filter service life.

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