Mesh weave filter

Claim 1

In a filter fabric composed of single strand filaments consisting of filaments disposed in a first system intersecting with a second system, the filaments in said first system being thicker than the filament in said second system, said first system consisting of a plurality of mutually equidistantly spaced filaments, the axes whereof lies substantially in a common plane, said second system consisting of a plurality of filaments disposed in substantially sinusoidal form, adjacent filaments in said second system being juxtaposed in contact with each other substantially at 0° and 180° points on said sinusoidal curve, said mutually adjacent filaments being displaced exactly out of phase to provide interstices of equal cross-sectional area and shape therebetween, said second system interacting with said first system in a manner that the filaments of said first system are embraced in the interstices formed between the filaments of said second system, the apertures in said filter fabric having substantially triangular cross-section, the sides of said triangle being defined by the inner edges of any predetermined adjacent pair of thinner filaments and the corresponding thicker filament embraced in the interstices therebetween, said thinner filaments being designated as having a diameter d, said thicker filaments being designated as having a diameter D and the pitch between the axes of said thicker filaments being designated as t, the filter gauge of said filter fabric being defined as the diameter of the sphere to which all the edges of said triangular aperture formed by said two thinner and one thicker filaments are tangential, the diameter of said sphere being designated as μ, the improvement which comprises providing the maximum distance between the mutually facing surfaces of any predetermined pair of adjacent mutually contacted, out of phase, thinner filaments of said second system, between which a thicker filament of said first system is disposed, designated as H, is greater than the cross-sectional width, designated as B, of said thicker filament measured in the common plane of axes of said first system of thicker filaments, providing the filaments in such a relationship that d is between 0.7 μ and 1.2 μ, and 1.2 μ, and the relationship between the pitch-spacing of the thicker filaments t to the diameter of the thicker filaments D corresponds to the following Table: Where D is: then t is: 2to 2.5 times μ 7.15 to 6.8 times μ 2.5 to 3 times μ 6.8 to 7.1 times μ 3 to 3.5 times μ 7.1 to 7.35 times μ 3.5 to 4 times μ 7.35 to 7.7 times μ.