Dutch weaves, filter media

There are three important types of metallic filter medium wire mesh, sintered powder, and random fiber. Wire mesh comes in a square weave or Dutch twill (woven in parallel diagonal lines). The different filter media do not perform equally with respect to their ability to hold contaminant, capture gels, etc. [11, 12]. A relative performance comparison is shown in Table 3.7. 

Textiles, as a woven cloth or a nonwoven fabric, are probably the most common industrial filter medium, and are made from natural (cotton, silk, wool) and synthetic fibres. Wire cloths and meshes are also widely used in industrial filtrafions, produced by weaving monofilaments of ferrous or non-ferrous metals the simpler plain weave is used for sieving and sizing operations, and the more complex weaves such as Dutch twills are used on pressure and vacuum filters. At the small scale, particularly for laboratory use, filter papers are common, made from fibrous cellulosic materials, glass fibre or synthetic polymers these papers are made using developments from conventional paper manufacturing processes. 

The liquid is passed under centrifugal force through a filter medium or perforated plate. Filtration occurs as the liquid passes through the interstices of the solid particles that have built up on the medium surface. Depending upon the degree of separation desired, fdter media can be a filter fabric of twilled weave, dutch weave or plain weave in either stainless steel or synthetic fibre. 

Generally, any septum having an opening of less than 0.005 in. should be satisfactory for the medium flow rate filter aids. In metal cloths the most commonly used weave is 24 X 110 single dutch with 0.016 in. x 0.011 in. wire. A 60 x 60 twill with 0.011 in. wire and a 70 X 80 twill with 0.007 in. wire are also satisfactory. Keep in mind that mesh does not necessarily indicate the size opening it also depends upon the wire diameter. 

---