Apertures filter media

Metal and plastic wedge wire screens are commonly used in the construction of filters and other separators, as either the support for finer filter media or as the filtering medium itself. The screens have typical aperture sizes of >50 pm with an average tolerance of 10%. Metal, usually steel, screens are used in applications where separator robustness needs to be combined with slurry dewatering duties or when the solids are particularly coarse or abrasive. 

It should be noted, however, that the edge filters described in Section 2E are also mainly made of metal and made with precise apertures. It should also be noted that every type of filter medium described in this part as made from metal can also be made of plastic materials, with almost as much strength and almost as much precision in aperture size. Corrosion resistance may actually be higher with plastic wire screens or sheets than for some metals. 

Test solution After 2 h, filter the Medium containing the pellets through a sieve with an aperture of not more than 0.2 mm. Collect the pellets on the sieve, and rinse them with water. Using approximately 60 ml of 0.01 M sodium borate solution, carefully transfer the pellets quantitatively to a 100-ml volumetric flask. Sonicate for about 20 min until the pellets are broken up. Add 20 ml of alcohol to the flask, dilute with 0.01 M sodium... 

Surface coatings applied to filter fabrics can enhance one or more of the filtration properties of the fabric. The coating may be sprayed on as a liquid or laid down as a sheet which is then bonded to the fabric. Microporous polymer coatings may be used to provide a smoother and fine aperture size to the fabric surface, which may enable easier detachment of the cake and prolong the lifetime of the medium. 

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