What are the various types of filter media?

Uses of filters range from purifying the filtrate to prolonging the life of machineries used while production. Otherwise, use of filtration grew as a result of massive industrialization. Focus on industrial expansion somewhat moved the focus away from the ill-effects associated it. Pollution is one of the ill-effects of the growing industrialization which came to notice when the problem became severe.

Pollution concerns made environmental authorities proclaim certain standards that production companies must follow in order pay their contribution towards the pollution control campaign. One of those laws required the production plants to install filtration equipment. Some of these industrial units were flour mills, pharmaceutical sector, chemical manufacturing plants, iron and steel industry, etc. Some of these filter made out different media, e.g. micron rated filter bags made out of fibers. Some different types of filter media are:

1.    Woven materials like felts or cloths:

Woven filter media can be made out of wool, cotton, silk or synthetic fiber. However, synthetic fiber has relatively more endurance as compared to wool, cotton or silk. Choice of woven medium depends upon the physical state and chemical composition. Woven materials can be further classified into:

·       Monofilament woven cloth: This material is highly permeable, fairly smooth and cylindrical. Resistance of these materials can be analyzed using orifice analogy and drag theory.

·       Multifilament woven cloth: Multifilament woven cloth can easily tolerate harsh conditions, but there is only one difficulty associated with its use; the geometry of its fiber is highly complicated.

2.    Perforated sheet metal:

Perforated sheet metal plates are the stainless steel plates. These sheets have some pores which act as channels as those in the case of Meta filters.

3.    Bed of granular solid:

This bed of solid is built on a supporting medium. Examples of granular solids are gravel, sand, asbestos, paper, pulp & kieselguhr.

4.    Prefabricated porous solid unit:

Materials used to fabricate this medium are sintered glass, sintered metal, earthenware and porous plastics.