Filter media classification
1 woven material, filter cloth and sieve woven from natural or synthetic fiber, metal wire, etc., is the most commonly used filter medium in industrial production. Such materials are inexpensive, easy to clean and replace, and have a minimum particle size of 5 to 65 μm. A single-twist filter made of fibers such as polyamide, polyester or polypropylene is gradually replacing other fabric filter cloths with uniform texture, corrosion resistance and fatigue resistance.
2 Porous solids, including bisque, sintered metal or glass, or porous plastic pipes made of plastic fine powder. Such materials can be trapped with a minimum particle size of 1-3 μm and are commonly used to treat suspensions containing small amounts of fine particles.
3 Stacking medium, such as granular materials such as sand, gravel, charcoal and diatomaceous earth, or a layer of non-woven fibers such as glass wool. It is generally used to treat suspensions with low solid content, such as municipal feed water and sugar liquid to be purified. In addition, industrial filter paper can also be used in combination with the above filter media to intercept small amounts of fine particles in the suspension. The manufacture and application of polymeric porous membranes has been greatly developed for the filtration of finer particles to obtain highly clarified liquids. A membrane suitable for filtering 0.1 to 1 μm particles is called a microporous membrane; a membrane suitable for filtering 0.01 to 0.1 μm particles is called an ultrafiltration membrane (see membrane separation). Microporous membranes and ultrafiltration membranes are widely used in the pharmaceutical, food and biochemical industries.