Fabric filter bags are usually round tubes, made of woven fabric or nonwoven fabric. Each fabric material used in bag filters has its own characteristics and use. This article highlights the fabric types used in bag filters that are used in a range of applications.
These synthetic fibers provide good hydrolytic resistance for a limited temperature range, 127°C for continuous and 135°C for rush application. Acrylic fibers are also used in the production of ferrous and nonferrous metals, cement, carbon black, lime, and fertilizers. They are also used widely in wet filtration applications.
The primary advantage of polypropylene is that it is non-hygroscopic (it is unable to chemically react with water). It shows great resistance to the static abrasion and build-up and offers a slick surface for sufficient dust cake release during bag cleaning. Polypropylene is extensively used in the food, chemical processing, detergent, pharmaceutical, as well as tobacco industries. However, copper, oxidizing agents, and related salts may damage polypropylene.
Polyesters are one of the most extensively used fabrics for all-purpose applications. The main damaging agents are water (hydrolysis) and rigorous sulfuric, nitric, and carbolic acids.
Most of the fiberglass fabrics are woven from filaments. Numerous variations of yarn construction, fabric finishes, and fabric weaves are available. It is also manufactured in a felted form. Fiberglass bears the highest operating temperature range found in conventional fabrics. Above 260°C, the fiberglass itself is not damaged, but the finish offering yarn-to-yarn lubrication starts vaporizing, leading to accelerated mechanical wear of the glass fibers. Fiberglass is noncombustible, offers zero moisture absorption (cannot hydrolyze), possesses excellent dimensional stability, and has practically good strength features. Woven glass fabrics hold high tensile strength qualities but moderately low flex strength, particularly in the fill (circumference) direction of the bag, and low abrasion resistance.