Fabric Type Dust Collectors for Air Cleaning

Canadian Air Systems Co. is a well known manufacturer of industrial dust collection systems. Dust collecting equipment is available in numerous designs utilizing a number of principles and featuring wide variation in effectiveness, initial cost, operating and maintenance expense, space, arrangements and material of construction.

One of the most widely used type of dust collector is Fabric Dust Collector.

Fabric arresters are high efficiency, medium cost collectors. The effectiveness of passing air or gas through a fabric at low velocity has been recognized and used for many years in air cleaning devices. Fabric is arranged in envelope or tubular (stocking) shapes. While removal appears to take place by a staining action of the media, in reality dust collection is obtained by building up a mat of the material on the dirty side of the media. This mat provides the actual filtering or straining bed. By means of this bed a high degree of removal is obtained even on sub-micron size particles.

The dust collectors are used extensively in industry for a wide range of applications. They require more space than most other types of air cleaning devices, necessiating outdoor installation in most cases

The usual fabric is a specially wooven cotton, altough wool, paper , glass cloth and synthetic fabrics may be used in certain applications. In recent years glass cloth has come into wide use because of silicone treatment of the glass fibers and employment of reverse flow techniques for cleaning. Silicone treatment provides a lubricant between fibers and increases fabric life.

As dust is collected on the fibric, resistance to air flow increases. Periodically the fabric must be reconditioned by shaking, vibrating, reverse jet or reverse-flow collapse which agitates suffitiently to remove the bulk of adhering material allowing it to drop into the dust hopper. In most collectors air flow must be stopped during reconditioning, otherwise released material will be re-entrained and redeposited on the fabric. Sufficient dust must adhere to the fabric to maintain the dust mat needed for maximum efficiency; therfore, after reconditioning the pressure drop will be considerably higher than loss through new fabric.

Rate of flow through the media varies with dust collector type, application and dust concentration. Ratings are usually selected so pressure drop will not exceed 5" WG. The smaller the particle, the more rapid the resistance rise for a given loading. For the same air flow rate and dust loading, resistance rise increases directly in proportion to time.