Void bag 729, the air flow velocity changes, and other causes of dust size, the effects of various different mechanism of filtration performance of the filter are different. In fact, at the beginning of the new filter dust collection efficiency is very low. After a period of time, will be a layer of coarse dust cloth dust layer on the surface of the beginning. Because the primary layer of dust and the dust on the role and then gradually accumulate in the dust layer, the filter bag 729 to continuously improve efficiency, but also a corresponding increase resistance. When cleaning, can not undermine the primary layer, otherwise efficiency will decline. The structure of the primary layer of dust bag filter efficiency, resistance and cleaning effect plays a very important role in the early days baghouse filter bags are woven with 729 (also knitted fabrics and three-way), Such media are twisted, the warp and weft yarns, filaments interwoven with the loom. The density of the filter is relatively large, the porosity of between 30-40%. Compared with non-woven fabric has good strength and abrasion resistance, can withstand greater pressure and abrasive dust, dimensionally stable, smooth surface conducive to cleaning. 729 bags of density can be more precise control. The disadvantage is that large filtration resistance, in order to improve filtering accuracy should stand after the formation of dust.