Bag filters are best used in applications such as: bulk chemicals, food industry (vegetable oils, vinegar), semiconductors, coolants, cleaning fluids, paints, varnishes, waxes and plastisols. They are in general frequently used for dust removal in industrial applications.
Extended surface non-supported bag filters are designed for use in air filtration systems and equipment where medium to high efficiency filtration is required. The flow can be from the outside to the inside of the filter (that means, the separation of particles happens on the external surface of the filter) or the other way around, depending on the application. The particles are normally captured on the internal surface of the bag filter.
Bag filters are in general not designed for replacement when they are clogged, but some bag filters for gaseous applications like dust removal can be cleaned, for example by mechanical shaking or by backwashing with compressed air (so called reverse-flow bag filters). Bag filters are mostly surface-type filters.
A rule of thumb is that for concentrations higher than 5 mg/m3 a surface filter is favored, while for concentrations lower than 0.5 mg/m3 a depth-type filter is preferred. In general surface filters can by backwashed and cleaned more easily, while depth-type filters normally have to be disposed when clogged.