Bag filter are used for the clarification/filtration of fluids that have a relatively small loading of particles to be removed. The particle suspension passes through and the particles settle in the bag.Bag filter is a common dedusting facility, which is usually used to remove the PM with continuous and efficient filtration under the flue gas exhausted from combustion equipment in various industrial sites.

Bag filters, similar to cartridge filters, have various configurations and materials of construction, yet the flow in this process is inside-to-outside. A bag filter normally has a connection for a high-pressure inlet on the top and filtrates exit at the sides and bottom. The solids stay inside the bag. A metal or plastic cage (perforated basket) holds the bag in place during operation. The dirt-holding capacity is the important parameter for the filter design. Depending upon the bag construction—whether it is mesh or felt or single, multilayer, or pleated—the dirt-holding capacity will increase. For instance, a pleated bag has the largest filter area. Bag filters are used for noncritical aqueous applications where the bags and solids can be easily disposed.