Most bag-houses use long, cylindrical bags (or tubes) made of woven or felted fabric as a filter medium. (For applications where there is relatively low dust loading and gas temperatures are 250oF or less, pleated non-woven cartridges are sometimes used as filtering media instead of bags.) Dust-laden gas or air enters the bag house filter through hoppers (large funnel-shaped containers used for storing and dispensing particulate) and is directed into the bag house compartment.
The gas is drawn through the bags, either on the inside or the outside depending on cleaning method, and a layer of dust accumulates on the filter media surface until air can no longer move through it.