The fabric filters are modular bag filters in which the dust-laden air enters trough the base or side of the casing, and is evenly distributed between the filter bags. The dust is deposited on the outside of the bags, while the air passes through the felt into the clean air chamber at the top of the casing before release in the atmosphere. The bags are fixed to the tube sheet by use of a "snap-band". Inside each bag a cage is fitted and prevent the bag to folder during use. On the top of the cage is mounted a venturi which lead the clean-air to the bottom of the bag.