Economics is very important in almost all the area. When contamination level is high, it is better to use pre-filter. Bag filter is proven economical pre-filter. Many times it can be used as a final filter too. The advantage of bag filters are -

1. High solids collection capacity.
2. Easy change out saves manpower,
3. Cheapest solution,
4. Contaminant retained in bag is easy for disposal,
5. Minimum loss of processing fluids etc.

Bags are made from polypropylene or polyester. Normally woven material is used for making bags. For finer filtration non-woven media is preferable. It is properly stitched at the joints and the top rubber color. Color is used to hold the bag in the housing as shown here in the picture. A dispenser is inserted in to the bag housing to hold the bag and avoid by-pass. The bag is rested on perforated cylinder.