This mode incorporates the advantages of pulse jet bag filters, as well as that of a reverse air bag house. Each compartment is similar to an online pulse jet bag filter. The cleaning process consists of sequentially isolating each compartment and cleaning it with compressed air. All compartments are then cleaned automatically. Offline cleaning is suitable for light and fine dust, and for larger volumes where the occurrence of fluidisation is a distinct possibility.
The offline bag filter contains 4 to 6 bag filter compartments. Each compartment is similar to online bag filter. Gas flow through a compartment is stopped temporarily when the pulse cleaning of the bags is to be done. The dust dislodged from bags settles quickly in the hoppers because of absence of gas movement in the bag filter compartment. During this time the remaining compartments keep filtering the gases as usual. Each compartment is cleaned one after another in same manner.
The starting and stopping of gas flow through individual compartments is achieved through a compact pneumatic damper system. Generally the offline bag filter is employed for larger gas volumes.