The total volume of gas treated by a fabric filter run at constant pressure is proportional to the square root of the time of treatment. You are directed to any suitable advanced air pollution textbooks if you would like to look at the maths.

This demonstrates the need for a mechanism to clean the filters. Typical pressure drop is in the region of 0.5-3 ins water gauge.

A variety of bag cleaning techniques are used including the shaker type shown below.