Air-Cloth ratio has been center theme and primary parameter of dust collector design. What is often overlooked is overall dust collector structural design and flow pattern that contribute equally to maintaining effective filter area. A good design Air-Cloth ratio and high filter area don’t necessarily mean good effective filter area. A dust collector with 1000m2 filter may over time run at 500m2 effective area due to dust plugging. At any instances a dust collector performs at an equilibrium between dust plugging at filter surface vs dust removal. For a design without care for this equilibrium, effective filter area can deteriorate to mere fraction of its actual installed parameter. When effective area has halved, there could be nothing to stop the deterioration to continue. It behaves like a new filterbag half of its original size, ready to deteriorate further. This happens when structural condition to counter dust plugging is absent and plugging situation has tipped over a threshold. To solely focus on Air-Cloth ratio in design is a misallocation of resources. Designer should pay due attention to dust removal mechanism like pulse jet sizing, air flow pattern within bagfilter, interstitial and can velocity and potential of counter flow air leakage from under the hopper.