... ), filtering rate > 70%5. Air circulation System- Air-Intake Fan* 1unit, Centrifugal Fan with 4kw motor, 2 sets,air capacity 25000m3/h ... in total. - Air-Exhaust Fan* 1unit, Centrifugal Fan with 4kw motor, one set,air capacity 12500m3/h ... in total.- Cabinet for the fans* 1 unit, and Air Ducts ...