The air-to-cloth ratio is the volumetric flow rate of air (m3/minute; SI m3/second) flowing through a dust collector's inlet duct divided by the total cloth area (m2) in the filters. The result is expressed in units of velocity.
v = V / Δ t A {\displaystyle v={V/\Delta t \over {A}}}
The air-to-cloth ratio is typically between 1.5 and 3.5 metres per minute, mainly depending on the concentration of dust loading.
External links Details on how to calculate air-to-cloth ratio