A hot air popcorn popper operates by blowing air through the popping chamber, which carries the popped corn up through a duct and out of the popper leaving the un-popped grains behind. The un-popped grains weigh $0.15 \mathrm{~g}$, half of which is water, and have an equivalent spherical diameter of $4 \mathrm{~mm}$. The popped corn loses half of the water to steam and has an equivalent diameter of $12 \mathrm{~mm}$. What are the upper and lower limits of the air volumetric flow rate at $200^{\circ} \mathrm{F}$ over which the popper will operate properly, for a duct diameter of $8 \mathrm{~cm}$ ?