Convert mass to operating volume
A mixer is selected around the space occupied by the actual batch. Divide batch mass by representative operating bulk density, then verify that the result sits inside the mixer’s usable fill range.
Loose and packed density are not interchangeable
Powder may enter the vessel aerated and settle during loading or mixing. Using only packed density can understate required volume, while using an unrealistic loose value can oversize the system.
Check both minimum and maximum batches
The agitator must remain adequately engaged at minimum fill while retaining circulation space at maximum fill. A single nominal batch does not define the operating window.
Volume does not size the drive
Cohesion, moisture, startup condition, compaction and liquid addition can make two equal-volume batches require very different torque and power.