Centrifugal air classifiers, or classifiers with some sort of centrifugal field, are used in classifying particulate materials in the cut size range between a few hundred microns to below one micron. The sharpness of cut in these devices depends on adequate dispersion of the feed material and the maintenance of identical forces on the particles, regardless of their position, in the classifying zone. This paper demonstrates, on the basis of computer simulations, that the latter condition is not as easy to realize as one might wish.