The Advanced Classification System (ACS) is a high efficiency air classifier first introduced in 1992 and granted a US Patent in November 1994. Air classifiers are used to separate dry fine powders based upon particle size, particle shape and also density. In general air classifiers can be used effectively in the range of 1mm to one micron.

RSG Inc manufactures many styles and sizes of air classifier to suit varying applications from high density metal powders to ultra light weight mineral fillers, synthetics and fine chemicals.

Air classifiers are available for laboratory applications requiring only a few pounds per hour feed rate, all the way up to large industrial capacities of 500 tph or more. Air classifiers are often used in closed circuit with grinding mills, such as ball mills, hammer mills, roller mills or jet mills. The air classifier is used to select the onsize material and return the oversize to the milling system.