Keystone air system has designed rotary air filters especially for handling high volume of air laden with fibre and dust returning along with the air from the department/ waste recovery equipments. The fluff, fibre and dust arrested on the filtering media is sucked out by traveling suction nozzles, moving along the outer surface of the drum and are deposited in collection bags for easy disposal. The clean air is then either re-circulated or exhausted in to the atmosphere. Continuous filtering and cleaning enable uniform flow of return air at constant pressure.