5-Stage Air Dessicant Air Drying Systems. First Stage - 5 micron particulate filter removes water in a liquid form as well as dirt, debris and pipe scale. Second Stage - .01 micron oil removing filter removes oil aerosols and microscopic particles. Third Stage - Desiccant dryer absorbs water vapor from the air, producing a -30˚F dew point. Fourth Stage - 3 micron absolute filter filtrates desiccant dust. Fifth Stage - Precision regulator reduces pressure to required level.