Centrifugal fans blow air at right angles to the intake of the fan, and spin the air outwards to the outlet (by deflection and centrifugal force). The Centrifugal Fan has a moving component (called an impeller) that consists of a central shaft about which a set of blades are positioned. The impeller rotates, causing air to enter the fan near the shaft and move perpendicularly from the shaft to the opening in the scroll-shaped fan casing. A centrifugal fan produces more pressure for a given air volume and are typically quieter than comparable axial fans.