Centrifugal blowers are applied in many contexts. In offices, schools and in home carpet cleaning applications, centrifugal floor dryers are used after spills, carpet cleaning or other cases when carpet is exposed to moisture and needs to be dried quickly. Hand-held blow driers can be found in bathroom drawers all over the country. Centrifugal blowers are easy to recognize because their blades are enclosed, and because they draw air from the side as opposed to from behind, as is the case with axial fans.
Because of this feature, they can be used at angles in ductwork where axial blowers cannot fit or cannot generate enough airflow. Centrifugal blowers can be backward-facing, forward-facing or multi-staged. Centrifugal blowers are also useful for applications including vacuum conveying, waste water treatment, air and gas handling, paper dewatering, air purging, bio-gas recovery and pneumatic bulk conveying. Centrifugal blowers can also be used in reverse to provide vacuuming action in packaging applications.
Inside a centrifugal blower’s enclosure (which is called annular housing) is a collection of blades (which are also called impellers) that are attached to a shaft, which is attached to a motor system. Large centrifugal blowers feature a drive shaft, which is driven by a v-belt drive. The units are housed by a circular welded assembly that can be constructed from heavy-gauge sheet metal, though blowers that are intended for light industrial use can be housed in plastic as well.
When the impeller rotates, air is sucked into the input at the center of the centrifugal blower. As the impellers force the air through the annular housing, it becomes subject to centrifugal motion, which increases the degree to which it is pressurized. This property of centrifugal blowers allows for them to create more air pressure using lower RPM (an axial fan operating at the same RPM as a centrifugal fan will move air at lower speeds). This high level of efficiency makes centrifugal blowers popular in applications where a high level of air flow is required but where a minimum of energy is available to be expended.