Systems of ductwork, gratings and heaters or air conditioners all play important roles in ventilation and air temperature control. But in almost all of these systems, ventilation fans and other kinds of industrial blowers are necessary to move the air through the ductwork. Outside of temperature and air quality control contexts, blower fans are used in a great variety of applications.
In the carpet cleaning industry, small, portable high velocity fans are used to speed up carpet drying after cleaning. In building maintenance contexts, blower fans are used to dry surfaces after spills. Blower fans can be permanently affixed to ceilings to serve decorative and light-duty air circulation purposes, or they can be small and portable enough to fit on a desktop or workbench.
Every variety of blower fan fits into one of two fan configuration categories. Axial fans feature blades that rotate around an axis like hands on a clock. Slight blade curvature allows for the creation of positive and negative air pressure in front of and behind the blades. These changes in air pressure cause airflow.
Axial fans can be used in most of the settings in which blower fans are necessary. However, in some cases, axial configurations can be impractical or insufficient. In those cases, radial (or centrifugal) blowers are used. Radial blowers involve blades that spin around a fixed point within an enclosure (which is called annular housing), but their motion more resembles the forward-moving paddles on a water wheel than hands around a clock.
They also cause changes in air pressure to generate airflow, but because the blades spin within annular housing, the moving air becomes subject to centrifugal motion, which increased air velocity. Because of the effect of centrifugal motion, radial blowers can, when operating at the same RPM as axial blowers, generate more airflow. Also, all centrifugal blowers direct their airflow through a chute. For this reason, radial blowers are the most effective variety of blower fan in floor drying applications and in other settings where airflow must be directed carefully.