New for 2025 is a regular feature on basic fan knowledge from Chet White, our Sales and Marketing Manager. This month we look at the various types of impellers for centrifugal fans.
Radial
Centrifugal impellers come in various styles, each with unique characteristics and applications. The radial bladed paddle wheel, the oldest style, features radial blades extending outward from the hub like wheel spokes. As the paddles rotate, they expel air and materials through the outlet. While the least efficient, this design excels at handling debris and abrasive materials. Its lack of a leading edge prevents damage, and the radial profile minimizes buildup, reducing vibration and extending the life of general-purpose fans.
Radial Tipped
Radial-tipped impellers offer greater efficiency. Their blades have a leading edge that cuts through air and curves forward to the tip, aligning radially with the hub. This design improves efficiency over paddle wheels and resists particulate buildup. Positive energy along the blade face expels debris, preventing accumulation that affects other styles.
Backward Inclined
Backward-inclined impellers achieve higher efficiency for cleaner applications. Their flat blades, slanted opposite the rotation, slice air at the inner edge while maintaining low energy on the blade face. The backward angle reduces friction, enabling smoother gas flow and greater operational efficiency.
Backward Curved
Backward-curved impellers enhance the backward-inclined design with curved blades instead of flat ones. This curvature further reduces friction by encouraging gas to detach from the blade surface, resulting in slightly higher efficiency.
Airfoils
Airfoil impellers, similar to backward-inclined styles, feature hollow, foiled blades. Their aerodynamic design promotes smooth gas flow with minimal resistance, making them the most efficient for clean air movement. However, they are unsuitable for particulate-heavy environments due to buildup, punctures, and vibration issues.
Squirrel Cage
The forward-curved, or “squirrel cage,” impeller features many short, forward-curved blades around its outer edge, resembling a dryer drum. While less efficient, this design excels at moving large air volumes under low static pressure, making it ideal for specific airflow needs.
Our application engineers have extensive experience with a wide range of industrial applications. Contact our team today to discuss your project. We can help you select the best fan for your application.