Centrifugal Blowers & Fans
Centrifugal Fans and Blowers typically have one of seven types of wheels that draw the air into
the inlet of the blower housing, through the wheel, and discharges it at 90 degrees out through
the discharge of the housing.
The two most common types of Centrifugal Blowers are Pressure Blowers and Volume
Pressure Blowers are designed to draw or push air at high pressures, rated in static pressure water
gauge ( SPWG). Volume Blowers are designed to draw or push larger volumes of air, rated in
cubic feet of air per minute (CFM), at lower static pressures than Pressure Blowers.
Centrifugal Blowers are typically made of fabricated steel, stainless steel or cast aluminum.
There are 6 basic types of blower wheels or centrifugal impellers used in industrial blowers.
1. Shrouded Radial Blade
2. Open Radial Blade
3. Open Paddle Wheel
4. Backward Inclined (with flat blades or airfoil blades)
5. Forward Curved Multi-vane (Squirrel Cage)
6. Backward Curved Radial
Shrouded Radial Blade
Open Radial Blade
Open Paddle Wheel
Type 1, Shrouded Radial Blade blower wheels are designed to deliver higher pressures for
pressurizing, blow-off systems and long duct or pipe runs.
Type 2, Open Radial Blade with Back Plate blower wheels are designed for conveying
powdery or granular material and long stringy paper trimmings or fibers.
Type 3, Open Paddle Wheel is primarily for conveying powdery or granular material.
Type 4, Backward Inclined blower wheels are available with a flat blade design or a more
efficient airfoil design blade where each blade has a cross section similar to an airplane wing.
These wheel types are commonly used for general ventilation, forced cooling at higher pressures
and in dust collection systems where the fan is on the clean air side of the dust collector.
Type 5, Forward Curve Multi-vane blower wheels are for moving large volumes of air at lower
pressures. Typically selected for general ventilation or forced cooling at slower speeds.
Type 6, Backward Curved Radial blower wheels are a modified version of the Open Radial
Blade wheel. It is designed to expand the performance ratings of open radial bladed wheels in
some direct driven fans. In some cases, it can be used to convey granular material but should not
be used to convey powdery or stringy material.