Airfoil

Airfoil Blowers have Highest efficiency of all centrifugal fan designs. 9 to 16 blades of airfoil contour curved away from the direction of rotation. Air leaves the impeller at a velocity less than its tip speed and relatively deep blades provide for efficient expansion within the blade passages. For given duty, this will be the highest speed of the centrifugal fan designs.

For Clean Air Service Only. Make Up Air Blowers, Filtered Supply Fans, Forced Draft Ventilation, Combustion Air, Air Strippers, Decarbonators, Emergency Exhaust, and applications requiring Non-Overloading Horsepower curve Characteristics.Text...

Backward Inclined

Backward Inclined Blower Efficiency is only slightly less than that of airfoil fans. Backward-inclined or backward-curved blades are single thickness, 9 to 10 blades curved or inclined away from the direction of rotation. Efficient for the same reasons given for the airfoil fan
above.

Thermal Oxidizers, Boiler Exhaust, Clean Side of Dust Collectors and Bag Houses, Odor Control Systems, Fume Scrubbers, Oven and Furnace Exhaust.

Radial Blower Wheels

Radial Blower Wheels: Simplest of all impellers, least efficient. Has
and the wheel centrifugal fans and least high mechanical strength
I is easily repaired. For a given point of rating, this Blower design requires medium speed. This classification
includes radial blades (R) and modified radial blades (M), usually 6 to 10 Blades.

Used primarily for material-handing applications in industrial plants. Impellers can be of extra heavy duty construction, utilizing Abrasion Resistant "AR" Construction materials such as Tungsten Carbide.  Radial wheels do not use close tolerance Inlet Cones and typically do not allow material build up. 

Forward Curved Blower Wheels:

Forward Curve Blowers for High Volume and Lower Pressures than Backward Inclined or Airfoil Blowers. Available in Single Width SWSI and Double Width DWDI Design.  Efficiency is usually less than airfoil and backward-curved bladed fans. Typically constructed using 24 to 64 shallow blades with both the heel and tip curved forward.  Air exits the wheel at a velocity greater than wheel. Tip speed and primary energy transferred to the air is by use of high
velocity in the wheel. For given duty,
wheel is the smallest of all centrifugal
types and operates at lowest speed.

Used primarily in low-pressure heating, ventilating, and air-conditioning applications such as domestic furnaces, central station air handling units, and packaged airconditionig equipment, make-up air units and roof top units..