Blower Information
Backward Curve Impeller
Backward curved blades have slightly lower efficiencies compared to airfoil blades. These blades are better suited to handle contaminated air because they are single thickness and can be made of heavier material that can resist the effects to fan blades by the contaminated air.
impeller blades are inclined opposite to the direction of fan rotation. This type usually has higher tip speeds and provides high fan efficiency
and relatively low noise levels with "non-overloading" horsepower characteristics. In a non-overloading fan, the maximum horsepower occurs near the optimum operating point so any variation from that point due to a change in system resistance will result in a reduction in operating horsepower. The blade shape is conducive to material buildup so fans in this group should be limited as follows:
Backward Incline Impeller
Backward inclined blades have lower structural strength and efficiencies. They are easier to produce due to the elimination of the blade Curvature.
Radial Blades (Transport Impeller)
Radial blades are rugged and self-cleaning, but have low efficiencies. They are suited for airflows containing corrosive fumes and abrasive material from grinding operations.
Radial Impellers have blades which are straight or radial from the hub. The housings are designed with their inlets and outlets sized to produce material conveying velocities. There is a variety of impeller types available ranging from "high efficiency, minimum material" to "heavy impact resistance" designs. The radial blade shape will resist material buildup. This fan design is used for most exhaust system applications when particulates will pass through the fan. These fans usually have medium tip speeds and are used for a variety of exhaust systems which handle either clean or dirty air.
