SUBJECT: All about impellers 10-1

First the types:

Radial flow impellers (low specific speed numbers)

Axial flow impellers (high specific speed numbers)

Impellers can be manufactured from a variety of materials:

We would like a combination of a hard material to resist wear and a corrosion resistant material to insure long life. This is often a conflict in terms because when we heat treat a metal to get the hardness we need, we lose corrosion resistance. The softer metals can have corrosion resistance, but they lack the hardness we need for long wear life. The best materials that combine these features are called the "Duplex Metals". These duplex materials are now in their second generation. They can be identified by letters and numbers such as Cd4MCu

If a new impeller is required because of cavitation, the new design should incorporate those features we have learned that will increase impeller performance:

Impellers can be designed for a variety of applications:

People often inquire about forward curved vanes. Tests have shown:

Impellers can be single or double suction designs.

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