Which impeller type is best suited for high flow with moderate head?

Which impeller type is best suited for high flow with moderate head?

• A. Radial flow
• B. Axial flow
• C. Mixed flow
• D. Diffuser

Answer: (B)

The idea is that the shape and orientation of the impeller determine how much fluid you can move (flow) versus how much pressure rise (head) you can achieve. An axial-flow impeller is built so the fluid mostly moves parallel to the shaft, like a propeller. This creates a large flow passage and keeps the velocity rise relatively small, so you get a high flow with only a moderate increase in pressure. That makes axial-flow impellers ideal when you need to push a lot of fluid through a system without needing a large head. Radial-flow impellers, by contrast, speed the fluid outward from the center, converting velocity into higher pressure, which gives higher head but lower overall flow. Mixed-flow designs sit in between. A diffuser isn’t an impeller type at all—it's a stationary set of vanes that helps convert remaining velocity into pressure after the impeller, often boosting head, but it doesn’t define the primary flow versus head characteristics the way the impeller design does.

The idea is that the shape and orientation of the impeller determine how much fluid you can move (flow) versus how much pressure rise (head) you can achieve. An axial-flow impeller is built so the fluid mostly moves parallel to the shaft, like a propeller. This creates a large flow passage and keeps the velocity rise relatively small, so you get a high flow with only a moderate increase in pressure. That makes axial-flow impellers ideal when you need to push a lot of fluid through a system without needing a large head.

Radial-flow impellers, by contrast, speed the fluid outward from the center, converting velocity into higher pressure, which gives higher head but lower overall flow. Mixed-flow designs sit in between. A diffuser isn’t an impeller type at all—it's a stationary set of vanes that helps convert remaining velocity into pressure after the impeller, often boosting head, but it doesn’t define the primary flow versus head characteristics the way the impeller design does.