What are the differences between closed impellers, semi-open impellers, and open impellers?

Vanes enclosed between front shroud and back shroud

Time:

2025-12-10

	Closed Impeller	Semi-Open Impeller	Open Impeller
Structure	Vanes enclosed between front shroud and back shroud	Vanes attached to back shroud only, no front shroud	Vanes attached directly to hub, no shrouds
Efficiency	Highest (minimal recirculation losses)	Medium (some leakage across vane tips)	Lowest (significant tip leakage)
Wear Resistance	Good (shrouds protect vanes)	Moderate (vane tips exposed to wear)	Poor (vanes fully exposed to wear)
Ability to Handle Large Particles	Poor (narrow internal passages)	Moderate	Excellent (wide open passages)
NPSH Required	Low (smooth inlet flow)	Medium	High (more flow disturbance)
Adjustment for Wear	Difficult (requires shroud trimming or replacement)	Moderate (can adjust front clearance)	Easy (can adjust front clearance easily)
Manufacturing Cost	High	Medium	Low
Maintenance	Complex (hard to clean, difficult to inspect internal wear)	Moderate	Simple (easy to clean and inspect)
Clogging Risk	High (small particles can lodge between shrouds)	Medium	Low
Typical Mining Applications	Clean liquids, fine slurries, high-head applications	Medium-size solids, moderate slurry concentration	Coarse solids, fibrous materials, thick slurries