Rotating machines with an impeller immersed in a tank — the dominant mixing equipment in the process industries. A motor drives a vertical shaft that spins the impeller at a speed set by the flow regime (Reynolds number) × viscosity pair.
Usual types
Classified by the direction of the generated flow:
- Axial — marine propeller, hydrofoil: vertical pumping, ideal for solids suspension and low-viscosity mixing.
- Radial — Rushton turbine, flat blades: intense shear, gas dispersion in liquids.
- Mixed flow — intermediate: transitional-regime application.
Reliability: shaft sealing (the most frequent liability — leakage is the dominant mode), gearbox bearings, impeller corrosion-erosion in abrasive services, shaft-motor misalignment. The same RCM baseline as fluid machinery applies.