Impellers 

Impellers are rotating devices that force liquids, gases and vapors in a desired direction. They are widely used in pumping, blowing, and mixing applications. This area gives the ability to search for impellers for pumping and mixing of media and allows selection of type of impeller and size. Impeller applications, specifications and features, types, and materials are all important parameters to consider when searching for impellers.

Types of impellers include axial flow fan turbine, axial flow pitched blade, axial flow propeller, screw centrifugal impellers, open radial vane, semi open radial vane, closed radial vane, vortex, radial flow anchor, radial flow paddle impellers, radial flow turbine, helical, hydrofoil, mixed flow, and rotating coil. Axial flow impellers are used at high speeds to promote rapid dispersion and are used at low speeds for keeping solids in suspension. Axial flow fan turbines are impellers that have multiple fins and convey the pumped media in the direction along the revolving axis of the impeller.

Axial flow pitched blade impellers are used for mixing and have one or more paddles. Axial flow propeller impellers are impellers that have 2 to 4 blades and convey the pumped media in the direction along the revolving axis of the impeller. Screw centrifugal impellers are impellers used within a pump used for pumping liquid with solid objects and fibrous materials. Radial vane impellers are impellers used within a pump used for pumping liquid or air. Open radial vanes are typically seen on smaller pumps and are used to pump liquids with stringy materials within. These impellers are vanes mounted to hubs. Semi open radial vanes have a full shroud is on one side of the vanes. The shroud increases the structural strength of the impeller.

Closed radial vanes have a full shroud is on both sides of the vanes. The shrouds increase the structural strength of the impeller. With a vortex pump, flow through the hydraulic unit is produced not by the actual impeller, but rather by a rotating vortex created by the impeller. A radial flow anchor is used for mixing, it is an impeller designed for mixing higher viscosity products. Radial flow paddles have impellers that convey the media outward to the side of the tank. Radial flow turbines are the multi-blade type impellers that convey the media outward to the side of the tank. Helical impellers have a blade that act like an auger and a blade that fully sweeps the bottom and sides of the vessel. Hydrofoils are high efficiency axial flow blade assembly. Mixed flow impellers provide mixing in both radial and axial direction. Rotating coil impellers have a coil (spring) shaped impeller mounted perpendicular to the impeller shaft. Common applications served by impellers include mixing, pumping, air movement, chemical, compressor or refrigeration, heat exchangers or radiations, high viscosity media, propulsion, and water or wastewater.

Important impeller specifications to consider include the number of blades or vanes, outside diameter, and bore size. Features include adjustable pitch, anti-static, coated or plated, corrosion resistant, custom fabricated, folding blades, and multistage. Choices for materials of construction include aluminum, brass or bronze, cast iron, composite, plastic, rubber, stainless steel, and titanium.