Small blade high speed

Small blade high speed agitators are used to mix low to medium viscosity liquids. Two of the most common types are the six-blade flat blade turbine and the marine type propeller shown in Figures 5.1 and 5.2 respectively. Flat blade turbines used to mix liquids in baffled tanks produce radial flow patterns primarily perpendicular to the vessel wall as shown in Figure 5.3. In contrast marine type propellers used to mix liquids in baffled tanks produce axial flow patterns primarily parallel to the vessel wall as shown in Figure 5.4. Marine type propellers and flat blade turbines are suitable to mix liquids with dynamic viscosities up to 10 and 50 Pa s, respectively. 

Impellers with a small blade area, whieh rotate at high speeds. 

These are made up of a large number of wide, shallow blades with a very large inlet area relative to the wheel diameter. For equal duty the speeds are lower than other centrifugal fans. They are sometimes called multivane the operating efficiencies are in the 65-75% range. They consist of a large number of relatively small blades mounted on the impeller. The blade tips are inclined toward the direction of rotation. The actual flow rate can be 2.5 times as high as the same size backward-curved fan. 

The basic high-speed dispersing impeller blade is a flat disk with teeth or similar serration around the diameter, as shown in Fig. 17.1. On some models, disks may be without teeth, or several may be stacked up with small gaps between disks so that material between the disks is sheared as the impeller turns. Sometimes two shafts are used in the same mixing chamber their disks may interlock and counterrotate, thereby enhancing shear. 

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