Volute pumps

Bypassing is occurring between volute channels in a double-volute pump casing due to a casting defect or extreme erosion. 

Some pump manufacturers use a different taetie to expand the operating window of their products. This is why the dual ohite pump exists. The dual volute pump is designed to operate over a wide range of flows and heads. 

In the easting procedure of the dual volute pump, a second cutwater is designed 180° opposite the first cutwater and another volute channel added. This way, all areas e.xposed to velocity and pressure around the volute easing are equal. All forces around the volute are equalized or eaneelled (Figure 9-15). 

Centrifugal pumps with diffusion vanes are called diffusion pumps or, more recently, vertical turbine pumps. Those pumps with volute casings are called volute pumps. 

Wet-pit volute pumps, 21 65, 66 Wet-process kilns, 5 489-490 Wet process lead refining, 14 751 Wet-process phosphoric acids, 18 819-820, 824-826... 

Wet pit, vertically-suspended, single-casing volute pumps with discharge through the column are designated pump type VS2. 

Figure 7.9. Some types of centrifugal pumps, (a) Single-stage, single suction volute pump, (b) Flow path in a volute pump, (c) Double suction for minimizing axial thrust, (d) Horizontally split casing for ease of maintenance, (e) Diffuser pump vanes V are fixed, impellers P rotate, (f) A related type, Ihe turbine pump.

Rotary centrifugal pumps with no valve action open impeller, closed impeller, volute pumps, turbine pumps... 

Volute Pump.—The impeller is surrounded by a spiral casing (the volute) of gradually increasing cross-section, Fig. 7. 

Approximate rules For short vanes, or open impellers Eh == 30per cent, for Volute Pumps Eh 50 to 60 per cent, for Turbine Pumps Eh 57 to 69 per cent. 

Centrifugal pumps can also be constructed in a manner that results in two distinct volutes, each receiving the liquid that is discharged from a 180 degrees region of the impeller at any given time. Pumps of this type are called double volute pumps. In some applications the double volute minimizes radial forces imparted to the shaft and bearings due to imbalances in the pressure around the impeller. 

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