Pumps double volute

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

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. 

Vertically suspended double casing pumps are designated Type VS6 for diffuser construction and VS7 for volute construction. 

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.

Double volute the liquid leaving the impeller is collected in two similar volutes displaced 180° with a common outlet radial thrust is counterbalanced and shaft deflection is minimized, resulting in lower maintenance and repair, used in high speed pumps producing above 500 ft per stage. 

Figure 5 Three types of pump casings (a) single volute, (b) double volute, and (c) diffuser. [16]...

Pumps using double volute or diffuser casing will have lower radial force imbalance inside the pump. Usually, pump radial imbalance force is at minimum, if pump is operating at its best efficiency point (BEP). 

Multistage pumps may be of the volute type (Fig. 10-41), with single- or double-suc tion impehers (Fig. 10-42), or of the diffuser type (Fig. 10-43). They may have horizontahy split casings or, for... 

Double-casing volute vertically-suspended pumps shall be designated pump type VS7. 

Volute centrifugal pumps (a) single suction (fi) double suction. 

Centrifugal pumps constitute the most common type of pumping machinery in ordinary plant practice. They come in a number of types other than the simple volute machine shown in Fig. 8.8a. A common type uses a double-suction impeller, which accepts liquid from both sides, as shown in Fig. 8.8h. Also, the impeller itself may be a simple open spider, or it may be enclosed or shrouded. Handbooks, texts on pumps, and especially the catalogs of pump manufacturers show many types, sizes, and designs of centrifugal pumps. 

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