Centrifugal pumps

Centrifugal pumps are further classified as either horizontal or vertical, referring to the orientation of the pump shaft. A vertical volute pump is shown in figure 3. In comparison to horizontal pumps, vertical pumps take up less floor space; the pump suction can be positioned more easily below the water surface to eliminate the need for priming; and the pump motor can be located above the water surface to prevent damage in the event of flooding. Vertical pumps can be either dry-pit or wet-pit. Dry-pit pumps are surrounded by air, while wet-pit pumps are either fully or partially submerged. The dry-pit pumps commonly are used in medium to high head, large capacity pumping plants.




 These large dry-pit pumps are generally volute pumps with closed, radial flow impellers. There are a variety of wet-pit pump designs for differing applications. One of the most common types is the vertical turbine pump. The vertical turbine pump is a diffuser pump with either closed or semi-open, radial-flow, or mixed-flow impellers. Vertical turbine pumps, while most commonly used for deep well applications, have a wide variety of uses, including irrigation pumping plants and sumps in powerplants and dams
This type of pump normally is constructed of several stages. A stage consists of an impeller and its casing, called a bowl. The main advantage of this type of construction is that system pressure can be varied by simply adding or reducing the number of stages of the pump. Horizontal pumps are classified according to the location of the suction pipe

 The suction can be from the end, side, top, or bottom. Also common in horizontal pumps is the use of double suction impellers. In a double suction impeller pump, water flows symmetrically from both sides into the impeller which helps to reduce the axial thrust load . In a hydroelectric plant, horizontal pumps are normally used for fire water and cooling water applications.