Rotodynamic pumps

INTRODUCTION:
Liquids have to be moved from one location to another and one level to another in domestic, agricultural and industrial spheres. The liquid is more often water in the domestic and agriculture spheres. In industries chemicals, petroleum products and in some cases slurries have to be moved, by pumping. Three types of pumps are in use.(1) Rotodynamic pumps which move the fluid by dynamic action of imparting momentum to the fluid using mechanical energy. (2) Reciprocating pumps which first trap the liquid in a cylinder by suction and then push the liquid against pressure. (3) Rotary positive displacement pumps which also trap the liquid in a volume and push the same out against pressure.
Reciprocating pumps are limited by the low speed of operation required and small volumes it can handle.
Rotary positive displacement pumps are limited by lower pressures of operation and small volumes these can handle. Gear, vane and lobe pumps are of these type .Rotodynamic pumps i.e. centrifugal and axial flow pumps can be operated at high speeds often directly coupled to electric motors. These can handle from small volumes to very large volumes. These pumps can handle corrosive and viscous, fluids and even slurries. The overall efficiency is high in the case of these pumps. Hence these are found to be the most popular pumps in use. Rotodynamic pumps can be of radial flow, mixed flow and axial flow types according to the flow direction. Radial flow or purely centrifugal pumps generally handle lower volumes at higher pressures. Mixed flow pumps handle comparatively