General Components of Centrifugal Pumps
A centrifugal pump has two main components:
a . A rotating component comprised of an impeller and a shaft.
b. A stationary component comprised of a casing, casing cover, and bearings.
Stationary Components
Casing :
Casings are generally of two types: volute and circular. The impellers are fitted inside the casings.
1.Volute casings are a curved funnel increasing in area to the discharge port. As the area of the cross-section increases, the volute reduces the speed of the liquid and increases the pressure of the liquid.( Volute casings are building a higher head ).
2.Circular casing have stationary diffusion vanes surrounding the impeller periphery that convert velocity energy to pressure energy. Conventionally, the diffusers are applied to multi-stage pumps.( circular casings are used for low head and high capacity )
Suction and Discharge Nozzle
The suction and discharge nozzles are part of the casings itself. They commonly have the following configurations.
1. End suction/Top discharge The suction nozzle is located at the end of, and concentric to, the shaft while the discharge nozzle is located at the top of the case perpendicular to the shaft. This pump is always of an overhung type.
2. Top suction Top discharge nozzle The suction and discharge
nozzles are located at the top of the case perpendicular to the shaft. This pump can either be an overhung type or between-bearing type
2. Side suction / Side discharge nozzles The suction and discharge nozzles are located at the sides of the case perpendicular to the shaft. This pump can have either an axially or radially split case type.
Now ;that’s the most important stationary components.
There’s also (Seal Chamber , Gland , Throat Bushing , Internal circulating device , Mechanical Seal ).
1. Impeller The impeller is the main rotating part that provides the centrifugal acceleration to the fluid. They are often classified in many ways.
a- Based on major direction of flow in reference to the axis of rotation:
Axial flow
Mixed flow
b- Based on suction type
Single-suction: Liquid inlet on one side.
Double-suction: Liquid inlet to the impeller symmetrically
from both sides.
c- Based on mechanical construction
Closed: Shrouds or sidewall enclosing the vanes.
Open: No shrouds or wall to enclose the vanes.
Semi-open or vortex type.
2. Shaft
The basic purpose of a centrifugal pump shaft is to transmit the torques
encountered when starting and during operation while supporting the impeller and other rotating parts. It must do this job with a deflection less than the minimum clearance between the rotating and stationary parts.
There’s also (Shaft Sleeve , Coupling ).
But ;that’s the most important stationary components.
