Centrifugal Pump Cavitation, NPSHa, Power Consumption

The centrifugal pump is the most used pump type in the world.

1. Principle of centrifugal pump

An increase in the fluid pressure from the pump inlet to its outlet is created when the pump is in operation. This pressure difference drives the fluid through the system or plant. 

The centrifugal pump creates an increase in pressure by transferring mechanical energy from the motor to the fluid through the rotating impeller. The fluid flows from the inlet to the impeller centre and out along its blades. The centrifugal force hereby increases the fluid velocity and consequently also the kinetic energy is transformed to pressure. 

2. Performance Curve

The pump performance is normally described by a set of curves. 

2.1. Standard curves

Performance curves are used by the customer to select pump matching his requirements for a given application. 

The data sheet contains information about the head (H) at different flows (Q), see Figure 2.1. The requirements for head and flow determine the overall dimensions of the pump.

Figure 2.1 Pump Curve

In addition to head, the power consumption (P) is also to be found in the data sheet. The power consumption is used for dimensioning of the installations which must supply the pump with energy. The power consumption is like the head shown as a function of the flow.

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