Pumps

Vane

A curved blade used in a pump.

Impeller

Set of vanes attached to a disc or a cyllinder. Main rotating element in a pump.

In a pump, impeller is mounted on a shaft. The shaft is driven by an electric motor or IC engine.

Direction of the fluid flow

Axial flow

Fluid enters and exits the impeller axially.

Radial flow

Fluid enters the impeller axially. Leaves radially.

Mixed flow

Fluid enters the impeller axially. Leaves in both axial and radial directions. Aka. centrifugal pumps.

Note

For s1, only centrifugal pumps are studied.

Parameters

Head provided

The head provided by a pump depends on the flow rate.

Here:

• - provided head
• - flow rate

For a given pump running at a given speed, there is a unique variation of and .

Power input

Denoted by . Varies with .

Efficiency

Denoted by . Varies with .

Note

All these parameters, plotted vs , is known as performance characteristic of the pump. Will be given by the manufacturer. Can be found by laboratory testing.

In a pipeline system

is the head required (or received) to create the flow rate in the pipeline system. The above equation is known as system characteristic or system load curve.

Here is the loss coefficient and is given by:

Note

Working state of a pipeline system is given by the intersection of system characteristic and performance characteristic (of the pump) curves.

Resultant pumps

In serial

When 2 pumps are operating in a series, their head inputs are added.

In parallel

When 2 pumps are operating in a parallel, their flow rates are added.