Classification According to the number of stages

Classification According To THE NUMBER OF STAGES

1. SINGLE STAGE PUMP

A Single Stage Pump is one in which the total delivery head is developed by a single impeller. [Refer: Section 6]

2. MULTI-STAGE PUMP

 A single impeller may not be capable of producing the required total head efficiently. Therefore, two or more impellers may be used in series and fitted on the same shaft. The arrangement is such that the second impeller takes its suction from the discharge of the first impeller. If all the impellers acting in series are in a single casing, the pump is called a Multi-Stage Pump.

In the multi-stage pump, the pressure of the liquid gradually increases as it passes through successive stages of the impeller. A multi-stage pump has the following two important functions:

• To produce a high pressure head: If a high pressure head is to be developed, the impellers should be connected in series or on the same shaft.

 • To discharge large quantity of liquid: If large quantity of liquid is to be discharged, the pumps should be connected in parallel. This gives cumulative discharge.