Selecting a proper pump for a service involves four primary

Selecting a proper pump for a service involves four primary areas to be considered for system analysis. Briefly explain them. (8mark)

Solution

There are several factors/areas to be considered in pump selection for a particular service - amount and type of fluid handled, required height/head against which the fluid is to be pumped, type of power supply in use, nature of service, service environment etc.

1. Amount of fluid handled - This will determine the overall pump size (in terms of discharge capacity). It will also help in determining if pumps need to be arranged in parallel i.e. whether to operate a single large capacity pump or multiple small capacity pumps in parallel.

2. Type of fluid handled - Properties of fluid, like viscosity, temperature, vapour pressure etc. affect pump performance. So type of fluid needs to be taken into consideration in pump selection - e.g. water,oil,air.

3. Head - Rotary pumps develop lesser head as compared to reciprocating ones. So depending on required head, pump type will change. Head requirement also determines number of stages required.

4. Power supply - Can be either an electric motor or engine. High speed rotary pumps can be directly coupled to motor drives without use of belts or gears. So for electric motor drive, rotary pumps are preferred.

5. Nature of service - Continuous operation is less likely to cause corrosion problems as compared to intermittent working. Accordingly material of pump parts will be different.

6. Service environment - Again, special purpose materials are required for different environments like corrosive, radioactive, abrasive. Not only the materials but even pump construction also may change depending on the operation environment.