Question

Consider the following advantages of rotary pumps compared to reciprocating pumps:

1. Steady discharge which increases with decrease in head

2. Suitable for handling fluids with suspended solid particles

3. Less bulky than positive displacement pumps

4. Can be started with open delivery with least load

Which of the above advantages are correct?

1. 1 ,2 and 3
2. 1, 2 and 4
3. 1, 3 and 4
4. 2, 3 and 4

Answer 1

Correct Answer - Option 1 : 1 ,2 and 3

The hydraulic machines which convert the mechanical energy into hydraulic energy are called pumps. If the mechanical energy is converted into pressure energy by means of the centrifugal force acting on the fluid, the hydraulic machine is called a centrifugal pump.

Centrifugal pumps	Reciprocating pumps
The discharge is continuous and smooth	The discharge is fluctuating and pulsating
It can handle a large quantity of liquid	It handles a small quantity of liquid only
It can be used for lifting highly viscous liquids	It is used only for lifting pure or less viscous liquids
It is used for large discharge through smaller heads	It is meant for a small discharge and high heads
Cost of a centrifugal pump is less as compared to reciprocating pump	Cost of a reciprocating pump is approximately four times the cost of a centrifugal pump
Centrifugal pump runs at high speed. They can be coupled to an electric motor	It runs at low speed. Speed is limited due to consideration of separation and cavitation
The operation of a centrifugal pump is smooth and without much noise. The maintenance cost is low	The operation of a reciprocating pump is complicated and with much noise. The maintenance cost is high.
It requires a smaller floor area and installation cost is low	It requires a larger floor area and installation cost is high
Efficiency is high	Efficiency is low