Correct Answer - Option 1 : Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
Concept:
Centrifugal pumps have a rotating impeller also known as a blade that is immersed in the liquid. Liquid enters the pump near the axis of the impeller, and the rotating impeller sweeps the liquid out toward the ends of the impeller blades at high pressure.
So Roto-dynamic pumps must have to be centrifugal rather than centripetal, from the very basic principles of hydrodynamics.
When two centrifugal pumps are connected in series, or connected along a single line, head is added together and high head is developed. This is because the fluid pressure increases as the continuous flow passes through each pump, much like how a multi-stage pump works. So pumps in series operation allow the head to increase.
Pumps are operated in parallel when two or more pumps are connected to a common discharge line, and share the same suction conditions. Both pumps must produce the same head this usually means they must be running at the same speed, with the same diameter impeller. So when the Pumps in parallel operation increase the flow rate and head remains the same.
So as the stages are in series the head will increase.
So both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I).
Trick to remember:
Consider flow as current and head as voltage. So in series connection current remains constant and change in voltage occurs, so pumps in series increases the head. Where as in parallel connection voltage remains same and current increases, similarly head remains the same and flow increases.
