What is the basic difference in working principle?

Centrifugal is rotodynamic (centrifugal force of an impeller); reciprocating is positive displacement (piston)

Centrifugal is positive displacement; reciprocating is rotodynamic

Both are positive displacement but with different valves

Centrifugal uses a piston; reciprocating uses an impeller

Which statement about priming is correct?

A centrifugal pump needs priming before starting; a reciprocating pump is self-priming

A reciprocating pump needs priming; a centrifugal pump is self-priming

Compare discharge and head of the two pumps.

Centrifugal gives large smooth discharge at low to medium head; reciprocating gives small pulsating discharge at high head

Centrifugal gives small pulsating discharge at high head; reciprocating gives large smooth discharge

Both give large discharge at very high head

Centrifugal gives high head and pulsating flow

What happens if the delivery valve is closed while running?

Centrifugal pressure rises only to shut-off head (safe briefly); reciprocating pressure rises dangerously and needs a relief valve

Centrifugal pressure rises dangerously; reciprocating is safe

2079 Chaitra · 5 marks

Centrifugal versus reciprocating pumps

Short answer

Centrifugal pump: rotodynamic, large continuous discharge, low-medium head, needs priming, compact and low cost. Reciprocating pump: positive displacement, small pulsating discharge, high head, self-priming, large and expensive, handles only clean liquids.

Differentiate between Centrifugal and Reciprocating pumps.

A centrifugal pump is a rotodynamic pump that raises the pressure of a liquid by the centrifugal action of a rotating impeller. A reciprocating pump is a positive-displacement pump in which a piston or plunger moving to and fro in a cylinder sucks in and pushes out a fixed volume of liquid per stroke.

Basis	Centrifugal pump	Reciprocating pump
Working principle	Centrifugal force from a rotating impeller	Positive displacement by a piston
Discharge	Large, continuous and smooth	Small, pulsating (air vessels needed)
Head	Low to medium	High
Priming	Required before starting	Not required (self-priming)
Speed	High; can be coupled directly to a motor	Low; needs crank and gearing
Size and weight for same output	Small, compact, light	Large and heavy
Parts and maintenance	Few moving parts, easy maintenance	Many parts (valves, piston rings), more wear
Efficiency	Lower (about 60–80%)	Higher (about 85–90%) at its design point
Liquid handled	Can handle dirty, sandy or viscous liquids	Only clean liquids (valves get damaged)
Effect of closed delivery valve	Pressure rises only to shut-off head; safe for a short time	Pressure rises dangerously; needs a relief valve
Initial cost	Low	High
Uses	Water supply, irrigation, powerhouse drainage	Boiler feed, hydraulic presses, small high-head duties

Example: a municipal water supply pumping 100 L/s against 40 m uses a centrifugal pump, while a boiler feed of 1 L/s against 300 m uses a reciprocating (plunger) pump.

In short, centrifugal pumps are preferred for large flows at moderate heads because they are cheap, compact and smooth running, while reciprocating pumps are used where a small flow is needed at a very high pressure.

✓ Answer checked by Claude Opus 5.5 (high effort)

Working principle of centrifugal and reciprocating pumps · Hydro Power, chapter 7
Pumps in series and parallel on a system · Fluid Machines, chapter 4

All Hydro Power chapter 7 questions →

Centrifugal versus reciprocating pumps

Related questions