A centrifugal pump has the following characteristic: outerdiameter of impeller 800 mm,
width of impeller vanes at outlet 100 mm, angle of impellervanes at outlet 40 o . The impeller
runs at 550 rpm and delivers 0.98 m 3 /s of water under aneffective head of 35 m. A 500 kW
motor is used to drive the pump. Determine the manometric,mechanical and overall
efficiencies of the pump. Assume water enters the impeller vanesradially at inlet.
[ ?mano = 81% , ?m = 83% ?o = 67%].
5. A centrifugal pump has an impeller 0.29 m diameter running at960 rpm with an effective
outlet vane angle of 28 o . The velocity of the flow (assumeduniform throughout the system)
is 2 m/s. The static suction lift 2.8 m. The energy losses inmetres of water are: suction pipe
0.61 m, in impeller 0.49 m, and in volute casing 0.88 m. Fromthese particulars, calculate
the readings of vacuum or pressure gauges placed at (i) inlet ofthe pump (ii) impeller outlet
(in clearance space between impeller and volute), iii pumpoutlet or delivery flange located
0.2 m above the centreline of the pump.
[ (i) – 3.614 m, (ii) 6.01 m (iii) 10.89 m ]
6. Water is to be pumped out of a deep well under a total headof 95 m. A number of identical
pumps of design speed 1000 rpm and specific speed 900 rpm with arated capacity of 150
litres/s are available. How many pumps will be needed and howshould they be connected.
[ 3 pumps, connected in series ]
