Basics Of Centrifugal Pumps

1. AIM: To obtain the efficiency of a jet
pump.

2.  Jet pump is a device driven by power from
an external source which when interposed in
pipe transfers mechanical energy to the
liquid flowing through the pipe.
 This device consists of a stream of high
pressure water, its energy being converted
into kinetic energy in a nozzle, which is
made to impart a part of its energy to the
water surrounding the jet.

3.  This action projects a considerably large stream of
low pressure water into the delivery pipe.

4.  SUPPLY TANK
It is used to supply the water through the
pump.
 COLLECTING TANK
It is used to collect the water coming from
pump through a pipe.
 JET PUMP
Transfers the mechanical energy to the liquid
flowing through the pipe.

5.  PRESSURE GAUGE
Used to measure the pressure head of the fluid
flowing through the pipe after passing through the
pump.
 VACUUM GAUGE
Used to measure the suction head of the fluid
flowing through the pipe before passing through the
pump.

6.  The suction side is completely filled with
water and the pump is started.
 A stream of high pressure water from the
delivery pipe of the pump is allowed to flow
through the suction jet nozzle.
 The pressure energy of water is converted
into kinetic energy due to which a local drop
in the pressure takes place.
 Due to the pressure drop suction is created
and water is sucked from the bore well.

7.  This action ensures a considerably large supply of
low pressure water.
 When the stream with different velocities mix (in
the mixing zone), some pressure rise takes place in
the mixing zone.
 After the mixing zone, there is a diverging section
where further rise of pressure occurs due to
decrease in velocity.

10.  Determine the area of collecting tank.
 Fill the jet pump with the oil up the level
marked on the pointer.
 Prime the pump-set before starting.
priming means taking the air present in the
suction and pressure pipes, casing by filling
them with water.
 Before starting, ensure that the pump is free
to rotate.

11.  The flow control valve was adjusted to give the
maximum possible discharge.
 Conditions were allowed to steady before the rate
of discharge Q, suction head, discharge head and
load on the motor were recorded.

12.  Discharge (Q) = (h2-h1)A
t
Where, h1= initial height of water in collecting
tank.
h2= final height of water in collecting
tank.
t= time period for the run of pump.
A= area of collecting tank.

13.  Input power (Pi) = 0.6(VxI)
Where, V= voltage
I= current
 Output power (Po) = ρgHQ
Where, ρ= density of fluid
g= acceleration due to gravity
H= total head
Q= discharge
 Efficiency (η) = Po x 100
Pi

14.  7psi = 48.26Kpa
 17psi = 117.21Kpa
 690mmHg = 91.99Kpa
 660mmHg = 87.99Kpa
 Q1 =(h2-h1)A = (10.5-7.5)1225
t 20
= 1.84x10-4 m3/s
 Q2=1.63x10-4 m3/s

15.  Input power, Pi = 0.67xVxI
= 0.67x220x2 = 294.8 Watt
 Output power, Po1 = ρgHQ
= 1000x9.81x43.73x1.84x10-4
= 78.93 Watt
Po2 = 46.72 Watt
 Efficiency, η1 = Po1 x100
Pi
= 26.77 %
η2 = 15.84 %

16. Final
height
h2
(m)
Time
t
(sec)
Discharge
Q
(m3/s)
Suction
head
P1
(m)
Delivery
head
P2
(m)
Total
head
H
(m)
Input
power
Pi
(Watt)
Water
power
Po
(Watt)
Efficien
η
(%)
0.105 20 1.84x10-4 690
mmHg
7psi 43.73 294.8 78.93 26.77%
0.085 30 1.63x10-4 660
mmHg
17psi 29.22 294.8 46.72 15.84%

17. The efficiency of the jet pump is 26.77 % and 15.84
%.
USES OF JET PUMP
 A jet pump can be used to take out muddy water
from excavation trenches.
 To lift water from wells of smaller bores.
 Employed in mining and for pumping oil.

18.  Chandan kumar 131MC00213