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TECHNICAL MANUAL

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CENTRIFUGAL PUMP TEST RIG

Centrifugal pump is a roto dynamic machine which develops dynamic

pressure of liquid by virtue of rotation for pumping of liquid to a higher height. In

centrifugal pump, liquid in the impeller of a pump is made to rotate by external

force, so that it is thrown away from the center of rotation. As constant supply of

liquid is made available at the center, liquid can be pumped to higher level.

The DYNAMIC unit consist of a centrifugal pump driven by a A.C. motor.

Input to motor is measured on energymeter. A measuring tank is provided to

measure the discharge. Suction vacuum and discharge pressure is measured by

gauges. A gate valve on discharge pipe varies the head. Thus, performance of

pump can be estimated at various speed and heads.

SPECIFICATIONS : -

1) Centrifugal pump - 25 x 25 mm. size, base mounted, max. head 10 mtr.,

max. discharge 100 lpm. at 2700 rpm.

2) Motor :- A.C. 0.75 kw. 3ph. Induction motor.

3) Measuring tank 400 x 400 x 450mm. height, fitted with gauge tube and drain

valve.

4) Sump tank - 600 x 900 x 600 mm. height.

5) Gate valve to control the head.6) Pressure gauge to measure discharge pressure.

7) Vacuum gauge to measure suction vacuum.

8) Energymeter to measure input the motor.

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EXPERIMENTAL PROCEDURE :

1) Fill up sufficient water in the sump tank.

2) Open the priming cock ( fitted on the delivery pipe ) and fill up water upto the

funnel. Close the cock properly.

3) Shut off the discharge valve.

4) Start the pump. As discharge valve is closed, no discharge will be observed,

but discharge pressure will be indicated. This is called Shut off head of the

pump.

5) Slowly open the discharge valve, so that small discharge is observed.

6) Note down discharge head, suction vacuum, time required for 10 ltr. water

collection in measuring tank and 10 revolutions of energymeter disc.

7) Note down the observations at different valve openings.

OBSERVATIONS:

Sr.No.

Pumpspeed

rpm

DischargePr.

(Kg/cm 2)

SuctionVacuum

mm of Hg

Time for10 lit.water collection,

Sec.

Time for 10 rev.of Energymeter

Sec

( Note : Pump speed is to be noted from laboratory tachometer which is not suppliedalong with the equipment )

CALCULATIONS:

1) Discharge Pressure, P d = Kg/cm 2

For water, 10 m height corresponds to 1 kg/cm 2

Discharge head h d = P d x 10 m of water.

2) Suction Head -

Suction vacuum, P s = mm of Hg.

P S 13.6 suction head, h S = ______ x _____

1000 1

Where,

Sp. gravity of hg = 13.6

Sp. gravity of water = 1

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3) Total Head,

h t = h d + h S + h f

Where, h f = 2 mtr. is the assumed head loss due to friction.

4) Discharge -

Let time for 10 lits.water collection be t w sec.then, 0.01

Discharge, Q = ________________ m 3 / sec.tw

5) Output power ( or water power )W. Q. h t

WP = ____________ kw1000

Where ,

W = Specific weight of water = 9810 N / m 3

Q = discharge m3

/ sec.ht = total head, mtrs.

6) Electrical Input -

Let time required for 10 rev. of energymeter disc be t e - Sec.

5 3600Electrical input power, I P = ____ x _________ kw.

te 500

Taking motor efficiency as 75% we have input shaft power

S P = I P x 0.75

7) Over all efficiency of the pump -

W P o = _______ X 100 % S P

8) Graphs -

i) Operating characteristics - Plot the graph of discharge vs. total head, overall

efficiency, input power and water power, at rated speed.

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PRECAUTIONS:

1 ) Priming is must before starting the pump. Pump should never be run empty.

2) Use clean water in the sump tank.

3) Use all the controls and switches carefully.

4) Do not disturb the pressure gauge connections.

5) Drain all the water after the complition of experiments.