LAB MANUAL RPTR

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RECIPROCATING PUMP TEST RIG


Reciprocating pump is a positive displacement plunger pump. It is often used where relatively small quantity of water is to be handled and delivery pressure is quite large. Reciprocating pump is widely used as Automobile Service Stations, Chemical Industries, or as metering and dosing pumps.
The “UNICOOL” apparatus consists of a single cylinder, double acting reciprocating pump mounted over the sump tank. The pump is driven by Dimmer Control DC motor with stepped cone pulley. An energy meter measure electrical input to motor. Measuring tank is provided to measure discharge of the pump. The pressure and vacuum gauges provided to measure the delivery pressure and suction vacuum respectively.

SPECIFICATIONS

Ø Reciprocating pump – 37.5mm bore, stroke length 49mm, double acting with air vessel on discharge side, suction 28mm, discharge 22mm.
Ø D.C motor, Dimmer Control Type.
Ø Measuring tank – ___mm x ___mm x ___mm height.
Ø Sump tank – 600mm x 900mm x 600mm height.
Ø Measurements –
a) Pressure gauge –0-4 Kg/cm2 for discharge pressure.
b) Vacuum gau00ge –0-760mm Hg for suction vacuum.
c) 1 Ph. Energy meter for motor input measurement.

EXPERIMENTAL PROCEDURE

Ø Fill up sufficient water in sump tank.
Ø Fill up the air vessel for about 2/3rd capacity.
Ø Open the gate valve in the discharge pipe of the pump fully.
Ø Close the Ball valve and drain valve of the measuring tank.
Ø Check nut bolts & the driving belt for proper tightening.
Ø Driven the outlet pipe into funnel and slowly increase the pump speed, slightly close the discharge valve. Note down the various reading in the observations table. Repeat the procedure for different gate valve openings. Take care that discharge pressure does not rise above 4 Kg/cm2.
Ø Change the speed and tank readings for different Ball valve openings. Repeat the procedure for different speeds and complete the observation table.

OBSERVATIONS


Sr No.
Pump speed
NpRpM
Discharge
Vacuum
Kgs/cm2
Suction
Vacuum
Mm of Hg
Time for 10 Lts.
In measuring tank
t sec
Time for 10 rev of
Energy meter
te sec



















CALCULATIONS


1) Suction head

Hs = suction vacuum of Hp x (pHg - pw)
Where,
pHg = Sp gravity of mercury 13.6
pw = Sp gravity of water 1
Hs = 12.6 x suction vacuum mtrs.

2) Delivery head

Ha = Discharge pressure, Kg / cm2 x 10
(as 10m of water = 1 Kg / cm2)

3) Total head

Hq = Hs + Hp + 3mtr
Where,
Loss of head in piping and fittings is assumed to be 3 mtrs.

4) Discharge
L x B x .01
Actual discharge, Qa = --------- m3 / sec
T


5) Out put power of pump

W. Qa. Hp
Pw = -------------------- Kw
1000
Where,
W = Specific weight of water = 9810 N/m3
Qa = Discharge m3/sec
Hp = total head. Mtr.

6) Input power to pump

Let time required for 10 rev of energy meter is to sec.
Then,
10 3600
IP = --------- x -------------- Kw
te 1200
where,
Energy meter constant is 1200 Rev/ Kwh.
Taking motor efficiency 60%, we have input shaft power
S.P = I.P. x 0.6

7) Over all efficiency of pump
Pw
ŋo = -------- x 100%
SP

PRECAUTIONS


Ø Operate all the controls gently.
Ø Sever allow to rise the discharge the pressure above 4 Kg/cm2.
Ø Always use clean water for experiment.
Ø Before starting the pump ensure that discharge valve is opened fully.

SAMPLE CALCULATION
OBSERVATIONS
Sr
No.
Pump speed
NpRPM
Discharge
Pressure
(Kg/cm2)
Suction
Vacuum
mm of Hg
Times for 10 lit rise in measuring tank
t sec
Time for 10 rev of Energy meter te Sec
1
445
0.5
452
16.12
354.1
2
437
1
445
16.75
317.6
3
434
2
440
17.16
269.6
4
425
3
422
17.37
225.0


Suction head –
Hs = 12.6 x 0.452 mtrs
= 5.695 mtrs
Delivery head –
Ha = 0.5 x 10
= 5 mtrs
Total head –
Hq = 5.695 + 5 + 3 mtr
= 13.695 mtrs.
Where,
Loss of head in piping and fitting is assumed to be 3 mtrs.
Discharge
0.01
Actual discharge, Qa = ------------ m3/sec
16.12
= 6.20 x 10-4 m3/sec
Output power of pump
9810 x 6.20 x 10-4 x 13.695
Pw = ----------------------------------------- kw
1000
= 0.083 kw
Input power to pump –
Let time required for 10 rev. of energy meter be to sec.
Then, 10 3600
IP = ------------ x ---------------- kw
354.1 240
= 0.42 kw
Where, energy meter constant 240 rev/kwh
Taking motor efficiency 80% we have input shaft power
Sp = 0.42 x 0.8
= 0.34 kw
Overall efficiency of pump –
0.083
ηO = ------------ x 100%
0.34
= 24.41%

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