Introduction A pump is a mechanism used to move liquids or gases from lower pressure to a higher
pressure. One of the main type of the pump is a centrifugal pump. A centrifugal pump is a device that rotates the impeller in order to increase the velocity of the flowing fluid. This equipment works by the conversion of energy supplied from a motor or turbine into kinetic energy and potential energy and this operation is described by Ber Bernou noulli' lli'ss pri princi nciple ple (entrifugal (entrifugal !ump !ump "emonstration #nit$ %&). *o$ this laboratory work is related to the operation of the centrifugal pumps$ which consists of two e+periments such as introduction to centrifugal pump characteristics and the observation of the pump characteristic curves. The purpose of the both e+perim e+periments ents was to under understan stand d the operati operations ons of ,-& ,-& entrif entrifuga ugall !ump !ump and obtain obtain head$ head$ power and efficiency graphs for a centrifugal pump according to the measured data. The ,-& entrifugal entrifugal !ump "emonstration "emonstration is ad/usted ad/usted with electronic electronic sensors$ which allows to make the measurements through the software by regulating the flow rate and the speed of the water (entrifugal (entrifugal !ump "emonstratio "emonstration n #nit #nit ,-&$ ,-&$ %&%). %&%). Both Both e+perim e+periment entss involv involvee readin readings gs through through the software and drawing drawing the graphs of main pump characteristics characteristics for the &0$ 1&0$ 1&0$ &0$ 2&0$ 3&0$ &&0 of pump speed . Experimental objectives and Hypothesis Theoretical background Experimental Procedure
Equipment The main equipment needed for this laboratory work is ,-& entrifugal !ump. The ,-& entrifugal !ump "emonstration #nit is used to move the liquid between two different places$ thus the water may flow to and from a centrifugal pump. The speed of water can be regulated by slightly opening or closing the gate valve.
,igure . ,-& entrifugal !ump
,-& entrifugal !ump is supplied with Armfield *oftware on a computer through the Armfield interface device (4,"). The software allows to do the measurements automatically by providing all necessary values.
,igure %. IFD7 Armfeld interace device Experimental Protocol 5+periment A6 4ntroduction to !ump haracteristics . *witch on the 4," Armfield interface device %. By pressing !ower on or *tandby button switch on the ,-& centrifugal pump within the computer software. 7. *et the speed to 2&0 and eliminate any bubble by slightly opening and closing the inlet 8. . 1. . 2.
and gate valves. -ake the flow rate equal to 9ero by closing the gate valve. !ress the icon :;o< in order to record the readings. *lightly open the gate vale to increase the flow rate of water. After each opening$ press the icon :;o< until the valve is fully open. =educe the speed from 2&0 to &0 and save all measured data by pressing :*ave as< icon.
5+periment B6 !ump haracteristic >urves . 2. 7. 8. . 1. 7. 2.
Open a new spreadsheet in a computer software. Increase the speed of the pump until it reaches to 50%. -ake the flow rate equal to 9ero by closing the gate valve. !ress the icon :;o< in order to record the readings. *lightly open the gate vale to increase the flow rate of water. After each opening$ press the icon :;o< until the valve is fully open. *ave all measured data by pressing :*ave as< icon. 4ncrease the speed of the pump to 1&0$ &0$ 3&0$ &&0 and follow the same procedure
above ?steps @. 9. *ave all measured data for the speed 1&0$ &0$ 3&0$ &&0 by pressing :*ave as< icon. &. =educe the speed of the pump bit by bit from &&0 to &0 and switch off the centrifugal pump.
Safety As the equipment involves the useflow of water$ which under certain conditions can cause a health problems due to infection by harmful micro@organisms. 4n order to avoid this problems the apparatus should be cleaned properly and the water must be changed regularly. #sually$ the temperature of the water should be %&C and if it is not practicable to maintain this temperature$ then the water should be disinfected. Calculations: Results: Plots and Tables Results description Part ! "lo#
Total
Rate $ %l&s'
Head
(echanic al Po#er Pm %)'
Pump E**icien cy E %+'
Ht %m' &$&& 8$% 11$2 &$& &$&7 8$82 18$ $3 &$%8 8$%2 &$7 8$% &$1 8$2 $7 7$ &$2 8$% $ 81$ $&3 8$2 2$% $& $%3 7$32 21$2 2$& $8 7$3% 28$3 11$1 Table . -easured data for !art A. By using the obtained dataDs from computer software following graph was constructed.
Head Ht (m)
4.60
100.0
4.50
90.0
4.40
80.0
4.30
70.0
4.20
60.0
4.10
50.0
4.00
40.0
3.90
30.0
3.80
20.0
3.70
10.0
3.60
0.0
0.00
0.50
1.00
1.50
Eciency (%) and Power (W)
2.00
Volume fow rate Q (l/s)
;raph . Eead$ !ower and 5fficiency vs Folume flow rate at 2&0 setting.
Part ,
-.+ Flow Rate Q [l/s]
/.+
Total Head Ht [m]
Flow
Total
Rate Q [l/s]
Hea d Ht [m]
0.+ Flow Rate Q [l/s]
1.+ Total Head Ht [m]
2.+
3..+
Flow
Total
Flow
Total
Flow
Total
Rate
Rate
Head
Q [l/s]
Hea d Ht [m]
Rate
Q [l/s]
Hea d Ht [m]
Q [l/s]
Ht [m]
0,00
1,78
0,00
2,62
0,00
3,60
0,00
4,52
0,00
5,78
0,00
6,86
0,08
1,82
0,13
2,55
0,19
3,54
0,03
4,48
0,21
5,45
0,21
6,28
0,20
1,76
0,35
2,50
0,40
3,48
0,24
4,28
0,43
5,09
0,49
6,05
0,41
1,82
0,48
2,54
0,56
3,49
0,61
4,18
0,69
5,27
0,77
6,21
0,56
1,74
0,65
2,55
0,72
3,42
0,85
4,27
0,90
5,28
1,00
6,34
0,66
1,73
0,76
2,43
0,90
3,42
1,09
4,18
1,18
5,16
1,36
6,09
0,77
1,68
0,90
2,43
1,06
3,25
1,29
3,98
1,39
4,95
1,36
6,13
0,86
1,58
1,06
2,32
1,09
3,30
1,47
3,92
1,63
4,77
1,57
5,95
0,93
1,55
1,14
2,31
1,31
3,05
1,79
5,75
1,77
5,72
Table %. =equired data for !art B.
#sing the required dataDs following graph was obtained.
;raph %. Eead vs Folume flow rate for different settings and curve at constant efficiencies. ;raph shows the changes in total head loss as flow rate increases. *ettings were written on the right end of corresponding curves which are &@&&0. The smooth curve which corresponds to the constant efficiencies (70$ 8&0$ 80 and &0) in different settings has been obtained by /oining the points at which this efficiency is achieved. These points have been calculated by interpolation method as follows6 ,or 70 efficiency &0 setting doesnDt correspond$ thus 1&0 setting was chosen6 ,rom the measurements obtained by computer software6
The pump efficiency of 70 lies between %3.30 and 7.20 which corresponds to total head loss of %.87 meaning that it will be the same at required efficiency. But values of flow rate are &.1 and &.3&$ respectively meaning that needed value lies between this numbers. By applying the interpolation method6
37.8 −29.9 0.9 − 0.76
37.8 −35 =
0.9− x
By solving the equation6 + G &.2 and h G %.87. These values give the corresponding point on the curve. All other points on the graph are obtained in similar manner. 4t is important to note that at 70 efficiency the curve lies on the right of the &0 setting curve$ but 8&0$ 80 and &0 lies above the curve. The same procedure was applied for the constant mechanical power and the required graph was obtained6
;raph 7. Eead vs flow rate for different settings and curve at constant -echanical !ower.
4iscussion: Results explanation Conclusion Re*erence list
apture ,luid -achines. %&. '' entrifugal !ump "emonstration #nit''. Accessed ,ebruary %$ %&. http6discoverarmfield.comenproductsviewfm¢rifugal@pump@demonstration@unit Armfield HT". %&%. ''entrifugal !ump "emonstration #nit ,-&''. Accessed ,ebruar y %$ %&. http6www.nqaco.comsanIpham83thiet@bi@mo@phong@bom@ly@tam@fm&eng
