Service Contract No 2007 / 147-446 - Swaziland

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hf6375kQ4d2………………………………….. (4)A summation of friction loss across the river pumps foot valves, the suction pipe, and theeccentric reducer gave a total hf of 0.72m, 0.2m and 0.5m for PS1, PS 2 and PS 3respectively. Friction in the suction pipe has a direct effect on maximum suction height andconsequently the available net positive suction head (NPSH) and is discussed below.Where: hf = secondary friction loss in fitting (m)k = friction loss factor (annexure 1)Q = flow rate in the fitting (m³/h)d = inner diameter of the fitting (mm).4.1.1.5 Suction heightThe essence of this evaluation was to determine the actual static suction head of the installedpumps and then compare it to the designers suction height assumption. The maximumsuction height is calculated using equation 5 below;hs(max) hdhfhvp NPSHrequired ………………. (5)Where: hs (max) = maximum suction height (m)hdhfhvp= atmospheric pressure on terrain (m)= suction side losses (friction losses, as well as secondary losses in fittings, m= vapour pressure of water (m)NPSH required = net positive suction head from the pump curve (m)Maphobeni Farmers Association Report - 2009 Page - 21 -
Figure 12. Atmospheric pressure vs. height above sea levelThe suction height of PS 1 and PS 2 was measured to be approximately 4 and 3 metersbelow the impellor eye respectively. The NPSH required (NPSHr) of the pumps in this pumpstations is 1.5m and 4.5m respectively (see attached pump curves). PS 3 pumps have anNPSHr of 3 meters. From the above formula the maximum allowable suction height is 7.38m,4.9m and 6.1m for the pumps in the three pump stations respectively. These calculationsconfirm that all pumps were installed with correct suction height.Further analysis compared NPSH available to NPSH required and all pumps in this irrigationscheme conforms to the recommendation of NPSHr
Page 1 and 2: Restructuring and DiversificationMa
Page 3 and 4: DISCLAIMERThe contents of this repo
Page 5 and 6: 5.2 Delivery tests ................
Page 8 and 9: LIST OF APPENDICESAppendix 1: SEB u
Page 10 and 11: 1 I N T R O D U C T I O NAssociatio
Page 12 and 13: pumps. 2 x Howden 100-400 in the ri
Page 14 and 15: 3.1.2 R e v i e w o f C o n t a c t
Page 16 and 17: 9 SCHEDULE OF BLOCKS THAT IRRIGATE
Page 18 and 19: Maphobeni Farmers Association Repor
Page 24 and 25: Based on equation 1 above the flow
Page 26 and 27: ReducersThe inlet on the pump sucti
Page 28 and 29: d1.5d0.5dd3d 3d 1.5dFigure 9. Spaci
Page 32 and 33: Table 1. Pump and motor specificati
Page 34 and 35: Table 2. Irrigation pumps evaluatio
Page 36 and 37: Phase two river pump station‣ Pum
Page 38 and 39: Filters: 3%Capital Recovery Rate (C
Page 40 and 41: 4.3.1 M a i n l i n e s i z eThe So
Page 42 and 43: 5 F I E L D E V A L U A T I O N O F
Page 44 and 45: 5.1.2 S p r i n k l e r p r e s s u
Page 46 and 47: 0 L/4 L/2 3L/4 LL3L/4LL/2Test block
Page 48 and 49: Phase two booster Pumps running und
Page 50 and 51: The installation of this unit (on t
Page 52 and 53: Old AgePhase one of the irrigation
Page 54 and 55: The effects of different nozzles/em
Page 56 and 57: Interest RatesIt can be argued that
Page 58 and 59: 6 . 2 M a n a g e m e n t P r a c t
Page 60 and 61: 6 . 3 M a i n t e n a n c e S u r v
Page 62 and 63: 7 C O N S T R A I N T S T O E F F I
Page 64 and 65: phase one and two was found to be 1
Page 66 and 67: 8 R E C O M M E N D A T I O N STo e
Page 68 and 69: OVERALL MANAGEMENT AND MAINTENANCEM
Page 70 and 71: 10 L I T E R A T U R E R E F E R E
Page 72 and 73: 11 P R O D U C T I N F O R M A T I
Page 80 and 81:
Maphobeni Farmers Association Repor
Page 82 and 83:
Page 84 and 85:
Page 86 and 87:
SEB usage for River pump station Ph
Page 88:
Appendix 2: capital recovery factor
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Service Contract No 2007 / 147-446 - Swaziland

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