Service Contract No 2007 / 147-446 - Swaziland

More documents

Recommendations

Info

4.3.1 M a i n l i n e s i z eThe South African Irrigation Institute (SABI) norm suggests that for raising main lines with adiameter of 200mm or smaller a maximum of 1.5% is allowed (ARC, 2003). Mainlines withpipe sizes greater than 200mm are evaluated by determining the most economical pipediameter; capital and annual cost for different pipe diameters are compared and the followingequation is used;dkQ0.37i …..……………………….……… (8)Where: di = inside diameter of pipe, mmK= constantQ= flow rate (m3/h)<strong>No</strong> information was available on mainline pipe sizes, lengths and class and because thereare no pressure measuring points on hydrants, friction loss through the mainline could not becalculated. An undisputed conclusion, therefore, on whether the supply system was correctlydesigned or not cannot be drawn until details on pipe size, pipe classes, and distancesoccupied by the different sizes are obtained.4.3.2 M a i n l i n e c l a s sJust like above, this evaluation could not identify as to whether the mainline classes wereover-specified or not. Pipe bursts are one major indicator of under-specification in pipeclasses and recurrent pipe breakages were experienced only in phase one mainlines, submainsand laterals.4 . 4 S y s t e m C a p a c i t y E v a l u a t i o nPhase One:‣ Phase one of 56 hectares is supplied by one pump and requires at least 222m3/hr.‣ Pressure requirements are estimated at approximately 80m‣ This pump duty point is within the operating range of the installed ETA 125-50/2 pump. Infact, a smaller and cheaper ETA 100-250 single stage pump could have been used.‣ Pressure measurements results reflected that this pump is operating below their designduty point.Maphobeni Farmers Association Report - 2009 Page - 31 -
Phase Two:‣ This phase is supplied by a river pump and a booster pump station, each of these pumphouses have two pumping units‣ This phase is 95 hectares and requires at least 376m3/hr flow to meet irrigationrequirements.‣ Water from the Usuthu River is pumped by two identical Howden 100-400 pumps eachdriven by a 30kW two pole motor into a small balancing dam.‣ In order to meet irrigation requirements each of these pumps must generate at least188m3/hr system flow.‣ Pressure requirements from the pump station to the balancing dam are estimated at 35m‣ This duty point is within the operating range of the installed river pumps.‣ Pressure requirements from the balancing dam to the critical sprinkler are estimated at90m. The impellor diameter of these pumps is 246mm and in order for these pumps togenerate the required pressure a 255mm impellor diameter must be installed in thesepumps.‣ Both booster pumps can deliver the required 188m3/hr system flow.Maphobeni Farmers Association Report - 2009 Page - 32 -
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 30 and 31: hf6375kQ4d2……………………
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 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 86 and 87: SEB usage for River pump station Ph
Page 88: Appendix 2: capital recovery factor

Service Contract No 2007 / 147-446 - Swaziland

Create successful ePaper yourself

Delete template?

Save as template?