Service Contract No 2007 / 147-446 - Swaziland

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Old AgePhase one of the irrigation systems was installed in 1994, almost 19 years ago, and as yearselapsed, system efficiency reduces due to equipment wearing out. As a matter of urgencysome equipment must be replaced and the rest maintained for optimal performance. Apartfrom nozzles, sprinklers, due to old age, are underperforming. Some draglines have morethan the allowed tolerance of three joints and hydraulic valves are missing/broken pilots.These and other equipment has to be replaced.Possible ways of improving the hydraulic variation include readjustment of pressureregulating device (installing pilots on all Gulf valves) repair and/or removal of pinchedlateral/sub-main lines and the redesign of the hydraulic system.5 . 2 D e l i v e r y t e s t sThe following delivery tests were conducted:5.2.1 S p r i n k l e r d i s c h a r g eAccording to the ARC the difference in discharge in a specific irrigation block may not vary bymore than 10% from the average discharge, hence this evaluation. The discharge of thesprinklers was tested by collecting water into a container of known volume with a hose pipeconnected to the sprinkler nozzle. A minimum container size of 20 litres is recommended andtogether with a stopwatch the time it took to fill the container was recorded. The open end ofthe hose pipe was not held under water in the container, but also not so high that the watersplashed out of the container.Measurements were again taken at distances 0, L/4, L/2, 3L/4 and L on the lateral and thesprinkler line. The same points where pressure measurements were done were used and bytaking the time it took to fill the container, the discharge was calculated with the followingformula and results are shown in table 4.qe=average volume water measured incontaineraverage duration to fill container (sec)(litres)36001000…………… (10)m3/hourWhere q e = sprinkler discharge [m 3 /h]Maphobeni Farmers Association Report - 2009 Page - 43 -
Flow variation was above the recommended maximum of 10% averaging a high of 45.86%and 51.24% in the two phases respectively. The average sprinkler application for phase oneand two was found to be 1.51m3/hr and 1.28m3/hr respectively; instead of 1.4m3/hrstipulated in the <strong>Swaziland</strong> sugar industry standards (table 5). Excluding Block I dischargemeasurements the average sprinkler application increases to 1.35m3/hr. Due to the highaverage sprinkler operating pressure phase one sprinkler are discharging more than required.Table 5. Discharge variation calculated from field measurementsType of sprinkler/nozzle sizeMeasured nozzle discharge (m3/hr)RC 140 11/64" nozzle 1.62Rain bird BH30 11/64" nozzle 1.29Rain bird 14070 11/64" nozzle 1.23Rain bird 14070 11/64" nozzle 1.50Rain bird 14070 11/64" nozzle 1.93VYRSA 35 11/64" nozzle 1.28VYRSA 70 11/64" nozzle 1.13RC 130 11/64" nozzle 1.08VYRSA 70 11/64" nozzle 1.24VYRSA 70 11/64" nozzle 1.20RC 130 11/64" nozzle 1.39VYRSA 70 11/64" nozzle 1.05VYRSA 70 11/64" nozzle 1.17VYRSA 70 11/64" nozzle 1.70VYRSA 70 11/64" nozzle 1.31VYRSA 70 11/64" nozzle 1.48Minimum Discharge (m 3 /hr) 1.23 1.05Maximum Discharge (m 3 /hr) 1.93 1.70Average Discharge (m 3 /hr) 1.51 1.28Flow variation (%) 45.86 51.24Sprinkler operating pressure and sprinkler discharge are directly proportional. When pressuredecreases, sprinkler nozzle discharge also decreases and vice versa. This therefore, meansall factors contributing to the low system pressure also contribute to the sprinkler nozzledischarge. The sprinklers that recorded a high operating pressure but low application rate hadleaking draglines, tripods, and/or hydromatic-pipelet connection.Maphobeni Farmers Association Report - 2009 Page - 44 -
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 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 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

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