Service Contract No 2007 / 147-446 NYANYALI ... - Swaziland

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Figure 11. Atmospheric pressure vs. height above sea levelThe suction height was measured to be approximately 4.5 meters. The NPSH required(NPSHr) of the ETA 80-250 end suction pump is 4.3m (from attached pump curve). From theabove formula the maximum allowable suction height is therefore 4.55m and this calculationconfirms that river pumps are installed with a correct suction static height.Further analysis compared NPSH available (NPSHa) to NPSH required. The NPSHrequirements of 4.3 meters are well within the available NPSH of 4.55 meters. A safety factorof 0.5 is factored in this calculation as per manufacture’s requirement. This conforms to therecommendation of NPSHr < NPSHa (ARC, <strong>2007</strong>) required for optimum pump performance.The difference between these two figures is too small and might be affecting pumpperformance.4.1.1.2 Pump evaluationThe essence of evaluating this pump was to determine whether the pump function asindicated by the pump curve and to ascertain, if any, design, installation and managementfaults. The performance curve of the installed pump is attached under ‘product information’below and table 1 below indicates Nyanyali Farmers irrigation pump and motor specificationsas observed from the information plate.Nyanyali Farmers Cooperative Report - 2009 Page - 17 -
Table 1. pump and motor specifications and measurements conducted on pumpPUMP SPECIFICATIONS FROM INFORMATION PLATE AND MEASUREMENTSMake / model KSB ETA 80-250Number of units 1Pump duty point148m³/hr @ 80mImpeller diameter mm 248Pressure under normal operation m -Flow under normal operation m³/hr -MOTOR SPECIFICATIONS FROM INFORMATION PLATE AND MEASUREMENTSModel and typeVEMPower (P motor) kW 55Power factor (cos ø) 0.91Motor efficiency, % 93.6Speed rpm 29604.1.1.2.1 Pump OperationThis pump was not in operation during the evaluation. The assessment was carried out aftera period of heavy rains which not only raised the river level but also conceded a lot of ironoxide. According to Nyanyali management irrigating during this time causes this material toaccumulate inside the pipelines and in the long run reduces their capacity. Pumpperformance is, also, seriously affected when operated during the time, more so, because theiron oxide changes the specific gravity of the water. This evaluation, in any case could nothave been conclusive because there is no flow meter to measure pump discharge.Figure 12. Iron oxide accumulates in the Mkhondvo RiverNyanyali Farmers Cooperative Report - 2009 Page - 18 -
Page 1: Restructuring and DiversificationMa
Page 5 and 6: 8 RECOMMENDATIONS .................
Page 7 and 8: ABBREVIATIONSAbbreviationAEARCASAEC
Page 9 and 10: 2 B A C K G R O U N D O N I R R I G
Page 11 and 12: 3 T E C H N I C A L A U D I T R E P
Page 13 and 14: 7,1 Type type Vyrsa 70 Vyrsa 707,2
Page 15 and 16: Soil informationSoil properties use
Page 17 and 18: 4 F I E L D E V A L U A T I O N O F
Page 19 and 20: Figure 5. 2 x 300mm x 45° bends on
Page 21 and 22: 4.1.1.1.3 Suction Pipe InletsSpacin
Page 23: hf6375kQ4d2……………………
Page 27 and 28: Figure 13. Inside Nyanyali pump hou
Page 29 and 30: pipe:Filters:Pumpingequipmentand el
Page 31 and 32: 4.1.3 S u p p l y S y s t e mThe ev
Page 33 and 34: When down -stream pressure falls be
Page 35 and 36: 5.1.1 S p r i n k l e r p r e s s u
Page 37 and 38: 6 A S S E S S M E N T O F O P E R A
Page 39 and 40: indication of the amount small grow
Page 41 and 42: 7 C O N S T R A I N T S T O E F F I
Page 43 and 44: ‣ The optimum sprinkler operating
Page 45 and 46: 8 R E C O M M E N D A T I O N STo e
Page 47 and 48: ‣ A consortium could be formed fo
Page 49 and 50: Accurate details are required also
Page 51 and 52: 12. Solomon K.H. 1988a, Irrigation
Page 53 and 54: Nyanyali Farmers Cooperative Report
Page 57 and 58: SEB usage for River pump station Ph

Service Contract No 2007 / 147-446 NYANYALI ... - Swaziland

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