Nearly 1600 individual tests were done. It was established that the pump was most efficient (over 50 per cent) with a high head, a slow rotational speed, a smaller-diame- ter tube, and with a scoop of 100 to 120 per cent of the outer coil volume. An interesting observation was that regardless of the depth of immersion of the wheel into the water, and the design of the water intake scoop, it was not possible to fill the outer coil with water to more than 50 per cent of the volume of the outer coil, a fact first described by Olinthus Gregory in 1815. 7 Field tests Field tests of the Los Banos model were conducted in co-operation with the Abra River Irrigation Pro- ject (ARIP). ARIP is a large irriga- tion project in the province of Abra, about 400km north of Manila, and is helped financially by Misereor. Abra is one of the poorest provinces in the Philippines, where the aver- age area of land per family is less than half a hectare. In the past, rainfed (dryland) fields could be planted with crops (such as rice) only during the rainy season, which lasts about six months. To increase agricultural production the Abra river was tapped, and a diversion canal was constructed which now feeds several thousand hectares of agricultural fields. The fields situ- ated above the irrigation canals, however, do not benefit from this new development. The field tests were initiated because of the strong interest shown by farmers for cost- effective pumps that could supply water to these disadvantaged fields. Spiral pumps with outer dia- meters of 2.5m, 4.0m and 5.0m were constructed and installed at different sites going into the main diversion canal. The canal was 3m wide and the water depth fluctuated from 1.2m to 1.6m. At a velocity of about 1.59 m/sec, approximately 7.5m 3 of water was passing through the canal per second. To make the most efficient use of a given streamflow, the size of the paddles should be adjusted accordingly. In this case the paddle size of 0.5 xO.8m was increased to 1.2 xO.8m, which resulted in a (see Figure I). The pump is partially submerged in the stream and the wheel is rotated by the streamflow, so that alternating plugs of water and air are scooped into the intake tube. The large diameter of the pump makes hand-turning easy dur- ing decreased streamflow. To in- crease the water intake into the pump, and therefore the efficiency, a scoop has to be attached. The end of the hose leads into the rotating axle, and by means of a water- and pressure-tight swivel, the water moves into the stationary water- delivery pipe. The swivel is similar to an oil seal used commonly in cars, and can be made locally in a workshop. During water delivery, the individual plugs in each of the loops of the hose are forced against the head, resulting in the build-up of a differential pressure in each of the loops of the spiral. To test its efficiency, prototypes of the spiral pump with 2.0m overall (wheel) diameters were constructed at the University of the Philippines at Los Banos, using different tube materials and tube diameters (1.91, 2.54, 3.8 I, 5.08 and 7.62cm), differ- ent speeds of rotation, and different total heads. Designing a spiral pump for irrigation by L.C.A. Naegel, J.G. Real and A.M. Mazaredo New experiments on an old idea have deter- mined the ideal conditions for achieving maxi- mum efficiency from a spiral pump. THE SEARCH FOR cost-effective pumps is a top research priority worldwide. Studies to develop mod- els which can be powered by renew- able energy sources, which can pump water to a higher head than the pump structure itself, and which can be built out of available materi- als by local craftsmen have pro- duced two types of stream-driven pumps: the coil and the spiral pump. The coil pump and the spiral pump work on the same principle, but the designs differ significantly. In the coil pump, flexible tubing is wound concentrically around a drum or floating framework. I • 2 The major drawback of the coil pump is that the size of the drum limits the pump's use in narrow irrigation canals. A simpler inclined coil pump with an internal coil for low head applications also exists. 3 The second option is the stream- driven spiral pump, invented origi- nally in 1746 by H.A. Wirtz 4 .5 and re-invented by P. Morgan 6 in 1984. The pump consists of a flexible plastic hose coiled spirally on the same axis and plane, so that each loop of the hose differs in diameter from the next, and the whole device resembles a large wheel with the axis parallel to the water surface Figure 1. A spiral pump being tested in the laboratory. 30 WATERLINES VOL.lO NO.2 OCTOBER 1991
Transcript
Nearly 1600 individual tests weredone It was established that thepump was most efficient (over 50per cent) with a high head a slowrotational speed a smaller-diame-ter tube and with a scoop of 100 to120 per cent of the outer coilvolume
An interesting observation wasthat regardless of the depth ofimmersion of the wheel into thewater and the design of the waterintake scoop it was not possible tofill the outer coil with water to morethan 50 per cent of the volume ofthe outer coil a fact first describedby Olinthus Gregory in 18157
Field testsField tests of the Los Banos modelwere conducted in co-operationwith the Abra River Irrigation Pro-ject (ARIP) ARIP is a large irriga-tion project in the province of Abraabout 400km north of Manila andis helped financially by MisereorAbra is one of the poorest provincesin the Philippines where the aver-age area of land per family is lessthan half a hectare In the pastrainfed (dryland) fields could beplanted with crops (such as rice)only during the rainy season whichlasts about six months To increaseagricultural production the Abrariver was tapped and a diversioncanal was constructed which nowfeeds several thousand hectares ofagricultural fields The fields situ-ated above the irrigation canalshowever do not benefit from thisnew development The field testswere initiated because of the stronginterest shown by farmers for cost-effective pumps that could supplywater to these disadvantaged fields
Spiral pumps with outer dia-meters of 25m 40m and 50mwere constructed and installed atdifferent sites going into the maindiversion canal The canal was 3mwide and the water depth fluctuatedfrom 12m to 16m At a velocityof about 159 msec approximately75m3 of water was passing throughthe canal per second
To make the most efficient useof a given streamflow the size ofthe paddles should be adjustedaccordingly In this case the paddlesize of 05 xO8m was increased to12 xO8m which resulted in a
(see Figure I) The pump is partiallysubmerged in the stream and thewheel is rotated by the streamflowso that alternating plugs of waterand air are scooped into the intaketube The large diameter of thepump makes hand-turning easy dur-ing decreased streamflow To in-crease the water intake into thepump and therefore the efficiencya scoop has to be attached The endof the hose leads into the rotatingaxle and by means of a water- andpressure-tight swivel the watermoves into the stationary water-delivery pipe The swivel is similarto an oil seal used commonly in carsand can be made locally in aworkshop During water deliverythe individual plugs in each of theloops of the hose are forced againstthe head resulting in the build-upof a differential pressure in each ofthe loops of the spiral
To test its efficiency prototypesof the spiral pump with 20m overall(wheel) diameters were constructedat the University of the Philippinesat Los Banos using different tubematerials and tube diameters (191254 38 I 508 and 762cm) differ-ent speeds of rotation and differenttotal heads
Designing a spiral pump for irrigationby LCA Naegel JG Real and AM MazaredoNew experiments on an old idea have deter-mined the ideal conditions for achieving maxi-mum efficiency from a spiral pump
THE SEARCH FOR cost-effectivepumps is a top research priorityworldwide Studies to develop mod-els which can be powered by renew-able energy sources which canpump water to a higher head thanthe pump structure itself and whichcan be built out of available materi-als by local craftsmen have pro-duced two types of stream-drivenpumps the coil and the spiral pump
The coil pump and the spiralpump work on the same principlebut the designs differ significantlyIn the coil pump flexible tubing iswound concentrically around adrum or floating frameworkIbull2 Themajor drawback of the coil pump isthat the size of the drum limits thepumps use in narrow irrigationcanals A simpler inclined coil pumpwith an internal coil for low headapplications also exists3
The second option is the stream-driven spiral pump invented origi-nally in 1746 by HA Wirtz45 andre-invented by P Morgan6 in 1984The pump consists of a flexibleplastic hose coiled spirally on thesame axis and plane so that eachloop of the hose differs in diameterfrom the next and the whole deviceresembles a large wheel with theaxis parallel to the water surface
Figure 1 A spiral pump being tested in the laboratory
The major drawback of the coil pump is that the size of the drum limits thepumps use in narrow irrigation canals
is available) spiral pumps are anexcellent alternative in particularfor developing countries withouttheir own oil resources
ReferencesI Danish Guide and Scout Association
The Stream-driven Coil Pump TheDanish Scout Association CopenhagenDenmark 1984
2 Reimer M The Stream-Driven CoilPump Waterlines 4( I) pp20-21 1985
3 Hilton DJ Further development ofthe inclined coil pump Waterlines 8(2)pp20-22 1989
4 Ewbank T Descriptive and historicalaccount of hydraulic and other machinesfor raising water ancient and modernThe Steam Engine Vol3 Ch9 pp363-4Greeley and McElrath Tribune Build-ings New York 1849
5 West 1 and Tailer P The Spiral Pump- A High-Lift Slow-Turning PUlllpWindfarm Museum Inc Vinyard HavenMass USA 1986
6 Morgan P A Spiral Tube Water WheelPump Blair Research Bulletin NoIOHarare Zimbabwe 1984
7 Gregory 0 Hydraulic Engines Trea-tise of Mechanics VolI pp227-33 1815
LcA Naegel is with the Fanning Systemsand Soil Resources Institute University ofthe Philippines at Los Banos College 403 ILaguna Philippines JG Real is in theDepartment of Agronomy InternationalRice Research Institute (IRRI) and AMMazaredo is in the Department of Agricul-tural Engineering IRRI PO Box 933 1099Manila Philippines
AcknowledgementsThis research project was financially sup-ported by GA TEGTZ Eschborn Ger-many The axle and the swivel were manufac-tured by DESCO Manila The project wasinitiated through the great hospitality of theUPLB College of Engineering where thelaboratory tests were conducted The fieldtests were successfully completed throughthe active co-operation of the Abra RiverIrrigation Authority (through Fr E Rein-hardt and Mr Darwin One)
Comparing the actual cost price ofa factory-produced Japanese gaso-line pump (about 6000 pesos) ordiesel-driven pump (about 12 000pesos) an individually built spiralpump is more expensive (about14 000 pesos) The axle the tubematerial and the swivel are the maincost factors but a group couldmass-produce the axle and theswivel thereby lowering the price
Considering the high efficiencyof the pump at high heads and slowspeeds of rotation its non-use offossil fuel and its adaptability toexisting natural conditions (iewhere a strong streamflow streamin narrow rivers or irrigation canals
much faster rotating of the wheeland an increase in delivered water
The pumps were running withoutmajor problems for nearly fourmonths from February 1990 andthe field tests had to be interruptedonly because of the rainy season
The tube diameter used theheight of the water delivery and thewater volume scooped into the tuberesulted in varying speeds of rota-tion of the wheel and thus differentvolumes of delivered water Theseresults agreed with the formulaeobtained from the previous labora-tory tests
In view of the successful opera-tion of the pumps and the readinessof the farmers to accept this newtechnology the Abra River Irriga-tion Authority is planning to installmore pumps in the main irrigationcanal This will make possible inten-sive vegetable production on fieldssituated above the irrigation canal
Although the amount of watersupplied per minute is less than aconventional gasoline or diesel-driven pump would provide this ismade up for by the continuousfree-of-cost day and night opeFationof the pump An additional advan-tage of the pump is that the mainte-nance requirements are minimalconsisting mainly of cleaning andchecking and repairs can be carriedout by local craftsmen
Cost comparisonsThe main drawback at the momentis that the pump is expensive be-cause each one is built individually Water for irrigation is now within reach even from this narrow canal
The major drawback of the coil pump is that the size of the drum limits thepumps use in narrow irrigation canals
is available) spiral pumps are anexcellent alternative in particularfor developing countries withouttheir own oil resources
ReferencesI Danish Guide and Scout Association
The Stream-driven Coil Pump TheDanish Scout Association CopenhagenDenmark 1984
2 Reimer M The Stream-Driven CoilPump Waterlines 4( I) pp20-21 1985
3 Hilton DJ Further development ofthe inclined coil pump Waterlines 8(2)pp20-22 1989
4 Ewbank T Descriptive and historicalaccount of hydraulic and other machinesfor raising water ancient and modernThe Steam Engine Vol3 Ch9 pp363-4Greeley and McElrath Tribune Build-ings New York 1849
5 West 1 and Tailer P The Spiral Pump- A High-Lift Slow-Turning PUlllpWindfarm Museum Inc Vinyard HavenMass USA 1986
6 Morgan P A Spiral Tube Water WheelPump Blair Research Bulletin NoIOHarare Zimbabwe 1984
7 Gregory 0 Hydraulic Engines Trea-tise of Mechanics VolI pp227-33 1815
LcA Naegel is with the Fanning Systemsand Soil Resources Institute University ofthe Philippines at Los Banos College 403 ILaguna Philippines JG Real is in theDepartment of Agronomy InternationalRice Research Institute (IRRI) and AMMazaredo is in the Department of Agricul-tural Engineering IRRI PO Box 933 1099Manila Philippines
AcknowledgementsThis research project was financially sup-ported by GA TEGTZ Eschborn Ger-many The axle and the swivel were manufac-tured by DESCO Manila The project wasinitiated through the great hospitality of theUPLB College of Engineering where thelaboratory tests were conducted The fieldtests were successfully completed throughthe active co-operation of the Abra RiverIrrigation Authority (through Fr E Rein-hardt and Mr Darwin One)
Comparing the actual cost price ofa factory-produced Japanese gaso-line pump (about 6000 pesos) ordiesel-driven pump (about 12 000pesos) an individually built spiralpump is more expensive (about14 000 pesos) The axle the tubematerial and the swivel are the maincost factors but a group couldmass-produce the axle and theswivel thereby lowering the price
Considering the high efficiencyof the pump at high heads and slowspeeds of rotation its non-use offossil fuel and its adaptability toexisting natural conditions (iewhere a strong streamflow streamin narrow rivers or irrigation canals
much faster rotating of the wheeland an increase in delivered water
The pumps were running withoutmajor problems for nearly fourmonths from February 1990 andthe field tests had to be interruptedonly because of the rainy season
The tube diameter used theheight of the water delivery and thewater volume scooped into the tuberesulted in varying speeds of rota-tion of the wheel and thus differentvolumes of delivered water Theseresults agreed with the formulaeobtained from the previous labora-tory tests
In view of the successful opera-tion of the pumps and the readinessof the farmers to accept this newtechnology the Abra River Irriga-tion Authority is planning to installmore pumps in the main irrigationcanal This will make possible inten-sive vegetable production on fieldssituated above the irrigation canal
Although the amount of watersupplied per minute is less than aconventional gasoline or diesel-driven pump would provide this ismade up for by the continuousfree-of-cost day and night opeFationof the pump An additional advan-tage of the pump is that the mainte-nance requirements are minimalconsisting mainly of cleaning andchecking and repairs can be carriedout by local craftsmen
Cost comparisonsThe main drawback at the momentis that the pump is expensive be-cause each one is built individually Water for irrigation is now within reach even from this narrow canal
