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- Nearly 1600 individual tests were
done. It was established that the
mined the ideal conditions for achieving maxi- pump was most efficient (over 50
mum efficiency from a spiral pump. per cent) with a high head, a slow
rotational speed, a smaller-diame-
ter tube, and with a scoop of 100 to
THE SEARCH FOR cost-effective (see Figure I). The pump is partially 120 per cent of the outer coil
pumps is a top research priority submerged in the stream and the volume.
worldwide. Studies to develop mod- wheel is rotated by the streamflow, An interesting observation was
els which can be powered by renew- so that alternating plugs of water that regardless of the depth of
able energy sources, which can and air are scooped into the intake immersion of the wheel into the
pump water to a higher head than tube. The large diameter of the water, and the design of the water
the pump structure itself, and which pump makes hand-turning easy dur- intake scoop, it was not possible to
can be built out of available materi- ing decreased streamflow. To in-
als by local craftsmen have pro- fill the outer coil with water to more
crease the water intake into the than 50 per cent of the volume of
duced two types of stream-driven pump, and therefore the efficiency,
pumps: the coil and the spiral pump. the outer coil, a fact first described
a scoop has to be attached. The end by Olinthus Gregory in 1815.7
The coil pump and the spiral
of the hose leads into the rotating
pump work on the same principle,
axle, and by means of a water- and
but the designs differ significantly.
pressure-tight swivel, the water Field tests
In the coil pump, flexible tubing is
wound concentrically around a moves into the stationary water- Field tests of the Los Banos model
drum or floating framework.I2 The delivery pipe. The swivel is similar were conducted in co-operation
major drawback of the coil pump is to an oil seal used commonly in cars, with the Abra River Irrigation Pro-
that the size of the drum limits the and can be made locally in a ject (ARIP). ARIP is a large irriga-
pump's use in narrow irrigation workshop. During water delivery, tion project in the province of Abra,
canals. A simpler inclined coil pump the individual plugs in each of the about 400km north of Manila, and
with an internal coil for low head loops of the hose are forced against is helped financially by Misereor.
applications also exists.3 the head, resulting in the build-up Abra is one of the poorest provinces
The second option is the stream- of a differential pressure in each of in the Philippines, where the aver-
driven spiral pump, invented origi- the loops of the spiral. age area of land per family is less
nally in 1746 by H.A. Wirtz4.5 and To test its efficiency, prototypes than half a hectare. In the past,
re-invented by P. Morgan6 in 1984. of the spiral pump with 2.0m overall rainfed (dryland) fields could be
The pump consists of a flexible (wheel) diameters were constructed planted with crops (such as rice)
plastic hose coiled spirally on the at the University of the Philippines only during the rainy season, which
same axis and plane, so that each at Los Banos, using different tube lasts about six months. To increase
loop of the hose differs in diameter materials and tube diameters (1.91, agricultural production the Abra
from the next, and the whole device 2.54, 3.8 I, 5.08 and 7.62cm), differ- river was tapped, and a diversion
resembles a large wheel with the ent speeds of rotation, and different canal was constructed which now
axis parallel to the water surface total heads. 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
7.5m3 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
Figure 1. A spiral pump being tested in the laboratory. 1.2 xO.8m, which resulted in a

30 WATERLINES VOL.lO NO.2 OCTOBER 1991

 is available), spiral pumps are an
excellent alternative, in particular
Selfaligning
for developing countries without
rotor ahaft
bearings (steel
their own oil resources.
en greaaed wood)
References
I Danish Guide and Scout Association,
'The Stream-driven Coil Pump', The
Danish Scout Association, Copenhagen,
Denmark, 1984.
Water
pipe 2 Reimer, M., 'The Stream-Driven Coil
freme
Pump', Waterlines 4( I), pp.20-21, 1985.
3 Hilton, DJ., 'Further development of
the inclined coil pump', Waterlines 8(2),
pp.20-22, 1989.
4 Ewbank, T., 'Descriptive and historical
account of hydraulic and other machines
)
for raising water, ancient and modern'.
The Steam Engine Vol.3 Ch.9, pp.363-4,
Greeley and McElrath, Tribune Build-
ings, New York, 1849.
5 West, 1., and Tailer, P., The Spiral Pump
Direction of
river current - A High-Lift Slow-Turning PUlllp,
Windfarm Museum Inc., Vinyard Haven,
Mass., USA, 1986.
6 Morgan, P., 'A Spiral Tube Water Wheel
Pump', Blair Research Bulletin No.IO,
Harare, Zimbabwe, 1984.
The major drawback of the coil pump is that the size of the drum limits the 7 Gregory, 0., 'Hydraulic Engines', Trea-
pump's use in narrow irrigation canals. tise of Mechanics Vol.I, pp.227-33, 1815.
Acknowledgements
much faster rotating of the wheel Comparing the actual cost price of This research project was financially sup-
and an increase in delivered water. a factory-produced Japanese gaso- ported by GA TE/GTZ, Eschborn, Ger-
The pumps were running without line pump (about 6000 pesos) or many. The axle and the swivel were manufac-
major problems for nearly four diesel-driven pump (about 12 000 tured by DESCO, Manila. The project was
initiated through the great hospitality of the
months from February 1990, and pesos), an individually built spiral
UPLB College of Engineering where the
the field tests had to be interrupted pump is more expensive (about laboratory tests were conducted. The field
only because of the rainy season. 14 000 pesos). The axle, the tube tests were successfully completed through
The tube diameter used, the material and the swivel are the main the active co-operation of the Abra River
height of the water delivery, and the cost factors, but a group could Irrigation Authority (through Fr E. Rein-
hardt and Mr Darwin One!).
water volume scooped into the tube mass-produce the axle and the
resulted in varying speeds of rota- swivel, thereby lowering the price.
L.c.A. Naegel is with the Fanning Systems
tion of the wheel, and thus different Considering the high efficiency and Soil Resources Institute, University of
volumes of delivered water. These of the pump at high heads and slow the Philippines at Los Banos College, 403 I
results agreed with the formulae speeds of rotation, its non-use of Laguna, Philippines; J.G. Real is in the
obtained from the previous labora- fossil fuel and its adaptability to Department of Agronomy, International
Rice Research Institute (IRRI); and A.M.
tory tests. existing natural conditions (i.e.
Mazaredo is in the Department of Agricul-
In view of the successful opera- where a strong streamflow stream tural Engineering, IRRI, PO Box 933, 1099
tion of the pumps and the readiness in narrow rivers or irrigation canals Manila, Philippines.
of the farmers to accept this new
technology, the Abra River Irriga-
tion Authority is planning to install
more pumps in the main irrigation
canal. This will make possible inten-
sive vegetable production on fields
situated above the irrigation canal.
Although the amount of water
supplied per minute is less than a
conventional gasoline or diesel-
driven pump would provide, this is
made up for by the continuous,
free-of-cost day and night opeFation
of the pump. An additional advan-
tage of the pump is that the mainte-
nance requirements are minimal,
consisting mainly of cleaning and
checking, and repairs can be carried
out by local craftsmen.

Cost comparisons
The main drawback at the moment
is that the pump is expensive be-
cause each one is built individually. Water for irrigation is now within reach, even from this narrow canal.

WATERLINES VOL. 10 NO.2 OCTOBER 1991 31