Difference between revisions of "Rope pump"

Revision as of 02:32, 10 December 2013

Rope pump on a borehole, made in a local workshop in Mozambique

The modern Rope pump is a highly efficient and low cost pump, it can be produced with local materials and can be truly operated and maintained at a village level. The basic design has a wheel with a continuous loop of rope with pistons that fit with a small clearance in the pump pipe. The low end of this pipe is at the bottom of the well. By turning the wheel the rope passes up through the PVC pump pipe and pushes the water up. At the top end of the pump pipe, the diameter increases and the water comes out via a Tee piece.

If produced and installed well, Rope pumps prove to be sustainable and now there are somer hundred and twenty thousand of these pumps world wide used for communal and domestic water supply, irrigation and cattle watering. Modern models can pump from wells as deep as 35 m and compared to imported hand pumps, Rope pumps are three to five times cheaper. Good quality pumps can last for 20 years or more as is proven in Nicaragua where the first improved models that were installed in 1990 are still working. Rope pumps can be powered by hand, bicycle, motor, horse, or wind power.

Origins

The almost intuitive design is known by many names, including the paternoster (after the beaded prayer chain it resembles), Noria pump, liberation pump or chain-and-washer pump but all have the same pump principle. Evidence of this pump principle dates back as far as two thousand years, to feudal China ¹. The earliest report of the design in the west is cited ² as that illustrated by the Sienese early renaissance engineer, Tacolla, circa 1433 ³, a copy of which is given in the figure to the right ⁴. In the 1970 and 80s the basic design was adapted by numerous individuals, the most prominent of which were R. van Tijen of Demotech, J. Haemhouts ^{5 6} and R. Lambert ⁷. They applied the simple design as a tool aimed at economic and social development. They took advantage of low cost and versatile modern plastics to produce the modern rope-pump design. They applied this pump as a homemade, low lift pump. However the early models did not really take off and a successful scaling up of the Rope pump only started in 1988 in Nicaragua where the pump was technically improved by Van Hemert of the organization SNV and Alberts of Bombas de mecate. They made it into a compact metal model fit for commercial sales, produced and sold by local private companies. V. Hemert and Alberts ⁸ Holtslag.

Rope Pump first illustrated in the west circa 1433 ⁹

Suitable conditions

Horse Rope pump, powered by horses or donkeys. Pumps from wells to 65 m deep. Pump capacity 5 times more than a hand powered model. Used in Nicaragua. Photo: Henk Holtslag

A Rope pump can be used to draw water from large diameter hand dug wells of 3 meters to boreholes as small as 6 cm. One person can draw water up from 35 m deep, two persons can pump from 60 m deep (using a second crank) and if powered by an engine it can pump from 100 meters or more. A Rope pump can be driven by hand, bicycle, animals, wind or engines. If well made, a hand Rope pump delivers 35 litres / min from 10 meters depth and halve of that if the well is 20 metres deep. Hand pump models are most commonly used at depths less than 35m.

Some 70,000 Rope pumps are now in use in Nicaragua, 10,000 in countries like Mexico, Honduras, Guatemala, El Salvador and Bolivia. 30,000 in African countries like Ethiopia, Ghana, Senegal, Tanzania, Zambia, Mozambique, Zimbabwe, Malawi and 6000 in Cambodia and India. In total, the Rope pump is used in over 25 countries.

The Rope pump is most suitable for single families, but is also often used for communities up to 20 families (150 people).

Construction, operations and maintenance

Rope pump, An illustration of the pumping action of a rope pump. However, this drawing needs adaptation. The pipe diameter at and above the Tee piece should be larger than the pump pipe. This is essential for good functioning of the pump. Now most of the water will come out at the top!

Rope pump, (Victory model) on a hand-dug of 20 meters deep well, made in a local workshop in northern Ghana. Photo: Netherlands Water Partnership.

With deeper wells, smaller diameter pump pipes are needed, otherwise the pumping becomes too heavy. See manuals on websites of Practica Foundation, Connect International, and ropepumps.org.

Many different types of rope pump exist, powered by hand, bicycle, wind, horse, etc.

Similar to piston pumps, a cement slab and a good soak away are needed to avoid splash water and recontamination of the water in the well.

Design

• Pumping depth (Lift): 0 to 35 m
• Cylinder diameter: (pump pipe) 32 mm for 1 to 10 metres deep, 25 mm for 10 to 20 metres deep and 19 mm for 20 to 35 metres deep
• Pistons: Rubber or HD PE (plastic) pistons spaced at 1 m
• Yield: (50 watt input) at a 10 m head the yield is 2 m³/hour
• Population/field area served: Max 150 people or irrigation of 0.1 hectare
• Type of well: dug well of 3 metres to borehole of 6 to 20 cm diameter

The Rope pump can be made in any country since the design can be adapted to the materials that are locally available. After due training it can be produced, by small or medium metal companies or blacksmiths that have a welding machine and standard hand tools. Although simple does not mean easy. It is essential to build the pump with 10 basic design rules. (See ropepumps.org FAQs). In general, training is needed for good quality in production and, as important, good installation.

The pump frame is made of galvanized pipes or mild steel. The handle is a galvanized steel pipe with metal bushings (there are also designs with ball bearings, or wooden bushings). The pulley wheel is made of the sides of a used car tire and mounted with clamps and spokes on the handle. The wheel should have a sharp 'v' shape to get a good traction on the rope. The ropes are made of Polyethylene, Polypropylene, or Polyamide fibers varying from Ø 4 to Ø 8 mm. Natural fibers are not suitable, as they will stretch when wet, and degrade too fast. The pistons are made of the side of the siude of a used car tire or injection molded HD polyethylene. The rising main are PVC pipes with wall thickness of 1.5 to 2 mm and diameters of 20 to 50 mm (depending on depth of the water level). The guide box is made of concrete (with a ceramic piece or small glass bottle as turning point), galvanized pipe or wood with a PVC turning point.

Maintenance

One of the main strengths of the Rope pump is that maintenance and repairs are relatively simple and can easily and genuinely be done at village level by local technicians. Because of the local production, spares are available and knowledge to do repairs. The most frequent repairs consist of replacing the rope and pistons and weekly oiling of the bushings. The installation and repairs of the pump part does not require special tools, and pump pipes are very light so no need for any lifting equipment.

Although easy and simple, it is important that users are instructed in why and how to maintain and repair their pump. Evaluations show that pumps (including Rope pumps) on communal wells have a tendency to fail for reasons like a lack of ownership and problems with generating funds for repairs and replacements. See example of Ghana, below. If Rope pumps are produced and installed properly (and if the users have ownership), 90% of Rope pumps remain operational, even after many years as is proven by pumps in Nicaragua, Zimbabwe Tanzania, Malawi and other countries. Compared to piston pumps the repairs of Rope pumps is simpler and cheaper, plus because of local production, spares are available.

Other Rope pump models

Besides hand powered Rope pumps there are models powered by Pedals, Horse, Wind, Electric motor or petrol engines. Common available petrol pumps are suction pumps for shallow wells down to 7 m. deep. Deeper wells require generator pump sets or long-shaft diesel pumps costing US$ 1000 or more.

Where there is electricity, submersible pumps can be used but these are relatively expensive and many small farmers do not have electricity. Motorized Rope pumps can pump from wells down to 60m ¹⁰ Similar to the Hand pump model, it can be produced in local workshops using engines that are common in the country. The cost of a Motor Rope pump is 600 US$. This is far cheaper than long-shaft diesel pumps or submersible pumps with the advantage that in case of emergency, the pump can be powered by hand. Similar to the hand powered model, maintenance and repairs are relatively easy. There are motorized Rope pumps in Niger, Ethiopia and Nicaragua.

Costs

• The Hand Rope pumps cost between US$ 30-150 depending on model, location of production, and cost of materials and labour.
• Cost of introduction: between US$ 10,000-30,000 per project, including 20 pumps, engineering and hands-on training.
• Rural water programme: US$ 150,000-200,000 per project, including 1,000 pumps, start up of production facility and hands-on training.

Field experiences

Pedal Rope pump, bicycle model, produced and used in Nicaragua

Motor Rope pump, powered by a diesel motor, used for irrigation. Pumping from a 25m well. Photo: Netherlands Water Partnership.

Hand Rope pump used for irrigation in Zambia

Rope pump Cross section diagram of a Rope pump with a complete wheel cover, 95% of the Rope pumps have a small wheel cover to reduce cost and make maintenance easier. Also water quality of semi-covered Rope pumps is the same as completely closed Rope pumps.

Because of its low cost, the pump is also popular for domestic use. A survey among 5,025 rural families in Nicaragua indicates that a rope pump increases income, even if used for domestic purposes only. Families with a pump earn US$ 220 per year more than families without a pump. In Nicaragua the pumps are now being produced commercially by 20 workshops.

Different models of Rope pumps were introduced in Africa. This introduction has not always been successful: in one projects over 80% of the pumps did NOT work after one year! However, with the "right" models and the "right" user training, up to 90% remain in operation in Africa, as the Victory model in Ghana and the Elephant model in Zimbabwe have proved.

In 2008, rope pumps are used in over 30 countries. Below the experiences in Nicaragua, Zimbabwe and Ghana are listed.

Nicaragua Some 70.000 rope pumps have been installed since 1990. The shift from imported piston pumps of 600$ to locally produced rope pumps of 70$ has doubled rural water supply in ten years, much faster than countries that apply piston pumps. Users do the maintenance and over 95% of the pumps remain in operation. The rope pump has been adopted as the standard water pump by the government.

Zimbabwe A rope pump model called the Elephant Pump was introduced by the organisation Pump Aid in 1990. The main difference with the traditional rope pump is the solid round structure around the wheel, to protect the well and to avoid splashing. Now some 3,000 pumps serve 950,000 people and some 95% of the pumps are working. Many more pumps are planned to be installed before 2015 and if this can be realized, this will reach 3 million more people.

Ghana The first experiences with rope pumps in Ghana were discouraging. In a World Bank funded project, 80% did not function after one year because of lack of user involvement and production errors. After improvements some 1.600 pumps were installed.

Malawi, Blantyre trials Several rope pumps were introduced in order to provide a better alternative for the Afridev Community handpump, which is the standard handpump in Malawi. The Afridev is not popular due to many breakdowns and not available spare parts, especially in the more remote areas. However, the rope pumps also broke down many times, sometimes several times per month, due to the high number of users and was therefor not considered by the users as a good alternative for a community pump, although repairs were possible. Another disadvantage mentionned was that children found it difficult to pump and sometimes got hurt when the handle security break system was not functioning (in that case the handle turns back with a high speed due to the weight of the water in the riser pipe). The communities now prefer a more reliable handpump than the Afridev, with less need for spares.

Mozambique As in Malawi, the rope pump was seen as a viable alternative to the Afridev which is generally the official pump of choice. WaterAid had first introduced a bucket and windlass system in the Niassa provice as an alternative due to the high failure rate of Afridev pumps, but the Mozambican government refused to accept these as official community water supplies. WaterAid, in partnership with the Swiss Agency for Development Cooperation (SDC), UNICEF, CARE and the Government of Mozambique, therefore began a lengthy process of piloting a robust community rope pump, first relying on support from Bombas de Mecate in Nicaragua, but later adapting the design from Madagascar. The new model meets a number of key well protection and water quality criteria set down by the development team. Three manufacturers are now in operation in three provinces and through a process of skill sharing improvements have been made to the design resulting in a robust high quality model. A manufacturing standard has also been produced with the help of SKAT. The final stages of this process are currently underway which include the final approval of the pump as well as the licensing of the manufacturers by the Governments standards laboratory.

There are now more than 300 rope pumps installed across three provinces (Niassa, Cabo Delgado and Zambezia)and in Niassa particularly WaterAid funded projects continues to offer communities a choice of either the Rope Pump of the Afridev. In addition the installed pumps are monitored twice per year in order to better understand the pumps sustainability.

Apart from this initiative, PumpAid has also been active in the Chimoio province installing Elephant Pumps which are also rope pumps.

Please see the external links below for further information.

Burkina Faso WaterAid in Burkina Faso is also currently developing a rope pump model suitable to local conditions. This project has resulted in a renewed understanding across WaterAid of the need to ensure that rope pumps destined for community water supplies require high quality manufacturing and installation techniques in order to improve their sustainability. WaterAid now intends to renew its efforts across the organisation to improving the quality of rope pumps in countries where this is supported. A training course for manufacturers from Burkina Faso, Ghana, Mali, Zambia and Malawi was held in early 2010 as part of this process.

A recent interesting development in Burkina Faso has been the re-design of the bottom guide box to include a non-return valve (foot valve) thereby ensuring that water is immediately available from the first turn of the pump handle. This is currently being piloted on a few pumps.

Project 1349

Akvo RSR Project: Safe water for Wajir WASH promotion in Makaror a suburb of Wajir Town through technical education and demonstration of WASH. Wajir is constructed on top of an ancient aquifer. Wajir has 130.000 inhabitants by 2013 and has a growth rate of 10 percent per year. Most wells have ecoli pollution. Lining wells helps. Closure and pump installation is better. Combination with Ecosan is an adequate solution.

Manuals, videos and links

Manuals

• Jan Nederstigt, Arjen van der Wal. Rope Pump: Low Cost Pump Series. TECHNICAL TRAINING HANDBOOK ON ROPE PUMP PRODUCTION, INSTALLATION AND MAINTENANCE. Practica Foundation. August 2011 (3rd edition). French version: A POMPE A CORDE: Séries de la pompe à moindre coût.

• Rope Pump production manual, produced by PRACTICA and ETC Foundation. It has 86 pages and contains detailed instructions.

• Construction manual Connect International.

• ERPF, K. (2006) Installation and Maintenance Manual for Rope Pumps, Skat, Rural Water Supply Network, St Gallen, Switzerland.

• ERPF, K. (2006) Manufacturing Guidelines for the Production of Rope Pumps in Mozambique., Skat, Rural Water Supply Network, St Gallen, Switzerland English, Portuguese.

• RANDRIANASOLO, A. and ERPF, K. (2004) Madagascar Rope Pump Specification. First Edition 0 - 2004, Skat, Rural Water Supply Network, St Gallen, Switzerland.

• RWSN (2006) Maintenance Card for Rope Pump, Skat, Rural Water Supply Network, St Gallen, Switzerland.

Videos

External links

Rope pump used for rice paddy irrigation in Vietnam

Wind Rope pump used in Nicaragua, produced by AMEC

• www.ropepumps.org website
• Rope pumps: out-perform conventional handpumps on most counts in Ghana test. Article on IRC.
• Rope pump: local production and installation capacity being developed in Senegal. Article on IRC.
• Overview of community handpumps at the RWSN website
• Low-cost pump alternatives for rural communities in Honduras (rope- and EMAS pumps), SKAT website
• Pump Aid works in Malawi and Zimbambwe with the Elephant pump, a kind of rope pump.
• www.ropepump.com
• Ideas at Work, Cambodia
• Rope Pump - WaterAid in Mozambique
• Rope pump article at Appropedia
• Akvo solution of the week 7
• Akvo solution of the week 9
• 'Low Cost Handpumps' RWSN Field Note 2011-3
• RWSN: Rope Pumps (Nicaragua)
• RWSN: Rope Pumps (Madagascar)
• RWSN: The Rope Pump Concept English, French, Portuguese

References

1. ↑ Fraenkel, Peter, and Thake, Jeremy. Water Lifting Devices, A handbook for users and choosers, 3rd ed. UK, Rugby: Intermediate Technology Publications Ltd, 2006.
2. ↑ Olsen, J. P. Greek & Roman Mechanical Water-Lifting Devices: The History of a Technology. Toronto, Canada: University of Toronto Press, 1984.
3. ↑ Tacolla, Mariano. De Ingeineis, Liber Primus Leonis, Liber Secundis Draconis, Addenda. c. 1433, folio 80.
4. ↑ Weisbaden, Ludwig, ed. et al. Facsimile of De Ingeineis, Liber Primus Leonis, Liber Secundis Draconis, Addenda [online]. Germany: Satz Und Druck, 1984. [April 2009]
5. ↑ Sandiford, Peter, et al. The Nicaraguan Rope-pump. Waterlines, January 1993, Vol. 11 (3).
6. ↑ Lammerink, M.P. et al. EVALUATION REPORT NICARAGUAN EXPERIENCES WITH ROPE PUMP The Netherlands: IRC, 1995.
7. ↑ Lambert, R. A. How to make a rope-and-washer pump. London: Intermediate Technology Design Group, 1990.
8. ↑ Alberts, J. H. The rope-pump - an example of technology transfer. Waterlines, January 2004, Vol. 22 (3), 22-25.
9. ↑ Weisbaden, Ludwig, ed. et al. Facsimile of De Ingeineis, Liber Primus Leonis, Liber Secundis Draconis, Addenda [online]. Germany: Satz Und Druck, 1984. [April 2009]
10. ↑ Information on Motorized rope pumps from the Practica Foundation