|Sourcebook of Alternative Technologies for Freshwater Augmentation in Africa (International Environmental Technology Centre - United Nations Environment Programme, 1998, 182 p.)|
|Part B - Technology profiles|
|2. Domestic water supply|
|2.1 Fresh water augmentation technologies|
The rope-washer pump consists of a rope with knots or rubber washers, whose diameters are slightly less than the diameter of the pipe, placed at intervals along it (Figure 32). This assembly is drawn up inside a rising pipe, and is capable of drawing relatively large volumes of water to the height of the pump. During operation, the pipe is inserted into water and the rope drawn upwards through the pipe by means of a winding drum with a crank. Water is also drawn up and discharged at the top. The rope and washers pass round the winding wheel and return to the bottom of the pipe thus completing the circuit. This design can be modified to avoid slippage of the rope on the pulley by using old tyre casings to make the pulley wheel. To prevent the washers getting caught, and to support the bottom of the pipe above the bottom of the well or river bed, a suitable pipe stand and rope guide is necessary. Friction should be kept low by allowing leakage between the washers and the pipe stem.
Extent of Use
The rope-washer pump is receiving moderate use in Kenya, Zimbabwe and Burkina Faso.
Operation and Maintenance
Rope-washer pumps rely are manufactured locally, and, therefore, are amenable to local repair and maintenance using simple, locally-available materials.
Level of Involvement
The components of this technology are community-manufactured and operated. Government and NGOs are often involved in the promotion of this technology and development of refinements.
Rope-washer pumps cost between $30 to $50 to construct. The construction cost increases in proportion with the lift required.
Effectiveness of the Technology
This technology is appropriate for all domestic uses and micro-irrigation or garden irrigation uses. This pump can pump high volumes with a low lift.
The technology is suitable for abstraction from shallow wells of up to 10 m depth or from rivers and streams. It is easily adaptable to changing volumes by adapting the diameter of the pipe and washers.
The introduction of a simple device such as the rope washer pump, lends itself to micro-scale gardening and the accompanying positive environmental management practices.
The pump has no valves and does not require complicated bearings. It is easy to manufacture, with local resources, and is ideal for flood irrigation of small gardens.
The pump has limited lift and poor pumping efficiency, as water is allowed to leak through the valves.
There are no known cultural inhibitions.
Further Development of the Technology
The rope-washer pump technology needs to be further disseminated to gain additional field experience of its operation. The efficiency of the pump needs to be improved.
Chleq, J.L. and H. Dupriez 1988. Vanishing Land and Water. Soil and Water Conservation in Drylands. Macmillan, 117 p.
Lambert, R.A. 1990. How to Make a Rope Washer Pump. Intermediate Technology Publications, London.