Bangladeshi Rower Travels To Africa
This article written by Gwynne Power originally appeared in World Water magazine, June 1984.
When Richard Cansdale of SWS Filtration Ltd of Morpeth, UK, first saw the shallow well Rower pump and met its designers and manufacturers in Bangladesh, he recognised its potential significance for Africa and elsewhere and began working accordingly.
Richard Cansdale had long been involved in the development of sub-sand river and canal bed filters for use in remote rural communities. He saw the Rower pump and his filter systems as naturally complementary and set about certain modifications to the Bangladesh pump to make it suitable for wider application.
The Rower had been developed by the Mennonite Central Committee in the 1970s, and the Mirpur Agricultural Workshop and Training School had taken over its manufacture. It is now used extensively in Bangladesh for both irrigation and domestic water supply purposes. It lifts water up to a maximum of 5m though operation through its 65mm (21/2 in) diameter ABS plastic cylinder is most efficient to lifts of 3.7m.
Richard Cansdale finds the Rower interesting because he feels it cuts across the recurrent argument over hand versus foot pump. The Rower, he insists, is a “body” pump, in which arms, legs and back work together in “natural harmony”.
The pump gets its name from the operating action, which is similar to that of an oarsman propelling a rowing boat. Because the whole body is used in the action, pumping can be sustained for a considerable period of time. It can also be installed for operation from a standing or sitting position. It works without a pivot, which greatly reduces the complexity of the pump removing the need for bearings, and it weighs just 4kg, making transportation to remote and
inacccessible villages that much easier.
The cylinder is installed at an angle of 30 degrees to the ground and buried for most of its length to provide stability, protection against theft and from the effects of ultra violet rays from sunlight. If correctly installed at the best angle, the T-handled piston rod does not rub against the edge of the cylinder. Developers recommended that the cylinder be covered for protection from sunlight, though ABS has a better record against ultra violet light than other plastics.
At the base of the cylinder there is a surge chamber to compensate for velocity variations in the water column, and a foot valve, which can be removed with a looped cord to save dismantling the rest of the pump.
The major modification in the SWS Rower from the original design from Bangladesh is in the composition of the cup seals on the piston valve at the base of the piston rod. In Bangladesh the pump operates with a single piston valve cup seal manufactured in leather while the SWS Rower Pump uses two Nitrile seals back to back.
In ideal conditions, a healthy man should be able to lift 1.5 l/sec, with long, steady pulls recommended rather than a short, jerky stroke.
Length of pull has a direct and constant relationship to discharge per stroke. For example, a short pull of 450mm will yield 1.5 litres while a 900mm pull brings 3 litres.
Standard handpump precautions need to be taken when the pump is being used for domestic purposes. For irrigation it is usually sufficient for the water to discharge into a trench or other channel leading to the cultivation area.
For household use, the most comfortable height is at knee level to the operator, though a block to stand on, or some adjustment, will be needed for children.
Domestic use calls for a concrete base and drainage channel to avoid erosion around the pump, or standing pools of muddy water which would create a health hazard.
Richard Cansdale feels that the combination of Rower pump and his own attachable filter, which uses the sand of the river or canal bed for filtration purposes, could make a substantial impact on the workload and health profile of villages in developing countries.