A rope pump is a kind of pump where a loose hanging rope is lowered into a well and drawn up through a long pipe with the bottom immersed in water. On the rope, round disks or knots matching the diameter of the pipe are attached which pull the water to the surface. It is commonly used in developing countries for both community supply and self-supply of water and can be installed on boreholes or hand-dug wells.
Description
A rope pump is a type of pump of which the main or most visible component is a continuous piece of rope, in which the rope is integral in raising water from a well. Rope pumps are often used in developing areas, the most common design of which uses PVC pipe and a rope with flexible or rigid valves. Rope pumps are cheap to build and easy to maintain. One design of rope pump using a solar-powered rope pump can pump 3,000 litres to 15 meters per day using an 80 watt solar panel. Rope pumps can be powered by low speed gasoline/diesel engines, electricity, human energy, wind and solar energy.
History
Chain or washer pumps were used by the Chinese over 1000 years ago. In the 1980s Reinder van Tijen an inventor and grass roots activist, with the support of the Royal Tropical Institute of Amsterdam, created and began instructing various communities around the world how to make a rope pump from simple available parts using PVC pipes and plastic moldings. He began at Burkina Faso in Africa, continued to Tunisia, Thailand and Gambia among others. In Nicaragua, the technology was rapidly disseminated over the whole country and 25% of the rural population in Nicaragua now use rope pumps. It is also used in other parts of Central America with over 25,000 pumps installed to date. In Africa the rope pump is now being used with solar energy. By the end of 2009 more than 4 million people in 20 countries worldwide were using rope pumps for domestic and irrigation water.
Construction
The original rope pumps used knots along the rope length but can be made with flexible or rigid valves on the rope instead of knots. Alternatively they may use only rope, simply relying on the water clinging to the rope as it is quickly pulled to the surface.
Flexible valve rope pumps
Flexible valves can be made from cut pieces of bicycle wheel tubing. The valves are positioned approximately 20 cm apart on the rope. One disadvantage of flexible valve rope pumps is that they must be appropriately sized and thickness for different types, sizes and length of pipes.
Rigid valve rope pump
Rigid valves using plastic or metal washers that fit tightly into the PVC pipe as the rope is dragged through are also used. If the fit is tight, the washers can be spaced up to half a meter apart. The deeper the well, the smaller the pipe inner diameter must be, given the available power constraints. These rope pumps are often worked with a hand crank Valves can also be made from knots in the rope itself.
Valveless rope pumps
Valveless pumps rely on friction with water clinging to the rope, which is moved at high speed, often using a bicycle to produce the required speed. It is a less efficient design but is simpler to construct than the other rope pumps.
