Hand pumps are manually operated pumps; they use human power and mechanical advantage to move fluids or air from one place to another. They are widely used in every country in the world for a variety of industrial, marine, irrigation and leisure activities. There are many different types of hand pump available, mainly operating on a piston, diaphragm or rotary vane principle with a check valve on the entry and exit ports to the chamber operating in opposing directions. Most hand pumps are either piston pumps or plunger pumps, and are positive displacement. [1]
Hand pumps are commonly used in developing countries for both community supply and self-supply of water and can be installed on boreholes or hand-dug wells.
One sort of pump once common worldwide was a hand-powered water pump, or 'pitcher pump'. It was commonly installed over community water wells in the days before piped water supplies.
In parts of Britain and Ireland, it was often called the parish pump. Though such community pumps are no longer common, people still used the expression parish pump to describe a place or forum where matters of local interest are discussed. [3]
Because water from pitcher pumps is drawn directly from the soil, it is more prone to contamination. If such water is not filtered and purified, consumption of it might lead to gastrointestinal or other water-borne diseases. A notorious case is the 1854 Broad Street cholera outbreak. At the time it was not known how cholera was transmitted, but physician John Snow suspected contaminated water and had the handle of the public pump he suspected removed; the outbreak then subsided.
Modern hand-operated community pumps are considered the most sustainable low-cost option for safe water supply in resource-poor settings, often in rural areas in developing countries. A hand pump opens access to deeper groundwater that is often not polluted and also improves the safety of a well by protecting the water source from contaminated buckets. Pumps such as the Afridev pump are designed to be cheap to build and install, and easy to maintain with simple parts. However, scarcity of spare parts for these type of pumps in some regions of Africa has diminished their utility for these areas.
Suction and lift are important considerations when pumping fluids. Suction is the vertical distance between the fluid to be pumped and the centre of the pump, while lift is the vertical distance between the pump and the delivery point. [4] The depth from which a hand pump will suck is limited by atmospheric pressure to an operating depth of less than 7 meters. [5] The height to which a hand pump will lift is governed by the ability of the pump and the operator to lift the weight in the delivery pipe. Thus the same pump and operator will be able to achieve a greater lift with a smaller diameter pipe than they could with a larger diameter pipe.
In addition to their use in drawing water from shallow groundwater sources for water supplies, another version of the hand-powered suction pump, with low lift and high delivery, was developed in the later 19th century for use as a ship's bilge pump (for smaller coastal vessels) and as a building site contractor's pump. It was known as a deluge pump. [6] One manufacturer who illustrated this product from the late 1880s onwards into the early 20th century was Goulds Manufacturing Co. [7]
Where it is necessary to raise water to a height above that to which a suction or lift pump will operate effectively (about 7 metres), or to raise the pressure so that it will exit a nozzle with a strong force, such as through a fire hose, a force pump may be used. As with a suction pump, in its manual form it relies on an operator to pump a handle. The difference is however that after the water is sucked through the lower valve (as a result of raising the piston that is attached to the handle), its means of exit is via a pipe or nozzle in the side of the main cylinder. The water, once it has been drawn up above the lower valve and trapped there, is forced out the exit when the piston or plunger is pushed down again on the next stroke. [8]
A siphon (or syphon) at its simplest is a bent tube, with one end placed in the water to be moved, and the other end into the vessel to receive the water. The receiving vessel must be at a lower level than the supplying vessel. [9] Water will always try to find its lowest level. Using this principle, very simple pumps with plastic or rubber bulb with flap valve at each end are used for emptying fuel or water cans into tanks. Once the bulb is full, the fluid will flow without further effort from the higher to the lower container. Many hand pumps will allow the passage of fluid through them in the direction of flow and diaphragm pumps are particularly good at this. Thus where the levels are correct large volumes of liquid such as swimming pools can be emptied with very little effort and no expensive energy use.
A chain pump is made of an endless chain carrying a series of discs that descend into the water, and then ascend inside a tube, carrying with them a large quantity of water. They are a simply made, old hand-powered pumping technology [10] In the 18th century they were used as ship's bilge pumps. [11]
A chain pump is a type of water pump that uses a chain to move water from one place to another. It works on the principle of a continuous loop of chain moving through a series of sprockets, with attached buckets that lift water as the chain passes over the top sprocket and discharge it as the chain reaches the bottom. [12]
Direct action hand pumps have a pumping rod that is moved up and down, directly by the user, discharging water. Direct action handpumps are easy to install and maintain but are limited to the maximum column of water a person can physically lift of up to 15 m. Examples of direct action pumps include the canzee pump [13] and the EMAS pump. [14]
Deep well hand pumps are used for high lifts of more than 15 m. The weight of the column of water is too great to be lifted directly and some form of mechanical advantage system such as a lever or flywheel is used. High lift pumps need to be stronger and sturdier to cope with the extra stresses. The installation, maintenance and repair of deep well hand pumps is more complicated than with other hand pumps.
A deep well hand pump theoretically has no limit to which it can extract water. In practice, the depth is limited by the physical power a human being can exert in lifting the column of water, which is around 30 m
Diaphragm pumps have the advantage that they pump relatively lightly due to the lack of pulling rods and are corrosion resistant. Their disadvantage is that they need a specific length of tubing and high quality rubber diaphragms, which are costly and are relatively inefficient due to the extra work needed to deform the diaphragm.
Rubber diaphragms will eventually leak and need to be replaced. Because this is usually complicated and costly, diaphragm pumps operating in poor rural areas are often abandoned once the diaphragm wears out.
Progressive cavity pumps consist of a single helix rotor inserted into a double helix stator. As the rotor is turned, the voids in the stator are screwed upwards along the axis of rotation. Progressive cavity pumps can have complicated gearing mechanisms and are difficult for local pump technicians to maintain and repair.
A rope and washer pump is a type of progressive cavity hand pump.
The range of lift of different types of hand pumps is given below: [15] [16]
Type | Range |
---|---|
Suction pumps | 0–7 meters |
Low lift pumps | 0–15 meters |
Direct action pumps | 0–15 meters |
Intermediate lift pumps | 0–25 meters |
High lift pumps | 0–45 meters, or more |
In November 2002, the United Nations Committee on Economic, Social and Cultural Rights asserted that access to clean, safe water goes beyond the classification of water as an economic commodity. The committee stressed the fundamental right of sufficient access to clean water for both domestic and personal use. "The human right to water is indispensable for leading a life in human dignity". [17] With this in mind, manufacturers of water pumps, like those produced by GOAZ Development in Malaysia, have a wide range of potential customers: governments, non- governmental organizations, women's groups, community groups and other organizations of various types interested to developing access to groundwater. [15]
VLOM, meaning Village Level Operation and Maintenance, is a term first used during the UNDP and World Bank Rural Water Supply Hand Pumps Project. This project lasted from 1981 to 1991, and studied the availability and maintenance of hand pump systems. 40 kinds of hand pumps were analyzed in laboratories, and the performance of 2700 hand pumps was analyzed in the field. The study established that centralized maintenance structure was a cause of many problems in hand pump programs, and that maintenance at the village level is best. [1]
The VLOM concept was initially applied to hardware, with the following aims: the possibility of maintenance by village workers, having spare parts manufactured within the country to make sure spare parts are available, endurance in the field, and cost effectiveness. With time, more emphasis was placed on maintenance management. Thus, the "M" came to represent "management of maintenance". Therefore, greater community choice of service, who will service, and financial accountability by the community to the caretakers of the pump have gained more importance within the VLOM concept. [1]
The Swiss Centre Resource Centre and Consultancies for Development, Skat, [18] continues to work on design and support structure for hand pump development as the host of Secretariat of the Rural Water Supply Network [19] (RWSN).
An example of a Bank funded project that highlights many issues of hand pumps is the 1992 Mali Rural Supply Project. The project brought approximately 230 rural villages inclined towards periods of drought, and 228,000 people access to safe water. [20] The project is notable in its attempt to bring responsibility for the upkeep of the pumps to the villages themselves. The complexity of the pumps is a fundamental problem for all programs of this kind, as well as the quality of the pumps given the heavy demands of a village. [20] A 1994 study, also Bank funded, of the endurance of hand pumps in Africa showed that only 41 to 51 percent of hand pumps were still functioning. [20] The Mali Rural Supply Project did positively affect the longevity of hand pumps by doing the following: establishing local depots of spare parts, training individuals to maintain pumps, scheduling inspections from officials of the project, forming local committees and recruiting volunteers.
Much attention has been given to the benefits of the use of hand pumps in developing nations, as opposed to more traditional methods. In communities reliant on groundwater, through a borehole or well, the utilization of a bucket and rope system has hygienic issues. The bucket and rope system is not compatible with the use of a cover slab, which can prevent pollution of groundwater. In addition, unwashed hands can contaminate the bucket and rope. Hand pumps avoid these issues and are therefore preferable. [1]
However, villagers did not stop using traditional means of gathering water during this project. This was especially true when rain provided villagers with shallow water sources. These shallow wells were often easier to access than the wells with hand pumps. When faced with the option of using near surface water or traveling to the hand pumps, many villagers chose the former. [20]
In addition, animal contamination and the mixing of groundwater and surface water were factors in sub- par sanitation. [20]
Another issue that faced the project was the fact that the pumps could only provide a maximum of 20 liters of water per person day, which required an unrealistic staggering of water retrieval. [20] In addition, many depots withdrew support after the donated inventory ran out, the contracts given to consultants eventually closed, and maintenance was not kept up to a high standard. [20]
A June 2008 study, conducted by the World Bank, Review of Effectiveness of Rural Water Supply Schemes in India, showed that approximately 45 percent of rural piped water projects focused on breakdown maintenance instead of scheduled maintenance. In addition, about 20% were reported to be in "serious or somewhat serious neglect of maintenance". [21]
Whether or not a project to use hand pumps in a developing country is an affordable alternative certainly depends on who or what organization pays the bill. However, the example of a 1992 Ethiopia aid project illustrates what the cost would be for the locals who benefit from the project. [22] This example relates to isolated, rural communities in the rural South.
165 Afridevs hand pumps were imported from India. Each cost approximately US$700, including clearing, transportation and installation. These pumps serve around 55 households each. At that time, the World Bank established that the average per capita income in Ethiopia was $120. A hand pump, first produced by researchers at the University of Waterloo and then refined at the University of Malaya, has been designed with local access to parts in mind. Materials readily available, like a rope covered in chicken fat or leather belt, can be used to ensure maintenance. GOAZ Development sells these pumps from $160 to $300. Therefore, 11% of one's annual income would go towards accessing clean water. This is over twice as much as the 5% that the World Bank stated should be the maximum amount paid by a family. [22]
A hydraulic ram pump, ram pump, or hydram is a cyclic water pump powered by hydropower. It takes in water at one "hydraulic head" (pressure) and flow rate, and outputs water at a higher hydraulic head and lower flow rate. The device uses the water hammer effect to develop pressure that allows a portion of the input water that powers the pump to be lifted to a point higher than where the water originally started. The hydraulic ram is sometimes used in remote areas, where there is both a source of low-head hydropower and a need for pumping water to a destination higher in elevation than the source. In this situation, the ram is often useful, since it requires no outside source of power other than the kinetic energy of flowing water.
A pump is a device that moves fluids, or sometimes slurries, by mechanical action, typically converted from electrical energy into hydraulic energy.
A windpump is a wind-driven device which is used for pumping water.
Dredging is the excavation of material from a water environment. Possible reasons for dredging include improving existing water features; reshaping land and water features to alter drainage, navigability, and commercial use; constructing dams, dikes, and other controls for streams and shorelines; and recovering valuable mineral deposits or marine life having commercial value. In all but a few situations the excavation is undertaken by a specialist floating plant, known as a dredger.
A piston pump is a type of positive displacement pump where the high-pressure seal reciprocates with the piston. Piston pumps can be used to move liquids or compress gases. They can operate over a wide range of pressures. High pressure operation can be achieved without adversely affecting flow rate. Piston pumps can also deal with viscous media and media containing solid particles. This pump type functions through a piston cup, oscillation mechanism where down-strokes cause pressure differentials, filling of pump chambers, where up-stroke forces the pump fluid out for use. Piston pumps are often used in scenarios requiring high, consistent pressure and in water irrigation or delivery systems.
An airlift is device based on a pipe, used in nautical archaeology to suck small objects, sand and mud from the sea bed and to transport the resulting debris upwards and away from its source. It is a type of suction dredge. A water dredge or water eductor may be used for the same purpose.
A treadle pump is a human-powered suction pump that sits on top of a well and is used for irrigation. It is designed to lift water from a depth of seven metres or less. The pumping is activated by stepping up and down on a treadle, which are levers, which drive pistons, creating cylinder suction that draws groundwater to the surface.
Village Level Operation and Maintenance (VLOM) is an unofficial classification given to handpumps used in developing countries that require minimal maintenance or that can be done "at the village level." Not all maintenance and repair needs to be done by the villagers for a pump to be classed as a VLOM pump. VLOMM, or Village Level Operation and Management of Maintenance is often used synonymously. This addition emphasizes the role of users as the managers of maintenance able choose to use someone from outside the village to assist with more complicated repairs.
Access to water supply and sanitation in Ethiopia is amongst the lowest in Sub-Saharan Africa and the entire world. While access has increased substantially with funding from foreign aid, much still remains to be done. Some factors inhibiting the achievement of these goals are the limited capacity of water bureaus in the country's nine regions, two city administrations and water desks in the 770 districts of Ethiopia (woredas); insufficient cost recovery for proper operation and maintenance; and different policies and procedures used by various donors, notwithstanding the Paris Declaration on Aid Effectiveness.
A well is an excavation or structure created in the earth by digging, driving, or drilling to access liquid resources, usually water. The oldest and most common kind of well is a water well, to access groundwater in underground aquifers. The well water is drawn up by a pump, or using containers, such as buckets or large water bags that are raised mechanically or by hand. Water can also be injected back into the aquifer through the well. Wells were first constructed at least eight thousand years ago and historically vary in construction from a simple scoop in the sediment of a dry watercourse to the qanats of Iran, and the stepwells and sakiehs of India. Placing a lining in the well shaft helps create stability, and linings of wood or wickerwork date back at least as far as the Iron Age.
Bangladesh is faced with multiple water quality and quantity problems along with regular natural disasters, such as cyclones and floods. Available options for providing safe drinking water include tubewells, traditionally dug wells, treatment of surface water, desalination of groundwater with high salinity levels and rainwater harvesting.
A rotodynamic pump is a kinetic machine in which energy is continuously imparted to the pumped fluid by means of a rotating impeller, propeller, or rotor, in contrast to a positive-displacement pump in which a fluid is moved by trapping a fixed amount of fluid and forcing the trapped volume into the pump's discharge. Examples of rotodynamic pumps include adding kinetic energy to a fluid such as by using a centrifugal pump to increase fluid velocity or pressure.
A reciprocating pump is a class of positive-displacement pumps that includes the piston pump, plunger pump, and diaphragm pump. Well maintained, reciprocating pumps can last for decades. Unmaintained, however, they can succumb to wear and tear. It is often used where a relatively small quantity of liquid is to be handled and where delivery pressure is quite large. In reciprocating pumps, the chamber that traps the liquid is a stationary cylinder that contains a piston or plunger.
The India Mark II is a human-powered pump designed to lift water from a depth of 50–80 m. The Mark II is world's most widely used water handpump. The pump was designed in the 1970s to serve village water needs in developing countries and rural areas. The pump is installed on top of a drilled well or borehole and lifts water from the bottom of the well through repeatedly moving the pump handle up and down. Several manufacturers, primarily in India, manufacture the pump which now falls under public domain. By the mid-1990s, five million of the pumps had been manufactured and installed. India Mark ll Pumps' bored hole may be fitted with solar thermal siphon pump to run on solar energy. The resulting assembly may be called the India Mark IV Solar Pump.
Water supply and sanitation in Kenya is characterised by low levels of access to water and sanitation, in particular in urban slums and in rural areas, as well as poor service quality in the form of intermittent water supply. Seasonal and regional water scarcity in Kenya exacerbates the difficulty to improve water supply.
Water supply and sanitation in Burkina Faso are characterized by high access to water supply in urban areas, while access to an at least basic water sources in rural areas – where three quarters of the population live – remains relatively low. An estimated one third of water facilities in rural areas are out of service because of a lack of maintenance. Access to at least basic sanitation lags significantly behind access to water supply.
Water supply in Afghanistan is managed by the National Water Affairs Regulation Authority (NWARA), which is based in Kabul, Afghanistan. The nation's water supply is characterized by a number of achievements and challenges. Among the achievements are:
The bush pump, also known as the Zimbabwe bush pump, is a positive displacement pump based on lever action used to extract water from a bore hole well. It is the standard hand pump in Zimbabwe, and is used in Zimbabwe and Namibia. There are approximately 40 000 pumps (2009) in Zimbabwe, and annually about 3000 pumps are installed.
Water supply in Southern Sudan is faced with numerous challenges. Although the White Nile runs through the country, water is scarce during the dry season in areas that are not located on the river.
Self-supply of water and sanitation refers to an approach of incremental improvements to water and sanitation services, which are mainly financed by the user. People around the world have been using this approach over centuries to incrementally upgrade their water and sanitation services. The approach does not refer to a specific technology or type of water source or sanitation service although it does have to be feasible to use and construct at a low cost and mostly using tools locally available. The approach is rather about an incremental improvement of these services. It is a market-based approach and commonly does not involve product subsidies.
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