EMAS pump

From Akvopedia

The EMAS pump is a very cheap PVC piston pump for family use, which can both pump water from a well and pump it to an elevated point. For example, it can pump water from 20 meters underground directly to an elevated tank another 20 meters above the ground level. The ability to pump directly to a storage tank avoids handling of the water, which avoids contamination.

The EMAS pump compresses water between two one-way valves (check valves produced with glass marbles), a footvalve and a piston valve. Water is forced up the piston tube and comes out of the pump handle.

History and social context

EMAS is the acronym for Escuela Móvil de Agua y Saneamiento (Mobile School for Water and Sanitation), in Bolivia, whose director, Wolfgang Eloy Buchner, developed this pump in the 1990's.

EMAS is not only the name of the mobile school for water and sanitation, but also a whole technical and social concept of water and sanitation which includes rain water harvesting, solar water heaters, windpower, hydraulic rams, water treatment, small tanks and sinks, a variety of hand and foot pumps, and ferrocement tanks.

Suitable conditions

The EMAS pump is designed for household water supply at family level. Large diameter models can be used for small scale irrigation if the water is very superficial.

Several variants of the EMAS pump exist, such as adaptations to shallow wells (larger diameter, higher output), very high pressure (up to 60 m head) and foot-operated balancing devices. It can be coupled to windmills, children's seesaws, animal roundabouts etc. An EMAS pump can fit in boreholes as narrow as 1.25", which means that cheap, hand drilled boreholes are possible, such as with the EMAS well drilling method.

EMAS pumps can be used to pump to a depth of 40-50 m. Deeper than 40-50 m, the pumping becomes very heavy. The EMAS pump can pump up to 30 l/min from a depth of 10 m, when operated by hand. Total production is up to about 5 m⁴/day. (That is: 5 m³ from 1 m depth or 0.5 m³ from 10 m or 250 l/day from 20 m depth etc.).

The lifespan of an EMAS pump can be estimated as 2 million liters pumped. PVC pumps are not as sturdy as metal ones. Ideally, they should serve a single family who owns and maintains it. Communal use is possible if maintenance and repair are well organized, but a single pump is not recommended to serve more than 100 people.

Advantages	Disadvantages/limitations
- Can pump directly into an elevated storage tank, avoiding water handling in buckets. - Can be built and repaired by users themselves - Very cheap (less than one tenth of a rope pump in Nicaragua)	- Less resistant to very intensive use and mistreatment than metal pumps. - Output is on down-stroke. That makes it slightly more complicated to fit a lever or treadle.

Some 20,000 EMAS pumps are in use in Bolivia and some 10,000 in Brazil. It is used in Peru, Equador and Nicaragua. In Asia and Africa, hundreds are in use.

Technical specification

The EMAS pump is a deep well positive displacement piston pump, with two one-way valves.

Operation

The EMAS pump is direct action and hand operated, but can be fitted with a foot pedal that increases ease of pumping and is described in EMAS videos and literature.

Maintenance

The piston gasket (made from the nylon-reinforced section of a used tire) can wear slowly over time and and must occasionally be replaced. This can be done easily and in less than an hour by a user that understands the simple operation of the pump. If the pump is constructed properly, there will be a range in which the gasket can be adjusted to achieve the proper balance between ease of pumping and hydraulic efficiency between replacements.

Manufacturing

Rural people are easily taught to build their own, using two (glass) marbles, simple PVC pipes, thread adapters and (galvanized) iron pipe, available in any hardware store. The pump uses a gasket that is made from the nylon-reinforced sidewall of used tires, which is widely available and already used in most rural areas for other purposes. Having built their own pump, people are able to maintain it forever. Only basic hand tools required.

Cost

The EMAS pump costs about US$ 5 (mainly the metal handle), with 1 US$ extra for each meter depth. (prices from Nicaragua, 2006).

Cost of introduction (project cost with knowledge transfer, hands on training, plus 20 pumps):

• Training: 1 day (depending on level of participants)
• Materials for 20 pumps: US$ 100.
• Tools: US$ 50 - 200 if everything has to be bought new.

Country experiences

In use in Latin America, Asia and Africa. More than 20,000 are in use in Bolivia and more than 10,000 in Brazil. Successfully introduced in Central America (a.o. Honduras and Nicaragua), South-East Asia (a.o. post-tsunami Sri Lanka) and several African countries.

Success of introduction is variable however, depending on capacity and motivation of early adopters. If people built their pump themselves, they are usually kept in good working condition for years.

Manuals

• Illustrated EMAS pump construction manual, by Paul Cloesen
• A similar design published by ECHO

Movies

• Build an EMAS pump with PVC thread adapters, Playlist with 9 video clips, Spanish spoken, English subtitles. Presented by Wolfgang Buchner.
• Large collection of EMAS movies on different subjects.

Links

• The Technology Demonstration Center EMAS works with EMAS pumps. See Akvopedia article on Technology Demonstration Centers.
• EMAS website in English
• Low-cost pump alternatives for rural communities in Honduras (rope- and EMAS pumps), SKAT website
• Comité Sí a la Vida (Nicaragua, in Spanish)
• Akvo solution of the week 7

References

• This article is based on an article by Paul Cloesen