[PDF]human water lifters

HUMAN-POWERED
WATER-LIFTERS

The choice of water lifters available is large and varied, making the selection of an
appropriate device difficult. In America and Europe during the 19th century the design of
mass-produced hand pumps evolved by trial and error rather than through scientific
research and development. There is now a large number of adequate, rather than
optimum, designs conceived by local manufacturers, and it is hard to know which pump is
the best for each application. This brief presents an overview of the types of human-
powered water-lifters available, the applications appropriate to them and their comparative
advantages.

Water-lifters can be broken down into the following categories:

• Groundwater (open-well, shallow-well and deep-well pumps)

• Surface Water (shadouf, dhone, chain and washer and archimedean screw)

Groundwater

When rain falls, it seeps into the ground and collects in an underground reservoir known
as groundwater. The upper limit of this reservoir, the "water-table", may vary in depth, from
just below the surface (like in a spring or oasis) to well over 100 metres. The only way to
get at this water is to dig down.

Open-well

The simplest and cheapest method of lifting groundwater remains the rope and bucket in a
wide, shallow well. These can operate to a depth of 100 metres, although they rarely
exceed 45 metres, and can last for a very long time without maintenance. It is worth
considering this design before proceeding with more complicated methods.

It may not be possible to construct an open-well if the water table is too deep or if the
foundations are very hard (such as rock) or very soft (such as fine running sands). These
restrictions also depend on the method of construction.

If the groundwater can only be accessed through a bore, then a groundwater pump must
be used. Groundwater pumps can be split into two categories, shallow-well and deep-well.

Shallow-well pumps

Most types of groundwater pump have
a piston that moves back and forth
inside a two-valve cylinder (a valve
allows water to pass in only one
direction - in this case, upwards):

Suction pumps have the cylinder
situated above ground or near the
surface. This means that they can
only be used for shallow wells. It is
called a suction pump because pulling
up on the piston creates a low
pressure ("suction") in the cylinder,
causing the atmospheric pressure
outside to push the water up to the Figure 1 : How most types of pump cylinders work

surface. Because atmospheric

pressure is fairly low, the pressure difference between inside and outside the cylinder is only large

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Human Powered Water Lifting Devices Intermediate Technology Development Group

enough to raise water from a maximum depth of about 7 metres.



It should also be noted that if a shallow-well is used too much, the water-table may fall as the
underground reservoir of water is reduced. If this level falls below 7 metres, the pump will not
work.

Four types of shallow-well pumps are shown below: rower, piston, diaphragm and semi-rotary.
Rower

The rower pump is a simpler and
cheaper version of the traditional
piston pump (see below). Its
simple design means it can be
easily manufactured and
maintained using locally available
skills and materials. This type of
pump may require "priming",
which means pouring water into
the cylinder so that the seal
around the piston is airtight. It is
very important that clean water is
used, to avoid contamination of
the pump and the spread of
water-borne diseases.




Piston

Piston pumps, based on the same design as
shown in Figure 1 , are more widely used. There
is a similar risk of contamination from dirty
priming water. In cases where the water is to be
delivered under pressure (such as to a village
water mains) or to a point higher than the
cylinder (such as a water storage tank), a "force"
pump is required. The operation is the same, but
the design is slightly altered so that the top is
airtight. This is done by putting a valve on the
spout and adding a "trap tube" and air chamber
which maintains the pressure (and therefore the
flow) during the up-stroke.



Figure 3: Shallow-well piston pump
Diaphragm

This design is often used for fuel pumps in
cars. The Vergnet pump is an adaptation
of this principle for deep-well use, which
can be used in crooked wells, where a rod-
operated pump would have problems, and
which is fairly easy to maintain.



Figure 2: Rower pump




Figure 4



Diaphragm pump



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Treadle pump

Because leg muscles are stronger than arm muscles, this design is less tiring to use.
Most of the parts can be manufactured locally, the exceptions being the cylinders and
pulley.




Figure 5: Treadle pump
Deep-well pumps

Deep-well pumps can be used for depths over 7 metres because the cylinder or lifting device is
below ground, as shown in Figure 6, often below the groundwater line. They are often known as
"lift" pumps because they do not rely on suction to raise the water. As a result of their depth, they
are harder to maintain than surface pumps, since the pump-rod must be removed to get at the
cylinder. Like suction pumps, lift pumps can be made into force pumps by the addition of a spout
valve, air chamber and trap tube. Three types of deep-well pump are described below: piston,
helical rotor and direct action.

Piston

The design is very similar to the shallow-well pump and is capable of lifting water from depths of up
to 50 metres. However, the cylinder is situated deep underground, below the groundwater-line,
connected to the pump handle via a long rod called a "pump rod" (see Figure 6). Sometimes the
outside pipe, called the "rising main", is of a larger diameter so that it is possible to pull the whole
cylinder up to the surface for repair without taking the pump apart. However, this is more
expensive.

Helical rotor (or "progressive cavity")

Helical rotors are capable of lifting water from depths of up to 100 metres. Instead of a piston,
there is a metal "rotor" which has a corkscrew shape and which turns inside a rubber "stator" or
sleeve (see Figure 6). The lever is replaced with one or two turning handles.

Direct action ( or "direct drive")

This design is capable of lifting from a depth of 12 metres. The narrow pump rod is replaced by a
hollow plastic pipe which displaces water as the pump handle is pushed down. During the up-
stroke, the pipe acts as a pump rod, the valve on the piston

closes and water is lifted up. The pump is therefore capable of pushing water up the rising main
during both strokes. Because the pipe is hollow, it floats, so the handle does not have to be pulled
up so hard.



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Piston Pump Helical Rotor Pump Direct Action Pump

(Direct Drive Pump)




•0



Figure 6: Types of deep-well lift pumps - piston, helical rotor and direct action



Surface Water

Surface water lifters are generally less complicated than groundwater lifters, because the water is
so much more accessible. Four types are described below: shadouf, dhone, chain and washer
and archimedean screw.

Shadouf (picottah)

The basic shadouf consists of a rope, pole, bucket and counterweight and is capable of lifting
water up to 4 metres. The counterweight can be just a heavy rock, but in the more advanced
"picottah" design, one person guides the bucket while the other acts as a moving counterweight.



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Dhone

This design replaces the bucket with a channel. It can also be adapted for picottah-style
operation.




Figure 7: Picottah-style shadouf and dhone



Chain/rope and washer (or "paternoster")
These pumps have been used in China and Europe
for many centuries. Water is lifted by close-fitting
washers in a pipe. Although in theory it is possible
to construct a vertical chain and washer pump to
raise water to any height, most do not exceed 20
metres. A variation of this design is called the
"dragon-spine" pump, which lies at a shallow angle
to the horizontal. In this case, lifting height is
rarely more than 6 metres. However, the design is
very flexible and can easily be adapted to
circumstances.



Figure 8: Chain and washer pump




Archimedean screw

Although this design looks quite complicated, it is fairly easy to build using local materials and is
readily transportable. The inside, which is shaped like a corkscrew, is turned by a handle, trapping
water in the cavities as shown in Figure 9. Although on a much larger scale, this is very similar to
the operation of the helical rotor. However, the lifting range is much smaller.



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Figure 9: Archimedean screw

Selecting a water-lifter

The choice of water-lifter is determined by the application and the resources available to the
users. Demand for water may come from domestic, community, industrial and agricultural
needs. It is first necessary to determine:

• where the water will come from (the source)

• where it will go to (the destination)

Figure 10 shows the types of source and destination to be considered.




Figure 10: Sources and 2 < 7 meters

destinations of water

1 >7 meters



Once the source and destination has been determined, it is possible to narrow down the choice
of water-lifter. The table below summarises the options available for different combinations of source
and destination.





Source






Destination


1. (> 7m)


2. (<7m)


3. (river/pool)


4 (Surface)


Deep-well Lift Pump


Shallow well suction


Shallow-well suction






pump or open-well


pump


5 (hill/tank)


Deep-well lift & Force


Shallow-well force


Surface water system




Pump


pump


or suction & force


6 (village)


Dee-well lift & Force


Shallow-well force


Shallow well force




Pump


pump


pump



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Table 1 : Water-lifter options

Apart from the source and destination of the water, there are many other criteria which should be
considered before making a selection. Where possible, the lifter should be suitable for Village
Level Operation and Maintenance (VLOM) or Management of Maintenance (VLOMM). This
reduces the reliance of the villagers upon large institutions to sustain the development of the water
supply. A check-list of things to consider when choosing a pump is shown below.



Capital cost

How much does the lifter cost initially?

Will a loan be needed, or does the village have sufficient funds?

Running cost

What is the on-going cost of operating the lifter?

Does the village have sufficient manpower available to operate the lifter for all the time it is
needed?

Maintenance cost

What is the cost of and skill required for the maintenance of the lifter?
Can the pump be repaired in the village or somewhere nearby?
Are spare parts available?

Can the villagers afford them? How often is it likely to need repair?

How long would it take to repair the lifter and what will the villagers do in the meantime?

NB Maintenance is an integral part of lifter management. For more complicated designs, such as
the deep-well pumps, it is important that this maintenance is preventative. Problems should be
avoided by regular inspection and servicing of the mechanical parts. Wear and tear will be less
severe this way, and any problems will be solved before they cause more damage.

Manufacture and materials

Can the lifter be manufactured locally using local skills and materials?
Life expectancy

How long is the lifter expected to last before it has to be replaced?
How resistant is the lifter to abuse?

Lift height and flow rate

How much water does the community need? The maximum flow capacity of the lifter should be
matched to the demand from the community, including home, industrial and irrigation needs. (In
the case of pumps, this flow rate given by the flow-rate/lift-height, or "Q/h", curve, which should
be supplied by the manufacturer)
How high does the lifter have to raise the water?

How deep is the groundwater and is it likely to fall in future (such as from over-use)?
Operators

Is the lifter suitable and acceptable to the people who will actually operate it?

Are there health and safety considerations, such as dangerous machinery or risk of

contamination?

Is the operation ergonomic (comfortable to use)? For instance, are the average and maximum
handle forces required realistic for women and children?

Community

Is there a capable community organisation which can oversee maintenance and management of
the device and the water?

Will the users be instructed how to use and look after the device?



Table 2 below gives a summary of some of these criteria for each of the designs. The values given
are very approximate, and should be taken only as a rough guide. As lift height increases, flow



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rate falls, so at maximum lift, the actual How rate will be much less than the maximum How rate.
Also, the flow rates are given for one person operating the pumps, except in the case of the
picottah, which requires a minimum of two.



Table 2: Assessment criteria



Type


Construction


Maximum


Maximum




(Traditional/


lift height


flow rate




Industrial)


(metres)


(m 3 /hour)


SUCTION








Rower


Traditional


7


3


Suction piston


Industrial


7


8


Diaphragm


Industrial


7


10


Treadle


Traditional


7


18


LIFT








Rope and bucket


Traditional


100


15


Lift piston


Industrial


50


1.5


Helical rotor


Industrial


100


1.5


Direct action


Industrial


15


1


SURFACE WATER








Shadouf


Traditional


4


6


Picottah


Traditional


8


6


Dhone


Traditional


1.5


6


Chain and washer


Trad / Industrial


15


25


Archimedean screw


Traditional


1.5


25



References and resources

Resources

• Human and Animal-powered Water-lifting Devices: A state-of-the-art survey

by W. K. Kennedy & T. A. Rolgers. ITDG Publishing, 1985.

• Water pumping devices - A handbook for users and choosers

by Peter Fraenkel, ITDG Publishing, 1986.

• Tools for Agriculture - a buyer's guide to appropriate equipment

Introduction by lab Carruthers & Marc Rodriguez, ITDG Publishing, 1992.

• How To Make and Use The Treadle Irrigation Pump

by Carl Bielenberg and Hugh Allen, ITDG Publishing, 1995.

• How to Make a Rope-and-Washer Pump by Robert Lambert, ITDG Publishing, 1990.

ITDG Publishing

1 03-1 05 Southampton Row

London, WC1B4HH, UK

Tel: +44 (0)20 7436 9761

Fax: +44 (0)20 7436 2013

E-mail: orders@itpubs.org.uk

Website: http://www.developmentbkookshop.com



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Organisations

Sue Sherry
WELL

London School of Hygiene & Tropical Medicine

Keppel Street, London, WC1E 7HT, United Kingdom

Tel: +44(0)20 7927 2214

Fax: +44(0)20 7636 7843

E-mail: well@lshtm.ac.uk

Web page: http://www.lboro.ac.uk/well/

WELL is a resource centre funded by the DfID to promote environmental health and well being in
developing and transitional countries. It is managed by the London School of Hygiene and
Tropical Medicine (LSHTM) and the Water, Engineering and Development Centre (WEDC),
Loughborough University for British & Southern NGOs working in water & sanitation.

WaterAid

Prince Consort House, 27-29 Albert Embankment, London, SE1 7UB, UK

Tel: +44 (0)20 7793 4500

Fax: +44 (0)20 7793 4545

E-mail: technicalenquiryservice@wateraid.org.uk
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