A HAND PUMP FOR RURAL AREAS OF DEVELOPING COUNTRIES
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- A HAND PUMP FOR RURAL AREAS OF DEVELOPING COUNTRIES
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SDA-RF-AT-3.13
? , U. Report No, 3£S 9(a)
DTiERNAIIONAL BANK FOR RECONSTRUCTION A2ro DEVELOPMENT
4
INTERNATIONAL DEVELOPMENT ASSOCIATION
RESEARCH WORKING
PAPERS SERIES
A HAND PUMP FOR RURAL AREAS OF DEVELOPING COUNTRIES
May 1973
i
Central Projects Staff
Energy, Water and Telecormunlcations Department
i
This paper is one of a series issued by the
Energy, Water & Telecommunications Department
for the information and guidance or Bank, starr
working in the power, water and wastes, and
«*t3i or'~,.TnTr^v-'n~f oaniens sectors. It may not be
published or quoted as representing the views
of the Bank Group, and the Bank Group does not
accept responsibility for its accuracy or
completeness.
i
I
A HAND PUMP FOR RURAL AREAS OF DEVELOPING COUNTRIES
Abstract
Only 20 per cent of the world's ratal pop
ulation have access to safe water. The best way of
remedying this situation is to provide shallow wells
and hand pumps, wherever possible.
However existing
hand pumps are expensive, complicated and have a hxgh
failure rate. The report suggests a very simple new
pattern of hand pump, in which polyvinyl chlorc.de well
casing is used as the pump cylinder, and other compo
nents can be standardized and nass-producec. The pump
is suitable for maintenance by villagers with minimal
mechanical skills.
I '
This paper was prepared by W,K. Journey (.Consultant)) as part of a research
project'jointly'sponsored by the Agriculture and Rural Development Department
and Che Energy, Water and Teleccnmunicaticns Department.
4
Mr. Journey is now
Prosram Officer of the Population and Health Sciences Division at the Inter
national Development Research Centre, Ottawa, Canada. Sank start pru.ncxpa_i.ly
concerned in the project were Messrs. R.N. Middleton (Energy, Water and
Telecommunications) and J.P. Edgerton and S.V. Allison (Agriculture and Rural
Development).
Note: This paper was originally issued in October 1976. This revision
incorporates in Annex 7 recent data tram field trials on the wear of the
PVC cylinder.
t .
May 1978
TABIZ OF CONTENTS
Page
The Problem
1
Conditions in Sural Water Systems
1
The Proposed Solution
2
Principal Features of the Design
2
(a) Plastic pipe serves as the well casing and pump cylinder
(b) Submerged f interchangeable piston and check valve increase
efficiency and reduce complexity
rod employs local materials
Pump
(a)
rod
guides may not be necessary
(d) Pump
(e) Upper parts can be designed by the users
(f) Local materials can be used to make pivot points
(3) Cup seals are made of leather
Well Developaent.
o
AdAp±ation for Irrigation
7
Differences between Proposed Design and Other
Systems Using plastic Pipe
7
Limits of the Materials
7
(a) Transport
(b) Storage
(c) Jointing
(d) Limits of plastic Casing
Rejuvenating Old Weils
ANNE33S
1.
2.
3.
*
U.
5.
6.
7.
Pendulum Pump
Clayton Mark Water Well Supplies (Catalogue No. h, May 1939;
PVC-Steel Costs
Relative Merits of ABS vs. PVC in Tubewell Construction
Rate of Wear of PVC Pump Cylinders
Oil Soaked Bearings: How to Make Them
Simple PVC Hand Pumps - Trial
TA-RT7.
1.
Cost Comparison Between Handpump Tubewells of Traditional
Design and Those Using PVC Extensively
9
TABLE OF COITTENTS (ConVd)
FIGURES
1.
2.
3.
lx.
5.
Proposed Design and Traditional Design of a Handpump
Tubewell
Interchangeable Piston and Check Valve
Homan Design of Hand Pump, Showing Conical Leather
Cup
Sealing of Pump Hod With Packing Gland in Order to
Pump to Elevated Storage
Roman Design for Pumping to Elevated Storage
(Agricola, "De Re MetaJlica11).
A Hand Pum-p and Well for Rural krsas of Developing Countries
The Problem
■
V
The World Health Organization has estimated that in 1975 only
20 percent of the world’s rural population had access to safe water. To
bring safe water to rural areas of developing countries, the World Bank
r^rrmnends in a recent reportV that, wherever possible, shallow wells and
hand pnTBp-? be used to raise groundwater. Groundwater, in contrast to sur
face water, needs little or no treatment to make it safe.
2.
Thea*1* hand pumps, the report advises, must be "rugged, designed
for simple, trouble-free maintenance by local technicians." But this is
exactly contrary to the nature of available hand pumps. Costly and com
plicated, a’gailabia wall* and hand pumps require developed industries
(such as fonndrias), parts marMnad to close tolerances, and skilled maintenance.
t
frtntilabia hand pumps were designed for particular condi••
for temperate climates, light use, and manufacture by developed industries.
Whan these imported hand pumps are installed in rural areas of developing
countries, they soon break down and cannot be repaired by villagers.
UNICEF indicated to a World Bank mission in 1975 that in India 70-60
percent of the hand pumps are out of order at any given time.
pand pumps most be redwei-gnad for the conditions that actually
obtain in rural areas. Bae purpose of this paper is to set out these ccaditions and to describe a design that suits them.
Conditions in Rural Water Systems
5.
nandpmpid wells for rural areas should yield as much safe drink
ing water as a person is willing and able to carry away (seldom more than
20 liters at a time), for reasonable expenditure of energy (the less the
better), in less than two or three odnntes.
Th* pump must perform reliably under almost continuous use, and
endure. Experience suggests that rural residents must maintain their water
supply themselves: support from outside agencies will probably be inade
quate.
quata« To meet these conditions of endurance and reliability under heavy
xise, the design for hand pump and well must:
— Employ local materials as much as possible
— Be mechanically very simple, and
— lend itself to local, untrained maintenance.
V World Bank, ’HTillage Water Supply, " March 1976.
- 2 Ths pTtrocsed Solution
This paper proposes a design wnich meets these conditions. It
7.
simplifies band pumps mechanicaliy, and substitutes plastic pipe for the
tradd rd rmai steel and cast iron. This simplification and substitution
significantly reduces costs, as indicated in Table 1. AH parts can be
made in deve^^ping countries, and replacement parts can be improvised
from local materials.
puorca designed on this principl
8.
water and irrigation.
■
can be used both for drinking
Princinal Features of the Design
9.
The general design proposed (-Hluatratad in Figui’e 1) consists
of a plastic upper well casing 3 Inches in diameter that extends at least
12 feet below the minimum static water level. A reducer connects the upper
well casing to a plastic lower well casing.VThe lower well casing termi
nates in a slotted plastic well screen sat in the aquifer. The principal
features of this design are briefly summarized below.
(a)
Plastic pine semes as the well casing and nunn cylinder.
In conventional designs, a aetal pump is lowered into a steel
Thia design eliminates the need for a complicated,
well
expensive metal pump and riser pipe. The well casing itself
becomes the pump cylinder, as i. 11 ustrated in Figure 1.
/
The casing is plastic, rather than steel. The walls are ex
ceptionally smooth,2/ and this reduces the coefficient of
friction between the pipe and parts that contact it, thus
saving wear on the piston cup seals.1/
Plastic pipe costs about one-fifth the price of metal pipe.
Polyvinyl chloride (P7C),-i/ the plastic specified in this
design, is extruded in many developing countries. It is
lightweight and can easily be transported and install led.
Installed, plastic pipe is inert and is not affected by
aggressive ground or water conditions.
1/ A prototype low-cost well screen, made from PVC pipe of a special section and
suitable for slotting locally, is described in -Daner RES It in this series.
2/ An off-the-shelf polyvinyl chloride pipe selected at random from the
stock of Preus sag, A.G. and tested at the Technische Eochschnle, Hannover,
Germany, had a micro-finish of 2 microns. This is comparable to the finish
of an extruded brass cylinder.
3/ Battali* Memorial Institute established conclusively in 1967 that wear
on the piston cup seals resulted from roughness of cylinder walls. (Fannon
(“
and Frink).
V Although other plastics, for example ABS or polyethylene, could also be
cansidei*ed and should be evaluated in field trials (see also Annex U).
j*,.'
- 3 The** characteristics support the substitution of P7C for metal
pipe as well casing. Since the PVC pipe also acts as the pump
cylinder, however, it is essential to establish the rate of wear
of PVC as a function of the number of strokes, pressure head,
and water quality. Amay $ summarizes a controlled laboratory
rate-of-wear experiment in progress: in addition, PVC pipe should
be field-tested under conditions of actual use.
(b)
Submerged, interchangeable piston and check valve increase
efficiency and reduce canplexity. In this design, piston and
check valve remain below the surface of water in the well.
Water is forced ahead of the piston, avoiding suction losses*
gubmar^ng th* piston «nd check valve also keeps piston seals
wet, mini Tai ring wear and cracks > This arrangement is therefore
more efficient hyrimnli rally than surface-mounted piston pumps.
Th* well is always ready for use, and need never be primed. The
piston and check valve can be hrought up for inspection and re
pair by pull ing up the pump rod, which, can be done by one person.
In contrast, inspection and repair of available deep well hand
pumps is a .three-person job because of the weight of the (often
full) riser pipe and cylinder.
Both piston and check valve are made of the same interchangeable
cmrocnentss perforated pl**tic discs with flapper valves cover
ing the holes. These are illustrated in Figure 2. Jfylonreinforced neoprene is proposed for the flapper valves: Battalia
Memorial Institute concluded from laboratory tests that flapper
valves made of this material wear indefinitely.^/ If the valves
ghcmld ever need to be replaced, substitutes can easily be cut
out of leather, rubber, or canvas.
The** valves should last longer than conventional types: in
th* conventional design, cast-iron poppet valves or ball valves
pound again*t the valve seat, and become distorted with heavy
use.
(c)
Pump rod employs local materials. A pump rod connects the
Irvwt - (handie) epd p^-Tton. Th* pcmp rod should add no weight
that, would require additional energy to lift. This ideal weight
lessness can be acccmpldshed by neutralising the pump—rod's
wl gh-t in water, by making the rod either of buoyant material,
such as locally av *H 1 ahi * wood, or galvanised steel tubing with
r
Th* wooden pump rod should be completely
?eal ed
Mubnerged to prevent rotting by aerobic bacteria. Bamboo might
be used where plentjfitly if adequate joints and couplings could
be devised.
1/ Battalia Memorial Institute, Fannon and Frink, 1967.
-U(d)
Pum'D-rod guides may not be necessary. The Bautella Memorial
Institute reports that Tumps are made the world over with oscil
lating unguided pump rods and with guided pump rods. Generally
.qpftalri ngj guided pump rods are used on the deeper wells. However,
there is no data for the effectiveness of the guided pump rod in
providing longer life for the cups. Apparently, the main reason
for using guided pump rods is to provide a more stable pump rod
for use with wind mills? pump jacks, force pumps, or heavy-duty
equipcieiit* ny The only two conditions that might indicate a need
for pump-rod guides in this design would be:
(i) If water is pumped to an overhead storage tank for
subsequent distribution, or
(ii) If the upper well casing is saall (1^5 inch diameter)
In the first case, the space around the pump rod above the outlet
would require sealing — probably with a packing gland (as indicated in Figure lx)2/. The guides serve to restrict movement of
the pump rod to the vertical axis of the well, so as to prevent
excessive wear on the packing gland.
In the second case, movement of the pump rod should be restricted
to avoid rubbing against the casing. However, these two cases
should only rarely occur in rural areas of developing countries:
overhead storage is seldom required, and using a pipe of suffi
cient diameter as both well casing and cylinder (as this design
specifies) should provide ample room for an oscillating pump rod.
Nevertheless, same workers report that, if guides are not used,
the flexing of the upper porticn. of the pump rod, may cause it to
uncouple. 1 heavy box and pin butt-joint pump-rod connector with
parallel threads to prevent uncoupling is therefore recommendeti
(typical examples are shown in Annex 2).
Should rod guides prove to be needed, the traditional arrangement
of a brass or bronze bushing, through which the top of the rod
reciprocates, should be replaced with plastic parts. The pump
rod could be centered by a polyethylene sacrificial disc held in
place between two joints. Polyethylene is slightly softer than
PVC, and can be expected to wear somewhat faster, but the inter
face of these two plastics, automatically lubricated by water,
would wear far better than the typical unlubricated steel/brass
rod guide. The sacrificial disc would be set one or two joints
from the top of the pump rod, and the inherent flexibility of
this upper porticn of the pump rod will allow oscillation as the
end of the pump handle swings through its arc during pumping.
V Ibid.
2/ An early Roman design, shown in Figure J. achieved overhead lift without
ghided pump rods. (Agricola, "De Re Metallica
j*'
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- 6 -
piston cup seals have been used since early Roman times,J/ as
illustrated in Figure 3.
Cup seals of good quality leather have lasted up to a year in a
PVC-lined well in Bangladesh.^/ Rubber cups, available in Thailand
and Korea, may also prove acceptable.
UNICEF determined in 1975 that P7C cups wear PVC cylinders.3/
Oversized leather cups also abrade plastic from cylinder walls
by overstressing the surface. A loose fit of the assembled dry
piston (up to 2 mm clearance) in the cylinder appears sufficient
to minimize wear from leather cups.
Laboratory tests (described in Annex 5) indicate that in a properly
developed well, wear between the piston cup seals and the cylinder
should be tasted in the field. Should
is negligible. This
wear occur faster than our evidence indicates, the pump rod can
easily be shortened so that the cup seals bear on an unworn section
of ths P7C cylinder/casing.
Wr H Deve loment
10.
Many wells fail because fine sand is drawn in through the well
screen and rapidly fills up the screen. To avoid this, the well must be
properly “developed” before it is brought into service.
By forcing water out through the screen and back in again at high
11.
velocity, and bailing out the screen, fine sand can be removed. Coarser
particles remain in the area around the screen, acting as a filter against
fine sand and increasing permeability. Once complete, this “development*
stabilizes the aquifer permanently.
A development tool (surge plunger) can be improvised for this
12.
process using the pump rod and piston, with the flapper valve on the latter
sandwiched between the discs rather than resting on top of them, and with
the leather cup removed to avoid damaging the walls of the well casing.
f '
V In the Honan design, a conical leather pouch hangs point-downward. When
the piston is pulled up, the large end presses against cylinder walls, making
a water-tight seal. The pouch folds up on the downstroke, allowing water to
pass.
2/ A PVC-lined Battalia pump was installed in an urban slum in Dacca, Bangla*
desh. in June 1973 • One year later the cup was worn to a nub, but still made
a hydraulic seal. The cylinder wear was negligible.
3/ PVC cups, however, work well in cast-iron cylinders in Bangladesh: plastic
hones the cast-iron cylinder walls smooth. PVC cups would not wear or crack
from cyclical wetting and drying in a suction pump with a leaky check valve.
).
- 7 Adaptation for Irrigation
Tiro change* in the design described above should enable rural
U.
resident.? to pump the greater volumes required for irrigation in dry sea
sons:
(•)
TTnlarging the diameter of the upper well-casing to
increase output per stroke, and
(b)
Incorporating a penduluni in the lever system to allow
the pump to be operated for several hours at a time
without excessive effort.
The** change^ are Hlxutrated on page 3 of Annex 1*
The pendulum-lever system hangs in wooden bearings from an iron
frame that also holds the four legs that support it. These legs nay be
wood or bamboo, and the counterweight sandbags or any other convenient
material. To suit local preferences, the natural frequency of the lever
may be adjusted by altering the position of the counterweight on the long
lever arm. Annex 1 gives more information on this modification, and appro-,
priate applications.
Differences between Prcncaed Design and Other Systama Using Plastic Pipe
15.
Annex 7 describes three pumps and wells that also substitute plas
tic for metal pipe. Three important differences distinguish this proposed
design frcm others employing PVC pipe:
(»)
Piston and check valve are always subaarged below the
static water level of the well.
(b)
Only bell flare and nipple Joints are used in the 3 inch
diameter upper well casing. Furthermore, the bell flares
(female ends) are oriented downwards. Separata socket fittings
are not used. Thi* allows the check valve to be easily with
drawn. The reverse orientation (nipple-ends downward — the
usual case) prevents the check valve from being pulled up for
maintenance.
(=)
The last 15 cm of the bottaa pipe of the upper well casing
taper, reducing in diameter about 0.5 cm over this length,
or approxlnately 1°. Compression of the leather cup in the
taper bn Id.? the check valve in place; building up several
layers of solvent cement on the inside of the pipe end has
the same effect.
Limits of the Materials
16. (a)
Transport. PVC pipe nay be handled successfully with minimum
precautions. For example, it should not be stacked under heavy
objects, and the ends of the pipe should be protected from
- 8 mechanical abuse. Whenever possible, smaller pipe can be tele
scoped inside larger pipe.
(’□)
Storage. PTC plastic is composed of long chains of polymers
that alter chemi,cally if exposed to direct sunlight for long
periods. Exposure to sunlight causes the material to become
brittle, interfering with solvent-cement welding.
PTC is rigid at ambient temperatures, but will gradually deform
under moderate pressure5 for example, from its cwn weight or that
of a point load. It should always be stacked on a level, solid
surface. The height of the stack should not exceed two meters,
and the pipe should never be stacked on end for long periods of
time.
(c)
Jointing. Only two methods of jointing PTC pipe are suitable
for this application:
(i) Solvent cementing., which fuses one pipe to the other, and
(ii) Threaded ends, alternatal7 nipples and bell flares.
Problems nay attend either method under field conditions, but
each offers corresponding advantages:
(i) Solvent cement has a limited shelf-life. The ends of the
pipe must be clean and dry and reasonably round. But un
threaded pipe is usually cheaper, and any damage it may
suffer easier to correct. Cnee the joint is made it is
permanent and must be destroyed to separate the pipe.
(ii) Threaded joints may be unmade and remade as necessary
without comproaising the joint. PTC pipe threads, espe
cially those on the nipple ends, should be protected with a
PTC slip-on cap, but if damaged may be re threaded with a
standard pipe die if a dowel is driven into the pipe before
threading is begun. Oval deformation of either male or
female ends makes starting the threaded joint di
cnl t,
and if the threaded hell flare is broken, reflaring the
pipe and cutting female threads under field conditions is
difficult. Usually, solvent cement is used as a stand-by
to join pipe when re threading is too troublesome.
(d)
Limits of Plastic Casing. Small-diameter (l^g inch diameter) rigid
PTC pipe has been used successfully in wells up to 200 maters
deep in Germany and Japan. Tension breaks are not likely to occur
when lowering PTC pipe into a borehole, e.specially one full of
water, since the specific gravity of PTC (1.38) makes the weight
of the pipe negligible when submerged.
)
- 9 -
Plastic pipe c-armo-t be driven. An open borehole must be maintained into which the plastic pipe is lowered. The borehole must
stand open naturally or must be induced to do so by hydrostatic
pressure, drilling mud or steel-pipe casing.
is a general rula, casing can be avoided when drilling in allu
vium with one of the various hydraulic techniques such as jetting,
hydraulic rotary, or the "hollow rod" method.i/ Where a borehole
will not remain open during dri lid ng (for example, in alternating
consolidated and unconsolidated strata using the cable tool method),
steel casing must be driven and PTC pipe lowered inside it. After
installation of the PVC well, the steel pipe is pulled and recovered
(if possible). This is, however, time-consuming and expensive.
Rejuvenating Old Wells
17•
Many developing countries have large numbers of tubewells which
are not in service. In most cases the pump is at fault; in others the
screen is stopped up with gradual ly accumulated sand. To put the wells
back into service the following procedure is recommended:
(a)
Remove the cast iron pump, steel riser pipe and brass cylinder.
(b)
If necessary alternately bail out the screen and surge the well
until it is clean and the aquifer has been stabilised*
(c)
Install 3"^ or
(d)
Install check valve and piston of the recommended pattern (Figure 2),
reusing the old pump rod.
(e)
Make upper structure from masonry or reinforced concrete; handle
and bearings fycm wood, pivots from old riser pipe*
(f)
Recover *11 brass, cast iron, fasteners and usable steel pipe
for sale to finance the rejuvenation of the well.
PTC riser pipe inside the steel upper casing.
V Known in Bangladesh as the "sludger" method.
Annex 1
Page 1
)'
PE2IDULUM PUMP
What is it?
A ama Uy operated pump
- incorporating a new principle (the pendulum) to conserve energy,
and a new
*1 (PVC) to minimize friction, corrosion and de
terioration.
Why do we need it?
As a minimum cost, minimum maintenance, solution to the problem
of lifting irrigation water from wells, and to avoid the social/
organisational problems associated with shared irrigation supplies.
Where will it work best?
Where high papul_aticn densities and high water tables coincide,
i.e., Northeastern
and Bangladesh, possibly the Nila Delta,
and some places in Indonesia.
Who will it work for?
The ynal 1 est farmers, who with even the United cash and energy
resources available to them, can use it to produce enough to feed
themselves and their families#
What will it cost?
Less than $100 (installed), with much of this being in labor and
local materials contributed by the farmer, the rest locally
manufactured.
How hard is it to work?
One man with this pump can lift 18 gpm, more or less steadily,
from a depth of 12 feet. (Visualize carrying a gal Inn jug in each
hand up a flight of stairs every 7 seconds I) • There is no way to
make this easy, regardless of the ingenuity of the machine employed,
but if the alternative is going without food, that is not exactly
easy either. In the course of a 120-day season, be may work, on
the average, 5 hours per day, for a total of 600 hours.
What will he get for this effort?
From a half-acre of land he should get about 1200 lbs of idee,
ioe«, for each hour of work he gets about 2 lbs, or two days’
food for a member of his family.
)
• Annex 1
Page 2
Tha Need for Lrorovad Technology1 in Manual
of Irrigation Water
by S. V* AllisonV
Background and Statement of Problem
1.
Over an area exceeding HO million ha in monsoon Asia, intensive
crop production is possible only with irrigation. Soils are good and
temperatures are sufficient for year round cultivation. Because of high
anzxual rain fall, water resources are generally adequate. The principal
problem is the difficulty of getting the water from wherever it is (under
ground, or in streams and ponds) onto the land, where it is needed to
support cropping activities.
2.
This situation,of course, provided the justification for in
numerable irrigation works which have been built over the centuries. A
wide variety of constraints are now operating however to prevent the rata
of construction of new facilities fraa equalling the rate of increase of
demand for food. Additional solutions are thus required.
3.
Manual pimping shews promise for this purpose because:
a)
these are typically labor surplus regions;
b)
the costs of other energy sources continue to rise sharply and
there is a continuing shortage of fuel;
c)
the capital costs of individually operated manual pumping units
are sufficiently low to pexmit their purchase by even the
smallest fiimers;
d)
the energy requirements for pumping can be provided from within
the small est farm family;
e)
the water output of manual pumping units can meet the entire
irrigation needs of the small blocks of land typically owned; and
f)
because of the happy match between resources and requirements,
these units can be installed and operated without the need for
cooperation between farmers, which has proved to be a major
block for most other types of irrigation facility*
Manual li ^ting of irrigation water has, of course, been practised
lu
in Asia for centuries. Bzcept where lifts were very low (less than 1 m) it
has however been found too costly in countries which had the possibility
V October 1975 (Internal World Bank memorandum)<
Annex 1
Page 3
of one major rainfad crop per year; the eccnomics of rainfed cropping
kept food prices below the opportunity cost of the labor needed to produce
more food by manual pumping. In more arid areas, where all cropping depended
on irrigation, man/land ratios were lower and much irrigation was done by
animal powered pumps. Where semi-arid conditions and high population
densities coincide, as in China, manual pumping became and still is cannon.
The principal factor which has created the current need for manual
5.
pumping in South Asia in the course of the last few years is thus the
population increase, which has:
a)
pushed the demand for food up faster than the supply, with the
expected effect on food prices, and
b)
made more human labor available at coats which are lower relative
to the cost of food.
6.
One of the most important limitations of the manual pumping approach
is the balance between the amount of energy available in a (not very well
nourished) human body, and the large quantities of water required in the
irrigation of any crop, particularly rice. The critical nature of this
balance means that, for manual pumping to pay, absolutely minimal, quantities
of energy must be wasted overoauing friction or lifting water which is then
permitted to slip back down the well. It is in thia respect that most cur
rently available handpumps are unsatisfactory. They were designed primarily
for drinking water purposes and conservation of the human energy input was
never an important consideratinn.
Description of Improved Technology
Under the pressure of rising food costs and severe unemployment
7«
attention is again being focussed on this problem. There is now reason
to believe that ingenious mechanical design, coupled with the use of new
materials, can minimiza energy losses to make manual pumping for irrigation
purposes a feasible and attractive proposition.
8.
One such desi^x is illustrated in Fig. 1.
here are:
The distinctive features
a)
elimination of the standard cast iron pump body, by expanding the
upper 6 n of well casing to become the pump cylinder;
b)
setting of a simple piston below the water table in such a
position that water will be lifted directly rather than by suction,
and the piston gasket (pump leather) will
moist at all
instead of passing through the wetting and drying cycles which
cause deterioration of gaskets in surface mounted pumps which have
their pistons above the water table;
c)
use of low cost F7C pipe with very smcoth interior surfaces for
-tty of corrosion
all dcwnwell components, eliminating the
and minimizing energy losses due to friction. TM-q pipe is easy
Annex 1
Page U
to transport and may be installed without difficulty by local
ajrtisans;
d)
use of a ribbed and fine slotted PVC well screen, in which the
ribs act to facilitate the development of a natural granular
filter around the screen, and the slots are sized to pass the
required fraction of fines — and not more — of the material
from the surrounding aquifer;
«)
use of a simply supported pendulum above the well, to maximize
Tier hen i
advantage and conservation of the energy expended in
pumping.
The pump has been designed to use energy at a rata which can be
sustained up to 5 hours a day, by a .small man working under tropical
conditions (i.e. about 0.067 HP). The actual horizontal force which has
to be applied to the push handle is between 7 and 10 kg, for lifts of
3 and 5 n respectively.
9.
With this energy input, the pump will perform as summarized on
10.
performance has been tested successfully under
Hydraulic
Fig. 1.
laboratory conditions but not, to date, in the field.
U4
A poop of this design will cost about $100 installpd, as detailed
in Annex 1«
Cost/Bene-flt AnalTsia
12.
To Hbta'S-n perspective on the economic merits of this design
it may be compared with two principal alternatives: power-pumped shallow
tubewells, and iotik U/ operated units using pump of designs currently
in use. As all alternatives show economic returns well in excess of
the opportunity cost of capital and range upwards, depending on the
assumptions used, to well over 100%, a more relevant criterion for com
parative purposes is the contribution of irrigation to the cost of the
rice produced. The important variables and assumptions in this analysis
are presented in Annex 1, and the results are summarized in Fig. 2.
13.
Several conclusions can be drawn from Fig. 2. It appears that,
except at very near zero wage rates, power pumping is substantially more
attractive than manual pimping. Thi* is certainly tna frem the engineering
and economic viewpoints, but it is valid only within bounds defined by
social and oi*ganizatioxxal nonstreints too complex to be neatly quantified.
For a start the process of comparison implies that we have a choice, or
must choose, between these technologies. Bie fact is that the power pumped
walla are bring inntall ad throughout the region at a high rata and in fact
about as fast as financial and organizational constraints peimit. Under
these circumstances what we would recccmend is not that manual pumping
1nstai 1 afjnns should be supported instead of power pumps, but in addition
to them.
Annex 1
Page 5
Hi.
Secondly, electricity is simply not available in some areas, so
power pumping implies the use of an internal combustion engine, For the
necessary degree of •^liability this means diesel engines and these are
not made
than about Lt.5
h.5 HPHP. If one is used it means either:
a)
producing enough water for 5 to 15 farmers, with associated
requirements for organization or cooperation, or
b)
leaving a costly piece of equipment unused for between 50 and
90% of the time it could be working.
Wnally, it has to be emphasized that, with the minimum cost of
15.
a power pump installation being about $1,300, only the larger farmers have
the cash, or the influence necessary to get credit instead of cash. The
manual pumping alternative, by contrast, is biased toward the smaller farmer
because, fran the farmers' perspective, this approach is considerably more
attractive financially when labor internal to the farm family is used for
pumping. A farmer with more than 3 ha of land would be incapable of having
a family large enougi to irrigate it all by manual pumping.
Potential for Develoment
16.
It is clear that manual pumping, by any means, is a practical
proposition for irrigation only when the static lift is less than 5 m.
There are substantial areas (probably U -co 5 million gross ha) in the most
densely populated parts of the Indo-Cange tic plain, where the water table
rises to near or above the surface during the rainy season and then falls
to U. m or less before the onset of the next monsoon. This condition is
typically reached only in April or May, while the winter rice crop matures
in March and may even benefit from drying out in April. During the important
irrigation months, December to February, the average lift will thus be less
than 3 m.
17.
Irrigation from wells of any type will hasten the depletion of
the water table as shown in the following table:
Fraction of Area Irrigated (^)
10
25
50
Additional Depth of Water Table (m)
2nd December
2nd March
0.26
0.66
1.32
0.85
2.12
h.21i
18.
This suggests that, in h, million ha, manual wells should not be
installed to serve more than about a million ha. This would still require
3 million wells — scope enough for a major investment program.
Azmex 1
Page 6
Next Steps
19.
What is needed next is a series of tests, to ensure that the new
pump functions as well in the field as it does in the workshop. Performance
in terms of areas irrigated under different conditions, and the reactions of
the farmers to the pendulum nperating principle, need to be closely monitored
through an entire irrigation season.
20.
Only when this phase, which shoxild, ideally. Include 30 to 50
installations in differing areas, is canpleta will the concept be suf
ficiently proven to include in large quantities and xajor projects. At the
present time we have several projects in the pipeline which nay include
aanual pumping. Unless the penduluax principle is proven first, however,
pumps of tT*d1 ti oral design will be used, and project benefits will be
significantly lower than if the human a-nergy input was expended more ef
ficiently.
A2JNEX 1
Page 7
Detailed Cost Estjjiate
A.
Local
Quantity
Iten
mm dia.)
Upper well casing (120)
Lower well casing ( 37.5 nnn dia.)
( 37.5 nna ldia.)
_
Well screen
Pump
Installation
6 m
11 n
5.5 Hl
Contingencies
B.
12.00
15.00
27.00
3.00
30.00
Cost ($)
Foreign
y
Total
18.00
22.00
18.00
22.00
11.00
12.00
n.co
211.00
15.00
90.00
10.00
100.00
63.00
7.00
70.00
and As -Silnrritions in Cost/Bene.fit Analysis
Variables
Power Puinped
Shal low Well
Manually Pumped
New Design
Pre sen's Design
1,300
70.00
100.00
Area Irrigated (ha)
6
0.13
0.25
Incremental Rice Production
(to ns/crop)
15
0.h5
0.825
90.00
165.00
1.28
1.65
Capital Cost ($)
07? at 5200/ton
3,000
G7?/Capital Investment
2.3
Puiroing Energy Use
Power (gals diesel)
Manual (kg rice)
13U
Value of Energy Consumed
Diesel orice range
(0.110 - 1.00/gal)
53.60 to
13U.0O
Bice price ( .20 cts./kg.)
Operating Labor Bequirements
(man/day/crop)
12
Labor Costs ($/crcp)
1.20 to
12.00
(Range $0.10-1.00/day)
9 •
30.00
6.00
120
12.00 to
120.00
I
lenex 1
?*«• 3 ’
I
r
r>-
r'
3
^i.h
ii
so
l‘
I
I
1
gw^
WlKlp
ssass^pfeaSss1
I
SH gsMass
I
I
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i- '. -
■=3« T’-'*-’
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' 5"®5|K
wsT*'
—
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> •- ■■'•'• t.
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7
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p
b- •
.
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h\'" ^JA-;--'' vs ? c : k7'-*
O
^6
3i
Si
/p
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8?
ft*.
/«
Si
#»
2
k.
nnsw
.?3
?--3
j- £ S
&
t
t
t
E
'S -*
*0
© *
- i>
o
Cujt tUM»;>arl *011 Utycun IUi.JtMi»p Tiibuvclli Uf Tiu.lltlunal Iteulen «nJ Tl...be
..........................TVs I UK L L A
Steel pipe, uoli caalu^and acroon, caal iruu
|»iap aland, bika< cylludar
Ileali.Tt Xjio"’ &>• t/Ud f
*■“ t
0.1. pipa
15
1
io
3
h" a ij" 0.1. rcducar
1|M it 0.1. pipe
1' if Siali.lauu Clad wall acraan
6>o
2.25
h9.29
Bub-Tutai j
Coat Iron p<ia>p aland
J"
tiaaa cylinder and valvaa
"Alrtlta" alaal poop roda
. <i/a“ *0
l.l- ll 0.1 . pipa
90.uV
I
1
116.10
>5
15
5.6o
2.25
--------------------------T u p E W E L L
0----------------------------------------IVC pipe, well caei.-ig and acreou, caal Iron
-- -----------------L»-!B gl^ajMdba.cylinder
H«*»
1J2
6
.60
Pis
IT
llnlt
rye pip«
M 1J* FVC reducer
l|“ / rvc pipa
1|M 0 rvc wall acrecn
CoTr/Unlt
15
1
10
4:8'
Ji1*
90
116
lib
3<.-
Caul lron.|auap aland
3“ ji braaa ppllnder and kalvaa
“AlrtJLaJ>'atacl'p((a.p roda
u-(ya- fi)
’ (I 0.1. pl|a>
15
15
X,
cu. C><
10OJ< aack
x****-<lay
9
2
2
0.50
2.00
5.00
5
10
cu. fl.
loo lb. aack
nan-day
? ■
2
Sub-Totali
Total»
£/
UHlCtl awaraga purdtaaa |>r|ca Tor a
I
tn.
IXiajialar daap well pu<ap aland) utlxr pua<p MMaponanla priced Troa “Clayton Hark"
Bum
2.9*1
13 hi
Sub-Totalt
nu
1/
90.0.,-'
116.10
90
116
5.6o
2.25
0.50
2.00
CM
3"
l.
26
ho
Sub-Total»
A^grcgala
Caaaiil
lot bar
(VC pl|ia
_____ ______________
Ho.
JiA
Aurcgata
L'cau.-|>t
Labor
llalua rvc k.lenal vely
i'VC pl|M>
3“ x lj“ I’VC todiicor
li" / PVC pipe
1]** (I l-vc bell acree
1'1 aluii/cliock
Uoudai. hand Io
Uoudcu boar Inga
lj* |l 41.J. pipe ahu
Hi Iuka
Coiaoiil
labor
"Alrtlta" j/b“
3?«.
i
5.oo
10
S.ib-T..lul;
19
Aararcaeta
Ceauiit
Labor
Total;
cutaloniic. April
1976.
(i.l
A—2
EVANSTON, IXL. U.S.A.
.Ln' i ''.
ai 'i 'ii mj .
Octagon Ash Wood Pump Rods
For All-Depth Wells
Number 927 Type
Made a: drat auaiity ash wood with square ends and furnished tn random lengths 12 feet to 22 feet; exact lengths made
to order a: special prices. Couplings (No. =03 pattern) are steel painted black, ar galvanized, oxter tabr.cauon; box ana pin
parts are at solid hexagon steel with wrench-grip secdon; box is recessed to permit butt ;cinf threads cut sharp and true era
same size as. and interchangeable with, oil well couplings.
Order by Trade Number. Slating Size. Whether Blank, -with Slack Cauolings. or -vith Galvanized Couplings.
i
3o« «ad ?!a
I
I
Sixa
lachaa
Siu
lausM
!
1
IH
1H
1^
Tixaada
Par laca
12
10
10
Huabat
aiTat
Hoia«
?«r Siad*
U«ad is
?ipa
Six*
!acsw
4
5
2
Approuaata Watqat
Par LOO ~aat. Potiada
i'2
314 u
With
Cjapuaqr
35
45
70
45
75
ICO
Airtite Steel Pump Rod
Galvanized
Suitable far Single and double Acting Cylinder Service in AU-Oecth ’■Veils.
Much stranger ana aiare durable in any service than carrespcnding sice -vcod sucker rad; can be installed with tccis
same as used with wood sucker rad.
Made ct standard steel pine with couplings welded to pipe, tucking each secnon a sealed air chamber.
Couplings are solid steel with square shoulders; box is recessed to permit butt joints; threads cut snarp. true, and treated
to prevent corrasion, are same size as. and serf be usea with, wood sucker rad cr oil well couplings.
Airtite steel pump rad in ten !eet lengths wtuh No. 560 guide couplings (see page 53) will not swerve ar whip an downstrake and is the best tor aouble acting evtinder aperation.
Order by Trade Number. Slating Length.
Trad*
Mttsxbx
*
f
!
1
2H
2
3
4
5
?!pe
!
Sica
tacaaa
h
1
IPX
2
J
CorraaoaodinQ
Wood Bod SUaa
tacaaa
3aa <m ?ta
Sira
lacaaa
Tiraada
?«r Laca
IK
IK
12
12
10
10
8
8
1*
LH
Ihor 1H
2^
3 or 3*
j
Appteaxmata Waiqhi
Haaaoa par ICO faa*
.’suada
II
50
122
122
180
250
420
;
J__________
f
I-
I
I
’
EVG-SPEEL COSTS
$/meter
COST COMPARISON OF 2" DIAMETER STEEL V8t
3.50
DIAMETER PVC PIPE
I
I
!
3.00
1
I
i
I
: I
i
i
I
i
i !(
i
I
i
I
i
2.50
i
i
i
I
I
!
i
i
i
2.00
I
i
t
I
1
I
i
.•
i
I
i
i
I
I
I
I
I
i
I
i
i
1
i
t
I
I
i
I
i
!
I
II
1.50
■
!
i
i
i
I
I
i
I
i
1.00
!
0.50
73
7L1
Source: U
I /
Bureau of Labor Statistics.
7h
75
AHHEX 3
Page 2
QUANTITY OF PIPS 03TAI5A3LE FROM 7ABICUS 24ATERZALS
Length of Pipe (meters)
3" din.
2" dia.
I'1 dia.
Unit
(Mtons)
1 1/211 dia.
Steel
1
2U6
183
88
62
35
PVC
1
2,66?
1,869
1,111
78U
k21
3,1x18
2,U39
1A39
1,020
5^6
Material
A3S
o'? dia.
Anril 1976 pipe prices: Steel ^5^5/ton; PVC $957/tcn, ASS $1,114.1/ton
Co st/net er
Nominal Dianie~cer
*
(in)
(be )
*PVC
*A3S
**Steel
1 1/U
35
0.72
0.6?
1.90
1 1/2
10
0.86
0.72
2.25
2
50
1.21i
1 .12
3.01
3
80
2.08
1.90
5-98
1
100
2.9U
2.68
8.83
a
150
5.1x7
5.00
15.57
Based on April 1976 production and raw material costs plus a profit margin of
20% to approximate an F.O.B. price.
** Quote from Bethlehem Steel Corporation, F.O.B., Baltimore, April 1976.
■Annex k
Relative Merits of Acrylonitrita Butadiene Styrene (IBS) vs. Polyvinyl
Chloride (PVC) in Tubewell Construction
Discussions with Borg-Warner, a manufacturer of ABS indicate that
the two thermoplastics are very similar in physical properties and equally
chemi cally inert in the ground. ABS has been used for years as drain pipe.
Specifications for ABS well casing are now being prepared for approval by
ASTM. The manufacturer expects that ABS will compete successfully with
PVC in groundwater applications because of its slight advantages:
- -relumetrinally less expensive;
- extrusion is somewhat simpler; less build-up on dies;
- higher distortion temperature (180° ? vs, 170° y);
- resists abrasion at least as well as PVC.
The most prominent difference between APS and PVC is that ABS has
only half the internal pressure rating of PVC.
■
A
Annex 5
Page 1
HATE OF WEAR OF PVC PUMP CTLINEEHS
(Conducted by-Preussag, Kunstatoffe u. Araaturen, Hannover, Gezaany)
Lengths of 3-inch dj ante ten PVC pipe are being tested for applicaticn as the working barrel of piston pump. The object of the test is to
measure ths wear (loss of material from the walls) of the pipe* Two test
benches were built each with sixteen cylinders mounted as individual units with a gate valve and a manometer*
The system is driven at 30 cycles/minuta through a transmissicu
which alternatively lifts and depresses two transverse bars to which the
piston push rods are connected*
Each piston consists of four PVC plastic discs with four 16 mm
di Arneter holes at 90° around a center hole (occupied by the 1x0 cm long push
rod); the holes are covered by a 2, mm thick flapper of nylon reinforced
neoprene* Two leather cups make a seal against the cylinder walls*
The 30 cm long PVC cylinders were cut from randomly selected
production pipe* The wall thickness was measured at selected points in
the middle of the cylinders and each point was marked. The cylinders were
installed in the test benches, the water tanks were placed under them and
filled with water.
When the piston ascends water is lifted frcm the tank and pushed
through the discharge pipe in which the gate valve is located* The gate
valve is throttled, creating a pressure which is measured by the manometer*
The water is then recirculated in the tank*
The water tank.? are open, allowing ateospheric dust and foreign
matter to enter the water. Periodically water is added to the tanks to
compensate for evaporation*
«
*
The test benches simulate pressure heads ranging from 0*5 to
3*0 atmospheres (pumping depths of 15 to 100 feet)*
The PVC cylinder* were removed after 31x0,000 cycles and measured
for wear at the marked positions* A maximum decrease in wall thickness
of 0*10 mm was recorded* pumping pressure was observed to remain constant*
AjTter ^00,000 cycles the cylinders were again measured for wear*
A maziaiuBi decrease in wall thickness of 0*15 mm was observed, also with an
unchanged pressure reading*
After 1,500,000 cycles the maTimum measured decrease was 0.1x0 mm
atill with unchanged pressure readings. The experiment continues as of
August 1976*
Page 2
jU
I HI
1
Manometer
Pushrod
Kcibenstange
Stuf.fiag box
Stop/duchse
AI
__ F
I
I
I
I
a
I
)• I
\1
I
fl \i/
-
I
I
?VC pipe
P'/C-Rohr
—
i
I
I
I
i
I
!
I
I
✓I
Cup Seals
I
Topfmcnscr ette
I
i
I
■
I
I
A
■/?
Test Stand for Rata-cf-Wear Experiment
Prufstand fur V^rschleinprufunq
PREUSSAG AG
g?z.: 10. 2.76 'A'/Oss
Kunststaffe <j.A.Tnctureri
Week Sr&lertcrf
) ?
Page 1
Oil Soaked Bearings: Howto Make Them
Compiled by John Collett, ITDG Project Officer, National College of Agricultural Engineering,
Silsoe, Beds, from designs by H. Pearson
(Calycophyllum
carididissimum)
(Phyllostylon brasihense)
Boxwood
(Pyrrus communis)
Pear
(Quercus robur)
Oak
Camphorwood (Dryobaianops aromatica)
De game
The purpose of this article is to provide some background
information for both constructors and designers who wish
to use wood bearings. The type of wood to use, its
treatment, lubrication and expected performance are
included.
Advantages
Some of the advantages of oil-soaked wood bearings are
obvious. They can be made from available materials by
local craftsmen with woodworking skills. They are easily
assembled, do not require lubrication or maintenance,
and operate under dirty conditions. They can be quickly
repaired or replaced and provide a temporary means of
repairing a more sophisticated production bearing. They
also require low tolerance on both the shafts and (he
housings.
One of the essential characteristics to look for in the
choice of wood is hardness. Because the harder the
bearing surface, the less the deformation and the smaller
the coefficient of friction and the lower the rate of
wear. It is also unlikely to break down prematurely,
singe or ultimately bum. It is also worth noting that,
generally, the harder the wood, the greater its weight
.and the mo* a difficult it is to work
The oiliness of the wood is a particularly important
consideration when the bearings are unlikely (or not
intended) to receive lubrication during their service.
Practical indicators chat assist the identification of timbers
which may have good self-lubricating properties are: they
are easily polished, do not react with acids, are difficult
to impregnate with preservatives and glue does not easily
stick to them.
Other considerations
High moisture content causes a reduction in hardness and
results in greater wear. For most applications low moisture
content is preferred and excess moisture must be removed
to prevent subsequent shrinkage, especially if the bearing
is to be used as a bush.
The hardest wood is to be found in the main trunk
just beiow the first branch.
If the timber is not of the self-lubricating variety (or of
doubtful sclf-lubncating characteristics) it can be soaked in
oil to minimize the need for subsequent lubrication. It is
important to have dry wood to assist maximum absorption
of oil.
Construction
The following notes relate to experience gained in the “field”
manufacture and testing of three types of wood bearing the bush bearing, the spiit-block bearing and the one-piece
block bearing. All are of the oil-soaked variety. H.S.
Pearson has suggested that as a general rule-of thumb
guide to the size of timber needed lor the bearing, the
axial length of the bearing should be at least twice die
shaft diameter. For example, for a 25mm diameter axle,
the bearing should be at least 50mm Iona.
In the case of the block bearings, the thickness of bearing
material at any point should not be less than the shaft
diameter.
The drilling of radial holes for lubrication purposes is
only recommended by Pearson for the bush type of bear
ing. He found that if lubricated holes were drilled in block
bearings not only were the bearings weakened but also the
holes acted as dirt traps.
Whenever possible the bearings should he located in a posi
tion where falling dii t will not directly enter the bearing.
For example, if the axle is carried in bearings mo mted
under the floor of a curt instead of a fixed axle with bear
ings at the hub of the wheel, then dirr falling from the rim
of the wheel will not fall directly onto the bearing.
If the bearing is expected to lake side-thrust, large llat
washers must be used, the one al the end of the bearing
being free to rotate on the shaft.
— suit !>alM
Grain direction should be considered, and if possible
advantage taken of the close grain to provide hardness
at the wearing surface.
The piece of timber selected for the bearing should be free
from cracks. Some suitable timbers are listed below:
“Greasy” woods Lignum vitae
Tallowood
Teak
Blackbutt
Poon
Other woods
Hornbeam
(Cuaiacum officinale)
(Eucaiiptus microcorys)
(Tectona grandis)
(Eucaliptus pilularis)
(Calophyiluni tomentosum)
(Carpinus botulus)
*xl« nal* -------
I
/ C-
3na-*lau alack *Mr1n<
AXZSCC 0
Page 2
The bearing surface of the shaft should be perfectly round
and smooth and polished in appearance.
How to make the bearings
Available umber often has rather doubtful self-lubricating
properties and high moisture content. In this instance, a
simple procedure for making an oil-soaked bush bearing
has been devised by the Industrial Development Centre,
Zana. Nigeria. Excess waler is removed and subsequent
shrinkage prevented.
First, reduce (he timber to a square cross section and bore
a hole through the centre (he same diameter as the journal
on which the bearing will be working.
Place (he blocks into a metal container of commercial
groundnut oil and keep (hem submerged by placing a brick
on top. Raise (he temperature of the oil until the water in
the wood is turned into steam - this will give the oil the
appearance of boiling vigorously. Main rain the temperature
until only single streams of small pin-size bubbles are rising
to the surface ot the oil. This may take anything from 30
minutes to 2 hours depending on the moisture content of
the wood.
Remove the heat source and leave the blocks in oil to cool
overnight if possible. Dunng this stage the wood will absorb
oil. Be very curejul if you need to handle rhe conrainer
whilst it is Jull of hot oiL If the temperature of the oil is
allowed to get too high after the bubbles have ceased to
appear, the wood wiil change to charcoal and the bearings
will be ruined. --------Rebore the centre hole to compensate for any shrinkage
that might have taken place.
Place on a mandrel or lathe and turn the outside diameter
to the required measurement that wiil give the bush a press
fit into the hub.
Bore four equally spaced holes through the wall of the bush
at its mid-point and fill with lubricant - in general terms,
the harder the lubricant the better, so animal fat, soap or
tallow are preferable although grease is an excellent alter
native. Finally press the bush into the hub.
The forty bush bearings made and tested at Zaria were
2’,i” long by 1.550” outside diameter with a 0.355” bore.
They were pressed into I'A” seamless black iron Class C
pipe, and turned on a !6” pipe journal. The wood used was
mahogany (being the most readily available) and rig tests
with a loading of 100 lbs and a speed of 100 - 200 rev/min
indicated sufficient lubrication. These test conditions were
chosen to simulate the working force on a 7” gauge wheel
of an ox-drawn plough. Tests performed on bush bearings
without (he four radial lubrication holes again indicated
sufficient lubrication.
On heavy equipment such as ox-carts or where it is not
possible to push the axle through a bush-bearing, the split
block bearing provides a more practical solution.
It is simple to fit and replace, and if wear takes place the
two halves cun be changed around. After further wear, the
life of the bearings cun be extended by removing a small
amount of material from the matching faces.
A simple procedure was devised by the CRZ/1TDG project^
at the .Magoyc Regional Research Station in Zambia fot^iS
(he production of such a bearing, again using an oil soaking
technique. The timber in (his case was teak, and used engine
oil provided a satisfactory alternative to groundnut oil.
Reduce the timber to a square cross-section and cut
lengthwise into (wo halves.
The two halves of (he bearing must be clamped firmly to
gether for the drilling operation. It is most important that
the hole for the axle is bored exactly square through the
blocks. For the best results an electric powered pillar-drill
should be used although a hand powered pillar-drill
would be quite satisfactory. If neither of these is available,
a jig would have to be made to keep the drill bit in line.
After drilling, the two halves should be tied together to
keep them in pairs.
For soaking in oil on old 20 litre (5 gal.) drum is needed.
Fill it three-quarters full with used engine-oil and bring to
the boil over an open fire. Great care is needed when
handling rhe dram of hot oil. Lift the drum off the fire
and carefully place the pairs of bearings into the hot oil.
Put a brick on top of the last pair to stop them floating,
and leave the drum and contents to cool slowly overnight.
The split-block bearings measured 150mm x 150mm x 75mm
with a 38mm diameter bore. They were field tested for
reliability by installing them on oxcarts fitted with iron or
■ pneumatic wheels and carrying loads of up to 2 tons.
A radial clearance on one of these assemblies of about
1mm was found to be essential. If carefully run in at low
speeds (ox draft) the clearance is increased to 1.5 - 2.0mm
and the bearing surface attained a higlily polished glass-like
appearance. Having reached this condition it was found
capable of withstanding journeys of a few kilometers at
higher speeds (Land Rover towing).
A soft pine-wood oil-soaked bearing was tested as an alter
native to the hardwood bearing, and this also gave satis
factory performance but might have a shorter life.
For lower load, lower speed applications such as the seed
drive mechanism on a small planter, a smaller one-piece
oil-soaked block bearing was used measuring 50mm x
50mm x 50mm with a 16m diameter bore, and this gave
satisfactory results although tests were not extensive.
4
The possibility of boring the axle hole using hot irons
was not investigated but there should be no serious
objection to this alternative.
Bibliography
The characteristics of bearings when employed in slow
running machinery. D.A. Atkinson. University of
Manchester Institute of Science (UMIST), 1972.
Cans Intermediate Technology Publications, 1975.
The wood bearing: how to make it Shambaugh, TJ.,
Pearson, H.S. &. Jibril, Center, Zaria, Nigeria, Dec. 1969.
).
Annex 6
Page 3
INITIAL PH£PAKATION.
Saw timber into shape of an oblong
block somewhat larger than the O.L
of the finished bearing to allow for
shrinkage and bore being off centre.
Bore hole through centre of block
the sire of the journal.
DmDHATION
Oil level
Soon after submersing the
bearing blocks in hot ground
nut oil, many surface bubbles
1" in diameter, cade from a
multitude of smaller bubbles,
will appear on the surface.
‘
*
As the moisture content of
blocks is reduced, the surface
bubbles will become smaller in
size.
*Zi*.
UUM
\ I H S0(
When the surface bubbles are
; • formed from single streams of
• *. pin-size bubbles, the dehydra
tion process has gone far enough.
Stop heating, and let blocks cool
in the oil overnight.
Heater
Mandrel
I
«
Shrunken block
•0
FINISHING
He-drill centre hole and place
shrunken oil-soaked bearing block
on mandrel and turn to the
desired size.
y////X \ /777/
o
'////A V//7/
Cross section of the finished oilsoaked wood bearing showing
grease reservoir holes.
• Oil snaked Wood llearincs: How to make them and how they
perform, available from IT l‘uh Hear ions price 25p net:£Q.J5 U.K.
postpaid; £0.50 airmail and £0.35 sort ace mail.
ANNEX 7
Page 1
SIMPLE
A)
EAffTPUMPS
TRIAL
Installations in Thailand
The following details were received from Mr. C.D. Spangler, who
has recently retired from the World Bank’s South Asia Water Supply Project
Division and was instrumental in introducing these tumns into Thailand.
’’Cast iron has become increasingly expensive, and in the deep -ell
pump the hea-'/y cylinder suspended on a galvanized iron discharge pipe with
the rod inside is difficult for the villager to remove and repair.
If a Governmental agency establishes mobile repair crews, as more
wells are installed with handpumps the maintenance cost increases rapidly.
For many years it wr 1
not be feasible or economic in most countries ^o pu>-
small piped systems in villages of less than 500 people.
There is a great
need for low-cost, dependable, easily-repaired handpump.
Such a pump is now
available using FfC pipe as the cylinder.
publication and two prototype
z
Th-i s pump was described m a ViTA
shallow well suction pumps have been fabricated
and tested by the Thail.and Department of Agriculture.
The test pump was shown
on the cover of their monthly Journal, with a report on its performance.
The cylinder was a section of 3" dia. PVC pipe above the platform
The pump rod was
with a 1 1/2” dia. suction pipe extending into the well.
both sides of the
3/8” <5t p.. steel with a small yoke at the top to fit on
wooden handle.
A stard-Q-rd piston with poppet valve was attached to the lower
end of the rod.
A foot valve was placed on the bottom of the 1 1/2” dia.
suction pipe.
The handle was supported by a 5'T x 5” wood peso set firmly
into the ground.
The Handl a T,aS of hard wood 2” x 1 1/2” x TO” long.
A
round, flat cover of wood with a small slot to permit free movement oi -he
)
Ainrax 7
?a~~ 2
dia.
pipe (see illustration).
The nunn had a ziazciniun Lift of 23 feet and the
ischarge was between 10 and
rod was used to close
,e top of the 3”
15 gallons a minute with an 3—10 inch stroke, depending upon tne suction li-u.
However, the F7C foot valve alone was US$5-'CO;
'The cost was about US$20.00.
using a sintier lower valve and making the pump in quantity, the cost could
be reduced to about US$15.00, compared to USS10C.Q0 - 150.00 - or a cast iron
pump.
The deep well version is based upon the use of ?VC pipe as the well
casing in small diameter driven, jetted or drilled wells.
.ne
?VC casing
becomes the cylinder and the casing is extended above the platform to act as
the channel for the water.
suction pump.
The
e arH support post is similar to the
If the casing is considered part of the cost of the well, the
pump cost only includes the handle, support post, pump rod, piston and lower
val\re.
The lower valve seat can be fixed in a length of PVC casing at the
shop.
PYC pipe should be supported from the bottom as it is lowered
into the well with a trip to release the support when the casing is in place..
The deep well pump has mt yet been field tested.
The suction pump has
been run 2C0-30C hours with only very slight wear on the leather '^bucket ”.
handle should be of such a length that
end of the handle attached to
the rod w^' 11, in sweeping a small arc, pass through the vertical position for
the rod.
This will
wear of the leather ’’bucket”.
A rubber bucket
is used in Korea and should give a superior performance when used in a PVC
pipe cylinder.
This dependable, low cost, easily repaired pump should z^ke wide
spread use of handpump wells feasible and economic.”
It will be seen that the
'’deep well
pump is essentially the same
as the one proposed in this report, whereas the ’’shallow weal' pump is a
suction pump.
It would be interesting to compare performances of the two
types in actual field trials.
A2DIZX 7
Page 3
M
7*
6
3
5
/
2
1
\
/
3
^T/TTTTTTZ
9
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AI-n-IEX 7
rage U
B)
Installations in Bangladeah.
The two esperimental pumps described below were built in early
197U in Bangladesh while Mr* Journey was a member of the UNICEF Water
Section. Both pumps shared the following features:
suction lift
5
b)
fulcrum pivot point supported independently of
ths punrp body on a steel pipe post
c)
aH-PVC poppet type check vains
d)
cyHnder housing and outlet made of jute reinforced
polyester resin.
The principal difference in the two (see photographs) was that pump No. 1
was anchored directly into the concrete slab while pump No. 2 had a con
ventional separable base.
Results of testing
Pump No. 1
Rd shortly after installation in an urban slum
when the cast iron clevis, which was screwed onto a lnd steel pipe post,
sheared off as a result of fatiguing the steel pipe threads (notch effect).
The failure is unrelated to the use cf plastic.
Pump No. 2 was install ad in April 197U and corrected the fault on
pump No. 1 by supporting the fulcrum point by employing an interference fit of the
clevis on the poet. As of 20 May 1976 the pump is still in daily use by
about UO families in Aliganj (a village near Dacca) at the CARE workshop.
Three leather cups were worn out during the two year period. The cylinder
was moderately scored, presumably by the metal follower plate of the piston
as the cup became too thin to fend the plate off the walls. These gouges,
however, did not appreciably affect the hydraulic seal. The PVC poppet
valve was observed still to hold a seal overnight and did not show noticeable
wear. The fiber reinforced plastic pump housing, while dirty did not show
damage of any sort. The steel pins in the cast iron journals shewed typical
wear (both on the cast iron parts and the pins) and needed replacement. Most
Mignificant, however, was the fact that little wear was noticeable on the
PVC pumping cylinder (estimated by the writer to be 1-2 mm increase in
diameter) ♦
ANNEX 7
Page 5
i
IV )
-1
k^S
7v^>;xu^. ',—~*lta
Pump No. 1 Installed
Plastic 3ody Pump No. 1
____
•4-i
A
All PVC Poppet Valve
)
ANNEX 7
Page 6
r
m"'" '
w
rlb^awr
3
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a»'
i
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•1
<->
- <-*-^7'
-W 7
■■
’Z.
o
%.
>
■i‘<"
■ ^-’i
Plastic Body Ptnnp No. 2
3”
0 ?VC Cylinder After Two Years
. ■—-TA'WVTT
:’0-
Z^' ■
*
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hgirgMffiu
-.-^l
(
■ "X-1
All PVC Poppet Valve
ANNEX 7
Page 7
In May 1977 the well screen failed, and a new well and pump were
installed. At that time Pump No. 2 was still in good working order. It
had operated for about 1,100 days pumping about 2,000 liters/day against
a head of about 3.7 m (with a bore of 78 mm and a stroke of 140 mm, this
corresponds to about 3,000 cycles (day or over 3 million cycles in all).
The portion of the PVC pipe forming the cylinder was sent in
January 1978 to Consumers’ Association (UK) testing laboratories to check
on the wear in use. The PVC pipe (Wavin ND 3 inch nominal diameter
Schedule 40) was found to be straight within the accuracy of measurement
(0.02 mm). The wear was measured as the deviations of the inside wall of
the cylinder from a straight line between the unworn ends of the pipe.
The results are shown on page 8. It will be seen that wear generally was
about 0.6 - 0.7 mm, more or less evenly divided between the spout side and
the handle side of the cylinder, with maximum wear of about 0.9 mm near the
bottom of the cylinder. These results indicate that, at least for the
shallow wells common in Bangladesh, the pump cylinder would be expected to
have a long life before leakage past the seal became a problem (when in the
proposed design, the pump rod would have to be slightly shortened so that
the piston cups seated on an unworn section of the PVC casing).
*
I,
t
Increnue in dlame ter(mm)
i
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nil
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fifi
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50
60
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1O0 1 10 1 20 1 30 140 150 160 170 180 100
Dletance from top
Cayl Co^parlaoii b«tween lUndpuap Tubewel); of Traditional Du»j|jii and Tlio«o Uali^ FVC txtenulvcly
--------- —T U B K W K L L
A----------------------- -----------Steel pipe, wall caelng and scresn, cast iron
pump stand, braes cylinder
I tew
Ooat/UnTF
tfcl¥
Bua
k" 0 0.1. pipe
st
•»" x 1J" 0.1. reducer
•
1|" J 0.1. pipe
Ij" {I Btalnlese Steel well screen ■
15
1
30
3’
Cast iron pump stand
3** 0 braaa cylinder and vaivea
"Alrllta" ateel pump roda
1
I
90.00^
116.10
lj- < 0.1. pipe
15
15
5.60
2.25
3*»
ftib-Totel|
32**
Q.50
2.00
9.00
5
It
10
Bub-Totali
Tg**l»
Aggregate
Ceaont
Labor
1/
cu. ft.
1O0 lb. SfCk
nan-day
9
8.83
6.00
2.25
*9.29
132
Bub-Total;
35«»
1/
———T U B K W K L L
B------------ --------JVC pipe, well caelog and screen, cast iron
______ pump
bjO/IB Qyll'ldqt
No.
Item___________________ Ij, lit
Coat/Unit
6
68
litS
90
116
UPW pipe
l|" x 1}** PVC reducer
Ik- If PVC pipe
I}- f PVC well screen
Cast iron puap atMid
3**
braaa cylinder and valves
“Alrtit*" steel puap rode
1 (yfl"
li" 9 8.1. P*l*
Aggregate
Ceaout
Labor
cu. ft.
100 lb. sack
nan-day
2.9'*
■i.OO
------------------ WC pipe, w
Boa
»t it
it
ItM
3“
pvC pipe
3" x 1J" JVC reducer
/ PVC pipe
1J“ if IVC well screen
15
1
30
3
0.86
13A3
26
11U
1
1
Bub-Total t
1/
90. Ou-7
116.10
90
116
15
15
5.60
2.25
Fiaton/check
Uoodeit handle
Uooden bearinga
1|" if 0.1. pipe abaft
3>»
bricks
Cement
Labor
"Alrtlte- 3/8" 0 Q.I.
Bub-Totali
3211
•tO
0.50
2.00
5.00
10
19
Bub-Total l
19
621
Totalt
•121
9
2
2
Aggregate
Ceacnt
Labor
UNICEF averan* purcbaaa price for a Beajater deep veil puap atand| other puap coaponeuts priced froa "Clayton Mark- catalogue, April 1976.
%-
?CD 5WCE
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TaADrncNAL
Jl^urs 2(a)
INTERCHANGEABLE PISTON AND CHECK VALVE COMPONENTS • SECTIONS
USED AS A
CHECK VALVE
/
EYE BOLT
FLAPPER VALVE
CUP
SEAL
PVC
DISC
I
USED AS A
PISTON
PUMP ROD
RETAINING
WASHER, TACK
WELDED IN
PLACE
C.
1
1
L
£
Figure 2(b)
ISOMETRIC SKETCH OF
FOOT VALVE
EYE BOLT
%
NYLON REINFORCED
NEOPRENE FLAPPER VALVE
UPPER MOLDED PVC
DISK
LEATHER CUP
LOWER MOLDED PVC
DISK
3
♦
RETAINING NUT
L\
Net to salt
3
Homan dasign of
hand pump, showing
conical laather cup
(component ”C”)
%
y,
ii
4
Sealing of pump rod
with packing gland
in order to puap t
elevated storage
4
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Roman design for
pumping to elevated
storage (Agrioola,
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