Village
Technology
Handbook
Volunteers in Technical Assistance
1815 North Lynn Street
Arlington, Virginia 22209 USA
Village Technology Handbook
Copyright [C] 1988 Volunteers in Technical Assistance
All rights reserved. No part of this publication may be
reproduced or transmitted
in any form or by any means, electronic or mechanical,
including photocopy,
recording, or any information storage and retrieval system,
without the written
permission of the publisher.
(This is the third edition of a manual first published in
1963, with the support of
the U. S. Agency for International Development, and revised
in 1970, which has
gone through eight major printings.)
Manufactured in the United States of America.
Set in Times Roman type on an IBM personal computer, a gift
to VITA from
International Business Machines Corporation, using
WordPerfect software donated
by WordPerfect Corporation.
Published by:
Volunteers in Technical Assistance
1815
North Lynn Street, Suite 200
Arlington, Virginia 22209 USA
10 9 8 7 6 5 4 3 2 1
Library of Congress Cataloging-in-Publication Data
Village technology handbook.
Bibliography: p.
413
1.
Building--Amateurs' manuals. 2. Do-it-yourself work. 3. Home economics,
Rural--Handbooks, manuals, etc. I. Volunteers in Technical
Assistance.
TH148.V64 1988
620'.41734
88-5700
ISBN 0-86619-275-1
Village Technology Handbook
Table of Contents
FOREWORD
NOTES ON USING THE HANDBOOK
ABOUT VITA
SYMBOLS AND ABBREVIATIONS
WATER RESOURCES
wr1.gif (393x393)
Developing Water Sources
Getting Ground Water from Wells and Springs
Ground Water
Flow of Water to
Wells
Where To Dig a
Well
Well Casing and
Seal
Well Development
Tubewells
Well Casing and
Platforms
Hand-Operated
Drilling Equipment
Dry Bucket Well
Drilling
Driven Wells
Dug Wells
Sealed Dug Well
Deep Dug Well
Reconstructing
Dug Wells
Spring Development
Water Lifting and Transport
Overview
Moving Water
Lifting Water
Water Transport
Estimating Small
Stream Water Flow
Measuring Water
Flow in Partially Filled Pipes
Determining
Probable Flow with Known Reservior Height and
Size and Length
of Pipe
Estimating Water
Flow from Horizontal Pipes
Determining Pipe
Size or Velocity of Water in Pipes
Estimating Flow
Resistance of Pipe Fittings
Bamboo Piping
Water Lifting
Pump
Specifications: Choosing or Evaluating a Pump
Determining Pump
Capacity and Horsepower Requirements
Determining Lift
Pump Capability
Simple Pumps
Chain Pump for
Irrigation
Inertia Hand Pump
Handle Mechanism
for Hand Pumps
Hydraulic Ram
Reciprocating Wire Power Transmission for Water Pumps
Wind Energy for Water Pumping
Overview
Decision Making
Process
Water Storage and Treatment
Cisterns
Cistern Tank
Catchment Area
Cistern Filter
Selecting a Dam Site
Catchment Area
Rainfall
Location
Water Purification
Boiler for
Drinking Water
Chlorinating
Wells, Springs, and Cisterns
Water Purification Plant
Sand Filter
HEALTH AND SANITATION
Sanitary Latrines
Overview
Privy Location
Privy Shelters
Privy Types
Pit Privy
Water Privy
Philippine
Water-Seal Latrine
Thailand
Water-Seal Privy Slab
Bilharziasis
The Parasites
Symptoms and Diagnosis
Treatment
Prevention
Ridding an Area of Bilharziasis
Malaria Control
Community Preventive Measures
Personal Preventive Measures
Treatment
Oral Rehydration Therapy
Dehydration--A Life-Threatening Condition
Treating or Preventing Dehydration
AGRICULTURE
Earth Moving Devices for Irrigation and Road Building
Drag Grader
Fresno Scraper
Barrel Fresno Scraper
Construction
Operation
Repairing the
Barrel Fresno Scraper
Adapting for
Heavy Duty
Float with Adjustable Blade
Buck Scraper
V-Drag
Multiple Hitches
Irrigation
Siphon Tubes
Using Tile for Irrigation and Drainage
Making a Concrete
Tile Machine
Making the Tile
Seeds, Weeds, and Pests
Seed Cleaner
Seed Cleaning Sieves
Drying Grain with Wooden Blocks
Preparing the
Blocks
Using the Blocks
Bucket Sprayer
Backpack Crop Duster
How the Duster
Operates
Adjusting the
Duster
Filling the
Duster
Making Springs
for the Duster
Poultry Raising
Brooder with Corral for 200 Chicks
Kerosene Lamp Brooder for 75 to 100 Chicks
Brooder for 300 Chicks
Bamboo Poultry House
House
Roof
Feeders
Nests
Poultry Feed Formulas
Intensive Gardening
The Soil
The Growing Beds
Fertilizing the Soil
Selection of Crops
Mulch
Silage for Dairy Cows
FOOD PROCESSING AND PRESERVATION
Storing Food at Home
How to Care for Various Kinds of Food
Dairy Foods
Fresh Meat, Fish,
Poultry
Eggs
Fresh Fruits and
Vegetables
Fats and Oils
Baked Goods
Dried Foods
Canned Goods
Leftover Cooked
Foods
Food Spoilage
When is Food
Spoiled?
Why Food Spoils
Containers for Food
Types of
Containers
Care of Food
Containers
The Storage Area
Good Ventilation
Keep the Storage
Area Cool and Dry
Keep the Storage
Area Clean
Keeping Foods Cool
Evaporative Food Cooler
Iceless Cooler
Window Box
Other Ways To Keep Foods Cool
Storing Vegetables and Fruits for Winter Use
Post Plank Cellar
Cabbage Pits
Storage Cones
Fish Preservation
Salting Fish
Preparing the
Fish
Salting
Washing and
Drying To Remove Excess Salt
Air Drying
Using Salted Fish
Smoking Fish
CONSTRUCTION
Concrete Construction
Overview
Importance of a
Good Mixture
Aggregates:
Gravel and Sand
Water
Calculating Amounts of Materials for Concrete
Using the
"Concrete Calculator"
Using the Water
Displacement Method
Using "Rule
of Thumb" Proportions
Mixing Concrete
Making a Mixing
Boat or Floor
Slump Tests
Making Forms for Concrete
Placing Concrete in Forms
Curing Concrete
Quick-Setting Concrete
Bamboo Construction
Preparing Bamboo
Splitting Bamboo
Bamboo
Preservation
Bamboo Joints
Bamboo Boards
Bamboo Walls, Partitions, and Ceilings
Walls
Partitions
Ceilings
Stabilized Earth Construction
Overview
Soil Characteristics
Testing the Soil
Composition Test
Compaction Test
Shrinkage Test
Making Adobe Blocks
Making Compressed Earth Blocks and Tiles
Building with Stabilized Earth Blocks
Construction Glues
Casein Glue
Making Casein
Powder
Mixing Casein
Glue
Using Casein Glue
Liquid Fish Glue
HOME IMPROVEMENT
Simple Washing Machines
Plunger Type Clothes Washer
Making the Washer
Using the Washer
Hand-Operated Washing Machine
Making the
Washing Machine
Using the Washing
Machine
Cookers and Stoves
Fireless Cooker
Making the
Fireless Cooker
Using the
Fireless Cooker
Charcoal Oven
How To Build the
Oven
How To Use the
Oven
Portable Metal Cookstoves
Principles of
Energy-Efficient Stoves
Cookstove Design
Producing the
Cookstoves
Outdoor Oven
Home Soap Making
Two Basic Methods
Ingredients for Soap
Fats and Oils
Lye
Borax
Perfume
Water
Soap Making with Commercial Lye
Recipes
How To Make the Soap
How To Know Good
Soap
Reclaiming
Unsatisfactory Soap
Soft Soap with Lye Leached from Ashes
Leaching the Lye
Making the Soap
Larger-Scale Soap Making
Bedding
A Nest of Low-Cost Beds
How To Make a Mattress
Making the
Mattress
Making a Rolled
Edge
CRAFTS AND VILLAGE INDUSTRY
Pottery
Waste-Oil Fired Kiln
Cost Advantages
of Waste Oil
Design of Kiln
and Fire Box
Operating the
Kiln
Small Rectangular Kiln
Construction
Firing
Salt Glaze for Pottery
Considerations
How To Fire the
Pottery
Hand Papermaking
Papermaking Processes
Pre-processing
Pulping
Lifting,
Couching, Stacking
Pressing and
Drying
Sizing
Calendering
Sorting and
Cutting
Making Paper in the Small Workshop
Pulping
Making the Sheets
Pressing and
Drying
Sizing and
Coating
Making Paper in the Micro-Factory
Candle Making
Making the Jigs
Preparing the Wax
Dipping the Candles
COMMUNICATIONS
Bamboo or Reed Writing Pens
Silk Screen Printing
Building the Silk Screen Printer
Printing
Preparing A Paper Stencil
Making Silk Screen Paint
Inexpensive Rubber Cement
REFERENCES
CONVERSION TABLES
Foreword
The Village Technology Handbook has been an important tool for
development
workers and do-it-yourselfers for 25 years. First published
in 1963 under the
auspices of the U.S. Agency for International Development,
the Handbook has
gone through eight major printings. Versions in French and
Spanish, as well as
English, are on shelves in bookstores, on desks in
government offices and local
organizations, in school libraries and technical centers,
and in the field kits of
village workers around the world. The technologies it
contains, like the chain and
washer pump, the evaporative food cooler, and the hay box
cooker, have been
built for technology fairs and demonstration centers
throughout the developing
world-and more importantly, have been adopted and adapted by
people everywhere.
Because the Handbook has been a faithful friend for so long,
this revision was
approached with care. As even the best of friendships needs
an occasional
reassessment, our question was how to update the book
without damaging its
fundamental utility-to avoid throwing the baby out with the
bath water.
We began by circulating sections of the book to VITA
Volunteers with expertise
in the various technical areas. We asked them to take a good
hard look at what
was presented and let us know what should be revised,
updated, discarded,
replaced. The volunteers' replies affirmed what tens of
thousands of users around
the world have recognized over the years, that the basic
material was sound.
Where they suggested changes, additions, and deletions, we
have done our best to
oblige.
Concurrently, we reviewed the comments that many of those
users have sent to
us over the years. Comments on what worked, what caused
trouble, and what
would be nice to have included. With so much going on in the
development of
small-scale, village technologies, the latter category was
extensive. But because so
much of the original book is still very applicable today, we
opted to make the
additions and changes selectively. We made the decision to
add to this volume
where it seemed most feasible, and to begin to compile a
companion volume that
will cover a selection of those other technologies.
Since the Handbook is primarily intended for
"do-it-yourselfers" in villages and
rural regions, most space still is allocated to the
development of water resources
and to agriculture. And rather than simply replacing
everything and starting over,
this new edition reorganizes some sections, updates several
of the original
articles, and includes a number of new ones on frequently
requested topics. The
new articles cover energy efficient stoves, the use of wind
power to pump water,
stabilized earth construction, a novel ceramics kiln,
small-scale candle and paper
production, high yield gardening, oral rehydration therapy,
and malaria control. An
all-new reference section is also provided.
VITA is committed to assisting sustainable growth: that is,
to progress, based on
expressed needs, that increases self reliance. Access to
clearly presented technical
information is a key to such growth. VITA searches out,
develops, and disseminates
techniques and devices that contribute to self suffiency.
The Village
Technology Handbook is one such VITA effort to support
sustainable growth with
easy to read technical information for the communities of
the world.
VITA Volunteers are similarly committed to helping VITA help
others, and many
of them were involved in this project, reviewing material in
their technical fields.
VITA wishes to thank Robert M. Ross and David C. Neubert for
reviewing the
sections on agriculture; Phil D. Weinert, Charles G. Burney,
Walter Lawrence, and
Steven Schaefer, water resources and purification; Malcolm
C. Bourne and Norman
M. Spain, food processing and preservation; Dwight R. Brown
and William Perenchio,
construction; Charles D. Spangler, sanitation; Jeff
Wartluft, Mark Hadley,
Marietta Ellis, Gerald Kinsman, and Peter Zweig, home
improvement; Dwight
Brown and Victor Palmeri, crafts and village industries; and
Grant Rykken,
communications.
Most especially, we would like to thank VITA Volunteer
engineer and literacy
specialist Len Doak, who was coaxed out of retirement and
away from the fishing
docks to coordinate the revision, sort out the comments, and
pull the new pieces
together.
VITA staff who were involved included Suzanne Brooks,
administrative support and
graphics; Julie Berman, administrative support; Margaret
Crouch, editorial; and
Maria Garth, typesetting.
And finally, this effort has given all of us a new respect
for Dan Johnson, one of
VITA's "founding fathers" and currently a member
of the Board of Directors, who
devoted a year of his life to putting the original Handbook
together a quarter of
a century ago. That so much of that work has stood the test
of time is due in no
small measure to the care with which he and the other VITA
Volunteers who
worked with him approached their task.
--VITA
Publications
January 1988
Notes on Using the Handbook
INTRODUCTION
The Village Technology Handbook contains eight major subject
sections, each containing
several articles. The articles cover both the broad topic
areas such as
agriculture, as well as specific agricultural projects such
as building a scraper.
If you are planning an entirely new project you would
benefit by reading the entire
section through. If you are planning a specific project
(such as building a
wind-driven water pump) only that article need be read.
The skills needed for each of the projects described vary
considerably, but none
of the projects requires more than the usual construction
and trade skills such as
carpentry, welding, or farming that are generally found in
most modest sized villages.
When the materials suggested in the Handbook are not available,
it may be possible
to substitute other materials. Be careful to make any
changes in dimensions
made necessary by such substitutions.
If you need translations of articles from the Handbook, we
ask that you let us
know. The book itself has been translated into English,
French, and Spanish, and
some individual articles may be available in other
languages.
The articles in the Handbook came from many sources. Your
comments and suggestions
for changes, difficulties with any of the projects described,
or ideas for
new articles are welcome. Those kinds of comments were a
very important element
in preparing this revised edition, and we expect to rely on
them in the
future as well. Please send your comments so that we may
continue to share.
SUMMARY OF THE HANDBOOK BY SECTION
Section 1. Water
Water resources are so vital that extensive coverage is
provided. Much of this
material is from the original, but it has been reorganized
and updated. The
sequence of articles begins with principles of hydrology
that explain where
underground water is likely to be found. This is followed by
articles on types of
wells and how to make well drilling tools and how to drill
or dig the wells.
Next come articles on practical methods to lift water from
wells and to transport
it. Articles on several pumps and water piping occur here. A
new article on wind-driven
pumps is in this section. A number of charts and tables help
in the
calculation of pipe size and water flow.
Water storage and purification are the topics of the next
series of articles. This
section is unchanged from the earlier edition, but several
new references are
fisted.
Section 2. Health and Sanitation
Next to pure water, sanitation is one of the most critical
health needs of any
society. This section begins with two brief articles on the
principles for disposal
of human waste. These are followed by details of how to
build various types of
latrines. Also included is an article on bilharziasis
(schistosomiasis) and a new
articles on malaria control and oral rehydration therapy.
Section 3. Agriculture
Seven topics are covered, beginning with earth moving
devices to level fields and
build irrigation ditches. This is followed by directions for
an irrigation system
based on concrete tile, including how to make the tile in
the field. A variety of
material on raising poultry is included, and a new article
on small, high yield
gardens has been added.
Section 4. Food Processing and Preservation
The articles in this section describe storage and handling of
different types of
food, evaporative coolers and other cold storage
technologies, and a variety of
other storage and processing systems and devices. The
section has been revised
and updated and new references have been added.
Section 5. Construction
Much of this section deals with construction of buildings
and walls using concrete
or bamboo. A new article on stabilized earth construction
has been added, and
instructions for making glues to use in construction are
also included.
Section 6. Home Improvements
Washing clothes, cooking, making soap, and making bedding
are covered here. An
important new addition is an article on the construction of
an energy efficient
cookstove developed in West Africa. The stove has shown more
than double the
fuel efficiency of the traditional open fire.
Section 7. Crafts and Village Industry
Traditional crafts that lend themselves to development as
small businesses are
discussed in this section--pottery, hand papermaking, and
candle making. Ceramic
kilns described include an alternative kiln design fueled by
waste motor oil.
Section 8. Communications
This section remains unchanged from the original on the
premise that while
changes, in communications could actually fill volumes on
their own, there are
many places in developing areas where the simple
technologies presented here are
still quite useful. Simple writing instruments and silk
screen printing are discussed.
The skills and materials described should be available in
most rural
villages.
SOURCES OF ADDITIONAL INFORMATION
Each article in the Handbook concludes with one or more
source references. These
and other sources of information have been compiled into the
new expanded
Reference section at the back of the book. VITA publications
that are listed may
be ordered directly from VITA Publications, Post Office Box
12028, Arlington,
Virginia 22204 USA.
You may also request technical assistance from VITA
Volunteer experts by writing
to VITA, 1815 North Lynn Street, Suite 200, Arlington,
Virginia 22209 USA.
About VITA
Volunteers in Technical Assistance (VITA) is a private,
nonprofit, international
development organization. It makes available to individuals
and groups in developing
countries a variety of information and technical resources
aimed at fostering
self sufficiency--needs assessment and program development
support; by-mail and
on-site consulting services; information systems training;
and management of long-term
field projects.
Throughout its history, VITA has concentrated on practical
and workable technologies
for development. It has collected, organized, tested,
synthesized, and
disseminated information on these technologies to more than
70,000 requesters and
hundreds of organizations in the developing countries. As
the information revolution
dawned, VITA found itself in a leadership position in the
effort to bring the
benefits of that revolution to those in the Third World who
are traditionally
passed over in the development process.
Perhaps of greatest significance is VITA's emphasis on
technologies that are
commercially viable. These have the potential of creating
new wealth through
adding value to local materials, thereby creating jobs and
increasing income as
well as strengthening the private sector. We have
increasingly translated our
experiences in information management to the implementation
of projects in the
field. This evolution from information to implementation to
create jobs, businesses,
and new wealth is what VITA is really about. It provides
missing links
without creating dependency.
VITA places special emphasis on the areas of agriculture and
food processing,
renewable energy applications, water supply and sanitation,
housing and construction,
and small business development. VITA's activities are
facilitated by the
active involvement of thousands of VITA Volunteer technical
experts from around
the world, and by its documentation center containing
specialized technical
material of interest to people in developing countries.
VITA currently publishes over 150 technical manuals, papers,
and bulletins, many
available in French and Spanish as well as English. Manuals
deal with construction
or implementation details for such specific topics as
windmills, reforestation,
water wheels, and rabbit raising. In addition, VITA
Technical Bulletins present
plans and case studies of specific technologies to encourage
further experimentation
and testing. The technical papers-"Understanding
Technology"-offer general
introductions to the applications and necessary resources
for technologies or
technical systems. Included in the series are topics that
range from composting to
Stirling engines, from sanitation at the community level to
tropical root crops.
Publications catalogues are available upon request.
VITA News is a quarterly magazine that provides an important
communications
link among far-flung organizations involved in technology
transfer and adaptation.
The News contains articles about projects, issues, and
organizations around the
world, reviews of new books, technical abstracts, and a
resources bulletin board.
VITA derives its income from government, foundation, and
corporate grants; fees
for services; contracts; and individual contributions.
For further information write to VITA, 1815 North Lynn
Street, Suite 200,
Arlington, Virginia 22209 USA.
Symbols and Abbreviations
Used in this Book
@ . . . . at
" . . . . inch
' . . . . foot
C . . . . degrees
Celsius (Centigrade)
cc . . . . cubic centimeter
cm . . . . centimeter
cm/sec . . centimeters per second
d or dia . diameter
F . . . . degrees
Fahrenheit
gm . . . . gram
gpm. . . . gallons per minute
HP . . . . horsepower
kg . . . . kilogram
km . . . . kilometer
l . . . . liter
l/pm . . . liters per minute
l/sec. . . liters per second
m . . . . meter
ml . . . . milliliters
mm . . . . millimeters
m/m. . . . meters per minute
m/sec. . . meters per second
ppm. . . . parts per million
R . . . . radius
Water Resources
<see image>
Developing Water Sources
There are three main sources of water for small water-supply
systems: ground
water, surface water, and rainwater. The choice of the
source of water depends
on local circumstances and the availability of resources to
develop the water
source.
A study of the local area should be made to determine which
source is best for
providing water that is (1) safe and wholesome, (2) easily
available, and (3)
sufficient in quantity. The entries that follow describe the
methods for tapping
ground water:
o
Tubewells
- Well
Casings and Platforms
-
Hand-Operated Drilling Equipment
- Driven
Wells
o
Dug Wells
o
Spring Development
Once the water is made available, it must be brought from
where it is to where it
is needed and steps must be taken to be sure that it is
pure. These subjects are
covered in the major sections that follow:
o
Water Lifting and Transport
o
Water Storage and Treatment
GETTING GROUND WATER FROM WELLS & SPRINGS
This section defines ground water, discusses its occurrence,
and explains its
movement. It describes how to decide on the best site for a
well, taking into
consideration the nearness to surface water, topography,
sediment type, and
nearness to pollutants. It also discusses briefly the
process of capping and sealing
the well and developing the well to assure maximum flow of
water.
Ground Water
Ground water is subsurface water, which fills small openings
(pores) of loose
sediments (such as sand and gravel) or rocks. For example,
if we took a clear
glass bowl, filled it with sand, and then poured in some
water, we would notice
the water "disappear" into the sand (see Figure
1). However, if we looked through
fig1pg4.gif (393x393)
the side of the bowl, we would see water in the sand, but
below the top of the
sand. The sand containing the
water is said to be saturated. The
top of the saturated sand is called
the water table; it is the level of
the water in the sand.
The water beneath the water table
is true ground water available (by
pumping) for human use. There is
water in the soil above the water table, but it does not
flow into a well and is
not available for use by pumping.
If we inserted a straw into the saturated sand in the bowl
in Figure 1 and sucked
on the straw, we would obtain some water (initially, we
would get some sand too).
If we sucked long enough, the water table or water level
would drop toward the
bottom of the bowl. This is exactly what happens when water
is pumped from a
well drilled below the water table.
The two basic factors in the occurrence of ground water are:
(1) the presence of
water, and (2) a medium to "house" the water. In
nature, water is provided by
precipitation (rain and snow) and surface water features
(rivers and lakes). The
medium is porous rock or loose sediments.
The most abundant ground water reservoir occurs in the loose
sands and gravels
in river valleys. Here the water table roughly parallels the
land surface, that is,
the depth to the water table is generally constant.
Disregarding any drastic
changes in climate, natural ground water conditions are
fairly uniform or balanced.
In Figure 2, the water poured into the bowl (analogous to
precipitation) is
fig2pg4.gif (393x393)
balanced by the water discharging out of the bowl at the
lower elevation (analogous
to discharge into a stream).
This movement of ground water is
slow, generally just centimeters or
inches per day.
When the water table intersects the
land surface, springs or swamps are
formed (see Figure 3). During a
fig3pg5.gif (486x486)
particularly wet season, the water
table will come much closer to the
land surface than it normally does
and many new springs or swampy
areas will appear. On the other hand, during a particularly
dry season, the water
table will be lower than normal and many springs will
"dry up." Many shallow
wells may also "go dry."
Flow of Water to Wells
A newly dug well fills with water a meter or so (a few feet)
deep, but after some
hard pumping it becomes dry. Has the well failed? Was it dug
in the wrong place?
More likely you are witnessing the phenomenon of drawdown,
an effect every
pumped well has on the water table (see Figure 4).
fig4pg5.gif (486x486)
Because water flows through sediments slowly, almost any
well can be pumped dry
temporarily if it is pumped hard enough. Any pumping will
lower the water level
to some degree, in the manner shown in Figure 4. A serious
problem arises only
when the drawdown due to normal use lowers the water table
below the level of
the well.
After the well has been dug about a meter (several feet)
below the water table, it
should be pumped at about the rate it will be used to see if
the flow into the
well is adequate. If it is not sufficient, there may be ways
to improve it. Digging
the well deeper or wider will not only cut across more of
the water-bearing layer
to allow more flow into the well, but it will also enable
the well to store a
greater quantity of the water that may seep in overnight. If
the well is still not
adequate and can be dug no deeper, it can be widened
further, perhaps lengthened
in one direction, or more wells can be dug. The goal of all
these methods is to
intersect more of the water-bearing layers, so that the well
will produce more
water without lowering the water table to the bottom of the
well.
Where to Dig a Well
Four important factors to consider in choosing a well site
are:
o
Nearness to Surface Water
o
Topography
o
Sediment Type
o
Nearness to Pollutants
Nearness to Surface Water
If there is surface water nearby, such as a lake or a river,
locate the well as
near to it as possible. It is likely to act as a source of
water and keep the water
table from being lowered as much as without it. This does
not always work well,
however, as lakes and slow-moving bodies of water generally
have silt and slime
on the bottom, which prevent water from entering the ground
quickly.
There may not seem to be much point to digging a well near a
river, but the
filtering action of the soil will result in water that is
cleaner and more free of
bacteria. It may also be cooler than surface water. If the
river level fluctuates
during the year, a well will give cleaner water (than stream
water) during the
flood season, although ground water often gets dirty during
and after a flood. A
well will also give more reliable water during the dry
season, when the water
level may drop below the bed of the river. This method of
water supply is used
by some cities: a large well is sunk next to a lake or river
and horizontal tunnels
are dug to increase the flow.
Wells near the ocean, and especially those on islands, may
have not only the
problem of drawdown, but that of salt water encroachment
(see Figure 5). The
fig5pg6.gif (540x540)
underground boundary between fresh and salt water generally
slopes inland:
Because salt water is heavier than fresh water, it flows in
under it. If a well
near the shore is used heavily, salt water may come into the
well as shown. This
should not occur in wells from which only a moderate amount
of water is drawn.
Topography
Ground water, being liquid, gathers in low areas. Therefore,
the lowest ground is
generally the best place to drill or dig. If your area is
flat or steadily sloping,
and there is no surface water, one place is as good as
another to start drilling or
digging. If the land is hilly, valley bottoms are the best
places to look for water.
You may know of a hilly area with a spring on the side of a
hill. Such a spring
could be the result of water moving through a layer of
porous rock or a fracture
zone in otherwise impervious rock. Good water sources can
result from such
features.
Sediment Type
Ground water occurs in porous or fractured rocks or
sediments. Gravel, sand and
sandstone are more porous than clay, unfractured shale and
granite or "hard
rock."
Figure 6 shows in a general way the relationship between the
availability of
fig6pg8.gif (540x540)
ground water (expressed by typical well discharges) and
geologic material (sediments
and various rock types). For planning the well discharge
necessary for
irrigating crops, a good rule of thumb for semi-arid
climates-37.5cm (15") of
precipitation a year-is a 1500- to 1900-liters (400 to 500
U.S. gallons)-per-minute
well that will irrigate about 65 hectares (160 acres) for
about six months. From
Figure 6, we see that wells in sediments are generally more
than adequate.
However, enough ground water can be obtained from rock, if
necessary, by
drilling a number of wells. Deeper water is generally of
better quality.
Sand and gravel are normally porous and clay is not, but
sand and gravel can
contain different amounts of silt and clay, which will
reduce their ability to carry
water. The only way to find the yield of a sediment is to
dig a well and pump it.
In digging a well, be guided by the results of nearby wells
and the effects of
seasonal fluctuations on nearby wells. And keep an eye on
the sediments in your
well as it is dug. In many cases you will find that the
sediments are in layers,
some porous and some not. You may be able to predict where
you will hit water
by comparing the layering in your well with that of nearby
wells.
Figures 7, 8, and 9 illustrate several sediment situations
and give guidelines on
fig7pg90.gif (540x540)
how deep to dig wells.
Aquifers (water bearing sediments) of Sand and Gravel.
Generally yield 11,400
LPM (300 gpm)
(but they may yield less depending on pump, well construction,
and well
development.
Aquifers of Sand, Gravel, and Clay (Intermixed or
Interbedded). Generally yield between
1900 LPM (500
gpm) and 3800 LPM (1000 gpm), but can yield more
--between 3800 LPM (1000 gpm) and 11,400 LPM
(3000 gpm)-- depending
on the
percentage of the constituents.
Aquifers of Sand and Clay. Generally yield about 1900 LPM
(500 gpm) but may
yield as much
as 3800 LPM (1000 gpm).
Aquifers of Fractured Sandstone. Generally yield about 1900
LPM (500 gpm) but
may yield more
than 3800 LPM (1000 gpm) depending on the thickness of the
sandstone and
the degree and extent of fracturing (may also yield less than
1900 LPM (500
and gpm) if thin and poorly fractured or interbedded with clay or
shale).
Aquifers of Limestone. Generally yield between 38 LPM
(10gpm) but have been
known to yield
more than 3800 LPM (1000 gpm) due to caverns or nearness
of stream, etc.
Aquifers of Granite and/or "Hard Rock." Generally
yield 38 gpm (10gpm) and may
yield less
(enough for a small household).
Aquifers of Shale. Yield less than 38 LPM (10gpm), not much
good for anything
except as a
last resort.
Nearness to Pollutants
If pollution is in the ground water, it moves with it.
Therefore, a well should
always be uphill and 15 to 30 meters (50 to 100 feet) away
from a latrine,
barnyard, or other source of pollution. If the area is flat,
remember that the flow
of ground water will be downward, like a river, toward any
nearby body of
surface water. Locate a well in the upstream direction from
pollution sources.
The deeper the water table, the less chance of pollution
because the pollutants
must travel some distance downward before entering ground
water. The water is
purified as it flows through the soil.
Extra water added to the pollutants will increase their flow
into and through the
soil, although it will also help dilute them. Pollution of
ground water is more
likely during the rainy than the dry season, especially if a
source of pollution
such as a latrine pit is allowed to fill with water. See
also the Overview to the
Sanitary Latrines section, p. 149. Similarly, a well that is
heavily used will
increase the flow of ground water toward it, perhaps even
reversing the normal
direction of ground-water movement. The amount of drawdown
is a guide to how
heavily the well is being used.
Polluted surface water must be kept out of the well pit.
This is done by casing
and sealing the well and providing good drainage around the
well cover.
Well Casing and Seal
The purpose of casing and seating wells is to prevent
contaminated surface water
from entering the well or nearby ground water. As water will
undoubtedly be
spilled from any pump, the top of the well must be sealed
with a concrete slab to
let the water flow away rather than re-enter the well
directly. It is also helpful
to build up the pump area with soil to form a slight hill
that will help drain away
spilled water and rain water.
Casing is the term for the pipe, concrete or grout ring, or
other material that
supports the well wall. It is usually impermeable in the
upper part of the well to
keep out polluted water (see Figure 7) and may be perforated
or absent in the
fig7pg9.gif (540x540)
lower part of the well to let water enter. See also
"Well Casing and Platforms," p.
12, and "Reconstructing Dug Wells," p. 57.
In loose sediment, the base of the well should consist of a
perforated casing
surrounded by coarse sand and small pebbles; otherwise,
rapid pumping may bring
into the well enough material to form a cavity and collapse
the well itself.
Packing the area around the well hole in the water-bearing
layer with fine gravel
will prevent sand from washing in and increase the effective
size of the well. The
ideal gradation is from sand to 6mm (1/4") gravel next
to the well screen. In a
drilled well it may be added around the screen after the
pump pipe is installed.
Well Development
Well development refers to the steps taken after a well is
drilled to ensure
maximum flow and well life by preparing the sediments around
the well. The layer
of sediments from which the water is drawn often consists of
sand and silt. When
the well is first pumped, the fine material will be drawn
into the well and make
the water muddy. You will want to pump out this fine
material to keep it from
muddying the water later and to make the sediments near the
well more porous.
However, if the water is pumped too rapidly at first, the
fine particles may
collect against the perforated casing or the sand grains at
the bottom of the well
and block the flow of water into it.
A method for removing the fine material successfully is to
pump slowly until the
water clears, then at successively higher rates until the
maximum of the pump or
well is reached. Then the water level should be permitted to
return to normal and
the process repeated until consistently clear water is
obtained.
Another method is surging, which is moving a plunger (an
attachment on a drill
rod) up and down in the well. This causes the water to surge
in and out of the
sedimentary layer and wash loose the fine particles, as well
as any drilling mud
stuck on the wall of the well. Coarse sediment washed into
the well can be
removed by a bailing bucket, or it may be left in the bottom
of the well to serve
as a filter.
Sources:
Anderson, K.E. Water Well Handbook. Rolla, Missouri:
Missouri Water Wells
Drillers Association, 1965.
Baldwin, H.L. and McGuinness, C.L. A Primer on Ground Water.
Washington, D.C.:
U.S. Government Printing Office, 1964.
Davis, S.N. and DeWiest, R.J.M. Hydrogeology. New York:
Wiley & Sons, 1966.
Todd, D.K. Ground Water Hydrology. New York: Wiley &
Sons, 1959.
Wagner, E.G. and Lanoix, J.N. Water Supply for Rural Areas
and Small Communities.
Geneva: World Health Organization, 1959.
Ground Water and Wells. Saint Paul, Minnesota: Edward E.
Johnson, Inc., 1966.
Small Water Supplies, Bulletin No. 10. London: The Ross
Institute, 1967.
U.S. Army. Wells. Technical Manual 5-297. Washington, D.C.:
U.S. Government
Printing Office, 1957.
TUBEWELLS
Where soil conditions permit, the tubewells described here
will, if they have the
necessary casing, provide pure water. They are much easier
to install and cost
much less than large diameter wells.
Tubewells will probably work well where simple earth borers
or earth augers work
(i.e., alluvial plains with few rocks in the soil), and
where there is a permeable
water-bearing layer 15 to 25 meters (50 to 80 feet) below
the surface. They are
sealed wells, and consequently sanitary, which offer no
hazard to small children.
The small amounts of materials needed keep the cost down.
These wells may not
yield enough water for a lane group, but they would be big
enough for a family
of a small group of families.
The storage capacity in small diameter wells is small. Their
yield depends largely
on the rate at which water flows from the surrounding soil
into the well. From a
saturated sand layer, the flow is rapid. Water flowing in
quickly replaces water
drawn from the well. A well that taps such a layer seldom
goes dry. But even
when water-bearing sand is not reached, a well with even a
limited storage
capacity may yield enough water for a household.
Well Casing and Platforms
In home or village wells, casing and platforms serve two
purposes: (1) to keep
well sides from caving in, and (2) to seal the well and keep
any polluted surface
water from entering it.
Two low-cost casing techniques are described here:
1. Method A (see Figure 1), from an American Friends Service
Committee (AFSC)
fig1pg13.gif (600x600)
team in Rasulia, Madhya Pradesh, India.
2. Method B, from an International Voluntary Services (IVS)
team in Vietnam.
Method A
Tools and Materials
Casing pipe (from pump to water-bearing layer to below
minimum water table)-Asbestos
cement, tile, concrete, or even galvanized iron pipe will do
Sand
Gravel
Cement
Device for lowering and placing casing (see Figure 2)
fig2pg14.gif (540x540)
Drilling rig - see "Tubewell Boring"
Foot valve, cylinder, pipe, hand pump
The well hole is dug as deep as
possible into the water-bearing
strata. The diggings are placed near
the hole to make a mound, which
later will serve to drain spilled
water away from the well. This is
important because backwash is one
of the few sources of contamination
for this type of well. The
entire casing pipe below water level
should be perforated with many
small holes no larger than 5mm
(3/16") in diameter. Holes larger
than this will allow coarse sand to
be washed inside and plug up the
well. Fine particles of sand,
however, are expected to enter.
These should be small enough to be
pumped immediately out through
the pump. This keeps the well
clear. The first water from the new
well may bring with it large
quantities of fine sand. When this
happens, the first strokes should be
strong and steady and continued
until the water comes clear.
Perforated casing is lowered, bell
end downward, into the hole using
the device shown in Figure 2. When
the casing is properly positioned,
the trip cord is pulled and the next
section prepared and lowered. Since
holes are easily drilled in asbestos
cement pipe, they can be wired
together at the joint and lowered
into the well. Be sure the bells
point downward, since this will
prevent surface water or backwash
from entering the well without the
purifying filtration effect of the
soil; it will also keep sand and dirt
from filling the well. Install the
casing vertically and fill the
remaining space with pebbles. This
will hold the casing plumb. The
casing should rise 30 to 60cm (1' to
2') above ground level and be
surrounded with a concrete pedestal
to hold the pump and to drain
spilled water away from the hole.
Casing joints within 3 meters (10
feet) of the surface should be
sealed with concrete or bituminous
material.
Method B
Plastic seems to be an ideal casing material, but because it
was not readily
available, the galvanized iron and concrete casings
described here were developed
in the Ban Me Thuot area of Vietnam.
Tools and Materials
Wooden V-block, 230cm (7 1/2') long (see Figure 3)
fig3pg15.gif (145x437)
Angle iron, 2 sections, 230cm (7 1/2') long
Pipe, 10cm (4") in diameter, 230cm (7 1/2') long
Clamps
Wooden mallet
Soldering equipment
Galvanized sheet metal: 0.4mm x 1m x 2m (0.01.6" x 39
1/2" x 79")
Plastic Casing
Black plastic pipe for sewers and drains was almost ideal.
Its friction joints could
be quickly slipped together and sealed with a chemical
solvent. It seemed durable
but was light enough to be lowered into the well by hand. It
could be easily
sawed or drilled to make a screen. Care must be taken to be
sure that any plastic
used is non-toxic.
Galvanized Sheet Metal Casing
Galvanized sheet metal was used to make casing similar to
downspouting. A
thicker gauge than the 0.4mm (0.016") available would have
been preferable.
Because the sheet metal would not last indefinitely if used
by itself, the well hole
was made oversize and the ring-shaped space around the
casing was filled with a
thin concrete mixture which formed a cast concrete casing
and seal outside the
sheet metal when it hardened.
The 1-meter x 2-meter (39 1/2" x 79") sheets were
cut lengthwise into three
equal pieces, which yielded three 2-meter (79") lengths
of 10cm (4") diameter pipe.
The edges were prepared for making seams by clamping them
between the two
angle irons, then pounding with a wooden mallet to the shape
shown in Figure 3.
The seam is made slightly wider at one
end than at the other to give the pipe a
slight taper, which allows successive
lengths to be slipped a short distance
inside one another.
The strips are rolled by bridging them over a 2-meter
(79") V-shaped wooden
block and applying pressure from above with a length of 5cm
(2") pipe (see Figure 4).
fig4pg15.gif (393x393)
The sheet metal strips are shifted from side to side over
the V-block as they
are being bent to produce as uniform a surface as possible.
When the strip is bent
enough, the two edges are hooked
together and the 5cm (2") pipe is slipped
inside. The ends of the pipe are set up
on wooden blocks to form an anvil, and
the seam is firmly crimped as shown in
Figure 5.
fig5pg15.gif (285x285)
After the seam is finished, any irregularities
in the pipe are removed by
applying pressure by hand or with the
wooden mallet and pipe anvil. A local
tinsmith and his helper were able to
make six to eight lengths (12 to 16
meters) of the pipe per day. Three
lengths of pipe were slipped together and soldered as they
were made, and the
remaining joints had to be soldered as the casing was
lowered into the well.
The lower end of the pipe was perforated with a hand drill
to form a screen.
After the casing was lowered to the bottom of the well, fine
gravel was packed
around the perforated portion of the casing to above the
water level.
The cement grouting mortar used around the casings varied
from pure cement to a
1:1 1/2 cement : sand ratio mixed with water to a very
plastic consistency. The
grout was put around the casing by gravity and a strip of
bamboo about 10
meters (33 feet) long was used to "rod" the grout
into place. A comparison of
volume around the casing and volume of grouting used
indicated that there may
have been some voids left probably below the reach of the
bamboo rod. These are
not serious however, as long as a good seal is obtained for
the first 8 to 10
meters (26 to 33 feet) down from the surface. In general,
the greater proportion
of cement used and the greater the space around the casing,
the better seemed to
be the results obtained. However, insufficient experience
has been obtained to
reach any final conclusions. In addition, economic
considerations limit both of
these factors.
Care must be taken in pouring the grout. If the sections of
casing are not
assembled perfectly straight, the casing, as a result, is
not centered in the well
and the pressure of the grouting is not equal all the way
around. The casing may
collapse. With reasonable care, pouring the grout in several
stages and allowing it
to set in-between should eliminate this. The grouting,
however, cannot be poured
in too many stages because a considerable amount sticks to
the sides of the well
each time, reducing the space for successive pourings to
pass through.
This method can be modified for use in areas where the
structure of the material
through which the well is drilled is such that there is
little or no danger of
cave-in. In this situation, the casing serves only one
purpose, as a sanitary seal.
The well will be cased only about 8 meters (26 feet) down
from the ground
surface. To do this, the well is drilled to the desired
depth with a diameter
roughly the same as that of the casing. The well is then
reamed out to a
diameter 5 to 6cm (2" to 2 1/4") larger than the
casing down to the depth the
casing will go. A flange fitted at the bottom of the casing
with an outside
diameter about equal to that of the reamed hole will center
the casing in the
hole and support the casing on the shoulder where the
reaming stopped. Grouting
is then poured as in the original method. This modification
(1) saves considerable
costly material, (2) allows the well to be made a smaller
diameter except near the
top, (3) lessens grouting difficulties, and (4) still
provides adequate protection
against pollution.
Concrete Tile Casing
If the well is enlarged to an adequate diameter, precast
concrete tile with
suitable joints could be used as casing. This would require
a device for lowering
the tiles into the well one by one and releasing them at the
bottom. Mortar
would have to be used to seal the joints above the water
level, the mortar being
spread on each successive joint before it is lowered.
Asbestos cement casing
would also be a possibility where it was available with
suitable joints.
No Casing
The last possibility would be to use no casing at all. It is
felt that when finances
or skills do not permit the well to be cased, there are
certain circumstances
under which an uncased well would be better than no well at
all. This is particularly
true in localities where the custom is to boil or make tea
out of all
water before drinking it, where sanitation is greatly
hampered by insufficient
water supply, and where small-scale hand irrigation from
wells can greatly
improve the diet by making gardens possible in the dry
season.
The danger of pollution in an uncased well can be minimized
by: (1) choosing a
favorable site for the well and (2) making a platform with a
drain that leads
away from the well, eliminating all spilled water.
Such a well should be tested frequently for pollution. If it
is found unsafe, a
notice to this effect should be posted conspicuously near
the well.
Well Platform
In the work in the Ban Me Thuot area, a flat 1.75-meter
(5.7') square slab of
concrete was used around each well. However, under village
conditions, this did
not work well. Large quantities of water were spilled, in
part due to the enthusiasm
of the villagers for having a plentiful water supply, and
the areas around
wells became quite muddy.
The conclusion was reached that the only really satisfactory
platform would be a
round, slightly convex one with a small gutter around the
outer edge. The gutter
should lead to a concreted drain that would take the water a
considerable
distance from the well. It is worth noting that in Sudan and
other very arid areas
such spillage from community wells is used to water
vegetable gardens or
community nurseries.
If the well platform is too big and smooth, there is a great
temptation on the
part of the villagers to do their laundry and other washing
around the well. This
should be discouraged. In villages where animals run loose
it is necessary to build
a small fence around the well to keep out animals,
especially poultry and pigs,
which are very eager to get water, but tend to mess up the
surroundings.
Sources:
Koegel, Richard G. Report. Ban Me Thuot, Vietnam:
International Voluntary
Services, 1959. (Mimeographed.)
Mott, Wendell. Explanatory Notes on Tubewells. Philadelphia:
American Friends
Service Committee, 1956. (Mimeographed.)
Hand-Operated Drilling Equipment
Two methods of drilling a shallow tubewell with
hand-operated equipment are
described here: Method A, which was used by an American
Friends Service
Committee (AFSC) team in India, operates by turning an
earth-boring auger.
Method B, developed by an International Voluntary Services
(IVS) team in
Vietnam, uses a ramming action.
Earth Boring Auger
This simple hand-drilling rig can be used to dig wells 15 to
20cm (6" to 8") in
diameter up to 15 meters (50') deep.
Tools and Materials
Earth auger, with coupling to attach to 2.5cm (1")
drill line (see entry on
tubewell earth augers)
Standard weight galvanized steel pipe:
For Drill Line:
4 pieces: 2.5cm
(1") in diameter and 3 meters (10') long (2 pieces have
threads
on one end only; others need no threads.)
2 pieces: 2.5cm
(1") in diameter and 107cm (3 1/2") long
For Turning
Handle:
2 pieces: 2.5cm
(1") in diameter and 61cm (2') long
2.5cm (1") T
coupling
For Joint A:
4 pieces: 32mm (1
1/4") in diameter and 30cm (1') long
Sections and
Couplings for Joint B:
23cm (9")
Section of 32mm (1 1/4") diameter (threaded at one end only)
35.5cm (14")
Section of 38mm (1 1/2") diameter (threaded at one end
only)
Reducer coupling:
32mm to 25mm (1 1/4" to 1")
Reducer coupling:
38mm to 25mm (1 1/2" to 1")
8 10mm
(3/8") diameter hexagonal head machine steel bolts 45mm (1
3/4") long,
with nuts
2 10mm
(3/8") diameter hexagonal head machine steel bolts 5cm (2")
long, with nuts
9 10mm
(3/8") steel hexagonal nuts
For Toggle Bolt:
1 3mm (1/8")
diameter countersink head iron rivet, 12.5mm (1/2") long
1 1.5mm
(1/16") sheet steel, 10mm (3/8") x 25mm (1")
Drills: 3mm (1/8"), 17.5mm (13/16"), 8.75mm
(13/32")
Countersink
Thread cutting dies, unless pipe is already threaded
Small Tools: wrenches, hammer, hacksaw, files
For platform: wood, nails, rope, ladder
Basically the method consists of rotating an ordinary earth
auger. As the auger
penetrates the earth, it fills with soil. When full it is
pulled out of the hole and
emptied. As the hole gets deeper, more sections of drilling
line are added to
extend the shaft. Joint A (Figures 1 and 2) is a simple
method for attaching new
fig1x200.gif (600x600)
sections.
By building an elevated platform 3 to 3.7 meters (10 to 12
feet) from the ground,
a 7.6-meter (25 foot) long section of drill line can be
balanced upright. Longer
lengths are too difficult to handle. Therefore, when the
hole gets deeper than 7.6
meters (25 feet), the drill line must be taken apart each
time the auger is
removed for emptying. Joint B makes this operation easier.
See Figures 1 and 3.
fig3x200.gif (600x600)
Joint C (see construction details for Tubewell Earth Auger)
is proposed to allow
rapid emptying of the auger. Some soils respond well to
drilling with an auger
that has two sides open. These are very easy to empty, and
would not require
Joint C. Find out what kinds of augers are successfully used
in your area, and do
a bit of experimenting to find the one best suited to your
soil. See the entries on
augers.
Joint A has been found to be faster to use and more durable
than pipe threaded
connectors. The pipe threads become damaged and dirty and
are difficult to start.
Heavy, expensive pipe wrenches get accidentally dropped into
the well and are
hard to get out. These troubles can be avoided by using a
sleeve pipe fastened
with two 10mm (3/8") bolts. Neither a small bicycle
wrench nor the inexpensive
bolts will obstruct drilling if dropped in. Be sure the 32mm
(1 1/4") pipe will fit
over your 25mm (1") pipe drill line before purchase.
See Figure 2.
fig2x20.gif (600x600)
Four 3-meter (10') sections and two 107cm (3 1/2') sections
of pipe are the most
convenient lengths for drilling a 15-meter (50') well. Drill
an 8.75mm (13/32")
diameter hole through each end of all sections of drill line
except those attaching
to Joint B and the turning handle, which must be threaded
joints. The holes
should be 5cm (2") from the end.
When the well is deeper than 7.6 meters (25'), several
features facilitate the
emptying of the auger, as shown in Figures 3 and 4. First,
pull up the full auger
fig4x200.gif (600x600)
until Joint B appears at the surface. See Figure 4A. Then
put a 19mm (3/4")
fig4x21.gif (600x600)
diameter rod through the hole. This allows the whole drill
line to rest on it
making it impossible for the part still in the well to fall
in. Next remove the
toggle bolt, lift out the top section of line and balance it
beside the hole. See
Figure 4B. Pull up the auger, empty it, and replace the
section in the hole where
it will be held by the 19mm (3/4") rod. See Figure 4C.
Next replace the upper
section of drill line. The 10mm (3/8") bolt acts as a
stop that allows the holes to
be easily lined up for reinsertion of the toggle bolt.
Finally withdraw the rod and
lower the auger for the next drilling. Mark the location for
drilling the 8.75mm
(13/32") diameter hole in the 32mm (1 1/4") pipe
through the toggle bolt hole in
the 38mm (1 1/2") pipe. If the hole is located with the
32mm (1 1/4") pipe resting
on the stop bolt, the holes are bound to line up.
Sometimes a special tool is needed to penetrate a
water-bearing sand layer,
because the wet sand caves in as soon as the auger is
removed. If this happens a
perforated casing is lowered into the well, and drilling is
accomplished with an
auger that fits inside the casing. A percussion type with a
flap, or a rotary type
with solid walls and a flap are good possibilities. See the
entries describing these
devices. The casing will settle deeper into the sand as sand
is dug from beneath
it. Other sections of casing must be added as drilling
proceeds. Try to penetrate
the water bearing sand layer as far as possible (at least
three feet-one meter).
Ten feet (three meters) of perforated casing embedded in
such a sandy layer will
provide a very good flow of water.
Tubewell Earth Auger
This earth auger (Figure 5), which is similar to designs
used with power drilling
fig5x22.gif (600x600)
equipment, is made from a 15cm (6") steel tube.
The auger can be made without
welding equipment, but some of the
bends in the pipe and the bar can
be made much more easily when
the metal is hot (see Figure 6).
fig6x23.gif (600x600)
An open earth auger, which is
easier to empty than this one, is
better suited for some soils. This
auger cuts faster than the Tubewell
Sand Auger.
Tools and Materials
Galvanized pipe: 32mm (1 1/4") in diameter and 21.5cm
(8 1/2") long
Hexagonal head steel bolt: 10mm (3/8") in diameter and
5cm (2") long, with nut
2 hexagonal head steel bolts: 10mm (3/8") in diameter
and 9.5cm (3 3/4") long
2 Steel bars: 1.25cm x 32mm x 236.5mm (1/2" x 1
1/4" x 9 5/16")
4 Round head machine screws: 10mm (3/8") in diameter
and 32mm (1 1/4") long
2 Flat head iron rivets: 3mm (1/8") in diameter and
12.5mm (1/2") long
Steel strip: 10mm x 1.5mm x 2.5cm (3/8" x 1/16" x
1")
Steel tube: 15cm (6") outside diameter, 62.5cm (24
5/8") long
Hand tools
Source:
U.S. Army and Air Force. Wells. Technical Manual 5-297, AFM
85-23. Washington,
D.C.: U.S. Government Printing Office, 1957.
Tubewell Sand Auger
This sand auger can be used to drill in loose soil or wet
sand, where an earth
auger is not effective. The simple cutting head requires
less force to turn than
the Tubewell Earth Auger, but it is more difficult to empty.
A smaller version of the sand auger made to
fit inside the casing pipe can be used to
remove loose, wet sand.
The tubewell sand auger is illustrated in
Figure 7. Construction diagrams are given in
fig7x24.gif (600x600)
Figure 8.
fig8x25.gif (600x600)
Tools and Materials
Steel tube: 15cm (6") outside diameter and
46cm (18") long
Steel plate: 5mm x 16.5cm x 16.5cm (3/16" x 6
1/2" x 6 1/2")
Acetylene welding and cutting equipment
Drill
Source:
Wells, Technical Manual 5-297, AFM 85-23, U.S. Army and Air
Force, 1957.
Tubewell Sand Bailer
The sand bailer <see figure 9> can be used to drill
from inside a perforated well casing when a
fig9x26.gif (600x600)
bore goes into loose wet sand and the walls start to cave
in. It has been used to
make many tubewells in India.
Tools and Materials
Steel tube: 12.5cm (5") in diameter and 91.5cm (3')
long
Truck innertube or leather: 12.5cm (5") square
Pipe coupling: 15cm to 2.5cm (5" to 1")
Small tools
Repeatedly jamming this "bucket" into the well
will remove sand from below the
perforated casing, allowing the bucket to settle deeper into
the sand layer. The
casing prevents the walls from caving in. The bell is
removed from the first
section of casing; at least one other section rests on top
of it to help force it
down as digging proceeds. Try to penetrate the water bearing
sand layer as far as
possible: 3 meters (10') of perforated casing embedded in
such a sandy layer will
usually provide a very good flow of water.
Be sure to try your sand "bucket" in wet sand
before attempting to use it at the
bottom of your well.
Source:
Explanatory Notes on Tubewells, Wendell Mott, American
Friends Service Committee,
Philadelphia, Pennsylvania, 1956 (Mimeographed).
Ram Auger
The equipment described here has been used successfully in
the Ban Me Thuot
area of Vietnam. One of the best performances was turned in
by a crew of three
inexperienced mountain tribesmen who drilled 20 meters (65')
in a day and a half.
The deepest well drilled was a little more than 25 meters
(80'); it was completed,
including the installation of the pump, in six days. One
well was drilled through
about 11 meters (35') of sedimentary stone.
Tools and Materials
For tool tray:
Wood: 3cm x 3cm x 150cm (1 1/4" x 1 1/4" x
59")
Wood: 3cm x 30cm x 45cm (1 1/4" x 12"x 17
3/4")
For safety rod:
Steel rod: 1cm (3/8") in diameter, 30cm (12") long
Drill
Hammer
Anvil
Cotter pin
For auger support:
Wood: 4cm x 45cm x 30cm (1 1/3" x 17 3/4" x
12")
Steel: 10cm x 10cm x 4mm (4" x 4" x 5/32")
Location of the Well
Two considerations are especially important for the location
of village wells: (1)
the average walking distance for the village population
should be as short as
possible; (2) it should be easy to drain spilled water away
from the site to avoid
creating a mudhole.
In the Ban Me Thuot area, the final choice of location was
in all cases left up to
the villagers. Water was found in varying quantities at all
the sites chosen. (See
"Getting Ground Water from Wells and Springs.")
Starting to Drill
A tripod is set up over the approximate location for the
well (see Figure 1). Its
fig1x28.gif (600x600)
legs are set into shallow holes with dirt packed around them
to keep them from
moving. To make sure the well is started exactly vertically,
a plumb bob (a string
with a stone tied to it is good enough) is hung from the
auger guide on the
tripod's crossbar to locate the
exact starting point. It is helpful
to dig a small starting hole before
setting up the auger.
Drilling
Drilling is accomplished by ramming
the auger down to penetrate the
earth and then rotating it by its
wooden handle to free it in the
hole before lifting it to repeat the
process. This is a little awkward
until the auger is down 30cm to
60cm (1' to 2') and should be done
carefully until the auger starts to
be guided by the hole itself.
Usually two or three people work
together with the auger. One
system that worked out quite well
was to use three people, two
working while the third rested, and
then alternate.
As the auger goes deeper it will be
necessary from time to time to
adjust the handle to the most
convenient height. Any wrenches or
other small tools used should be
tied by means of a long piece of
cord to the tripod so that if they
are accidentally dropped in the
well, they can easily be removed.
Since the soil of the Ban Me Thuot
area would stick to the auger, it
was necessary to keep a small
amount of water in the hole at all
times for lubrication.
Emptying the Auger
Each time the auger is rammed
down and rotated, it should be
noted how much penetration has
been obtained. Starting with an
empty auger the penetration is
greatest on the first stroke and becomes successively less
on each following one
as the earth packs more and more tightly inside the auger.
When progress
becomes too slow it is time to raise the auger to the
surface and empty it.
Depending on the material being penetrated, the auger may be
completely full or
have 30cm (1') or less of material in it when it is emptied.
A little experience
will give one a "feel" for the most efficient time
to bring up the auger for
emptying. Since the material in the auger is hardest packed
at the bottom, it is
usually easiest to empty the auger by inserting the auger
cleaner through the slot
in the side of the auger part way down and pushing the
material out through the
top of the auger in several passes. When the auger is
brought out of the hole for
emptying, it is usually leaned up against the tripod, since
this is faster and easier
than trying to lay it down.
Coupling and Uncoupling Extensions
The extensions are coupled by merely slipping the small end
of one into the large
end of the other and pinning them together with a 10mm
(3/8") bolt. It has been
found sufficient and time-saving to just tighten the nut
finger-tight instead of
using a wrench.
Each time the auger is brought up for emptying, the
extensions must be taken
apart. For this reason the extensions have been made as long
as possible to
minimize the number of joints. Thus at a depth of 18.3
meters (60'), there are
only two joints to be uncoupled in bringing up the auger.
For the sake of both safety and speed, use the following
procedure in coupling
and uncoupling. When bringing up the auger, raise it until a
joint is just above
the ground and slip the auger support (see Figures 2 and 3)
into place, straddling
fig2x290.gif (393x393)
the extension so that the bottom of
the coupling can rest on the small
metal plate. The next step is to put
the safety rod (see Figure 4)
fig4x30.gif (594x594)
through the lower side in the
coupling and secure it with either a
cotter pin or a piece of wire. The
purpose of the safety rod is to
keep the auger from falling into
the well if it should be knocked
off the auger support or dropped
while being raised.
Once the safety rod is in place,
remove the coupling bolt and slip
the upper extension out of the
lower. Lean the upper end of the
extension against the tripod between
the two wooden pegs in the front legs, and rest the lower
end on the tool
tray (see Figures 5 and 6). The reason for putting the
extensions on the tool tray
fig5x310.gif (393x393)
is to keep dirt from sticking to the lower ends and making
it difficult to put the
extensions together and take them apart.
To couple the extensions after emptying the auger, the
procedure is the exact
reverse of uncoupling.
Drilling Rock
When stone or other substances the auger cannot penetrate
are met, a heavy
drilling bit must be used.
Depth of Well
The rate at which water can be taken from a well is roughly
proportional to the
depth of the well below the water table as long as the well
keeps going into
water-bearing ground. However, in
village wells where water can only
be raised slowly by handpump or
bucket, this is not usually of major
importance. The important point is
that in areas where the water table
varies from one time of year to
another the well must be deep
enough to give sufficient water at
all times.
Information on the water table
variation may be obtained from
already existing wells, or it may be
necessary to drill a well before any
information can be obtained. In the
latter case the well must be deep
enough to allow for a drop in the
water table.
Source:
Report by Richard G. Koegel, International Voluntary
Services, Ban Me Thuot,
Vietnam, 1959 (Mimeographed).
Equipment <see figure 7>
fig7x32.gif (486x486)
The following section gives construction details for the
well-drilling equipment
used with the ram auger:
o
Auger, Extensions, and Handle
o
Auger Cleaner
o
Demountable Reamer
o
Tripod and Pulley
o
Bailing Bucket
o
Bit for Drilling rock
Auger, Extensions, and Handle
The auger is hacksawed out of standard-weight steel pipe
about 10cm (4") in
diameter (see Figure 8). Lightweight tubing is not strong
enough. The extensions
fig8x34.gif (600x600)
(see Figure 9) and handle (see Figure 10) make it possible
to bore deep holes.
fig9x34.gif (600x600)
fig10x35.gif (600x600)
Tools and Materials
Pipe: 10cm (4") in diameter, 120cm (47 1/4") long,
for auger
Pipe: 34mm outside diameter (1" inside diameter); 3 or
4 pieces 30cm (12") long,
for auger and extension socket
Pipe: 26mm outside diameter (3/4" inside diameter); 3
or 4 pieces 6.1 or 6.4 meters
(20' or 21') long, for drill extensions
Pipe: 10mm outside diameter (1/2" inside diameter); 3
or 4 pieces 6cm (2 3/8")
long
Hardwood: 4cm x 8cm x 50cm (1 1/2" x 3 1/8" x 19
3/4"), for handle
Mild steel: 3mm x 8cm x 15cm (1/8" x 3 1/8" x
6")
4 Bolts: 1cm (3/8") in diameter and 10cm (4") long
4 Nuts
Hand tools and welding equipment
In making the auger, a flared-tooth cutting edge is cut in
one end of the 10cm
pipe. The other end is cut, bent, and welded to a section of
34mm outside-diameter
(1" inside-diameter) pipe, which forms a socket for the
drill line
extensions. A slot that runs nearly the length of the auger
is used for removing
soil from the auger. Bends are made stronger and more easily
and accurately when
the steel is hot. At first, an auger with two cutting lips
similar to a post-hole
auger was used; but it became plugged up and did not cut
cleanly. In some soils,
however, this type of auger may be more effective.
Auger Cleaner
Soil can be removed rapidly from the auger with this auger
cleaner (see Figure 11).
fig11x36.gif (486x486)
Figure 12 gives construction details.
fig12x36.gif (600x600)
Tools and Materials
Mild steel: 10cm (4") square and 3mm (1/8") thick
Steel rod: 1cm (3/8") in diameter and 52cm (20
1/2") long
Welding equipment
Hacksaw
File
Demountable Reamer
If the diameter of a drilled hole has to be made bigger, the
demountable reamer
described here can be attached to the auger.
Tools and Materials
Mild steel: 20cm x 5cm x 6mm (6" x 2" x
1/4"), to ream a well diameter of 19cm
(7 1/2")
2 Bolts: 8mm (5/16") in diameter and 10cm (4")
long
Hacksaw
Drill
File
Hammer
Vise
The reamer is mounted to the top of the auger with two hook
bolts (see Figure 13).
fig13x37.gif (600x600)
It is made from a piece of steel 1cm (1/2") larger than
the desired well
diameter (see Figure 14).
fig14x38.gif (600x600)
After the reamer is attached to the
top of the auger, the bottom of the
auger is plugged with some mud or
a piece of wood to hold the
cuttings inside the auger.
In reaming, the auger is rotated
with only slight downward pressure.
It should be emptied before it is
too full so that not too many
cuttings will fall to the bottom of
the well when the auger is pulled
up.
Because the depth of a well is
more important than the diameter
in determining the flow and
because doubling the diameter
means removing four times the
amount of earth, larger diameters
should be considered only under
special circumstances. (See "Well
Casing and Platforms," page 12.)
Tripod and Pulley
The tripod (see Figures 15 and 16), which is made of poles
and assembled with
fig15390.gif (393x393)
when it extends far above ground; (2) to provide a mounting
for the pulley (see Figures 17 and 19)
fig17400.gif (600x600)
place for leaning long pieces of casing, pipe for pumps, or
auger extensions while
they are being put into or taken out of the well.
When a pin or bolt is put through the holes in the two ends
of the "L"-shaped
pulley bracket (see Figures 15 and 18) that extend
horizontally beyond the front
fig18390.gif (393x393)
formed.
To keep the extensions from falling when they are leaned
against the tripod, two
30cm (12") long wooden pegs are driven into drilled
holes near the top of the
tripod's two front legs (see Figure 19).
fig19x41.gif (600x600)
Tools and Materials
3 Poles: 15cm (3") in diameter and 4.25 meters (14')
long
Wood for cross bar: 1.1 meter (43 1/2") x 12cm (4
3/4") square
For pulley wheel:
Wood: 25cm (10") in diameter and 5cm (2") thick
Pipe: 1.25cm (1/2") inside diameter, 5cm (2") long
Axle bolt: to fit close inside 1.25cm (1/2") pipe
Angle iron: 80cm (31 1/2") long, 50cm (19 3/4")
webs, 5mm (3/16") thick
4 Bolts: 12mm (1/2") in diameter, 14cm (5 1/2")
long; nuts and washers
Bolt: 16mm (5/8") in diameter and 40cm (15 3/4")
long; nuts and washer
2 Bolts: 16mm (5/8") in diameter and 25cm (9 7/8")
long; nuts and washers
Bore 5 places through center of poles for assembly with 16mm
bolts
Bailing Bucket
The bailing bucket can be used to remove soil from the well
shaft when cuttings
are too loose to be removed with the auger.
Tools and Materials
Pipe: about 8.5cm (3 3/8") in diameter, 1 to 2cm
(1/2" to 3/4") smaller in
diameter than the auger, 180cm (71") long
Steel rod: 10mm (3/8") in diameter and 25cm (10")
long; for bail (handle)
Steel plate: 10cm (4") square, 4mm (5/32") thick
Steel bar: 10cm x 1cm x 5mm (4" x 3/8" x
3/16")
Machine screw: 3mm (1/8") diameter by 16mm (5/8")
long; nut and washer
Truck innertube: 4mm (5/32") thick, 10mm (3/8")
square
Welding equipment
Drill
Hacksaw
Hammer
Vise
File
Rope
Both standard weight pipe and thin-walled tubing were tried
for the bailing
bucket. The former, being heavier, was harder to use, but
did a better job and
stood up better under use. Both the
steel bottom of the bucket and the
rubber valve should be heavy
because they receive hard usage.
The metal bottom is reinforced
with a crosspiece welded in place
(see Figures 20 and 21).
fig20420.gif (393x393)
When water is reached and the
cuttings are no longer firm enough
to be brought up in the auger, the
bailing bucket must be used to
clean out the well as work
progresses.
For using the bailing bucket the pulley is mounted in the
pulley bracket with a
16mm (5/8") bolt as axle. A rope attached to the
bailing bucket is then run over
the pulley and the bucket is lowered into the well. The
pulley bracket is so
designed that the rope coming off the pulley lines up
vertically with the well, so
that there is no need to shift the tripod.
The bucket is lowered into the well, preferably by two
people and allowed to drop
the last meter or meter and one-half (3 to 5 feet) so that
it will hit the bottom
with some speed. The impact will force some of the loose
soil at the bottom of
the well up into the bucket. The bucket is then repeatedly
raised and dropped 1
to 2 meters (3 to 6 feet) to pick up more soil. Experience
will show how long
this should be continued to pick up as much soil as possible
before raising and
emptying the bucket. Two or more people can raise the
bucket, which should be
dumped far enough from the well to avoid messing up the
working area.
If the cuttings are too thin to be brought up with the auger
but too thick to
enter the bucket, pour a little water down the well to
dilute them.
Bit for Drilling Rock
The bit described here has been used to drill through layers
of sedimentary stone
up to 11 meters (36') thick.
Tools and Materials
Mild steel bar: about 7cm (2 3/4") in diameter and
about 1.5 meters (5') long,
weighing about 80kg (175 pounds)
Stellite (a very hard type of tool steel) insert for cutting
edge
Anvil and hammers, for shaping
Steel rod: 2.5cm x 2cm x 50cm (1" x 3/4" x 19
3/4") for bail
Welding equipment
The drill bit for cutting through stone and hard formations
is made from the 80kg
(175-pound) steel bar (see Figures 22 and 23). The 90-degree
cutting edge is hard-surfaced
fig22440.gif (393x393)
handle) for attaching a rope or
cable is welded to the top. The bail
should be large enough to make
"fishing" easy if the rope breaks. A
2.5cm (1") rope was used at first,
but this was subject to much wear
when working in mud and water. A
1cm (3/8") steel cable was substituted
for the rope, but it was not
used enough to be able to show
whether the cable or the rope is better. One advantage of
rope is that it gives a
snap at the end of the fall which rotates the bit and keeps
it from sticking. A
swivel can be mounted between the bit and the rope or cable
to let the bit
rotate.
If a bar this size is difficult to find or too expensive, it
may be possible,
depending on the circumstances, to make one by welding a
short steel cutting end
onto a piece of pipe, which is made heavy enough by being
filled with concrete.
In using the drilling bit, put the pulley in place as with
the bailing bucket, attach
the bit to its rope or cable, and lower it into the well.
Since the bit is heavy,
wrap the rope once or twice around the back leg of the
tripod so that the bit
cannot "get away" from the workers with the chance
of someone being hurt or
the equipment getting damaged. The easiest way to raise and
drop the bit is to
run the rope through the pulley and then straight back to a
tree or post where it
can be attached at shoulder height or slightly lower.
Workers line up along the
rope and raise the bit by pressing down on the rope; they
drop it by allowing the
rope to return quickly to its original position (see Figure
24). This requires five
fig24x46.gif (393x393)
to seven workers, occasionally more. Frequent rests are
necessary, usually after
every 50 to 100 strokes. Because
the work is harder near the ends
of the rope than in the middle, the
positions of the workers should be
rotated to distribute the work
evenly.
A small amount of water should be
kept in the hole for lubrication and
to mix with the pulverized stone to
form a paste that can be removed
with a bailing bucket. Too much
water will slow down the drilling.
The speed of drilling, of course,
depends on the type of stone
encountered. In the soft water-bearing
stone of the Ban Me Thuot
area it was possible to drill several meters (about 10 feet)
per day. However,
when hard stone such as basalt is encountered, progress is
measured in centimeters
(inches). The decision must then be made whether to continue
trying to
penetrate the rock or to start over in a new location.
Experience in the past has
indicated that one should not be too hasty in abandoning a
location, since on
several occasions what were apparently thin layers of hard
rock were penetrated
and drilling then continued at a good rate.
Occasionally the bit may become stuck in the well and it
will be necessary to use
a lever arrangement consisting of a long pole attached to
the rope to free it (see Figure 25).
fig25x47.gif (437x437)
Alternatively, a windlass may be used, consisting of a
horizontal pole
used to wrap the rope around a vertical pole pivoted on the
ground and held in
place by several workers (see Figure 26). If these fail, it
may be necessary to
fig26x47.gif (437x437)
rent or borrow a chain hoist. A worn rope or cable may break
when trying to
retrieve a stuck bit. If this happens, fit a hook to one of
the auger extensions,
attach enough extensions together to reach the desired
depth, and after hooking
the bit, pull with the chain hoist. A rope or cable may also
be used for this
purpose, but are considerably more difficult to hook onto
the bit.
Drilling Mechanically
The following method can be used for raising and dropping
the bit
mechanically:
o Jack up the
rear wheel of a car and replace the wheel with a small
drum (or use
the rim as a pulley).
o Take the rope
that is attached to the bit, come from the tripod on
the pulley,
and wrap the rope loosely around the drum.
o Pull the
unattached end of the rope taut and set the drum in
motion. The
rope will move with the drum and raise the bit.
o Let the end of
the rope go slack quickly to drop the bit.
It will probably
be necessary to polish and/or grease the drum.
Dry Bucket Well Drilling
The dry bucket method is a simple and quick method of
drilling wells in dry soil
that is free of rocks. It can be used for 5cm to 7.5cm
(2" to 3") diameter wells in
which steel pipe is to be installed. For wells that are
wider in diameter, it is a
quick method of removing dry soil before completing the bore
with a wet bucket,
tubewell sand bailer, or tubewell sand auger.
A 19.5-meter (64') hole can be dug in less than three hours
with this method,
which works best in sandy soil, according to the author of
this entry, who has
drilled 30 wells with it.
Tools and Materials
Dry bucket
Rope: 16mm (5/8") or 19mm (3/4") in diameter and 6
to 9 meters (20' to 30')
longer than the deepest well to be drilled
3 Poles: 20cm (4") in diameter at large end and 3.6 to
4.5 meters (12' to 15') long
Chain, short piece
Pulley
Bolt: 12.5mm (1/2") in diameter and 30 to 35cm
(12" to 14") long (long enough to
reach through the upper ends of the three poles)
A dry bucket is simply a length of pipe with a bail or
handle welded to one end
and a slit cut in the other.
The dry bucket is held about 10cm (several inches) above the
ground, centered
above the hole location and then dropped (see Figure 1).
This drives a small
fig1x49.gif (600x600)
amount of soil up into the bucket. After this is repeated
two or three times, the
bucket is removed, held to one side and tapped with a hammer
or a piece of iron
to dislodge the soil. The process is repeated until damp
soil is reached and the
bucket will no longer remove soil.
To make the dry bucket, you will need the following tools
and materials:
Hacksaw
File
Iron rod: 10mm (3/8") or 12.5mm (1/2") in diameter
and 30cm (1') long
Iron pipe: slightly larger in diameter than the largest part
of casing to be put in
the well (usually the coupling) and 152cm (5') long
Bend the iron rod into a U-shape small enough to slide inside
the pipe. Weld it in
place as in Figure 2.
fig2x49.gif (486x486)
File a gentle taper on the inside of the opposite end to
make a cutting edge (see Figure 3).
fig3x49.gif (393x393)
Cut a slit in one side of the sharpened end of the pipe (see
Figure 2).
Source:
John Brelsford, VITA Volunteer, New Holland, Pennsylvania
Driven Wells
A pointed strainer called a well point, properly used, can
quickly and cheaply
drive a sanitary well, usually less than 7.6 meters (25')
deep. In soils where the
driven well is suitable, it is often the cheapest and
fastest way to drill a sanitary
well. In heavy soils, particularly clay, drilling with an
earth auger is faster than
driving with a well point.
Tools and Materials
Well point and driving cap (see Figure 1):
fig1x50.gif (486x486)
usually obtainable through mail order houses
from the United States and elsewhere
Pipe: 3cm (1") in diameter
Heavy hammer and wrenches
Pipe compound
Special pipe couplings and driving arrangements
are desirable but not necessary
Driven wells are highly successful in coarse sand where
there are not too many
rocks and the water table is within 7 meters (23') of the
surface. They are usually
used as shallow wells where the pump cylinder is at ground
level. If conditions
for driving are very good, 10cm (4") diameter points
and casings that can
accept the cylinder of a deep well can be driven to depths
of 10 - 15 meters (33'
to 49'). (Note that suction pumps generally cannot raise
water beyond 10 meters.)
The most common types of well points are:
o a pipe with
holes covered by a screen and a brass jacket with holes. For
general use, a
#10 slot or 60 mesh is recommended. Fine sand requires a
finer screen,
perhaps a #6 slot or 90 mesh;
o a slotted steel
pipe with no covering screen, which allows more water to
enter but is less
rugged.
Before starting to drive the point, make a hole at the site
with hand tools. The
hole should be plumb and slightly larger in diameter than
the well point.
The joints of the drive pipe must be carefully made to
prevent thread breakage
and assure airtight operation. Clean and oil the threads
carefully and use joint
compound and special drive couplings when available. To
ensure that joints stay
tight, give the pipe a fraction of a turn after each blow,
until the top joint is
permanently set. Do not twist the whole string and do not
twist and pound at the
same time. The latter may help get past stones, but soon
will break the threads
and make leaky joints.
Be sure the drive cap is tight and butted against the end of
the pipe (see Figure 2).
fig2x51.gif (600x600)
check with a plumb bob to see that the pipe is vertical.
Test it occasionally
and keep it straight by pushing on the pipe while driving.
Hit the drive cap
squarely each time or you may damage the equipment.
Several techniques can help avoid damage to the pipe. The
best way is to drive
with a steel bar that is dropped inside the pipe and strikes
against the inside of
the steel well point. It is retrieved with a cable of rope.
Once water enters the
well, this method does not work.
Another way is to use a driver pipe, which makes sure that
the drive cap is hit
squarely. A guide rod can be mounted on top of the pipe and
weight dropped over
it, or the pipe itself can be used to guide a falling weight
that strikes a special
drive clamp.
The table in Figure 3 will help identify the formations
being penetrated. Experience
fig3x52.gif (600x600)
is needed, but this may help you to understand what is
happening. When
you think that the water-bearing layer has been reached,
stop driving and attach
a handpump to try the well.
Usually, easier driving shows that the water-bearing level
has been reached,
especially in coarse sand. If the amount of water pumped is
not enough, try
driving a meter or so (a few feet) more. If the flow
decreases, pull the point
back until the point of greatest flow is found. The point
can be raised by using a
lever arrangement like a fence-post jack, or, if a
drive-monkey is used, by
pounding the pipe back up.
Sometimes sand and silt plug up the point and the well must
be "developed" to
clear this out and improve the flow. First try hard,
continuous pumping at a rate
faster than normal. Mud and fine sand will come up with the
water, but this
should clear in about an hour. It may help to allow the
water in the pipe to drop
back down, reversing the flow periodically. With most
pitcher pumps this is easily
accomplished by lifting the handle very high; this opens the
check valve, allowing
air to enter, and the water rushes back down the well.
If this does not clear up the flow, there may be silt inside
the point. This can be
removed by putting a 19mm (3/4") pipe into the well and
pumping on it. Either
use the pitcher pump or quickly and repeatedly raise and
lower the 19mm (3/4")
pipe. By holding your thumb over the top of the pipe on the
upstroke, a jet of
muddy water will result on each downstroke. After getting
most of the material
out, return to direct pumping. Clean the sand from the valve
and cylinder of the
pump after developing the well. If you have chosen too fine
a screen, it may not
be possible to develop the well successfully. A properly
chosen screen allows the
fine material to be pumped out, leaving a bed of coarse
gravel and sand that
provides a highly porous and permeable water-gathering area.
The final step is to fill in the starting borehole with
puddle clay or, if clay is
not available, with well-tamped earth. Make a solid,
water-proof pump platform
(concrete is best) and provide a place for spilled water to
drain away.
Source:
Wagner, E.G. and Lanoix, J.N. Water Supply for Rural Areas
and Small Communities.
Geneva: World Health Organization, 1959.
DUG WELLS <see figure 1>
fig1x54.gif (600x600)
A village well must often act as a reservoir, because at
certain hours of the day
the demand for water is heavy, whereas during the night and
the heat of the day
there is no call on the supply. What is suggested here is to
make the well large
enough to allow the water slowly percolating in to
accumulate when the well is
not in use in order to have an adequate supply when demand
is heavy. For this
reason wells are usually made 183 to 213cm (6' to 7') in
diameter.
Wells cannot store rainy season water for the dry season,
and there is seldom any
reason for making a well larger in
diameter than 213cm (7').
The depth of a well is much more
important than the diameter in
determining the amount of water
that can be drawn when the water
level is low. A deep, narrow well
will often provide more water than
a wide shallow one.
Remember that tubewells are much
easier to construct than dug wells,
and should be used if your region
allows their construction and an
adequate amount of water can be
drawn from them during the busy
hours (see section on Tubewells).
Deep dug wells have several
disadvantages. The masonry lining
needed is very expensive. Construction
is potentially very dangerous;
workers should not dig deeper than
one and a half meters without
shoring up the hole. An open well
is very easily contaminated by
organic matter that falls in from
the surface and by the buckets
used to lift the water. There is an
added problem of disposing of the
great quantity of soil removed from
a deep dug well.
Sealed Dug Well
The well described here has an
underground concrete tank that is
connected to the surface with a
casing pipe, rather than a large-diameter
lining as described in the
preceding entry. The advantages are
that it is relatively easy to build,
easy to seal, takes up only a small
surface area, and is low in cost.
Many of these wells were installed in India by an American
Friends Service
Committee team there; they perform well unless they are not
deep enough or
sealed and capped properly.
Tools and Materials
4 reinforced concrete rings with iron hooks for lowering,
91.5cm (3') in diameter
1 reinforced concrete cover with a seating hole for casing pipe
Washed gravel to surround tank: 1.98 cubic meters (70 cubic
feet)
Sand for top of well: 0.68 cubic meters (24 cubic feet)
Concrete pipe: 15cm (6") in diameter, to run from the
top of the tank cover to at
least 30.5cm (1') above ground
Concrete collars: for joints in the concrete pipe
Cement: 4.5kg (10 pounds) for mortar for pipe joints
Deep-well pump and pipe
Concrete base for pump
Tripod, pulleys, rope for lowering rings
Special tool for positioning casing when refilling, see
"Positioning Casing Pipe,"
below
Digging tools, ladders, rope
A villager in Barpali, India, working with an American
Friends Service Committee
unit there, suggested that they make a masonry tank at the
bottom of the well,
roof it over, and draw the water from it with a pump. The resulting
sealed well
has many advantages:
o It provides pure
water, safe for drinking.
o It presents no
hazard of children falling in.
o Drawing water is
easy, even for small children.
o The well occupies
little space, a small courtyard can accommodate it.
o The cost of
installation is greatly reduced.
o The labor
involved is much reduced.
o There is no
problem of getting rid of excavated soil, since most of it is
replaced.
o The casing
enables the pump and pipe to be easily removed for servicing.
o The gravel and
sand surrounding the tank provide an efficient filter to
prevent silting,
allow a large surface area for percolating water to fill the
tank, and
increase the effective stored volume in the tank.
On the other hand, compared to a well where people draw
their own buckets or
other containers of water, there are three minor
disadvantages: only one person
can pump at a time, the pump requires regular maintenance,
and a certain amount
of technical skill is required to make the parts used in the
well and to install
them properly.
A well is dug 122cm (4') in diameter and about 9 meters
(30') deep. The digging
should be done in the dry season, after the water table has
dropped to its lowest
level. There should be a full 3 meter (10') reaccumulation
of water within 24
hours after the well has been bailed or pumped dry. Greater
depth is, of course,
desirable.
Spread 15cm (6") of clean, washed gravel or small rock
over the bottom of the
well. Lower the four concrete rings and cover into the well
and position them
there to form the tank. A tripod of strong poles with block
and tackle is needed
to lower the rings, because they weigh about 180kg (400
pounds) each. The tank
formed by the rings and cover is 183cm (6') high and 91.5cm
(3') in diameter. The
cover has a round opening which forms a seat for the casing
pipe and allows the
suction pipe to penetrate to about 15cm (6") from the
gravel bottom.
The first section of concrete pipe is positioned in the seat
and grouted (mortared)
in place. It is braced vertically by a wooden plug with four
hinged arms to brace
against the sides of the wall. Gravel is packed around the
concrete rings and over
the top of the cover till the gravel layer above the tank is
at least 15cm (6")
deep. This is then covered with 61cm (2') of sand. Soil
removed from the well is
then shoveled back until the shaft is filled within 15cm
(6") of the top of the
first section of casing. The next section of casing is then
grouted in place, using
a concrete collar made for this purpose. The well is filled
and more sections of
casing added until the casing extends at least 30cm (1')
above the surrounding
soil level.
The soil that will not pack back into the well can be used
to make a shallow hill
around the casing to encourage spilled water to drain away
from the pump. A
concrete cover is placed on the casing and a pump installed.
If concrete or other casing pipe cannot be obtained, a
chimney made of burned
bricks and sand-cement mortar will suffice. The pipe is
somewhat more expensive,
but much easier to install.
Source:
A Safe Economical Well. Philadelphia: American Friends
Service Committee, 1956
(Mimeographed).
Deep Dug Well
Untrained workers can safely dig a deep sanitary well with
simple, light equipment,
if they are well supervised. The basic method is outlined
here.
Tools and Materials
Shovels, mattocks
Buckets
Rope--deep wells require wire rope
Forms--steel, welded and bolted together
Tower with winch and pulley
Cement
Reinforcing rod
Sand
Aggregate
Oil
The hand dug well is the most widespread of any kind of
well. Unfortunately, in
many places these wells are dug by people unfamiliar with
good sanitation
methods and become infected by parasitic and bacterial
disease. By using modern
methods and materials, dug wells can safely be made 60
meters (196.8') deep and
will give a permanent source of pure water.
Experience has shown that for one person, the average width
of a round well for
best digging speed is 1 meter (3 1/4'). However, 1.3 meters
(4 1/4') is best for
two workers digging together and they dig more than twice as
fast as one person.
Thus, two workers in the larger hole is usually best.
Dug wells always need a permanent lining (except in solid
rock, where the best
method is usually to drill a tubewell).
The lining prevents collapse of the hole, supports the pump
platform, stops
entrance of contaminated surface water, and supports the
well intake, which is
the part of the well through which water enters. It is
usually best to build the
lining while digging, since this avoids temporary supports
and reduces danger of
cave-ins.
Dug wells are lined in two ways: (1) where the hole is dug
and the lining is built
in its permanent place and (2) where sections of lining are
added to the top and
the whole lining moves down as earth is removed from beneath
it. The second
method is called caissoning; often a combination of both is
best (Figure 2.)
fig2x58.gif (600x600)
If possible, use concrete for the lining because it is
strong, permanent, and made
mostly of local materials. It can also be handled by
unskilled workers with good
speed and results. (See section on Concrete Construction).
Masonry and brickwork are widely used in many countries and
can be very
satisfactory if conditions are right. In bad ground,
however, unequal pressures can
make them bulge or collapse. Building with these materials
is slow and a thicker
wall is required than with concrete. There is also always
the danger of movement
during construction in loose sands or swelling shale before
the mortar has set
firmly between the bricks or stones.
Wood and steel are not good for lining wells. Wood requires
bracing, tends to rot
and hold insects, and sometimes makes the water taste bad.
Worst of all, it will
not make the well watertight against contamination. Steel is
seldom used because
it is expensive, rusts quickly, and if it is not heavy
enough is subject to bulging
and bending.
The general steps in finishing the first 4.6 meters (15')
are:
o set up a tripod
winch over cleared, level ground and mark reference points
for plumbing and
measuring the depth of the well.
o have two workers
dig the well while another raises and unloads the dirt
until the well is
exactly 4.6 meters (15') deep.
o trim the hole to
size using a special jig mounted on the reference points.
o place the forms
carefully and fill one by one with tamped concrete.
After this is done, dig to 9.1 meters (30'), trim and line
this part also with
concrete. A 12.5cm (5") gap between the first and
second of these sections is
filled with pre-cut concrete that is grouted (mortared) in
place. Each lining is
self-supporting as it has a curb. The top of the first
section of lining is thicker
than the second section and extends above the ground to make
a good foundation
for the pump housing and to make a safe seal against ground
water.
This method is used until the water-bearing layer is
reached; there an extra-deep
curb is constructed. From this point on, caissoning is used.
Caissons are concrete cylinders fitted with bolts to attach
them together. They
are cast and cured on the surface in special molds, prior to
use. Several caissons
are lowered into the well and assembled together. As workers
dig, the caissons
drop lower as earth is removed from beneath them. The
concrete lining guides the
caissons.
If the water table is high when the well is dug, extra
caissons are bolted in place
so that the well can be finished by a small amount of
digging, and without
concrete work, during the dry season.
Details on plans and equipment for this process are found in
Water Supply for
Rural Areas and Small Communities, by E. G. Wagner and J. N.
Lanoix, World
Health Organization, 1959.
Reconstructing Dug Wells
Open dug wells are not very sanitary, but they can often be
rebuilt by relining
the top 3 meters (10') with a watertight lining, digging and
cleaning the well and
covering it. This method involves installation of a buried
concrete slab; see Figure 3
fig3x60.gif (600x600)
for construction details.
Tools and Materials
Tools and materials for reinforced concrete
A method for entering the well
Pump and drop pipe
Before starting, check the following:
o Is the well
dangerously close to a privy or other source of contamination? Is
it close to a
water source? Is it desirable to dig a new well elsewhere
instead of
cleaning this one? Could a privy be moved, instead?
o Has the well ever
gone dry? Should you deepen it as well as clean it?
o Surface drainage
should generally slope away from the well and there should
be effective
disposal of spilled water.
o What method will
you use to remove the water and what will it cost?
o Before entering
the well to inspect the old lining, check for a lack of
oxygen by lowering
a lantern or candle. If the flame remains lit, it is
reasonably safe to
enter the well. If the flame goes out, the well is dangerous
to enter. Tie a
rope around the person entering the well and have two
strong workers on
hand to pull him out in case of accident.
Relining the Wall
The first job is to prepare the upper 3 meters (10') of the
lining for concrete by
removing loose rock and chipping away old mortar with a
chisel, as deep as
possible (see Figure 4). The next task is to clean out and
deepen the well, if that
fig4x62.gif (600x600)
is necessary. All organic matter and silt should be bailed
out. The well may be
dug deeper, particularly during the dry season, with the
methods outlined in "Deep
Dug Wells." One way to increase the water yield is to
drive a well point deeper
into the water-bearing soil. This normally will not raise
the level of water in the
well, but may make the water flow into the well faster. The
well point can be
piped directly to the pump, but this will not make use of
the reservoir capacity
of the dug well.
The material removed from the well can be used to help form
a mound around the
well so water will drain away from the opening. Additional
soil will usually be
needed for this mound. A drain lined with rock should be
provided to take spilled
water away from the concrete apron that covers the well.
Reline the well with concrete troweled in place over wire
mesh reinforcement.
The largest aggregate should be pea-sized gravel and the mix
should be fairly rich
with concrete, using no more than 20-23 liters (5 1/2 to 6
gallons) of water to a
43kg (94 pound) sack of cement. Extend the lining 70cm (27
1/2") above the
original ground surface.
Installing the Cover and Pump
Cast the well cover so that it makes a watertight seal with
the lining to keep
surface impurities out. The cover will also support the
pump. Extend the slab out
over the mound about a meter (a few feet) to help drain
water away from the
site. Make a manhole and space for the drop pipe of the
pump. Mount the pump
off center so there is room for the manhole. The pump is
mounted on bolts cast
into the cover. The manhole must be 10cm (4") higher
than the surface of the
slab. The manhole cover must overlap by 5cm (2") and
should be fitted with a
lock to prevent accidents and contamination. Be sure that
the pump is sealed to
the slab.
Disinfecting the Well
Disinfect the well by using a stiff brush to wash the walls
with a very strong
solution of chlorine. Then add enough chlorine in the well
to make it about half
the strength of the solution used on the walls. Sprinkle
this last solution all over
the surface of the well to distribute it evenly. Cover the
well and pump up the
water until the water smells strongly of chlorine. Let the
chlorine remain in the
pump and well for one day and then pump it until the
chlorine is gone.
Have the well water tested several days after disinfection
to be sure that it is
pure. If it is not, repeat the disinfection and testing. If
it is still not pure, get
expert advice.
Sources:
Wagner, E.G. and Lanoix, J.N. Water Supply for Rural Areas
and Small Communities.
Geneva: World Health Organization, 1959.
Manual of Individual Water Supply Systems, Public Health
Service Publication No.
24. Washington, D.C.: Department of Health and Human Services.
SPRING DEVELOPMENT
Springs, particularly in sandy soil, often make excellent
water sources, but they
should be dug deeper, sealed, protected by a fence, and
piped to the home. Proper
development of a spring will increase the flow of ground
water and lower the
chances of contamination from surface water. If fissured
rock or limestone are
present, get expert advice before attempting to develop the
spring.
Springs occur where water, moving through porous and
saturated underground
layers of soil (aquifer), emerges at the ground surface.
They can be either:
o Gravity seepage,
where the water bearing soil reaches the surface over an
impermeable layer,
or
o Pressure or
artesian, where the water, under pressure and trapped by a hard
layer of soil,
finds an opening and rises to the surface. (In some parts of
the world, all
springs are called artesian.)
The following steps should be considered in developing
springs:
1)
Observe the seasonal flow variations over a
period of a year if possible.
2)
Determine the type of spring-seepage or
artesian-by digging a small
hole. An earth
auger with extensions is the most suitable tool for that
job. It may not
be possible to reach the underlying impermeable layer.
3)
Have chemical and biological tests made on
samples of the water.
Dig a small hole near the spring to learn the depth of the
hard layer of soil and
to find out whether the spring is gravity seepage or
pressure. Check uphill and
nearby for sources of contamination. Test the water to see
if it must be purified
before being used for drinking. A final point: Find out if
the spring runs during
long dry spells.
For gravity-fed springs, the soil is usually dug to the
hard, underlying layers and
a tank is made with watertight concrete walls on all but the
uphill side (see Figures 1 and 2).
fig1x650.gif (600x600)
The opening on the uphill side should be lined with porous
concrete or stone without mortar, so that it will admit the
gravity seepage water.
It can be backfilled with gravel and sand, which helps to
keep fine materials in
the water-bearing soil from entering the spring. If the hard
soil cannot be
reached easily, a concrete cistern is built that can be fed
by a perforated pipe
placed in the water-bearing layer of earth. With a pressure
spring, all sides of
the tank are made of watertight reinforced concrete, but the
bottom is left open.
The water enters through the bottom.
Read the section in this handbook on cisterns before
developing your spring. No
matter how the water enters your tank, you must make sure
the water is pure by:
o building a
complete cover to stop surface pollution and keep out sunlight,
which causes algae
to grow.
o installing a
locked manhole with at least a 5cm (2") overlap to prevent
entrance of
polluted ground water.
o installing a
screened overflow that discharges at least 15cm (6") above the
ground. The water
must land on a cement pad or rock surface to keep the
water from making
a hole in the ground and to ensure proper drainage away
from the spring.
o arranging the
spring so that surface water must filter through at least 3
meters (10') of
soil before reaching the ground water. Do this by making a
diversion ditch
for surface water about 15 meters (50') or more from the
spring. Also, if
necessary, cover the surface of the ground near the spring
with a heavy layer
of soil or clay to increase the distances that rainwater
must travel, thus
ensuring that it has to filter through 3 meters (10') of
soil.
o making a fence to
keep people and animals away from the spring's immediate
surroundings. The
suggested radius is 7.6 meters (25').
o installing a
pipeline from the overflow to the place where the water is to be
used.
Before using the spring, disinfect it thoroughly by adding
chlorine or chlorine
compounds. Shut off the overflow to hold the chlorine
solution in the well for 24
hours. If the spring overflows even though the water is shut
off, arrange to add
chlorine so that it remains strong for at least 30 minutes,
although 12 hours
would be much safer. After the chlorine is flushed from the
system have the
water tested. (See section on
"Superchlorination.")
Sources:
Wagner, E.G. and Lanoix, J.N. Water Supply for Rural Areas
and Small Communities.
Geneva: World Health Organization, 1959.
Manual of Individual Water Supply Systems, Public Health
Service Publication No.
24. Washington, D.C.: U.S. Department of Health and Human
Services.
Acknowledgements
John M. Jenkins III, VITA Volunteer, Marrero, Louisiana
Ramesh Patel, VITA Volunteer, Albany, New York
William P. White, VITA Volunteer, Brooklyn, Connecticut
Water Lifting and Transport
OVERVIEW
Once a source of water has been found and developed, four
basic questions must
be answered:
1.
What is the rate of flow of the water in
your situation?
2.
Between what points must the water be
transported?
3.
What kind and size of piping is needed to
transport the required flow?
4.
What kind of pump, if any, is necessary to
produce the required flow?
The information in this section will help you to answer the
third and fourth
questions, once you have determined the answers to the first
two.
Moving Water
The first three entries in this section discuss the flow of
water in small streams,
partially filled pipes, and when the height of the reservoir
and size of pipe are
known. They include equations and alignment charts (also
called nomographs) that
give simple methods of estimating the flow of water under
the force of gravity,
that is, without pumping. The fourth tells how to measure
flow by observing the
spout from a horizontal pipe.
Four entries follow on piping, including a discussion of
pipes made of bamboo.
You will note that in the alignment charts here and
elsewhere, the term "nominal
diameter, inches, U.S. Schedule 40" is used along with
the alternate term, "inside
diameter in centimeters," in referring to pipe size.
Pipes and fittings are usually manufactured to a standard
schedule of sizes. U.S.
Schedule 40, the most common in the United States, is also
widely used in other
countries. When one specifies "2-inch Schedule
40," one automatically specifies the
pressure rating of the pipe and its inside and outside
diameters (neither of which,
incidentally, is actually 2"). If the schedule is not
known, measure the inside
diameter and use this for flow calculations.
Lifting Water
Next, several entries follow the steps required to design a
water-pumping system
with piping. The first entry in this group, "Pump
Specifications: Choosing or
Evaluating a Pump," presents all the factors that must
be considered in selecting
a pump. Fill out the form included there and make a piping
sketch, whether you
plan to send it to a consultant for help or do the design and
selection yourself.
The first pieces of information needed for selecting pump
type and size are: (1)
the flow rate of water needed and (2) the head or pressure
to be overcome by
the pump. The head is composed of two parts: the height to
which the liquid must
be raised, and the resistance to flow created by the pipe
walls (friction-loss).
The friction-loss head is the most difficult factor to
measure. The entry "Determining
Pump Capacity and Horsepower Requirements" describes
how to select the
economic pipe size(s) for the flow desired. With the pipe(s)
selected one must
then calculate the friction-loss head. The entry
"Estimating Flow Resistance of
Pipe Fittings" makes it possible to estimate extra
friction caused by constrictions
of pipe fittings. With this information and the length of
pipe, it is possible to
estimate the pump power requirement using the entry,
"Determining Pump Capacity
and Horsepower Requirements."
These entries have another very important use. You may
already have a pump and
wonder "Will it do this job?" or "What size
motor should I buy to do this job
with the pump I have?" The entry "Pump
Specifications: Choosing or Evaluating a
Pump" can be used to collect all the information on the
pump and on the job you
want it to do. With this information, you can ask a
consultant or VITA if the
pump can be used or not.
There are many varieties of pumps for lifting water from
where it is to where it
is to be delivered. But for any particular job, there are
probably one or two kinds
of pumps that will serve better than others. We will discuss
here only two broad
classes of pumps: lift pumps and force pumps.
A lift or suction pump is located at the top of a well and
raises water by
suction. Even the most efficient suction pump can create a
negative pressure of
only 1 atmosphere: theoretically, it could raise a column of
water 10.3m (34') at
sea level. But because of friction losses and the effects of
temperature, a suction
pump at sea level can actually lift water only 6.7m to 7.6m
(22' to 25'). The entry
"Determining Lift Pump Capability" explains how to
find out the height a lift
pump will raise water at different altitudes with different
water temperatures.
When a lift pump is not adequate, a force pump must be used.
With a force pump,
the pumping mechanism is placed at or near the water level
and pushes the water
up. Because it does not depend on atmospheric pressure, it
is not limited to a
7.6m (25') head.
Construction details are given for two irrigation pumps that
can be made at the
village level. An easy-to-maintain pump handle mechanism is
described. Use of the
hydraulic ram, a self-powered pump, is described.
Finally, there are entries on Reciprocating Wire Power
Transmission for Water
Pumps, and on Wind Energy for Water Pumping. Further details
on pumps can be
found in the publications listed below and in the Reference
section at the back of
the book.
Margaret Crouch, ed. Six Simple Pumps. Arlington, Virginia:
Volunteers in
Technical Assistance, 1982.
Molenaar, Aldert. Water Lifting Devices for Irrigation.
Rome: Food and Agriculture
Organization, 1956.
Small Water Supplies. London: The Ross Institute, The London
School of Hygiene
and Tropical Medicine, 1967.
WATER TRANSPORT
Estimating Small Stream Water Flow
A rough but very rapid method of estimating water flow in
small streams is given
here. In looking for water sources for drinking, irrigation,
or power generation,
one should survey all the streams available. If sources are
needed for use over a
long period, it is necessary to collect information
throughout the year to determine
flow changes-especially high and low flows. The number of
streams that
must be used and the flow variations are important factors
in determining the
necessary facilities for utilizing the water.
Tools and Materials
Timing device, preferably watch with second hand
Measuring tape
Float (see below) <see figure 1>
fig1x69.gif (393x393)
Stick for measuring depth
The following equation will help you to measure flow
quickly:
Q = KxAxV,
where:
Q (Quantity) = flow
in liters per minute
A (Area) =
cross-section of stream, perpendicular to flow, in square meters
V (Velocity) =
stream velocity, meters per minute
K (Constant) = a
corrected conversion factor. This is used because surface flow
is normally
faster than average flow. For normal stages use K = 850; for
flood states use
]K = 900 to 950.
To Find Area of a Cross-Section
The stream will probably have different depths along its length
so select a place
where the depth of the stream is average.
o Take a measuring
stick and place it upright in the water about one-half
meter (1 1/2')
from the bank.
o Note the depth of
water.
o Move the stick 1
meter (3') from the bank in a line directly across the
stream. Note the
depth.
o Move the stick
1.5 meters (4 1/2') from the bank, note the depth, and
continue moving
it at half-meter (1 1/2') intervals until you cross the
stream.
Note the depth each time you place the stick upright in the
stream. Draw a grid,
like the one in Figure 2, and mark the varying depths on it
so that a cross-section
fig2x70.gif (437x437)
of the stream is shown. A
scale of 1cm to 10cm is often used
for such grids. By counting the
grid squares and fractions of
squares, the area of the water can
be estimated. For example, the grid
shown here has a little less than 4
square meters of water.
To Find Velocity
Put a float in the stream and measure the distance of travel
in one minute (or
fraction of a minute, if necessary.) The width of the stream
where the velocity is
being measured should be as constant as possible and free of
rapids.
A light surface float, such as a chip, will often change
course because of wind or
surface currents. A weighted float, which sits upright in
the water, will not
change course so easily. A lightweight tube or tin can,
partly filled with water or
gravel so that it floats upright with only a small part
showing above water,
makes a good float for measuring.
Measuring Wide Streams
For a wide, irregular stream, it is better to divide the
stream into 2- or 3-meter
sections and measure the area and velocity of each. Q is
then calculated for each
section and the Qs added together to give a total flow.
Example (see Figure 2):
Cross section is
4 square meters
Velocity of float
= 6 meters traveled in 1/2 minute
Stream flow is
normal
Q = 850 x 4 x 6
meters
--------
.5
minute
Q = 40,800 liters
per minute or 680 liters per second
Using English Units
If English units of measurement are used, the equation for
measuring stream flow
is: Q = K x A x V, where:
Q = flow in U.S.
gallons per minute
A = cross-section
of stream, perpendicular to flow, in square feet
V = stream
velocity in feet per minute
K = a corrected
conversion factor: 6.4 for normal stages; 6.7 to 7.1 for flood
stages
The grid used would be like the one in Figure 3; a common
scale is 1" to 12".
fig3x72.gif (393x393)
Example:
Cross-section is 15 square feet
Float velocity = 20' in 1/2 minute
Stream flow is normal
Q = 6.4 x 15 x 20
feet
-------
.5 minute
Q = 3,800 gallons
per minute
Source:
Clay, C.H. Design of Fishways and Other Fish Facilities.
Ottawa: P.E. Department
of Fisheries of Canada, 1961.
Measuring Water Flow in Partially-Filled Pipes
The flow of water in partially-filled horizontal pipes
(Figure 1) or circular
fig1x72.gif (317x393)
channels can be determined-if you know the inside diameter
of the pipe and the
depth of the water flowing-by using the alignment chart
(nomograph) in Figure 2.
fig2x73.gif (540x540)
This method can be checked
for low flow rates and small
pipes by measuring the time
required to fill a bucket or
drum with a weighed quantity
of water. A liter of water
weighs 1kg (1 U.S. gallon of
water weighs 8.33 pounds).
Tools and Materials
Ruler to measure water depth (if ruler units are inches,
multiply by 2.54 to
convert to centimeters)
Straight edge, to use with alignment chart
The alignment chart applies to pipes with 2.5cm to 15cm
inside diameters, 20 to
60% full of water, and having a reasonably smooth surface
(iron, steel, or
concrete sewer pipe). The pipe or channel must be reasonably
horizontal if the
result is to be accurate. The eye, aided by a plumb line to
give a vertical
reference, is a sufficiently good judge. If the pipe is not
horizontal another
method will have to be used. To use the alignment chart,
simply connect the
proper point on the "K" scale with the proper
point on the "d" scale with the
straight edge. The flow rate can then be read from the
"q" scale.
q =
rate of flow of water, liters per minute
8.33 pounds = 1 gallon.
d =
internal diameter of pipe in centimeters.
K =
decimal fraction of vertical diameter
under water. Calculate K by
measuring the depth of water (h) in the pipe and dividing it
by the
pipe diameter (d), or K = h (see Figure 1).
fig1x75.gif (600x600)
-
d
Example:
What is the rate of flow of water in a pipe with an internal
diameter of 5cm,
running 0.3 full? A straight line connecting 5 on the
d-scale with 0.3 on the K-scale
intersects the q-scale at flow of 18 liters per minute.
Source:
Greve Bulletin 32, Volume 12, No. 5, Purdue University,
1928.
Determining Probable Water Flow with Known
Reservoir Height and Size and Length of Pipe
The alignment chart in Figure 1 gives a reasonably accurate
determination of
water flow when pipe size, pipe length, and height of the
supply reservoir are
known. The example given here is for the analysis of an
existing system. To
design a new system, assume a pipe diameter and solve for
flow rate, repeating
the procedure with new assumed diameters until one of them
provides a suitable
flow rate.
Tools and Materials
Straightedge, for use with alignment chart
Surveying instruments, if available
The alignment chart was prepared for clean, new steel pipe.
Pipes with rougher
surfaces or steel or cast iron pipe that has been in service
for a long time may
give flows as low as 50 percent of those predicted by this
chart.
The available head (h) is in meters and is taken as the
difference in elevation
between the supply reservoir and the point of demand. This
may be crudely
estimated by eye, but for accurate results some sort of
surveying instruments are
necessary.
For best results, the length of pipe (L) used should include
the equivalent lengths
of fittings as described in the section, "Estimating
Flow Resistance of Pipe
Fittings," p. 76. This length (L) divided by the pipe
internal diameter (D) gives
the necessary "L/D" ratio. In calculating L/D,
note that the units of measuring
both "L" and "D" must be the same, e.g.,
feet divided by feet; meters divided by
meters; centimeters by centimeters.
Example:
Given available head (h) of 10 meters, pipe internal
diameter (D) of 3cm, and
equivalent pipe length (L) of 30 meters (3,000cm).
Calculate L/D = 3,000cm = 1,000
-------
3cm
The alignment chart solution is in two steps:
1. Connect internal
diameter 3cm to available head (10 meters), and make a
mark on the Index
Scale. (In this step, disregard "Q" scale)
2. Connect mark on
Index Scale with L/D (1,000), and read flow rate (Q) of
approximately 140
liters per minute.
Estimating Water
Flow from Horizontal Pipes
If a horizontal pipe is discharging a full stream of water,
you can estimate the
rate of flow from the alignment chart in Figure 2. This is a
standard engineering
fig2x77.gif (600x600)
technique for estimating flows; its results are usually
accurate to within 10
percent of the actual flow rate.
Tools and Materials
Straightedge and pencil, to use alignment chart
Tape measure
Level
Plumb bob
The water flowing from the pipe must completely fill the
pipe opening (see Figure 1).
fig1x76.gif (393x393)
The results from the chart will be most accurate when there
is no constricting
or enlarging fitting at the end of the pipe.
Example:
Water is flowing
out of a pipe with an inside diameter (d) of 3cm (see Figure 1).
The stream drops
30cm at a point 60cm from the end of the
pipe.
Connect the 3cm
inside diameter point on the "d" scale in Figure 2
with the 60cm
point on the "D" scale. This line intersects the "q" scale
at about 100
liters per minute, the rate at which water is flowing out
of the pipe.
Source:
Duckworth, Clifford C. "Flow of Water from Horizontal
Open-end Pipes." Chemical
Processing, June 1959, p. 73.
Determining Pipe
Size or Velocity of Water in Pipes
The choice of pipe size is one of the first steps in
designing a simple water
system.
The alignment chart in Figure 1 can be used to compute the
pipe size needed for
fig1x79.gif (600x600)
a water system when the water velocity is known. The chart
can also be used to
find out what water velocity is needed with a given pipe
size to yield the
required rate of flow.
Tools and Materials
Straightedge
Pencil
Practical water systems use water velocities from 1.2 to 1.8
meters (3.9 to 5.9
feet) per second. Very fast velocity requires high pressure
pumps, which in turn
require large motors and use excessive power. Velocities
that are too low are
expensive because larger pipe diameters must be used.
It may be advisable to calculate the cost of two or more
systems based on
different pipe sizes. Remember, it is usually wise to choose
a little larger pipe if
higher flows are expected in the next 5 to 10 years. In
addition, water pipes
often build up rust and scale, reducing the diameter and
thereby increasing the
velocity and pump pressure required to maintain flow at the
original rate. If extra
capacity is designed into the piping system, more water can
be delivered by
adding to the pump capacity without changing all the piping.
To use the chart, locate the flow (liters per minute) you
need on the Q-scale.
Draw a line from that point, through 1.8m/sec velocity on
the V-scale, to the d-scale.
Choose the nearest standard size pipe.
For example, suppose you need a flow of 50 liters per minute
at the time of peak
demand. Draw a line from 50 liters per minute on the Q-scale
through 1.8m/sec
on the V-scale. Notice that this intersects the d-scale at
about 2.25. The correct
pipe size to choose would be the next largest standard pipe
size, e.g., 1" nominal
diameter, U.S. Schedule 40. If pumping costs (electricity or
fuel) are high, it
would be well to limit velocity to 1.2m/sec and install a
slightly larger pipe size.
Source:
Crane Company Technical Paper #409, pages 46-47.
Estimating Flow
Resistance of Pipe Fittings
One of the forces a pump must overcome to deliver water is
the friction/resistance
of pipe fittings and valves to the flow of water. Any bends,
valves,
constrictions, or enlargements (such as passing through a
tank) add to friction.
The alignment chart in Figure 1 gives a simple but reliable
way to estimate this
resistance: it gives the equivalent length of straight pipe
that would have the
same resistance. The sum of these equivalent lengths is then
added to the actual
length of pipe. This gives the total equivalent pipe length,
which is used in the
entry, "Determining Pump Capacity and Horsepower
Requirements," to determine
total friction loss.
Rather than calculate the pressure drop for each valve or
fitting separately,
Figure 1 gives the equivalent length of straight pipe.
Valves
Note the difference in equivalent length depending on how
far the valve is open.
1. Gate Valve: full
opening valve; can see through it when open; used for
complete shut off
of flow.
2. Globe Valve:
cannot see through it when open; used for regulating flow.
3. Angle Valve: like
the globe, used for regulating flow.
4. Swing Check
Valve: a flapper opens to allow flow in one direction but
closes when water
tries to flow in the opposite direction.
Example 1:
Pipe with 5cm inside diameter
Equivalent Length in Meters
a. Gate Valve (fully open)
.4
b. Flow into line - ordinary entrance
1.0
c. Sudden enlargement into 10cm pipe
1.0
(d/D = 1/2)
d. Pipe length
10.0
Total Equivalent Pipe Length
12.4
Example 2:
Pipe with 10cm
inside diameter
Equivalent Length in Meters
a. Elbow (standard)
4.0
b. Pipe length
10.0
Total Equivalent Pipe Length
14.0
Fittings
Study the variety of tees and elbows: note carefully the
direction of flow through
the tee. To determine the equivalent length of a fitting,
(a) pick proper dot on
"fitting" line, (b) connect with inside diameter
of pipe, then using a straight edge
read equivalent length of straight pipe in meters, and (c)
add the fitting
equivalent length to the actual length of pipe being used.
Source:
Crane Company Technical Paper #409, pages 20-21.
Bamboo Piping
Where bamboo is readily available, it seems to be a good
substitute for metal
pipe. Bamboo pipe is easy to make with unskilled labor and
local materials. The
important features of the design and construction of a
bamboo piping system are
given here.
Bamboo pipe is extensively used in Indonesia to transport
water to villages. In
many rural areas of Taiwan, bamboo is commonly used in place
of galvanized iron
for deep wells up to a maximum depth of 150 meters (492').
Bamboos of 50mm (2")
diameter are straightened by means of heat, and the inside
nodes knocked out.
The screen is made by punching holes in the bamboo and
wrapping that section
with a fibrous mat-like material from a palm tree,
Chamaerops humilis. In fact,
such fibrous screens are also used in many galvanized iron
tube wells.
Bamboo piping can hold pressure up to two atmospheres (about
2.1kg per square
centimeter or 30 pounds per square inch). It cannot,
therefore, be used as
pressure piping. It is most suitable in areas where the
source of supply is higher
than the area to be served and the flow is under gravity.
Figure 1 is a sketch of a bamboo pipe water supply system
for a number of
fig1x83.gif (540x540)
villages. Figure 2 shows a public water fountain.
fig2x83.gif (540x540)
Health Aspects
If bamboo piping is to carry water for drinking purposes,
the only preservative
treatment recommended is boric acid: borax in a 1:1 ratio by
weight. The recommended
treatment is to immerse green bamboo completely in a
solution of 95
percent water and 5 percent boric acid.
After a bamboo pipe is put into operation it gives an
undesirable odor to the
water. This, however, disappears after about three weeks. If
chlorination is done
before discharge to the pipe, a reservoir giving sufficient
contact time for
effective disinfection is required since bamboo pipe removes
chlorine compounds
and no residual chlorine will be maintained in the pipe. To
avoid possible contamination
by ground water, an ever present danger, it is desirable to
maintain
the pressure within the pipe at a higher level than any
water pressure outside the
pipe. Any leakage will then be from the pipe, and
contaminated water will not
enter the pipe.
Design and Construction
Tools and Materials
Chisels (see text and Figure 3)
fig3x84.gif (270x540)
Nail, cotter pin, or linchpin
Caulking materials
Tar
Rope
Bamboo pipe is made of lengths of bamboo of the desired
diameter by boring out
the dividing membrane at the joints. A circular chisel for
this purpose is shown
in Figure 3. One end of a short length of steel pipe is
belled out to increase the
diameter and the edge sharpened. A length of bamboo pipe of
sufficiently small
diameter to slide into the pipe is used as a boring bar and
secured to the pipe by
drilling a small hole through the assembly and driving a
nail through the hole. (A
cotter pin or linchpin could be used instead of the nail.)
Three or more chisels
ranging from smallest to the maximum desired diameter are
required. At each
joint the membrane is removed by first boring a hole with
the smallest diameter
chisel, then progressively enlarging the hole with the
larger diameter chisels.
Bamboo pipe lengths are joined in a number of ways, as shown
in Figure 4. Joints
fig4x85.gif (600x600)
are made watertight by caulking with cotton wool mixed with
tar, then tightly
binding with rope soaked in hot tar.
Bamboo pipe is preserved by laying the pipe below ground
level and ensuring a
continuous flow in the pipe. Where the pipe is laid above
ground level, it is
protected by wrapping it with layers of palm fiber with soil
between the layers.
This treatment will give a life expectancy of about 3 to 4
years to the pipe; some
bamboo will last up to 5-6 years. Deterioration and failure
usually occur at the
natural joints, which are the weakest parts.
Where the depth of the pipe below the water source is such
that the maximum
pressure will be exceeded, pressure relief chambers must be
installed. A typical
chamber is shown in Figure 5. These chambers are also
installed as reservoirs for
fig5x86.gif (600x600)
branch supply lines to villages en route.
Size requirements for bamboo pipe may be determined by using
the pipe capacity
alignment chart in Figure 6.
fig6x87.gif (600x600)
Source:
Water Supply Using Bamboo Pipe. AID-UNC/IPSED Series Item
No. 3, International
Program in Sanitary Engineering Design, University of North
Carolina, 1966.
WATER LIFTING
Pump Specifications: Choosing or Evaluating a Pump
The form given in Figure 1, the "Pump Application Fact
Sheet," is a check list
fig1x89.gif (600x600)
for collecting the information needed to get help in
choosing a pump for a
particular situation. If you have a pump on hand, you can
also use the form to
estimate its capabilities. The form is an adaptation of a
standard pump specification
sheet used by engineers.
Fill out the form and send it off to a manufacturer or a
technical assistance
organization like VITA to get help in choosing a pump. If
you are doubtful about
how much information to give, it is better to give too much
information than to
risk not giving enough. When seeking advice on how to solve
a pumping problem
or when asking pump manufacturers to specify the best pump for
your service,
give complete information on what its use will be and how it
will be installed. If
the experts are not given all the details, the pump chosen
may give you trouble.
The "Pump Application Fact Sheet" is shown filled
in for a typical situation. For
your own use, make a copy of the form. The following
comments on each numbered
item on the fact sheet will help you to complete the form
adequately.
1. Give the exact
composition of the liquid to be pumped: Fresh or salt water,
oil, gasoline,
acid, alkali, etc.
2. Weight percent of
solids can be found by getting a representative sample in
a pail. Let the
solids settle to the bottom and decant the liquid (or filter
the liquid
through a cloth so that the liquid coming through is clear). Weigh
the solids and
the liquid, and give the weight percent of solids.
If this is not
possible, measure the volume of the sample (in liters, U.S.
gallons, etc.)
and the volume of solids (in cubic centimeters, teaspoons, etc.)
and send these
figures. Describe the solid material completely and send a
small sample if
possible. This is important; if the correct pump is not
selected, the
solids will erode and/or break moving parts.
Weight percent of
solids =
100 x
weight of solids in liquid sample
---------------------------------------
weight of liquid sample
3. If you do not
have a thermometer to measure temperature, guess at it,
making sure you
guess on the high side. Pumping troubles are often caused
when liquid
temperatures at the intake are too high.
4. Gas bubbles or
boiling cause special problems, and must always be mentioned.
5. Give the capacity
(the rate at which you want to move the liquid) in any
convenient units
(liters per minute, U.S. gallons per minute) by giving the
total of the
maximum capacity needed for each outlet.
6. Give complete
details on the power source.
A.
If you are buying an electric motor for the
pump, be sure to give your
voltage. If
the power is A.C. (Alternating Current) give the frequency
(in cycles
per second) and the number of phases. Usually this will be
single phase
for most small motors. Do you want a pressure switch or
other special
means to start the motor automatically?
B.
If you want to buy an engine driven pump,
describe the type and cost
of fuel, the
altitude, maximum air temperature, and say whether the air
is unusually
wet or dusty.
C.
If you already have an electric motor or
engine, give as much information
about it as
you can. Give the speed and sketch the machine, being
especially
careful to show the power shaft diameter and where it is
with respect
to the mounting. Describe the size and type of pulley if
you intend to
use a belt drive. Finally, you must estimate the power.
The best
thing is to copy the name plate data completely. If possible
give the
number of cylinders in your engine, their size, and the stroke.
7. The
"head" or pressure to be overcome by the pump and the capacity (or
required flow of
water) determine the pump size and power. The entry
"Determining
Pump Capacity and Horsepower Requirements," explains the
calculation of
simple head situations. The best approach is to explain the
heads by drawing
an accurate piping sketch (see Item 10 in the "Pump
Application Fact
Sheet"). Be sure to give the suction lift and piping separately
from the
discharge lift and piping. An accurate description of the
piping is
essential for calculating the friction head. See Figure 2.
fig2x91.gif (600x600)
8. The piping
material, inside diameter, and thickness are necessary for making
the head
calculations and to check whether pipes are strong enough to
withstand the
pressure. See "Water Lifting and Transport-Overview" for
comments on
specifying pipe diameter.
9. Connections to
commercial pumps are normally flanged or threaded with
standard pipe
thread.
10. In the sketch be sure to show the following:
(a) Pipe sizes;
show where sizes are changed by indicating reducing
fittings.
(b) All pipe
fittings-elbows, tees, valves (show valve type), etc.
(c) Length of
each pipe run in a given direction. Length of each size pipe
and vertical
lift are the most important dimensions.
11. Give information on how the pipe will be used. Comment
on such points as:
o
Indoor or outdoor installation?
o
Continuous or intermittent service?
o
Space or weight limitations?
Source:
Benjamin P. Coe, VITA Volunteer, Schenectady, New York.
Determining Pump Capacity and Horsepower Requirements
With the alignment chart in Figure 1, you can determine the
necessary pump size
fig1x93.gif (600x600)
(diameter or discharge outlet) and the amount of horsepower
needed to power the
pump. The power can be supplied by people or by motors.
An average healthy person can generate about 0.1 horsepower
(HP) for a reasonably
long period and 0.4HP for short bursts. Motors are designed
for varying
amounts of horsepower.
To get the approximate pump size needed for lifting liquid
to a known height
through simple piping, follow these steps:
1. Determine the
quantity of flow desired in liters per minute.
2. Measure the
height of the lift required (from the point where the water
enters the pump
suction piping to where it discharges).
3. Using the entry
"Determining Pipe Size or Velocity of Water in Pipes," page
74, choose a pipe
size that will give a water velocity of about 1.8 meters
per second (6'
per second). This velocity is chosen because it will generally
give the most
economical combination of pump and piping; Step 5 explains
how to convert
for higher or lower water velocities.
4. Estimate the pipe
friction-loss head (a 3-meter head represents the pressure
at the bottom of
a 2-meter-high column of water) for the total equivalent
pipe length,
including suction and discharge piping and equivalent pipe
lengths for
valves and fittings, using the following equation:
Friction-loss
head = F x total equivalent pipe length
--------------------------------
100
where F equals
approximate friction head (in meters) per 100 meters of pipe.
To get the value
of F, see the table below. For an explanation of total
equivalent pipe
length, see preceding sections.
5. To find F
(approximate friction head in meters per 100m of pipe) when
water velocity is
higher or lower than 1.8 meters per second, use the
following
equation:
F
[V.sup.2]
at
1.8/[sec.sup.x]
F=
----------------------------
1.8/[sec.sup.2]
where V = higher
or lower velocity
Example:
If the water
velocity is 3.6m per second and F at 1.8m/sec is 16, then:
F = 16 x
[3.6.sup.2] 16 x 13
---------------- = ------- = 64
[1.8.sup.2] 3.24
6. Obtain
"Total Head" as follows:
Total Head =
Height of Lift + Friction-loss Head
Average friction
loss in meters for fresh water flowing through steel pipe
velocity is 1.8
meters (6 feet) per second
Pipe inside
diameter: cm 2.5
5.1
7.6 10.2
15.2
20.4 30.6
61.2
inches(*) 1"
2"
3" 4"
6"
8"
12" 24"
F (approximate
friction 16
7
5 3
2
1.5 1
0.5
loss in meters
per 100
meters of pipe)
(*) For the
degree of accuracy of this method, either actual inside diameter in
inches, or
nominal pipe size, U.S. Schedule 40, can be used.
7. Using a
straightedge, connect the proper point on the T-scale with the
proper point on
the Q-scale; read motor horsepower and pump size on the
other two scales.
Example:
Desired flow: 400
liters per minute
Height of lift:
16 meters, No fittings
Pipe size: 5cm
Friction-loss
head: about 1 meter
Total head: 17
meters
Solution:
Pump size:
5cm
Motor
horsepower: 3HP
Note that water horsepower is less than motor horsepower
(see HP-scale, Figure 1).
This is because of friction losses in the pump and motor.
The alignment chart
should be used for rough estimate only. For an exact
determination, give all
information on flow and piping to a pump manufacturer or an
independent expert.
He has the exact data on pumps for various applications.
Pump specifications can
be tricky especially if suction piping is long and the
suction lift is great.
For conversion to metric horsepower given the limits of
accuracy of this method,
metric horsepower can be considered roughly equal to the
horsepower indicated by
the alignment chart (Figure 1). Actual metric horsepower can
be obtained by
multiplying horsepower by 1.014.
Source:
Kulman, CA. Nomographic Charts. New York: McGraw-Hill Book
Co., 1951.
Determining Lift Pump Capability
The height that a lift pump can raise water depends on
altitude and, to a lesser
extent, on water temperature. The graph in Figure 1 will
help you to find out
fig1x96.gif (600x600)
what a lift pump can do at various altitudes and water
temperatures. To use it,
you will need a measuring tape and a thermometer.
If you know your altitude and the temperature of your water,
Figure 1 will tell
you the maximum allowable distance between the pump cylinder
and the lowest
water level expected. If the graph shows that lift pumps are
marginal or will not
work, then a force pump should be used. This involves
putting the cylinder down
in the well, close enough to the lowest expected water level
to be certain of
proper functioning.
The graph shows normal lifts. Maximum possible lifts under
favorable conditions
would be about 1.2 meters higher, but this would require
slower pumping and
would probably give much difficulty in "losing the
prime."
Check predictions from the graph by measuring lifts in
nearby wells or by
experimentation.
Example:
Suppose your
elevation is 2,000 meters and the water temperature is
25[degrees]C. The
graph shows that the normal lift would be four meters.
Source:
Baumeister, Theodore. Mechanical Engineer's Handbook, 6th
edition. New York:
McGraw-Hill Book Co., 1958.
SIMPLE PUMPS
Chain Pump for Irrigation
The chain pump, which can be powered by hand or animal, is
primarily a shallow-well
pump to lift water for irrigation (see Figure 1). It works
best when the lift
fig1ax96.gif (486x486)
is less than 6 meters (20'). The
water source must have a depth of
about 5 chain links.
Both the pump capacity and the
power requirement for any lift are
proportional to the square of the
diameter of the tube. Figure 2
fig2x97.gif (437x437)
shows what can be expected from a
10cm (4") diameter tube operated
by four people working in two
shifts.
The pump is intended for use as an
irrigation pump because it is
difficult to seal for use as a
sanitary pump.
Tools and Materials
Welding or brazing equipment
Metal-cutting equipment
Woodworking tools
Pipe: 10cm
(4") outside diameter, length as needed
5cm
(2") outside diameter, length as needed
Chain with links about 8mm (5/16") in diameter, length
as needed
Sheet steel, 3mm (1/8") thick
Sheet steel, 6mm (1/4") thick
Steel rod, 8mm (5/16") in diameter
Steel rod, 12.7mm (1/2") in diameter
Leather or rubber for washers
The entire chain pump is shown in Figure 3. Details of this
pump can be changed
fig3x98.gif (600x600)
to fit materials available and structure of the well.
The piston links (see Figures 4, 5, 6 and 7) are made from
three parts:
fig4x990.gif (393x393)
1. a leather or
rubber washer (see Figure 4) with an outside diameter about
fig4x99.gif (317x317)
two thicknesses
of a washer larger than the inside diameter of the pipe.
2. a piston disk
(see Figure 5).
fig5x99.gif (437x437)
3. a retaining plate
(see Figure 6).
fig6x100.gif (317x317)
The piston link is made as shown in Figure 7. Center all
three parts and clamp
fig7x100.gif (317x317)
them together temporarily. Drill a hole about 6mm
(1/4") in diameter through all
three parts and fasten them together with a bolt or rivet.
The winch is built as shown in Figure 3. Two steel disks 6mm
(1/4") thick are
fig3x98.gif (600x600)
welded to the pipe shaft.
Twelve steel rods, 12.7mm (1/2") thick, are spaced at
equal distances, at or near
the outside diameter, and are welded in place. The rods may
be laid on the
outside of the disks, if desired.
A crank and handle of wood or metal is then welded or bolted
to the winch
shaft.
The supports for the winch shaft (see Figure 3) can be
V-notched to hold the
shaft, which will gradually wear its own groove. A strap or
block can be added
across the top, if necessary, to hold the shaft in place.
The pipe can be supported by threading or welding a flange
to its upper end (see Figure 8).
fig8x100.gif (540x540)
The flange should be 8mm to 10mm (5/16" to 3/8")
thick. The pipe
passes through a hole in the bottom of the trough and hangs
from the trough
into the well.
Sources:
Robert G. Young, VITA Volunteer, New Holland, Pennsylvania
Molenaar, Aldert. Water Lifting Devices for Irrigation.
Rome: Food and Agriculture
Organization, 1956.
Inertia Hand Pump
The inertia hand pump described
here (Figure 1) is a
fig1x101.gif (600x600)
very efficient pump for lifting
water short distances. It lifts
water 4 meters (13') at the
rate of 75 to 114 liters (20 to
30 U.S. gallons) per minute. It
lifts water 1 meter (3.3') at
the rate of 227 to 284 liters
(60 to 75 gallons) per minute.
Delivery depends on the number
of persons pumping and
their strength.
The pump is easily built by a
tinsmith. Its three moving
parts require almost no maintenance.
The pump has been
built in three different sizes
for different water levels.
The pump is made from galvanized
sheet metal of the
heaviest weight obtainable
that can be easily worked by
a tinsmith (24- to 28-gauge
sheets have been used successfully).
The pipe is formed
and made air tight by soldering
all joints and seams.
The valve is made from the
metal of discarded barrels and
a piece of truck inner tube
rubber. The bracket for
attaching the handle is also
made from barrel metal.
Figure 1 shows the pump in
operation. Figure 2 gives the
fig2x103.gif (600x600)
dimensions of parts for pumps
in three sizes and Figure 3
fig3x103.gif (393x393)
shows the capacity of each
size. Figures 4, 5, and 6 are
fig41030.gif (600x600)
Tools and Materials
(for 1-meter (3.3') pump)
Soldering equipment
Drill and bits or punch
Hammer, saws, tinsnips
Anvil (railroad rail or iron pipe)
Galvanized iron (24 to 28 gauge):
Shield: 61cm x 32cm, 1 piece (24" x 12 5/8")
Shield cover: 21cm x 22cm, 1 piece (8 1/4" x 8
5/8")
Pipe: 140cm x 49cm, 1 piece (55 1/8" x 19 1/4")
Top of pipe: 15cm x 15cm, 1 piece (6" x 6")
"Y" pipe: 49cm x 30cm, 1 piece (19 1/4" x
12")
Barrel metal:
Bracket: 15cm x
45cm, 1 piece (6" x 21 1/4")
Valve-bottom: 12cm
(4 3/4") in diameter, 1 piece
Valve-top: 18cm (7
1/8") in diameter, 1 piece
Wire:
Hinge: 4mm
(5/32") in diameter, 32cm (12 5/8") long
This pump can also be made from plastic pipe or bamboo.
There are two points to be remembered concerning this pump.
One is that the
distance from the top of the pipe to the top of the hole
where the short section
of pipe is connected must be 20cm (8"). See Figure 4.
The air that stays in the
fig4x103.gif (600x600)
pipe above this junction serves as a cushion (to prevent
"hammering") and
regulates the number of strokes pumped per minute. The
second point is to
remember to operate the pump with short strokes, 15 to 20cm
(6" to 8"), and at a
rate of about 80 strokes per minute. There is a definite
speed at which the pump
works best and the operators will soon get the
"feel" of their own pumps.
In building the two larger size pumps it is sometimes
necessary to strengthen the
pipe to keep it from collapsing if it hits the side of the
well. It can be strengthened
by forming "ribs" about every 30cm (12")
below the valve or banding with
bands made from barrel metal and attached with 6mm
(1/4") bolts.
The handle is attached to the pump and post with a bolt 10mm
(3/8") in diameter,
or a large nail or rod of similar size.
Source:
Dale Fritz, VITA Volunteer, Schenectady, New York.
Handle Mechanism for Hand Pumps
The wearing parts of this durable handpump handle mechanism
are wooden (see Figure 1).
fig1x105.gif (600x600)
They can be easily replaced by a village carpenter. This
handle has
been designed to replace pump handle mechanisms which are
difficult to maintain.
Some have been in use for several years in India with only
simple, infrequent
repairs.
The mechanism shown in Figure 1 is bolted to the top flange
of your pump. The
mounting holes A and C in the block should be spaced to fit
your pump (see Figure 6).
fig6x107.gif (600x600)
Figure 2 shows a pump with this handle mechanism that is
manufactured
fig2x106.gif (486x486)
by F. Humane and Bros., 28 Strand Road, Calcutta, India.
Tools and Materials
Saw
Drill
Bits
Tap: 12.5mm (1/2")
Tap: 10mm (3/8")
Chisel
Drawknife, spokeshave or lathe
Hardwoods 86.4cm x 6.4cm x 6.4cm
(34" x
2 1/2" x 2 1/2")
Mild steel rod: 10mm (3/4") in diameter
and
46.5cm (16") long
Strap iron, 2 pieces: 26.7cm x 38mm x 6mm
(10 1/2" x 1 1/2" x 1/4")
BOLT HARDWARE
Number
Number Number
Number
of bolts Dia.
Length
of nuts of lock-
of plain
Purpose-
needed
mm
mm needed
washers
washers fastens:
1
10
38 0
0
0 76mm bolt
to rod
1
10
76 0
0
2 Rod to
handle
2
12.5
89 2
4
4
Link to handle
Link to
block
2
12.5
? 2
2
2 Block to
pump
1
12.5
? 1
1
0 Rod to
piston
Handle
Make the handle of tough hardwood,
shaped on a lathe or by hand
shaving. The slot should be cut
wide enough to accommodate the
rod with two plain washers on
either side. See Figure 3.
fig3x106.gif (486x486)
Rod
The rod is made of mild steel as
shown in Figure 4. A 10mm (3/8")
fig4x107.gif (486x486)
diameter machine bolt 38mm (1
1/2") long screws into the end of
the rod to lock the rod hinge pin
in place. The rod hinge pin is a
10mm (3/8") diameter machine bolt
that connects the rod to the handle
(see Figure 1). The end of the rod
fig1x105.gif (486x486)
can be bolted directly to the pump
piston with a 12.5mm bolt. If the
pump cylinder is too far down for
this, a threaded 12.5mm (1/2") rod
should be used instead.
Links
The links are two pieces of flat steel strap iron. Clamp
them together for drilling
to make the hole spacing equal. See Figure 5.
fig5x107.gif (486x486)
Block
The block forms the base of the lever mechanism, serves as a
lubricated guide
hole for the rod, and provides a means for fastening the
mechanism to the pump
barrel. If the block is accurately made of seasoned tough
hardwood without knots,
the mechanism will function well for many years. Carefully
square the block to
22.9cm x 6.4cm x 6.4cm (9" x 1 1/2" x 1
1/2"). Next holes, A, B, C, and D are
drilled perpendicular to the block as shown in Figure 6. The
spacing of the
fig6x107.gif (540x540)
mounting holes A and C from hole B is determined by the
spacing of the bolt
holes in the barrel flange of your pump. Next saw the block
in half in a plane
3.5cm (13/8") down from the top side. Enlarge hole B at
the top of the lower
section with a chisel to form an oil well around the rod.
This well is filled with
cotton. A 6mm (1/4") hole, F, is drilled at an angle
from the oil well to the
surface of the block. A second oil duct hole E is drilled in
the upper section of
the block to meet hole D. Use lockwashers under the head and
nut of the link
bolts to lock the bolts and links together. Use plain
washers between the links
and the wooden parts.
Source:
Abbott, Dr. Edwin. A Pump Designed for Village Use.
Philadelphia: American
Friends Service Committee, 1955.
Hydraulic Ram
A hydraulic ram is a self-powered pump that uses the energy
of falling water to
lift some of the water to a level above the original source.
This entry explains
the use of commercial hydraulic rams, which are available in
some countries. Plans
for building your own hydraulic ram are also available from
VITA and elsewhere.
Use of the Hydraulic Ram
A hydraulic ram can be used wherever a spring or stream of
water flows with at
least a 91.5cm (3') fall in altitude. The source must be a
flow of at least 11.4
liters (3 gallons) a minute. Water can be lifted about 7.6
meters (25') for each
30.5cm (12") of fall in altitude. It can be lifted as
high as 152 meters (500'), but
a more common lift is 45 meters (150').
The pumping cycle (see Figure 1) is:
fig1x108.gif (600x600)
o Water flows
through the drive pipe (D) and out the outside valve (F).
o The drag of the
moving water closes the valve (F).
o The momentum of
water in the drive pipe (D) drives some water into the air
chamber (A) and
out the delivery pipe (I).
o The flow stops.
o The check valve
(B) closes
o The outside valve
(F) opens to start the next cycle.
This cycle is repeated 25 to 100 times a minute; the
frequency is regulated by
moving the adjustment weight (C).
The length of the drive pipe must be between five and ten
times the length of
the fall (see Figure 2). If the distance from the source to
the ram is greater than
fig2x109.gif (600x600)
ten times the length of the fall, the length of the drive
pipe can be adjusted by
installing a stand pipe between the source and the ram (see
B in Figure 2).
Once the ram is installed there is little need for
maintenance and no need for
skilled labor. The cost of a hydraulic ram system must
include the cost of the
pipe and installation as well as the ram. Although the cost
may seem high, it
must be remembered that there is no further power cost and a
ram will last for
30 years or more. A ram used in freezing climates must be
insulated.
A double-acting ram will use an impure water supply to pump
two-thirds of the
pure water from a spring or similar source. A third of the
pure water mixes with
the impure water. A supplier should be consulted for this
special application.
To calculate the approximate pumping rate, use the following
equation:
Capacity (gallons per hour) = V x F x 40
----------
E
V = gallons per
minute from source
F = fall in feet
E = height the
water is to be raised in feet
Data Needed for Ordering a Hydraulic Ram
1. Quantity of
water available at the source of supply in liters (or gallons) per
minute
2. Vertical fall in
meters (or feet) from supply to ram
3. Height to which
the water must be raised above the ram
4. Quantity of
water required per day
5. Distance from
the source of supply to the ram
6. Distance from the
ram to the storage tank
Sources:
Loren G. Sadler, New Holland, Pennsylvania
Rife Hydraulic Engine Manufacturing Company, Millburn, New
Jersey
Sheldon, W.H. The Hydraulic Ram. Extension Bulletin 171,
July 1943, Michigan
State College of Agriculture and Applied Science.
"Country Workshop." Australian Country. September
1961, pages 32-33.
"Hydraulic Ram Forces Water to Pump Itself."
Popular Science, October 1948,
pages 231-233.
"Hydraulic Ram." The Home Craftsman, March-April
1963, pages 20-22.
RECIPROCATING WIRE POWER TRANSMISSION
FOR WATER PUMP
A reciprocating wire can transmit power from a water wheel
to a point up to
0.8km (1/2 mile) away where it is usually used to pump well
water. These devices
have been used for many years by the Amish people of
Pennsylvania. If they are
properly installed, they give long, trouble-free service.
The Amish people use this method to transmit <see figure
1> mechanical power from small water
fig1x111.gif (486x486)
wheels to the barnyard, where the reciprocating motion is
used to pump well
water for home and farm use. The water wheel is typically a
small undershot
wheel (with the water flowing under the wheel) one or two
feet in diameter. The
wheel shaft is fitted with a crank, which is attached to a
triangular frame that
pivots on a pole (see Figure 2). A wire is used to connect
this frame to another
fig2x112.gif (600x600)
identical unit located over the well. Counterweights keep
the wire tight.
Tools and Materials
Wire: galvanized smooth fence wire
Water wheel with eccentric crank to give a motion slightly
less than largest
stroke of farmyard pump
Galvanized pipe for triangle frames: 2cm (3/4") by 10
meters long (32.8')
Welding or brazing equipment to make frames
Concrete for counterweight
2 Poles: 12 to 25cm (6" to 10") in diameter.
As the water wheel turns, the
crank tips the triangular frame
back and forth. This action pulls
the wire back and forth. One
typical complete back and forth
cycle takes 3 to 4 seconds.
Sometimes power for several
transmission wires comes from one
larger water wheel.
The wire is mounted up on poles to
keep it overhead and out of the
way. If the distance from stream to
courtyard is far, extra poles will be
needed to help support the wire.
Amish folks use a loop of wire
covered with a small piece of
garden hose attached to the top of
the pole. The reciprocating wire
slides back and forth through this
loop. If this is not possible, try
making the pole 1-2 meters higher
than the power wire. Drive a heavy
nail near the pole top and attach a
chain or wire from it to the power
wire as shown in Figure 3.
fig3x113.gif (486x486)
Turns can be made in order to
follow hedgerows by mounting a
small triangular frame horizontally
at the top of a pole as shown in
Figure 4.
fig4x113.gif (486x486)
Figures 5, 6, and 7 show how to
fig51140.gif (600x600)
wheel made from wood and bamboo.
Source
New Holland, Pennsylvania VITA Chapter.
References
REFERENCES
WATER RESOURCES
American Water Works Association. "AWWA Standard
D-100-79 for Welded Steel Water Storage Tanks."
Denver, Colorado: American Water Works Association, 1979.
American Water Works Association. "AWWA Standard D-105-80
for Disinfection of Water Storage Facilities."
Denver, Colorado: American Water Works Association, 1980.
American Water Works Association. Water Distribution
Operator Training Handbook. Denver, Colorado:
American Water Works Association, 1976.
Anchor, R.D. Design of Liquid-Retaining Concrete Structures.
New York: Wiley and Sons, 1982.
Blackwell, F.O., Farding, P.S., and Hilbert, M.S.
Understanding Water Supply and Treatment for Individual
and Small Community Systems. Arlington, Virginia: Volunteers
in Technical Assistance, 1985.
Brown, J.H. "Flexible Membrane: An Economical Reservoir
Liner and Cover." Journal of the American
Water Works Association. Vol. 71, No. 6, June 1979.
Cairncross, S., and Feachem, R. Small Water Supplies.
London: Ross Institute, 1978.
Crouch, Margaret (ed.). Six Simple Pumps. Arlington,
Virginia: Volunteers in Technical Assistance, 1983.
Helweg, O.J., and Smith, G. "Appropriate Technology for
Artificial Aquifers,"
Ground Water. Vol. 18, No. 3, May-June 1978.
Maddocks, D. Methods of Creating Low Cost Waterproof
Membranes for Use in the Construction of
Rainwater Catchment and Storage Systems. London:
Intermediate Technology Publications, Ltd., 1975
Mazariegos, J. F., and de Zeissig, Julia A. A. Water
Purification Using Small Artisan Filters. Guatemala:
Central American Research Institute for Industry, 1981.
McJunkin, F. and Pineo, C. U.S. Agency for International
Development. Water Supply and Sanitation in
Developing Countries. Washington, D.C.: USAID, 1976.
Pacey, Arnold, and Cullis, Adrian. Rainwater Harvesting: The
Collection of Rainfall and Runoff in Rural
Areas. London: Intermediate Technology Publications, Ltd.,
1996.
Remmers, J. Understanding Water Supply. General
Considerations. Arlington, Virginia: Volunteers in
Technical Assistance. 1985.
Ritter, C.M. Understanding Potable Water Storage. Arlington,
Virginia: Volunteers in Technical Assistance
(VITA), 1985.
Ryden, D.E. "Evaluating the Safety and Seismic
Stability of Embankment Reservoirs." Journal of the
American Water Works Association. Vol. 76, No. 1. Denver,
Colorado: American Water Works Association,
January 1984.
Salvato, JA., Jr. Environmental Engineering and Sanitation.
New York: Wiley-Interscience, 1972.
Schiller, E.J., and Droste, R.L., eds. Water Supply and
Sanitation in Developing Countries. Ann Arbor,
Michigan: Ann Arbor Science Publishers, 1982
Sharma, P.N., and Helweg, OJ. "Optimum Design of Small
Reservoir Systems." Journal of Irrigation and
Drainage Division--American Society of Civil Engineers. Vol.
108, IR4, December 1982.
Sherer, K, "Technical Training of Peace Corps
Volunteers in Rural Water Supply systems in Morocco."
Water and Sanitation for Health Project (WASH) Field Report
No. 43. Washington, D.C.: U.S. Agency
for International Development, May 1982.
Silverman, G.S.; Nagy, LA.; and Olson, B.H. "Variations
in Particulate Matter, Algae, and Bacteria in
An Uncovered, Finished Drinking-Water Reservoir."
Journal of the American Water Works Association.
Vol. 75, No. 4. Denver, Colorado: American Water Works
Association, April 1983.
Spangler, C.D. United Nations and World Bank. Low-Cost Water
Distribution: A Field Manual. Washington,
D.C.: World Bank, December 1980.
Swiss Association for Technical Assistance, ed. Manual for Rural
Water Supply. Zurich, Switzerland:
Swiss Center for Appropriate Technology, 1980.
Sylvestre, Emilio. "Water, Water Everywhere: Island
Communities Install Water Systems." VITA News,
October 1986, pp. 8-10.
United Nations. World Health Organization. "WHO
Guidelines for Drinking Water Quality," by H.G.
Gorchev and G. Ozolins. Geneva, Switzerland: World Health
Organization, 1982.
United Nations. World Health Organization. "The
Purification of Water on a Small Scale. WHO Technical
paper No. 3. The Hague, The Netherlands: WHO International
Reference Centre for Community
Water Supply, March 1973.
United Nations. World Health Organization. "Preliminary
List of References on Slow Sand Filtration and
Related Simple pretreatment Methods." The Hague, The Netherlands:
WHO International Reference Centre
for Community Water Supply, July 1976.
Upmeyer, D.W. "Estimating Water Storage
Requirements." Public Works. Vol. 109, No. 7, July 1978.
U.S. Environmental Protection Agency. Manual of Individual
Water Supply Systems. Washington, D.C.:
EPA, 1975.
"Wind Power for Roatan Island: Pumping Water in
Honduras." VITA News, October 1982, pp. 3-7.
HEALTH AND SANITATION
American Concrete Institute. "Concrete Sanitary
Engineering Structures." Report No. ACI 350R-83.
Detriot, Michigan: American Concrete Institute, 1983.
Baumann, Werner, and Karpe, Hans Jurgen. Wastewater
Treatment and Excreta Disposal in Developing
Countries. West Germany: German Appropriate Technology
Report, 1980.
Bull, David. A Growing Problem: Pesticides and the Third
World Poor. Oxford: OXFAM, 1982.
Canter, L.W. and Malina, J.F. Sewege Treatment in Developing
Countries. Norman, Oklahoma: The University
of Oklahoma (under contract to USAID), December 1976.
Cointreau, Sandra J. Environmental Management or Urban Solid
Wastes in Developing Countries (A
Project Guide). Washington, D.C.: World Bank, June 1982.
Davis, B.P. Understanding Sanitation at the Community Level.
Arlington, Virginia: Volunteers in Technical
Assistance, 1985.
Feachem, Richard G.; Bradley, David; Garelick, Hemda; and
Mara, D. Duncan. "Health Aspects of Excreta
and Sullage Management: A State-of-the-Art Review."
(Appropriate Technology for Water Supply
and Sanitation, vol. 3). Washington, D.C.: World Bank, 1980.
Feachem, Richard, et al. Water, Health and Development: An
Inter-disciplinary Evaluation. London: Tri-Med
Books, Ltd., 1977.
Feachem, Richard, McGarry, Michael, and Mara, D. Duncan
(eds). Water, Wastes and Health in Hot
Climates. New York: John Wiley and Sons, 1980.
Goldstein, Steven N., and Moberg, Walter J., Jr. Wastewater
Treatment Systems for Rural Communities.
Washington, D.C.: Commission on Rural Water, 1973.
Golveke, C.G. Biological Reclamation of Solid Wastes.
Emmaus, Pennsylvania: Rodale Press, 1977.
Grover, Brian. Water Supply and Sanitation Project
Preparation Handbook (vol. 1, Guidelines). Washington,
D.C.: World Bank, 1982.
Herrington, J.E. Understanding Primary Health Care for a
Rural Population. Arlington, Virginia: Volunteers
in Technical Assistance, 1985.
Kalbermatten, John M., et al. "A Planner's Guide."
(Appropriate Technology for Water Supply and Sanitation,
vol. 2). Washington, D.C.: World Bank. 1981.
Kalbermatten, John M.; Julius, De Anne S.; and Gunnerson,
Charles G. Appropriate Sanitation Alternatives.
A technical and Economic Appraisal. Baltimore, Maryland:
Johns Hopkins University Press (for
the World Bank), 1982.
Mann, H.T., and Williamson, D. Water Treatment and
Sanitation: Simple Methods for Rural Areas.
London. Intermediate Technology Publications, 1982.
Patel, Ishwarbhai. Safai-Marg Darshika (A Guide Book on
Sanitation). New Delhi: Udyogshala Press,
1970.
Reid, George and Coffey, Kay. (eds.). Appropriate Methods of
Treating Water and Wastewater in
Developing Countries. Norman, Oklahoma: Bureau of Water and
Environmental Resources Research
(University of Oklahoma), 1978.
Rybczynski, Witold, Polprasert, Changrak, and McGarry,
Michael. Low-Cost Technology Options for
Sanitation (A State-of-the-Art Review and Annotated Bibliography).
Ottawa: International Development
Research Centre, 1978.
Salvato, J.A., Jr. Environmental Engineering and Sanitation.
New York: Wiley-Interscience, 1972.
Sanitation in Developing Countries (Proceedings of a
workshop on training held in Lobatse, Botswana,
14-20 August 1980). Ottawa: International Development
Research Centre, 1981.
Stonerook, H. Understanding Sewage Treatment and Disposal.
Arlington, Virginia: Volunteers in Technical
Assistance, 1994.
Strauss, Martin. Sanitation Handbook (Community Water Supply
and Sanitation, Nepal). Pokhara, Nepal:
Pokhara Centre Press, June 1982.
van Wijk-Sijbesma, Christine. Participation and Education in
Community Water Supply and Sanitation
Programmes - A Literature Review. The Hague: WHO International
Reference Centre for Community
Water Supply, 1979.
Vogler, Jon. Work from Waste. Recycling Wastes to Create
Employment. Oxford: Intermediate Technology
Publications Ltd. and OXFAM, 1981.
Werner, D. Where There Is No Doctor. A Village Health Care
Handbook. Palo Alto, California:
Hesperian Foundation, 1980.
AGRICULTURE
Abrahams, P.J. Understanding Soil Preparation. Arlington,
Virginia: Volunteers in Technical Assistance,
1994
Archer, Sellers G. Soil Conservation. Norman, Oklahoma:
University of Oklahoma Press, 1969.
Attfield, Harlan. Gardening With the Seasons. Arlington,
Virginia: Volunteers in Technical Assistance,
1979.
Bartholomew, W.V. Soil Nitrogen--Supply Processes and Crop
Requirements. Technical Bullentin 6.
Raleigh, North Carolina: North Carolina State University,
1972.
Bird, H.R. Understanding Poultry Meat and Egg Production.
Arlington, Virginia: Volunteers in Technical
Assistance, 1984.
Bradenburg, N.R. Bibliography of Harvesting and Processing
Forage Seed, 1949-1964. U.S. Department of
Agriculture, Agricultural Research Service, ARS 42-135,
Washington: USDA, 1968.
Branch, Diana S. (ed.). Tools for Homesteaders, Gardeners,
and Small-Scale Farmers, Emmaus, Pennsylvania,
1978.
Corven, James. Basic Soil Improvement for Everyone.
Arlington, Virginia: Volunteers in Technical
Assistance, 1983.
Ensminger, M.E., and Olentine, C.G., Jr. Feeds and
Nutrition. Clovis, California: Ensminger Publishing
Co., 1978.
Fitts, J.W., and Fitts, J.B. Understanding Composting.
Arlington, Virginia: Volunteers in Technical
Assistance, 1984
Freeman, John A. Survival Gardening: Enough Nutrition from
1,000 Square Feet To Live On...Just in
Case! Rock Hill, South Carolina: John's Press, 1983.
Hughes, H.D. Forages. Ames, Iowa: Iowa State University Press,
1966.
Hunt, Marjorie, and Bartz, Brenda. High Yield Gardening.
Emmaus, Pennsylvania: Rodale Press, Inc.,
1986.
National Academy of Sciences. Nutrient Requirements of
Poultry. Washington, D.C.: National Academy
Press, 1977.
North, M.O. Commercial Chicken Production Manual. Second
Edition. Westport, Connecticut: AVI Publishing
Co., Inc., 1978.
Orr, H.L. Duck and Goose Raising. Publication 532. Ontario,
Canada: Ministry of Agriculture and Food.
Piliang, W.G.; Bird, H.R.; Sunde, M.L.; and Pringle, D.J.
"Rice Bran as the Major Energy Source for
Laying Hens." Poultry Science. 61 (1982): 357.
Reddy, K.R.; Khaleel, R.; and Overcash, M.R. "Behavior
and Transport of Microbial Pathogens and Indicator
Organisms in Soils Treated with Organic Wastes." Journal
of Environmental Quality. Madison,
Wisconsin: American Society of Agronomy, 1981.
Rodale, J., ed. The Complete Book of Composting. Emmaus,
Pennsylvania: Rodale Press, Inc., 1969.
Russel, F. W. Soil Conditions and Plant Growth. London,
England: Logmans Green and Co., Ltd., 1961.
Stern, Peter. Small Scale Irrigation. London: Intermediate
Technology Publications, 1979.
Young, J.A., Evans, R.A. & Budy, J.D. Understanding Seed
Collection and Handling. Arlington, Virginia:
Volunteers in Technical Assistance, 1986.
FOOD PROCESSING AND PRESERVATION
Anderson, Jean. The Green Thumb Preserving Guide. New York:
William Marrow & Company, Inc., 1976.
Barbour, Beverly. The Complete Food Preservation Book: New
York: David McKay Company, Inc., 1978.
Burch, Joan, and Burch, Monte. Home Canning and Preserving.
Reston, Virginia: Reston Publishing
Company, Inc., 1977.
Carruthers, R.T. Understanding Fish Preservation and
Processing. Arlington, Virginia: Volunteers in
Technical Assistance, 1995.
Central Food Technological Research Institute.
"Home-Scale Processing and Preservation of Fruits and
Vegetables." Mysore, India: The Wesley Press, 1981.
Etchells, John L., and Jones, Ivan D. "Preservation of
Vegetables by Salting or Brining," Farmers'
Bulletin No. 1932. Washington, D.C.: U.S. Department of
Agriculture, 1944.
Groppe, Christine C., and York, George K. "Pickles,
Relishes, and Chutneys: Quick, Easy, and Safe
Recipes." Leaflet No. 2275. Berkeley, California:
University of California, Division of Agricultural
Sciences, 1975.
Hertzberg, Ruth; Vaughan, Beatrice; and Greene, Janet.
Putting Food By. Brattleboro, Vermont: The
Stephen Greene Press.
Islam, Meherunnesa. Food Preservation in Bangladesh. Dacca,
Bangladesh: Women's Development Programme,
UNICEF/DACCA, 1977.
Kluger, Marilyn. Preserving Summer's Bounty. New York: M.
Evans and Company, Inc., 1978.
Levinson, Leonard Louis. The Complete Book of Pickles and
Relishes. New York: Hawthorn Books, Inc.,
1965.
Lindblad, Carl, and Druben, Laurel. Small Farm Grain
Storage. Arlington, Virginia: Volunteers in Technical
Assistance, 1976.
Murry, Sue T. Home Curing Fish. Washington, D.C.:
Agriculture and Rural Development Service, Agency
for International Development, 1967.
Schuler, Stanley, and Schuler, Elizabeth Meriwether,
Preserving the Fruits of the Earth. New York:
The Dial Press, 1973.
Stiebeling, Jazel K. "Solar Food Preservation."
Chicago, Illinois: Illinois Institute of Technology, 1981.
Stoner, Carol Hupping, Editor. Stocking Up: How To Preserve
the Foods You Grow, Naturally. Emmaus,
Pennsylvania: Rodale Press, 1977.
U.S. Department of Agriculture. Human Nutrition Research
Division. "Home Canning of Fruits and
Vegetables." Washington, D.C.: U.S. Department of
Agriculture, 1965.
Weber, Fred, with Stoney, Carol. Reforestation in Arid
Lands. Arlington, Virginia: Volunteers in Technical
Assistance, 1986.
Worgan, J.T. "Canning and Bottling as Methods of Food
Preservation in Developing Countries." Appropriate
Technology. 4 (November 1977): 15-16.
CONSTRUCTION
Action Peace Corps. Handbook for Building Homes of Earth.
Washington, D.C.: Department of Housing
and urban Develop ment, (undated).
Ahrens, C. Manual for Supervising Self-Help Home
Construction with Stabilized Earth Blocks Made in
the CINVA-Ram Machine. Kanawha County, West Virginia, 1965.
American Concrete Institute. Handbook of Concrete
Engineering. ACI-82 Manual of Practice. Detroit,
Michigan: American Concrete Institute, 1982.
Buchanan, W. Hand Moulded Burnt Clay Bricks: Labour
Intensive Production. Malawi Ministry of Trade,
Industry, and Tourism (United Nations Industrial Development
Organization, Project DP/MLW/78/003),
undated.
Building with Adobe and Stabilized Earth Blocks. Washington,
D.C.: United States Department of Agriculture,
1972.
Bush, Alfred. Understanding Stabilized Earth Construction.
Arlington, Virginia: Volunteers in Technical
Assistance, 1994.
Groben, E. W. Adobe Architecture: Its Design and
Construction. Seattle, Washington: The Shorey Book
Store, 1975.
International Institute of Housing Technology. The
Manufacturing of Asphalt Emulsion Stabilized Soil
Bricks and Brick Maker's Manual. Fresno, California:
California State University, 1972.
Lunt, M.G. Stabilized Soil Blocks for Building. Garston, Watford,
England: Building Research Establishment,
1980.
_________. "Stabilized Soil Blocks for Building."
Overseas Building Notes No. 184. Garston, England:
Building Research Establishment, February 1980.
Making Building Blocks with the CINVA-Ram Block Press.
Arlington, Virginia: Volunteers in Technical
Assistance, 1975.
Metalibec Ltd. CINVA-Ram Block Cement Soil in Large Scale
Housing Construction in East Punjab.
Bombay, India: Government of India Press, 1948.
Methods for Characterizing Adobe Building Materials.
Washington, D.C.: National Bureau of Standards,
1978.
Parry, J.P. Brickmaking in Developing Countries. Prepared
for Overseas Division, Building Research
Establishment, UK Garston, Watford, United Kingdom: Building
Research Establishment, 1979.
Salvadorean Foundation for Development and Low Cost Housing
Research Unit. Stabilized Adobe. Washington,
D.C.: Organization of American States, (undated)
Sidibe, B. Understanding Adobe. Arlington, Virginia:
Volunteers in Technical Assistance (VITA), 1985.
U.S. Agency for International Development. Handbook for
Building Homes of Earth. Action Pamphlet
No. 4200.36. By Lyle A. Wolfskill, Wayne A. Dunlop, and Bob
M. Callaway. Washington, D.C.: Peace
Corps, December 1979.
U.S. Dept of the Army. Concrete, Masonry and Brickwork: A
Practical Handbook for the Home Owner
and Small Builder. New York: Dover Publications, Inc., 1975.
HOME IMPROVEMENT
Baldwin, S. Biomass Stoves: Engineering Design, Development,
and Dissemination. Arlington, Virginia:
Volunteers in Technical Assistance, 1986.
Bruyere, John. Country Comforts: The New Homesteaders
Handbook. New York: Sterling Publishing Co.,
Inc., 1979.
Bramson, Ann. Soap. New York: Workman Publishing Co., 1975.
Clarke, R. (ed.). Wood-Stove Dissemination: Proceedings of
the Conference Held at Wolfheze, The
Netherlands. London: Intermediate Technology Publications,
Ltd., 1985.
de Silva, D. "A Charcoal Stove From Sri Lanka,"
Appropriate Technology, Vol. 7, No. 4,1981, pp. 22-24.
Donkor, Peter. Small-Scale Soapmaking: A Handbook. London:
Intermediate Technology Publications,
1986.
Foley, G. and Moss, P. "Improved Cooking Stoves In
Developing Countries." Earthscan Technical Report
No. 2, 1983, 175 pp. Illus.
Hassrick, P. "Umeme: A Charcoal Stove from Kenya."
Appropriate Technology Vol. 9, No. 1, 1982, pp.
6-7.
Making Soap and Candles. Pownal, Vermont: P. H. Storey
Communications, Inc., 1973.
Tata Energy Research Institute. Solid Fuel Cooking Stoves.
Bombay, India, 1980.
Testing the Efficiency of Wood-Burning Cookstoves:
International Standards. Arlington, Virginia: Volunteers
in Technical Assistance, 1985.
CRAFTS AND VILLAGE INDUSTRY
Berold, Robert, and Caine, Collette (eds.). People's
Workbook. Johannesburg, South Africa: Enrironmental
and Development Agency, 1981.
Cardew, M. Pioneer Pottery. New York, New York: St. Martin's
press, 1976.
Conrad, J.W. Ceramic Formulas: The Complete Compendium (A
Guide to Clay, Glazes, Enamel, Glass,
and Their Colors). New York, New York: MacMillan Publishing
Co., 1975.
Cooper, E. The Potter's Book of Glaze Recipes. New York, New
York: Charles Scribner's Sons, 1980.
Green, D. Pottery Glazes. New York: Watson Guptill
Publishing, 1973.
Lawrence and West. Ceramic Science for the Potter. Radnor,
Pennsylvania: Chilton Book Co.
Nelson, G. Ceramics: A Potter's Handbook. New York: Holt,
Reinhart & Winston, 1984.
Norton, F.H. Elements of Ceramics. Redding, Massachusetts:
Addison-Wesley Publishing Co., 1974.
____________. Kilns. Design, Construction and Operation.
Philadelphia, Pennsylvania: Chilton Book Co.,
1968.
Peter Starkey. Salt Glaze, London: Pitman Publishing Co.,
1977.
Petersham, M. Understanding the Small-Scale Clay Products
Enterprise. Arlington, Virginia: Volunteers
in Technical Assistance, 1984.
Schurecht, H.G. "Salt Glazing and Ceramic Ware."
Bulletin of the American Ceramic Society, Vol. 23,
No. 2.
"Simple Methods of of Candle Manufacture," London:
Intermediate Technology Publications, Ltd., 1985.
Small-Scale Papermaking. Technical Memorandum No. 8. Geneva:
International Labor Office, 1985.
Troy, J. Salt Glazed Ceramics. New York: Watson Guptill
Publications Co., 1977.
Troy, J. Glazes for Special Effects. New York: Watson
Guptill Publications Co.
Vogler, Jon, and Sarjeant, Peter. Understanding Small-Scale
Papermaking. Arlington, Virginia: Volunteers
in Technical Assistance, 1986.
Weygers, A.G. The Making of Tools. New York: Van Nostrand
Reinhold Company, 1973.
Young, Jean (ed.). Woodstock Craftsman's Manual. New York:
Praeger Publishers, 1972.
COMMUNICATION AND GENERAL REFERENCE
Berold, Robert, and Caine, Collette (eds.). People's
Workbook. Johannesburg, South Africa: Enrironmental
and Development Agency, 1981.
Darrow, Ken, and Saxenian, Mike. Appropriate Technology
Sourcebook. Stanford, California: Volunteers
in Asia, 1986.
McLaren, 1. The Sten-Screen: Making and Using a Low-Cost
Printing Process. London: Intermediate
Technology Publications, Inc., 1983.
Seymour, John. The Complete Book of Self Sufficiency.
London: Corgi Books div. Transworld Publishers,
Ltd., 1981
Conversion Tables
CONVERSION TABLES
MULTIPLY
BY TO OBTAIN
acres
43,560
square feet
acres
4,047 square
meters
acres
1.562 X [10.sup.-3] square
miles
acres
0.004047 square
kilometers
acres
4840
square yards
atmospheres
76.0 cms of
mercury
atmospheres
29.92 inches of
mercury
atmospheres
10,333 kgs/square
meter
atmospheres
14.70
pounds/square inch
British thermal units
0.2530
kilogram-calories
B.t.u.
777.5 foot-pounds
B.t.u.
3.927 X [10.sup.-4]
horsepower-hours
B.t.u.
1,054 joules
B.t.u.
107.5
kilogram-meters
B.t.u.
2.928 X [10.sup.-4]
kilowatt-hours
B.t.u./min.
0.02356 horsepower
B.t.u./min.
0.01757 kilowatts
B.t.u./min.
17.57 watts
calories
0.003968 B.t.u.
calories
3.08596 foot-pounds
calories
1.1622 X [10.sup.-6] kilowatt-hours
centimeters
0.3937 inches
centimeters
0.01 meters
centimeters of mercury
0.1934
pounds/square inch
centimeters/second
1.969 feet/minute
centimeters/second
0.036
kilometer/hour
centimeters/second
0.6
meters/minute
centimeters/second
0.02237 miles/hour
cubic centimeters
[10.sup.-6] cubic
meters
cubic centimeters
6.102 X [10.sup.-2] cubic
inches
cubic centimeters
3.531 x [10.sup.-5] cubic feet
cubic centimeters
1.308 X [10.sup.-6] cubic yards
cubic feet
1,728 cubic
inches
cubic feet
0.02832
cubic meters
cubic feet
2.832 X [10.sup.4] cubic
centimeters
cubic feet
7.481 gallons
cubic feet
28.32 liters
cubic feet/minute
472.0
cubic cms/second
cubic feet/minute
0.1247
gallons/second
cubic feet/minute
0.4720
liters/second
cubic feet/minute
62.4 pounds
water/min
cubic inches
5.787 X [10.sup.-4]
cubic feet
cubic inches
1.639 X [10.sup.-5] cubic
meters
cubic inches
2.143 X [10.sup.-5] cubic yards
cubic meters
35.31 cubic feet
cubic meters
264.2
gallons
cubic meters
[10.sup.3] liters
cubic yards
7.646 X [10.sup.5] cubic
centimeters
cubic yards
27.0 cubic feet
cubic yards
46,656
cubic inches
cubic yards
0.7646 cubic
meters
cubic yards
202.0 gallons
cubic yards
764.6 liters
cubic yards/min.
0.45 cubic
feet/second
MULTIPLY
BY TO OBTAIN
cubic yards/min.
3.367
gallons/second
cubic yards/min.
12.74
liters/second
degrees (angle)
60
minutes
degrees (angle)
0.01745 radians
degrees (angle)
3,600 seconds
dynes
1.020 X [10.sup.-3] grams
dynes
2.248 X [10.sup.-6] pounds
ergs
9.486 X [10.sup.-11]
B.t.u.
ergs
1
dyne-centimeters
ergs
7.376 X [10.sup.-8] foot-pounds
ergs
[10.sup.-7] joules
ergs
2.390 X [10.sup.-11]
kilogram-calories
ergs
1.020 X [10.sup.-8]
kilogram-meters
ergs/second
1.341 X [10.sup.-10] horsepower
ergs/second
[10.sup.-10] kilowatts
feet
30.48 centimeters
feet
0.3048 meters
feet/second
18.29
meters/minute
foot-pounds
1.286 X [10.sup.-3] B.t.u.
foot-pounds
1.356 X [10.sup.7] ergs
foot-pounds
5.050 X [10.sup.-7]
horsepower-hours
foot-pounds
3.241 X [10.sup.-4]
kilogram-calories
foot-pounds
0.1383
kilogram-meters
foot-pounds
3.766 X [10.sup.-7]
kilowatt-hours
foot-pounds/minute
1.286 X [10.sup.-3]
B.t.u./minute
foot-pounds/minute
0.01667
foot-pounds/second
Foot-pounds/minute
3.241 X [10.sup.-4]
kg-calories/min
foot-pounds/minute
2.260 X [10.sup.-5] kilowatts
foot-pounds/second
7.172 X [10.sup.-2]
B.t.u./minute
foot-pounds/second
1.818 X [10.sup.-3] horsepower
foot-pounds/second
1.945 X [10.sup.-2]
kg-calories/min
foot-pounds/second
1.356 X [10.sup.-3] kilowatts
gallons
0.1337 cubic feet
gallons
231 cubic
inches
gallons
3.785 X [10.sup.-3] cubic
meters
gallons
3.785 liters
gallons/minute
2.228 X [10.sup.-3] cubic
feet/second
gallons/minute
0.06308
liters/second
grams
[10.sup.-3] kilograms
grams
[10.sup.3] miligrams
grams
0.03527 ounces
grams
0.03215 troy ounces
grams/cubic centimeter
62.43
pounds/cubic feet
grams centimeters
9.297 X [10.sup.-8] B.t.u.
horsepower
42.44
B.t.u./minute
horsepower
33,000
foot-pounds/minute
horsepower
550
foot-pounds/second
horsepower
10.70
kg-calories/min
horsepower
0.7457 kilowatts
horsepower
745.7 watts
horsepower
1.014
horsepower(metric)
horsepower-hours
2547 B.t.u.
horsepower-hours
1.98 X [10.sup.6] foot-pounds
horsepower-hours
641.7
kilogram-calories
horsepower-hours
2.737 X [10.sup.5]
kilogram-meters
horsepower-hours
0.7457
kilowatt-hours
horsepower-hours
2.684 X [10.sup.6] joules
inches
2.540 centimeters
inches
254.0 millimeters
MULTIPLY
BY TO OBTAIN
inches of mercury
0.03342
atmospheres
inches of mercury
1.133 feet of
water
inches of mercury
345.3 kgs/sq
meter
inches of mercury
70.73 pounds/sq
foot
inches of mercury
0.4912
pounds/sq inch
inches of water
0.002458 atmospheres
inches of water
0.07355 inches of
mercury
inches of water
25.40 kgs/square
meter
inches of water
0.5781
ounces/square inch
inches of water
5.204
pounds/square foot
inches of water
0.03613
pounds/square inch
joules
0.0009458 B.t.u.
joules
0.73756
foot-pounds
joules
0.0002778 watt-hours
joules
1.0
watt-seconds
kilograms
980,665 dynes
kilograms
[10.sup.3]
grams
kilograms
2.2046 pounds
kilograms
1.102 X [10.sup.-3] short tons
kilogram-calories
3.968 B.t.u.
kilogram-calories
3,086
foot-pounds
kilogram-calories
1.558 X [10.sup.-3]
horsepower-hours
kilogram-calories
4,183 joules
kilogram-calories
426.6
kilogram-meters
kilogram-calories/min.
51.43 foot-pounds/second
kilogram-calories/min.
0.09351 horsepower
kilogram-calories/min.
0.06972 kilowatts
kilograms/hectare
.893 pounds/acre
kilometers
[10.sup.5] centimeters
kilometers
0.6214 miles
kilometers
3,281 feet
kilometers
1,000 meters
kilometers
1093.6 yards
kilometers/hour
27.78
centimeters/sec
kilometers/hour
54.68 feet/minute
kilometers/hour
0.9113 feet/second
kilometers/hour
0.5396 knots/hour
kilometers/hour
16.67 meters/hour
kilometers/hour
0.6214 miles/hour
kilowatts
56.92
B.t.u./minute
kilowatts
4.425 X [10.sup.4]
foot-pounds/minute
kilowatts
737.6
foot-pounds/second
kilowatts
1.341 horsepower
kilowatts
14.34
kg-calories/min
kilowatts
[10.sup.3] watts
kilowatts-hours
3,412
B.t.u.
kilowatts-hours
2.655 X [10.sup.6] foot-pounds
kilowatts-hours
1.341
horsepower-hours
kilowatts-hours
3.6 X [10.sup.6] joules
kilowatts-hours
860.5
kilogram-calories
kilowatts-hours
3.671 X [10.sup.5]
kilogram-meters
meters
100 centimeters
meters
3.2808 feet
meters
39.37 inches
meters
[10.sup.-3] kilometers
meters
[10.sup.3] millimeters
meters
1.0936 yards
meter-kilograms
9.807 X [10.sup.7]
centimeter-dynes
MULTIPLY
BY TO OBTAIN
meter-kilograms
[10.sup.5]
centimeter-grams
meter-kilograms
7.233 pound-feet
meters/minute
1.667
centimeters/second
meters/minute
3.281 feet/minute
meters/minute
0.05468 feet/second
meters/minute
0.06
kilometers/hour
meters/minute
0.03728 miles/hour
meters/second
196.8 feet/minute
meters/second
3.281 feet/second
meters/second
3.6
kilometers/hour
meters/second
0.06
kilometers/minute
meters/second
2.237 miles/hour
meters/second
0.03728
miles/minute
miles
1.609 X [10.sup.5] centimeters
miles
5,280 feet
miles
1.6093
kilometers
miles
1,760 yards
miles/min
88.0 feet/second
miles/min
1.6093
kilometers/minute
miles/min
0.8684
knots/minute
ounces
8.0 drams
ounces
437.5 grains
ounces
28.35 grams
ounces
0.625 pounds
ounces/square inch
0.0625
pounds/square inch
pints (dry)
33.60 cubic
inches
pints (liquid)
28.87 cubic
inches
pounds
444,823 dynes
pounds
7,000 grains
pounds
453.6 grams
pounds
0.45 kilograms
pounds of water
0.01602 cubic feet
pounds of water
27.68
cubic inches
pounds of water
0.1198 gallons
pounds of water/min.
2.669 X [10.sup.-4] cubic
feet/second
pounds/cubic foot
0.01602 grams/cubic
cms.
pounds/cubic foot
16.02
kgs/cubic meter
pounds/cubic foot
5.787 X [10.sup.-4]
pounds/cubic inch
pounds/square foot
4.882 kgs/sq
meter
pounds/square foot
6.944 X [10.sup.-3]
pounds/square inch
pounds/square inch
0.06304 atmospheres
pounds/square inch
703.1 kgs/square
meter
pounds/square inch
144.0
pounds/square foot
quarts (dry)
67.20 cubic
inches
quarts (liquid)
57.75 cubic
inches
quadrants (angle)
90 degrees
quadrants (angle)
5,400 minutes
quadrants (angle)
1.571 radians
radians
57.30 degrees
radians
3,438 minutes
radians/second
57.30
degrees/second
raidans/second
0.1592
revolutions/second
revolutions
360.0
degrees
revolutions
4.0 quadrants
revolutions
6.283 radians
revolutions/minute
6.0
degrees/second
square centimeters
1.076 X [10.sup.-3] square feet
square centimeters
0.1550 square
inches
square centimeters
[10.sup.-6] square
meters
MULTIPLY
BY TO OBTAIN
square centimeters
100 square
millimeters
square feet
2.296 X [10.sup.-5] acres
square feet
929.0 square
centimeters
square feet
144.0 square
inches
square feet
0.09290 square
meters
square feet
3.587 X [10.sup.-8] square
miles
square feet
0.1111 square
yards
square inches
6.452 square
centimeters
square inches
645.2
square millimeters
square meters
2.471 X [10.sup.-4] acres
square meters
10.764 square
feet
square meters
3.861 X [10.sup.-7] square
miles
square meters
1.196 square
yards
square miles
640.0 acres
square miles
2.7878 X [10.sup.7] square
feet
square miles
2.590 square
kilometers
square miles
3.098 X [10.sup.6] square
yards
square yards
2.066 X [10.sup.-4] acres
square yards
9.0 square
feet
square yards
0.8361 square
meters
square yards
3.228 X [10.sup.-7] square
miles
temp (degs C) + 237
1.0 abs temp
(degs K)
temp (degs C) + 17.8
1.8 temp (degs
F)
temp (degs F) - 32
5/9 temp (degs
C)
tons (long)
1,016 kilograms
tons (long)
2,240 pounds
tons (metric)
[10.sup.3] kilograms
tons (metric)
2,205 pounds
tons (short)
907.2 kilograms
tons (short)
2,000 pounds
tons (short)/sq. foot
9,765 kgs/square
meter
tons (short)/sq. foot
13.89
pounds/square inch
tons (short)/sq. inch
1.406 X [10.sup.6] kgs/square
meter
tons (short)/sq. inch
2,000
pounds/square inch
yards
0.9144 meters
TEMPERATURE CONVERSION
The chart in
Figure 1 is useful for
quick conversion from degrees Celsius
(Centigrade) to degrees Fahrenheit and
vice versa. Although
the chart is fast
and handy, you must use the equations
below if your answer must be accurate
to within one degree.
Equations:
Degrees Celsius = 5/9 x (Degrees
Fahrenheit -32)
Degrees Fahrenheit = 1.8 (Degrees
Celsius) +32
Example:
This example may
help to clarify the
use of the equations; 72F equals how
may degrees Celsius?
72F = 5/9 (Degrees
F -32)
72F = 5/9 (72 -32)
72F = 5/9 (40)
72F = 22.2C
Notice that the
chart reads 22C, an
error of about 0.2C.
========================================
========================================