Theory and Application of Hydraulic Ram Pumps (Hydrams) - S Hazarika
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Theory and Application of Hydraulic Ram Pumps (Hydrams)
INTRODUCTION ": '^ "M^'":':':^-: '^^/'^i-"
Hydraulic ram pumps commonly known, as hydrams
are water-lifting devices that are powered by falling
water. Such pumps work by using the potential energy
of water falling through a small height to lift a small
part of that amount of water to a much greater height.
In this way, water from a spring or stream in a valley
can be pumped to a village or irrigation scheme on
the hillside. The main advantage of hydraulic ram
p u m p s is that it operates automatically and
continuously with no other external energy source. It
uses a renewable energy source (stream of water) and
hence ensures low running cost. Hydraulic ram pumps
are simple, reliable and require minimal maintenance.
All these advantages make hydraulic ram pumps
suitable for rural c o m m u n i t y water supply and
irrigation where there are no other sources of power
and topography and hydrology is suitable.
Ram Pumps have been used for over two centuries in
many parts of the world. Their simplicity and reliability
had made them commercially successful, particularly
in Europe. As technology advanced and become
increasingly reliant on sources of power derived from
fossil fuels, the ram pump was neglected. In recent
years however, an increased interest in renewable
energy devices and an awareness of the technological
needs of a particular market in developing countries
have prompted a reappraisal of ram pumps. In hilly
areas with springs and streams, the potential for a
simple and reliable pumping device is large.
Fig 1 shows a typical layout of a hydram installation
D = Amount to be delivered in liters per 24 hours.
d = Amount to be delivered in liters/minute = D/
(60X24) = 0/1440
S = Quantity of water supplied from the source in
F = The fall or height of the source above the ram in
E = The efficiency of the ram (for commercial models
use 0.66, for home built use 0.33 unless otherwise
L = The lift height of the point of use above the ram
Equating the potential energy on the fall side and the
rise side we have
d X L = S X F X E
O r d = ( S x F x E ) / L
O r D = 1 4 4 0 X ( S x F x E ) / L • : ' ,
Table 1 gives the amount of water delivered in 24 hours
for a supply of 1 liter per minute for various working
fall and lift. An efficiency of 50% has been assumed
for the purpose. For supplies greater than 1 liter/
minute, simply multiply by the number of liters
Chief General Manager (Retd), HO
ISSUE 10, 2007 For Private circulation only
Table 1 :
Working Fall (F)
1 Vertical H
in 24 Hours (liters) for
ugh w h
r is to be lifi
a Supply of 1 Lits/Min
Efficiency 5 0 %
Design of Components of Hydraulic Ram
A hydraulic ram installation consists of a supply, a drive
pipe, the ram, a supply line and usually a storage tank.
These are shown in Figure 1. Each of these
component parts is discussed below:
Supply. The intake must be designed to keep trash
and sand out of the supply since these can plug up
the ram. If the water is not naturally free of these
materials, the intake should be screened or a settling
Table 2 : Range of Drive Pipe Lengths
for Various Pipe Diameters
IDrive Pipe Size
basin provided. When the source is remote from the
ram site, a supply line can be provided to conduct the
water to the drive pipe. The supply line, if needed,
should be at least one pipe diameter larger than the
Drive pipe. The drive pipe must be made of a non-
flexible material for maximum efficiency. This is
usually galvanized iron pipe, although other materials
cased in concrete will work. In order to reduce head
loss due to friction, the length of the pipe divided by
the diameter of the pipe should be within the range of
150-1,000. Table 2 shows the minimum and
maximum pipe lengths for various pipe sizes.
Table 3 : Sizing the Delivery Pipe
Delivery Pipe Size
3te 10,2007 Prat MR^HH I ^
The drive pipe diameter is usually chosen based on
the size of the ram and the manufacturer's
Delivery Pipe. The delivery pipe can be of any
material that can withstand the water pressure. The
size of the line can be estimated using Table 3.
Storage Tanl<. This is located at a level to provide
water to the point of use. The size is based on the
maximum demand per day.
In installing the ram, it is important that it be level,
securely attached to an immovable base, preferably
concrete, and that the waste water be drained away.
The pump cannot operate when submerged. Since
the ram usually operates on a 24-hour basis the size
can be determined for delivery over a 24-hour period.
APPLICATIONS AND LIMITATIONS OF HYDRAULIC
The advantages of a ram pump are :
• Use of a renewable energy source ensuring low
• Pumping only a small proportion of the available
flow has little environmental impact
• Simplicity and reliability give a low maintenance
• There is good potential for any particular site; there
is usually a number of potential water lifting options.
Choosing between them involves consideration of
many different factors. Ram pumps in certain
conditions have many advantages over other forms
of water lifting, but in others, it can be completely
inappropriate. The main advantages of ram pumps
are: for local manufacture in the rural villages
• Automatic, continuous operation requires no
supervision or human input.
The main limitations are;
• They are limited to hilly areas with a year-round
• They pump only a small fraction of the available
flow and therefore require source flows larger than
actual water delivered
• Can have a high capital cost in relation to other
• Are limited to small-scale applications, usually up
Specific situations in which other technologies may
prove more appropriate are:
• In terrain where streams are falling very rapidly, it
may be possible to extract water at a point above
the village or irrigation site and feed it under gravity.
• If the water requirement is large and there is a large
source of falling water (head and flow rate) nearby,
turbine-pump sets can provide the best solution.
Many ram pumps could be used in parallel to give
the required output but at powers over 2kW,
turbine-pump systems are normally cheaper.
• In small-scale domestic water supply, the choice
can often be between using a ram pump on a
stream or using cleaner groundwater. Surface
water will often need to be filtered or treated for
human consumption, increasing the cost of a
system and requiring regular filter maintenance.
Under these conditions, to select a hydram pump,
economical considerations compared to other
technologies has to be looked at.
REFERENCES £ >:
1. Jeffery, T. D., "Hydraulic Ram Pumps - A Guide to
Ram Pumps Water Supply System", Intermediate
Technology Publications, ^Q22.
2. Dr. Tessema, Abiy Awoke " Hydraulic Ram Pump
System Design And Application"
ESME 5th Annual Conference on Manufacturing
and Process Industry, September 2000