Hydraulic Ramp

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CHAPTER 1

INTRODUCTION

Mechanical pumps are the second most common machine in the world (after

electric motors). Ram Pumps have been used for over two centuries in many parts of

the world. Their simplicity and reliability made them commercially successful,

particularly in Europe, in the days before electrical power and the internal combustion

engine become widely available. As technology advanced and become increasingly

reliant on sources of power derived from fossil fuels, the ram pump was neglected. It

was felt to have no relevance in an age of national electricity grids and large - scale

water supplies. In recent years 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. Although there are

some examples of successful ram pump installation in developing countries, their use

to date has merely scratched at the surface of their potential [1].

Fig. 1.1: Hydraulic Ram Pump [5]

The main reason for this being, lack of wide spread localknowledge in the

design and manufacture of ram pumps. The requirement is a local manufacturer to

deliver quickly; give assistance in system design, installation, and provide an after-

sales service.

1.1 Principle of Hydraulic Ram Pump

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A hydraulic ram (or water ram) pump is a simple, motorless device for

pumping water at low flow rates. It uses the energy of flowing water to lift water from

a stream, pond or spring to an elevated storage tank or to a discharge point. The

device utilizes a phenomenon called stagnation pressure, also known as water

hammer, which is based on Bernoulli's principle.

In operation, a portion of the input water that powers the pump is lifted to a

point higher than where the water originally started. It is suitable in remote areas,

where there is both a source of low-head hydropower, and a need for pumping water

to a destination higher in elevation than the source, since it requires no outside source

of power other than the kinetic energy of water.

It is also used where small quantities of water are required and power supplies

are limited, such as for household, garden, or livestock water supply. A hydraulic ram

pump is useful where the water source flows constantly and the usable fall from the

water source to the pump location is at least 3 feet [2].

Fig. 1.2: Various terms associated with Hydraulic Ram Pump [7]

1.2 OperationA hydraulic ram has only two moving parts, a spring or weight loaded "waste"

valve and a "delivery" check valve, making it cheap to build, easy to maintain, and

very reliable. In addition, there is a drive pipe supplying water from an elevated

source, and a delivery pipe, taking a portion of the water that comes through the drive

pipe to an elevation higher than the

source [5].

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1. Inlet - drive pipe

2. Free flow at waste valve

3. Outlet - delivery pipe

4. Waste valve

5. Delivery check valve

6. Pressure vessel

Fig.1.3: Functioning of Hydram [5]

1.2.1 Sequence of operation: Initially, the waste valve (4) is open; the delivery

valve (5) is closed. The water in the drive pipe (1) starts to flow under the force of

gravity and picks up speed and kinetic energy until it forces the waste valve closed.

The momentum of the water flow in the supply pipe against the now closed waste

valve causes a water hammer, raises the pressure in the pump and opens the delivery

valve (5), so some water flows into the delivery pipe (3). Since this water is being

forced uphill through the delivery pipe farther than it is falling downhill from the

source, the flow slows down and when it reverses the delivery check valve closes. If

all water flow has stopped, the loaded waste valve reopens against the now static

head, allowing the process to begin again.

A pressure vessel (6) containing air, cushions the hydraulic pressure shock

when the waste valve closes, and it also improves the pumping efficiency by allowing

a more constant flow through the delivery pipe. Although, in theory, the pump could

work without it, the efficiency would drop drastically and the pump would be subject

to extraordinary stresses which would shorten its life considerably [5].

1.3 Objective of the Project

The objective of this project is to study the various factors related to the

construction, working, design, installation and testing of a Hydraulic Ram Pump. For

this purpose the site was selected such that the rain water from department roofs can

be used to fill the source water tank to pump the water to a delivery tank placed at a

higher elevation to use the water for different purpose in labs.

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CHAPTER 2

Types of RAM pump

Existing Ram PumpsThese are some type of hydraulic ram pumps manufactured by different

industries at initial stage of its implication.

.1 B and L ram pump

The B and L hydro-Ram is being manufactured since 1989. It is an efficient,

lightweight, dependable and inexpensive hydraulic ram pump [7].

B and L ram pumps [7]

It works on the same principle of physics that enabled its cumbersome

predecessors to water the farmlands of Europe, the Mid-East and Asia over the past

two hundred plus years.

Vulcan hydraulic ram pump

The Vulcan hydraulic ram pump is still their only product of green and carter

after more than 200 years. They were the inventors and patentees of the hydraulic ram

principle in 1774.

Green and Carter now make over 60 varieties of Vulcan Hydraulic Ram

Pumps, including models that can pump water to heads of over 1000 feet, with drive

pipe sizes of 3/4 of an inch (1.9cm) to 30 inches (76.2cm).

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Fig.2.2: Vulcan hydraulic ram pump [7]

Bam ford Hi- ram Pump

Principle of operation of the Bam ford Hi-Ram Pump is similar to that of a

traditional hydraulic ram pump; the new pump is considerably different in its

construction and operating characteristics [6].

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Fig.2.3: Bam ford Hi- rams Pump [6]

2.3 Factors in Design of Hydram

For existing pump the quantity of water delivered at destination as per given

fall and lift, can be found by using the formula:

D = (S x F x )/L

Where:

D = Amount delivered in liters per 24 hours.

S = Quantity of water supplied in liters per minute.

F = The fall or height of the source above the ram in meters.

= The efficiency of the ram (for commercial models use 0.66, for home built

use 0.33 unless otherwise indicated).L = The lift height of the point of use above the ram in meters.

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DESIGN CONSIDERATIONS AND CALCULATIONS

4.1 Factors in Design

Before a ram can be selected, several design factors must be known. These

are:

1. The difference in height between the water source and the pump site (called

vertical fall).

2. The difference in height between the pump site and the point of storage or use

(lift).

3. The quantity (Q) of flow available from the source.

4. The quantity of water required.

5. The length of pipe from the source to the pump site (called the drive pipe).

6. The length of pipe from the pump to the storage site (called the delivery pipe).

Once this information has been obtained, a calculation can be made to see if

the amount of water needed can be supplied by a ram [3].

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Fig. 4.1: Design Considerations for Hydram [3]

The formula is: D = (S x F x )/L

Where:

D = Amount delivered in liters per 24 hours.

S = Quantity of water supplied in liters per minute.

F = The fall or height of the source above the ram in meters.

= The efficiency of the ram (for commercial models use 0.66, for home built

use 0.33 unless otherwise indicated).

L = The lift height of the point of use above the ram in meters.

Fig.4.2: Case of ram pump being remote from source [3]

4.1.1 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 basin must be provided.

4.1.2 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 150-1000.

Table 2.2 shows the minimum and maximum pipe lengths for various pipe sizes.

It should be straight as possible without elbows, and normally the same pipe

size as Intake end of the Ram.

4.1.3 Foundation and ram pit: A concrete slab or a large flat rock provides a good

solid foundation to set the Ram. The best procedure is to put in a concrete slab as a

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foundation, slightly sloping towards the rear where the unused water will be carried

away. The Pit should be high enough to prevent flood water from getting in.

4.1.4 Ram: Rams can be constructed using commercially available check valves or by

fabricating check valves. They are also available as manufactured units in various

sizes and pumping capacities. Rams can be used in tandem to pump water if one ram

is not large enough to supply the need. Each ram must have its own drive pipe, but all

can pump through a common delivery pipe as shown in Figure 4.3

Fig.4.3: Multiple Rams with Common Delivery Pipe [3]

In installing the ram, it is important that it should be leveled, securely attached

to an immovable base, preferably concrete and waste-water must be drained away.

The pump can not operate when it is submerged. Since the ram usually operates on a

24 hour basis hence the size can be determined for delivery over a 24 hour period.

4.1.5 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 4.1

Table 4.1: Delivery Pipe Selection[6]

Delivery Pipe Size (mm) Flow (liters/min)

30 6-36

40 37-60

50 61-90

80 91-234100 235-360

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The correct size delivery pipe should match the dimension given for each

particular size of Ram. Do not install a delivery pipe smaller than that is specified. By

doing so you increase the amount of friction lost, consequently reducing the amountof water delivered. Avoid right-angled elbows wherever possible. This will minimize

friction loss.

4.1.6 Drain tile: The Ram Pit should be provided with a drain tile to carry off unused

water.

4.1.7 Storage tank: This is located at a level to provide water to the point of use. The

size is based on the maximum demand per day [3].

OPERATION AND TESTING

6.1 Operation of PumpThe concept behind the ram idea is a "water hammer" shock wave. Water has

weight, so a volume of water moving at a certain speed has momentum - it doesn't

want to stop immediately. If a car runs into a brick wall the result is crumpled metal.

If a moving water flow in a pipe encounters a suddenly closed valve, a pressure

"spike" or increase suddenly appears due to all the water being stopped abruptly (that

is what water hammer is - the pressure spike). If you turn a valve off in your house

quickly, you may hear a small "thump" in the pipes. That is water hammer.

Here is how the hydraulic ram pump actually works, step-by-step:

Step 1: Water (blue arrows) starts flowing through the drive pipe and out of the

"waste" valve (4 on the diagram), which is open initially. Water flows

faster and faster through the pipe and out of the valve.

Step 2: At some point, water is moving so quickly through the brass swing check

"waste" valve (4) that it grabs the swing check's flapper, pulling it up and

slamming it shut. The water in the pipe is moving quickly and doesn't

want to stop. All that water weight and momentum is stopped, though, by

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the valve slamming shut. That makes a high pressure spike (red arrows) at

the closed valve. The high pressure spike forces some water (blue arrows)

through the spring check valve (5) and into the pressure chamber. This

increases the pressure in that chamber slightly. The pressure "spike" the

pipe has now here else to go, so it begins moving away from the waste

valve and back up the pipe (red arrows). It actually generates a very small

velocity backward in the pipe.

Step 3: As the pressure wave or spike (red arrows) moves back up the pipe, it

creates a lower pressure situation (green arrows) at the waste valve. The

spring-loaded check valve (5) closes as the pressure drops, retaining the

pressure in the pressure chamber.

Step 4: At some point this pressure (green arrows) becomes low enough that the

flapper in the waste valve (4) falls back down, opening the waste valve.

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Fig.6.1: Step by step representation of sequence of operation of Hydram

Step 5: Most of the water hammer high pressure shock wave (red arrows) will

release at the drive pipe inlet, which is open to the source water body.

Some small portion may travel back down the drive pipe, but in any case

after the shock wave has released, pressure begins to build again at the

waste valve (4) simply due to the elevation of the source water above the

ram, and water begins to flow toward the hydraulic ram again.

Step 6: Water begins to flow out of the waste valve (4), and the process starts over

once again.

Steps 1 through 6 describe in layman's terms a complete cycle of a hydraulic

ram pump. Pressure wave theory will explain the technical details of why a hydraulic

ram pump works, but we only need to know it works. Each "pulse" or cycle pushes a

little more pressure into the pressure chamber. If the outlet valve is left shut, the ram

will build up to some maximum pressure (called shutoff head on pumps) and stop

working.

Ram Performance

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1. Volumetric efficiency :

100*

dw

d

vQQ

Q

+

=

2. Power efficiency :

100**H

h

Q

Q

w

dp =

6.1.1 Leakage problems: Ensure proper connections of the pipe, and any leakages

found either in connections or joints in the hydram are stopped using adhesive. Use of

rubber bushes is recommended at the joints.

6.1.2 Head losses in pipes: Headlose occurs in pipes due to sudden enlargement

and contraction, various pipe fittings, friction losses and bend in pipe. It deviates the

result from theoretical efficiency.

6.1.3 Choking of pipe:

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A filter may be used for filtering highly impure water.

Ensure that the hydram is placed vertically.

Ensure the free movement of the waste valve and the non-return valve.

Advantages of Hydram

For any particular site, there are usually a number of potential water lifting

options. Choosing between them involves consideration of many different factors.

The main advantages of ram pumps are:

Pollution free.

Does not consume petrol, diesel or electricity.

Simplicity and reliability give a low maintenance requirement.

There is good potential for local manufacture in the rural villages.

Use of a renewable energy source ensuring low running cost.

Automatic, continuous operation, no supervision or human input.

Pumping only a small proportion of the available flow has little environmental

impact.

Limitations of Hydram

They are limited in hilly areas with a year-round water sources

Hydraulic ram pump require source flows larger than actual water delivered

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Can have a high capital cost in relation to other technologies

REFERENCES

1. Bansal, R.K., Fluid Mechanics and Hydraulic Machines, ninth edition,

Laxmi Publications, 2005, pp 1045 - 47

2. Arora, K. R. Fluid Mechanics Hydraulics and Hydraulic Machines,

Standard publishers Distributers, India, 1989

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3. Tessema A. A, Hydraulic Ram Pump System Design and Application.

Development and Technology Adaptation Center, ESME 5th Annual

Conference on Manufacturing and Process Industry, September 2000

4. Chiang, Y.C. and Seireg, A.A., Simulating Fluid Transients in segmented

pipelines, CIME, Vol. 3, Nov. 1985, pp 31-35

5. http://en.wikipedia.org/wiki/Hydraulic_ram

6. http://www.bamford.com.au/rampump/about.htm

7. http://www.eng.warwick.ac.uk/dtu/pubs/tr/lift/rptr12/tr12.pdf

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