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Collection & Conveyance of Water 
Unit-II 
BTCI05006/ MBCI05006
Collection & Conveyance of Water 
Unit-II
Syllabus 
• Collection and conveyance of water: Types of intake structure, design 
of intake structure, estimation of fluid flows, engineering 
requirements of conduits with respect to their performance, types of 
conveyance system, hydraulic design of conveyance conduits, various 
materials of pipes, appurtenances, and issues associated with 
conveyance of water. 
• Pumps for lifting of water: Types of pumps, selection of pumps, 
design of pumping main for conveyance of water, economical 
diameter of pumping main, pumping station
Intake Structures
Introduction 
• In any water supply project the first step is to select 
the source of water from which water is drawn. The 
device Installed for the purpose of drawing water 
from the source of water are called Intakes
Intake Structures
Intake Structure 
• The basic function of intake structure is to help in safely withdrawing 
water from the source and then to discharge this water in to the 
withdrawal conduit, through which it reaches the water treatment 
plant. 
• It is constructed at the entrance of the withdrawal conduit and thereby 
protecting it from being damaged/clogged by ice,debris. 
• Some times from reservoirs where gravity flow is possible, water is 
directly transmitted to the treatment through intake structure. 
• If gravity flow is not possible, water entering intake structure is lifted by 
pumps and taken to the treatment plant.
Intake Structure
Intake Structure
Selecting Location Of Intake Structure 
• Site should be near the treatment plant to reduce conveyance cost. 
• Intake must be located in the purer zone of the source so that best quality 
water is withdrawn from source to reduce the load on the treatment plant. 
• Intake must never be located in the vicinity of waste water disposal point. 
• Intake must never be located near the navigation channels so as to reduce 
chances of pollution due to waste discharge from ships. 
• The site should be such as to permit greater withdrawal of water, if 
required in future.
Selecting Location Of Intake Structure
Selecting Location Of Intake Structure 
• Intake must be located at a place from where it can draw water even 
during the driest period of the year. 
• The intake site should remain easily accessible during floods and 
should not get flooded. 
• In meandering rivers, the intakes should not be located on curves or 
atleast on sharp curves.
Selecting Location Of Intake Structure
Intakes for Collecting Surface Water 
Types of Intakes 
According to type of source 
• River Intake 
• Canal Intake 
• Reservoir Intake 
• Lake Intake 
According to position of Intake 
• Submerged Intake 
• Exposed Intake 
According to presence of water in the tower 
• Wet Intake 
• Dry Intake
Intakes for Collecting Surface Water 
According to position of Intake 
• (a) Submerged Intake 
• (b) Exposed Intake 
• The submerged Intake structures are those which are constructed entirely 
under water. They are less expensive to construct but are difficult to 
maintain. Such intakes are commonly used to obtain water from lakes 
• The Exposed intakes is in the form of well or tower constructed near the 
bank of river or in some cases even away from the bank of river. They are 
more common due to ease in operation and maintenance
Intakes for Collecting Surface Water 
According to presence of Water in the tower 
Wet Intake 
Dry Intake 
A Wet intake is that type of the Intake tower in which the water level is 
practically the same as the water level of the source of supply. Such 
Intakes are also called as JackWell and is most commonly Used 
In Dry Intake There is no water in the intake tower. Water enters 
through entry port directly in to conveyance pipes. The dry Intake 
tower is simply used for the operation of valves.
Simple Lake Submerged Intakes 
• It consists of a simple concrete block or a rock filled timber crib 
supporting the starting end of the withdrawal pipe. 
• The intake opening is generally covered by screen so as to prevent the 
entry of debris, ice etc.. in to the withdrawal conduit. 
• In lakes, where silt tends to settle down , the intake opening is generally 
kept at about 2 to 2.5m above the lake bed level to avoid entry of silt. 
• They are cheap & do not obstruct navigation 
• They are widely used for small water supply projects drawing water from 
streams or lakes having a little change in water level through out year. 
• Limitation is that they are not easily accessible for cleaning & repairing.
Simple Submerged Intakes
Rock Filled Timber Crib -Submerged Intake
Intakes for Collecting Surface Water 
River Intake 
A River Intake is located on the upstream side of the city to get 
comparatively better quality of water. They are either located 
sufficiently inside the river so that necessary demand of water 
can be met in all the seasons of the year. 
The intake tower permits the entry of water through several entry 
ports located at various levels to cope with fluctuations in the water 
levels during different seasons. 
This are also called as penstocks. The penstocks are covered with 
suitable design screens to prevent entry of floating impurities.
Intake Towers 
• They are widely used on large water supply projects drawing water from rivers 
or reservoirs having large change in water level. 
• Gate controlled openings called Ports are provided at various levels in these 
concrete towers to regulate the flow. 
• If the entry ports are submerged at all levels, there is no problem of any 
clogging or damage by ice or debris etc.. 
• There are two major types of intake towers: 
(a)Wet intake towers 
(b) Dry intake towers
Wet Intake Towers 
• It consist of a concrete circular shell filled with water up to the reservoir 
level and has a vertical inside shaft which is connected to the 
withdrawal pipe. 
• The withdrawal pipe may lie over the bed of the rivers or may be in the 
form of tunnels below the river bed. 
• Openings are made in to the outer concrete shell as well as, in to the 
inside shaft. 
• Gates are usually placed on the shaft, so as to control the flow of water 
in to the shaft and the withdrawal conduit. 
• The water coming out of the withdrawal pipe may be taken to pump 
house for lift (if treatment plant is at high elevation) or may be directly 
taken to treatment plant (at lower elevation).
Wet Intake Towers
Dry Intake Towers 
• The water is directly drawn in to the withdrawal conduit through the 
gated entry ports. 
• It has no water inside the tower if its gates are closed. 
• When the entry ports are closed, a dry intake tower will be subjected 
to additional buoyant forces. 
• Hence it must be of heavier construction than wet intake tower. 
• They are useful since water can be withdrawn from any selected level 
of the reservoir by opening the port at that level.
Dry Intake Towers
Intake
Intake 
• There are two types of intakes as under 
• (i) Dry Intake Tower 
• In dry intake tower the entry ports are directly connected with the 
withdrawal conduit and water inside the tower when gates are in a 
closed position. Dry Intake tower has a merit that the intake tower 
being dry is made accessible for inspection and operation besides 
that the water can be withdrawn from any level by opening the port 
at that level. 
• However, dry intake tower is massive in structure, than wet intake to 
withstand additional buoyant forces to which it is subjected when the 
port gates are closed.
Dry Intake Tower
Dry Intake Tower
Dry Intake Tower
Intake 
Wet Intake Tower 
• A wet intake tower has entry ports at various levels and the vertical 
shaft is filled with water up to reservoir level. It differs from the dry 
intake tower is that the water enters from the ports into the tower 
and then into the withdrawal conduict through separate gated 
openings. As such it consists of a circular shell made of concrete 
filled with water up to reservoir level, housing another inside shaft 
directly connected to the withdrawal conduit. It is less costly to 
construct and is usually not subjected to flotation and certain other 
stress may not be the consideration.
Wet Intake Tower
Trash Racks 
• Trash rack is defined as a screen or grating provided at the entrance 
of intake to prevent entry of debris. Trash racks usually consists of 
trash sections 1.5 to 2 m wide and not too long for handling, made 
up of mild steel flats on edge 5 to 15 cm. Coarse trash racks are 
provided near the ports to prevent large drift, such as cakes of ice, 
roots, trees and timber from being drawn into the intake.
Trash Racks 
• In some part of the intake fine trash racks are provided to protect the 
machine & machine parts through which water flows. In cold region, 
trash racks is often clogged with fragile ice. Electrical heating for 
small trash racks are provided to prevent ice formation on the racks. 
• The floating debris accumulated, as are denied entry into the intake, 
are removed with the help of power driven rack-rakes.
Trash Racks
River Intake Structures 
• They are generally constructed for withdrawing water from 
almost all rivers. 
• They can be classified in to two types 
(1) Twin well type of intake structure 
(2) Single well type of intake structure
Twin Well Type Intakes 
• They are constructed on almost all types of rivers, where the river water hugs 
the river bank. 
• A typical river intake structure consists of 3 components: 
(a) An inlet well 
(b) An inlet pipe (intake pipe) 
(c) A jack well 
• Inlet well is usually circular in c/s, made of masonry or concrete. 
• Inlet pipe connects inlet well with jack well. It has a min dia of 45cm, laid at 
slope of 1 in 200. Flow velocity through it<1.2m/s 
• Water entering jack well is lifted by pumps & fed into the rising main 
• Jack well should be founded on hard strata having B.C> 450 kN/m2.
Twin Well Type Intakes
Single Well Type Intakes 
• No inlet well & inlet pipe in this type of river intake. 
• Opening or ports fitted with bar screens are provided in the jack 
well itself. 
• The sediment entering will usually be less, since clearer water will 
enter the off-take channel. 
• The silt entering the jack well will partly settle down in the bottom 
silt zone of jack well or may be lifted up with the pumped water 
since pumps can easily lift sedimented water. 
• The jack well can be periodically cleaned manually, by stopping the 
water entry in to the well.
Single Well Type Intakes
Single Well Type Intakes
Canal Intakes
Canal Intakes 
• In case of a small town a nearby Irrigation Canal can be used as 
the source of water. The Intake Well is generally located in the bank 
of the Canal. Since water level is more or less constant there is no 
need of providing inlets at different depth. It essentially consist of 
concrete or masonry intake chamber or well. 
• Since the flow area in the canal is obstructed by the construction 
of Intake well, the flow velocity in the canal decreases. So the 
canal should be lined on the Upstream & Downstream side of the 
intake to prevent erosion of sides and bed of channel
Intakes For Sluice Ways Of Dams
Intakes For Sluice Ways Of Dams
Intakes For Sluice Ways Of Dams
Intakes for Reservoirs 
• When the flow in the river is not guaranteed throughout the year, 
a dam is constructed across the river to store the water in the 
reservoir so formed. 
• Reservoir Intakes essentially consists of an Intake tower 
constructed on the slope of Dam at such a place where Intake can 
draw water in sufficient quantity even in the driest period. Intake 
pipes are fixed at different levels, so as to draw water near the surface 
in all variations of water levels.
An intake structure constructed at the entrance of conduit 
and thereby helping in protecting the conduit from being 
damaged or clogged by ice , trash, debris, etc.., can vary from a 
simple Concrete block supporting the end of the conduit pipe 
to huge concrete towers housing intake gates, Screens, pumps, 
etc.. and even sometimes, living quarters and shops for 
operating personnel.
Lake Intake 
• Lake Intake are mostly submerged intake. These Intakes are 
constructed in the bed of lake below the low water level so as to draw 
water even in dry season. It mainly consist of a pipe laid in the bed of 
the lake. One end of the pipe which is in middle of the lake is fitted 
with bell mouth opening covered with a mesh and protected timber 
or concrete crib. The water enters in the pipe through the bell mouth 
opening and flows under gravity to the bank where it is collected in a 
sump well and then pumped to the treatment plant for necessary 
treatment.
Submerged Intake
Advantages Intakes 
• No Obstruction to navigation 
• No danger of floating bodies 
• No ice trouble
Intake
Intake 
• The general requirement of an Intake Structure are: 
Structural Stability 
• The Intake structure is stable to resist water and wave thrust besides 
wind pressure when reservoir is empty as also against the shock of 
earthquakes. 
Hydraulic efficiency 
• There is smooth entry into the water conductor system to ensure 
gradual transformation of static head to conduct velocity so as to 
involve hydraulic losses.
Intake
Intake 
Velocity Limitation 
• The velocity through trash rack gates and ports is within economic and 
safe limits. 
Operational efficiency 
• The intake and the equipments are such as to prevent/ minimize ice, 
floating trash and coarse sediment entering the water conductor system 
to ensure good operational efficiency.
Intake 
• The main components of an irrigation intake structure are 
(i) Trash rack and supporting structure 
(ii) Bell mouth entrance with transition and rectangular circular 
opening, and 
(iii) Gate slot closing devices with air vents.
Trash Rack
Bell Mouth Entrance
Gate slot closing devices with air vents.
Intake 
Function of Intakes 
• Intake structure serve to permit withdrawal of water in the 
reservoir over a predetermined range of reservoir levels to the outlet. 
• The other functions served by an intake are to support necessary 
auxiliary appurtenances such as trashrack, fish screens and 
bypass devices, etc.,.
Intake
Intake
Intakes
Intake
Intake
Intake
Intake 
Run-of-River Intakes 
• In a run-of-River plants, intake is apparent to power house and 
draws water from the river without any appreciable storage 
upstream of the diversion structure. Characteristics of river flows., 
the intake is designed to withstand high peaks and short duration flood 
flows and high sediment loads. The bell mouth entrance is 
essentially provided with trash racks.
Run-of-River type Intake
Intake 
Canal Intake 
• It is also a variant of the run-of-river intake, that is provided 
adjacent to the diversion weir/ barrages to admit water into the 
canal. It is designed to function under low heads and the topography 
and geology permits straight reach suitable for it. Sediment 
excluder is an essential component of the intake. The crest of the 
intake is generally raised to prevent entry of coarse fraction of bed 
load into the canal.
Canal Intake
Intake 
Reservoir Type Intakes 
• Intake tower classified as Submerged, dry and wet intakes fall in 
this category. 
(i) Submerged Intake 
• An Intake Structure which remains entirely under water during 
its operation is termed as submerged intake. It is provided where 
the structure serves only as an entrance to the outlet conduct and 
where ordinarily cleaning of the trash is not required. The conduct 
intake may be inclined, vertical or horizontal in accordingly with 
the intake requirements. . An Inclined Intake may be provided 
with gates and operated on the upstream slopes of a low dam.
Submerged Intakes
Submerged Intake
Intake 
Intake tower 
• An Intake tower is used to draw water from the reservoir 
in which there are huge fluctuations in water level or 
quality water is to be drawn at the desirable depth or both. It 
Consist of an elaborate exposed or tower like structure 
rising above maximum reservoir level and closely located 
to the dam body or the bank of the stream so as to be 
approached by a connecting bridge of minimum span.
Intake
Intake 
• The Intake tower consist of circular concrete structure 
provided with openings or ports for water entry fitted 
with trash racks to prevent the entry of debris and ice large 
enough to injure the equipment and gates that control the 
flow through intakes into the feeding conduct outlet. 
• It has a merit that best quality of water available at 
different depths at different seasons of the year can be 
drawn through port openings at different elevations.
Design of Intake 
• An Intake should be designed and constructed on the basis of following 
points 
• Sufficient factor of safety should be taken so that intake work can resist 
external forces caused by heavy waves and currents, Impact of floating 
and submerged bodies, ice pressure etc.. 
• Intake should have sufficient self weight, so that it may not float by the up 
trust of water and washed away by the current 
• If Intake work is constructed in navigation channels, it should be protected 
against the impact of the moving ships by cluster of pile around 
• The foundation of Intake should be taken sufficient deep so that they may 
not be undermined and current may not overturn the structure.
Design of Intake 
• To avoid the entrance of large and medium objects and fishes screens 
should be provided on the Inlet, sides 
• The Inlet should be of sufficient size and should allow required 
quantity of water. 
• The positions of Inlet should be such that they can admit water in all 
seasons near the surface where quality of water is good. 
• Number of Inlets should be more so that if any one is blocked, the 
water can be drawn from others. The inlets should be completely 
submerged so that air may not enter the suction pipe.
Canal Intake
Design procedure for Intakes 
Canal Intake 
• If Population is given and rate of water Supply is given the discharge 
required by the city/town can be found 
• Q= Population x Rate of Supply 
Design of Coarse Screen 
• Generally the coarse screens are made of vertical bars of 15 to 20 
mm dia and are spaced at 20 to 50 mm Centre to Centre 
• Velocity through the screens is assumed to bearound 0.15 m/sec
Canal Intake
Design procedure for Intakes 
• Area of Screens= Discharge 
Velocity through screens 
Q= A x V 
Height of the screen is found assuming that the bottom of the screen is 
kept 0.15 m above canal bed and also considering the minimum water 
level in the canal. 
After finding height, length of the screen opening can be found out. 
Length of screen = Area 
Height
Canal Intake
Design procedure for Intakes 
• Number of bars required can be found after assuming the diameter 
and spacing of the bars. 
• Total length of screen will be length of opening + length occupied by 
bars . 
Design of bell mouth entry 
• To find the area of bell mouth entry first assume thevelocity through 
bell mouth generally around 0.3 to 0.35 m/sec . After getting the area 
find the dia of bell mouth
Canal Intake
Design Procedure for Intakes 
Design of Intake Conduit 
• Assume the velocity of flow through conduit, generally 1.0 to 1.5 
m/sec 
• Find , A= Q 
V 
Then Using Hazen William formula, find the head loss and the slope 
required, Charts can be used.
River Intake 
• First Design the Intake Well. Dia is generally between 4 to 7.5 m. 
Using discharge find the area and the diameter. 
• If rectangular find length and width after finding the length and 
width of the screen required. 
• Design procedure for coarse screen and outlet conduct is almost 
same as canal Intake.
Example 
• Design a bell mouth canal intake for a city of 70,000 
persons drawing water from a canal which runs only for 10 
hrs. a day with a depth of 1.6 m. Also calculate the head loss 
in the intake conduit if the treatment plant is 0.5 km away. 
Assume average consumption per person= 160 l/d. Assume 
the velocity through the screens and bell mouth to be 0.15 
m/s and 0.3 m/s respectively.
Example 
• Discharge required by the city 
= 70000 x 160 (Population x rate of supply) 
= 11,200,000 
11.2 MLD (Million litre per day) 
Since the canal only runs for 10 hrs. a day, this whole daily 
flow is required to be drain in 10 hrs.
Example 
Therefore the Intake load= 11.2 = 1.12 ML/Hour 
10 
= 1.12 x 10 6 m3 / hr.... 
10 3 
1.12 x 10 3 m3 /sec 
60 x 60 
= 0.311 m3 /sec
Example 
Design of Coarse Screen 
• Area of Coarse Screen = Discharge 
Velocity through the screen 
Velocity through the screen = 0.15 m /sec 
Area of the coarse screen = 0.311 = 2.075 m 2 
0.15 
Assume the minimum water level is 0.3 m below the normal water level. The 
bottom of the screen is kept at 0.15 m above the bed level. The top of screen is kept 
at minimum level 
Therefore available height= 1.6 – 0.3- 0.15 
= 1.15 m 
Minimum length of the screen= 2.075 = 1.80 m 
1.15
Canal Intake
Example 
Assume the clear opening between vertical bars to be 30 mm each we have 
• Number of opening = 1.8 = 60 
0.03 
Therefore no of bars= 59 
Assume the dia of bar as 20 mm 
Length occupied by the bar of 20 mm = 59 x 0.02 
= 1.18 m 
Therefore length of screen= 1.8 + 1.18 
= 2.98 
Say 3 m 
Hence provide coarse screen of length 3.0 m and height 1.15 in rectangular intake 
well
Canal Intake
Example 
Design of Bell Mouth Entry 
• Area of Bell mouth entry = Discharge 
Velocity through the bell mouth 
= 0.311 
0.3 
= 1.037 m 2 
Diameter d of the bell mouth entry as 
= Π d 2 = 1.037 
4
Example 
• D={ 4 x 1.037} 1/2 
Π 
= 1.15 m 
If the dia of small holes in the screen is assumed to be 15 mm (10 to 20mm). 
Then area of each hole= Π x (0.015) 2 
4 
= 1.767 x 10 -4 
Therefore number of holes on the bell mouth = Area of bell mouth 
Area of one hole 
= 1.037 
1.767 x 10 -4 
= 5868.2 
Say 5869
Canal Intake
Example 
Design of Intake Conduit 
• Assume Velocity of flow in the conduit as 1.5 m/sec 
• Area of conduit required = Discharge 
Velocity 
= 0.311 = 0.2073 m 2 
1.5 
Dia of pipe D will be 
Π D2 = 0.2073 
4= 
0.514 
Say 0.55 m
Canal Intake
Example 
• Flow velocity through this 0.55 m dia conduit will be 
= V = Q = 0.311 = 1.31 m /sec 
A 
= Π 
x (0.55) 2 
4 
assume velocity of 1.5 m /sec
Example 
• Head loss through the conduit up-to treatment plant is calculated by using 
Hazen William’s eq n 
• V= 0.85 CH R 0.23 S 0.54 
• Where , 
• CH= Coefficient of the Pipe 
• = 130 for Cast Iron Pipe 
• R= Hydraulic mean depth 
• = d/4 ( for pipe running full) 
• = 0.55 = 0.138 m 
4 
V= Velocity 
S= Slope
Example 
• Therefore, 
• 1.5 = 0.85 x 130 x (0.138 ) 0.63 S 0.64 
• S 0.54 = 150 
0.85 x 130 x (0.138) 0.63 
= 0.047 
S= (0.047) 1 /0.54 
= 3.51 x 10 -3 
Or 1 in 284.73 
S= HL = Head Loss 
L Length of Pipe 
Length of pipe is equal to the distance of Intake from treatment plants 0.5 km = 
500 m 
HL= 3.51 x 10 -3 x 500 
= 1.755 m
Example 
• Design a bell mouth canal Intake for a City of 1,00,000 persons 
drawing water from a canal which runs for 10 hrs.. a day with a 
depth of 2 m. Also calculate the head loss in the intake conduit if the 
treatment works are 1 km away. Draw a neat sketch of canal Intake. 
Assume average consumption per person= 150 l/day. Assume the 
velocity through the screens and bell mouth to be less than 15 cm/sec 
and 35 cm/sec
Canal Intake
Example 
Discharge through Intake 
Daily Discharge= 150 x 1,00,000= 15,000,000 l/day 
• Since the canal runs only for 10 hrs. per day. 
• Intake Load/hr = 15,000,000 = 15,000,00 lit/hr 
10 
= 15,00 m3 /hr.... 
Q= 1500 = 0.4166 m3 /sec 
60 x 60
Example 
Area of Coarse Screen I front of Intake 
• Area of Screen= 0.4166= 2.777 m 2 
0.15 
Let the area occupied by solid bars by 30 % of the total area 
Therefore the actual area= 3.96 m 2 
Let us assume minimum water level at 0.3 m below normal water level. Also let us keep 
bottom of the screen at 0.15 m above canal bed and top of screen at the minimum water 
level. 
Available height of screen= 2- 0.3-0.15 = 1.55 m 
Required length of screen= 3.96 = 2.55 m 
1.55 
Hence provide a length of 2.6 m 
Hence provide a screen of 1.55 x 2.6 m
Example 
Design of Bell Mouth Entry 
• Area of Bell mouth Ab= 0.4166 = 1.301 m 2 
0.32 
Dia db= { 1.301 x 4}1/2 = 1.65 m 
3.14 
Hence provide a bell mouth of 1.7 m dia
Example 
Design of Intake Conduit 
• Let us assume a velocity of 1.5 m/sec in the conduit 
• Dia of conduit D ={ 0.4166 x 4 } 1/2 = 0.35 m 
1.5 x 3.14 
However, provide 0.5 m dia, conduit, so that actual velocity of flow is 
V = 0.4166 x 4 = 2.12 m/sec 
3.14 x (0.5) 2
Example 
For head loss through the conduit 
• V= 0.849 C R 0.63 S 0.54 
• C= 130 
• R= D/4 = 0.5 /4 = 0.125 
• Hence Slope S of the energy line, 
• 2.12 = 0.849 (130) (0.125) 0.63 S 0.54 
• S= 7.533 x 10 -3 
• S= HL/L 
• HL= S x L= 7.53 m
Canal Intake
Conveyance of Water 
• Water is drawn from the sources by Intakes. After it’s drawing the 
next problem is to carry it to the treatment plant which is located 
usually within city limits. Therefore after collection, the water is 
conveyed to the city by mean of conduits. If the source is at higher 
elevation than the treatment plant, the water can flow under 
gravitational force. 
• For the conveyance of water at such places we can use open channel, 
aqueduct or pipe line, Mostly it has been seen that the water level in 
the source is at lower elevation than the treatment plant, In such case 
water can be conveyed by means of closed pipes under pressure
Conveyance of Water
Conveyance of Water 
• If the source of supply is underground water, usually there 
is no problem as, these sources are mostly in the 
underground of the city itself. The water is drawn from the 
underground sources by means of tube-wells and pumped 
to the over-head reservoirs, from where it is distributed to 
the town under gravitational force. Hence at such places 
there is no problem of conveyance of water from sources to 
the treatment works.
Conveyance of Water
Conveyance of Water 
• In case of sources of water supply is river or reservoir 
and the town is situated at higher level, the water will 
have to be pumped and conveyed through pressure 
pipes. If the source is available at higher level than 
the town, it is better to construct the treatment plant 
near the source and supply the water to the town 
under gravitational forces only,
Conveyance of Water
Conveyance of Water 
Open Channels 
• These ae occasionally used to convey the water from the source to the 
treatment plant. These can be easily and cheaply constructed by 
cutting in high grounds and banking in low grounds. 
• The channels should be lined properly to prevent the seepage and 
contamination of water. As water flows only due to gravitational 
forces, a uniform longitudinal slope is given. The hydraulic gradient 
line in channels should not exceed the permissible limit otherwise 
scouring will start at the bed and water will become dirty. In channel 
flow there is always loss of water by seepage and evaporation,
Open Channels
Conveyance of Water 
Aqueducts 
• Aqueducts is the name given to the closed conduit constructed with 
masonry and used for conveying water from source to the treatment 
plant or point of distribution. Aqueduct may be constructed with 
bricks, stones or reinforced cement concrete. In olden days 
rectangular aqueduct were used, but now a days horse-shoe or 
circular section are used. These aqueduct are mostly constructed 
with cement concrete The average velocity should be 1 m/sec
Aqueducts
Conveyance of Water 
Tunnels 
• This is also a gravity conduit, in which water flows under 
gravitational forces. But sometimes water flows under pressure and 
in such cases these are called pressure tunnels. Grade tunnels are 
mostly constructed in horse-shoe cross-section, but pressure tunnel 
have circular cross-section. In pressure tunnels the depth of water is 
generally such that the weight of overlying material will be sufficient 
to check the bursting pressure. Tunnels should be water tight and 
there should be no loss of water.
Tunnels
Conveyance of Water 
Flumes 
• These are open Channels supported above the ground over 
trestles etc.. Flumes are usually used for conveying water 
across valleys and minor low lying areas or over drains and 
other obstruction coming in the way. Flumes may be 
constructed with R.C.C, wood or metal. The common section 
are rectangular and circular.
Flumes
Conveyance of Water 
Pipes 
• These are circular conduits, in which water flows under pressure. 
Now a days pressure pipes are mostly used at every places and they 
have eliminated the use of channels, aqueducts and tunnels to a large 
extent. These are made of various materials like cast Iron, wrought 
Iron, steel, cement Concrete, asbestos, cement, timber, etc.. In the 
town pips are also used for distribution system. In distribution system 
pipes of various diameter, having many connections and branches 
are used. Water pipe lines follow the profile of the ground water and 
the location which is most economical, causing less pressure in pipes 
is chosen.
Pipes
Conveyance of Water 
• The cost of pipe line depends on the internal pressure to 
bear and the length of pipe line. Therefore as far as possible 
the hydraulic line is kept closer to the pipe line. In the valley 
or low points a scour valve is provided to drain the line and 
removing accumulated suspended matter. Similarly at high 
points air relief valves are provided to remove the 
accumulated air. To prevent the bursting of pipes due to 
water hammer, surge tanks or stand pipes are provided at 
the end of pipes.
Surge Tank or Surge Chamber
Conveyance of Water
Surge Tank or Surge Chamber
Conveyance of Water 
The selection of material for the pipes is done on the 
following points 
• Carrying Capacity of the pipes 
• Durability and life of the pipe 
• Type of water to be conveyed and its corrosive effect on the pipe 
material. 
• Availability of funds 
• Maintenance cost, repair etc.. 
• The pipe material which will give the smallest annual cost or capital 
cost will be selected, because it will be mostly economical.
Conveyance of Water
Conveyance of Water 
Following types of pipes are commonly Used 
• Cast Iron Pipes 
• Wrought Iron pipes 
• Steel Pipes 
• Concrete Pipes 
• Cement lined Cast Iron Pipes 
• Plastic or PVC pipes 
• Asbestos cement pipes 
• Copper and lead pipes 
• Wooden pipes 
• Vitrified Clay pipes
Conveyance of Water 
• Out of the types mentioned, plastic or PVC and Asbestos 
cement pipes, wooden pipes are not generally used for 
conveyance of water. They are used in house drainage or 
water connection within individual house.
Cast Iron Pipes 
• Cast – Iron Pipes are mostly used in water supply schemes. They have 
higher resistant to corrosion, therefore have long life about 100 
years. 
• Cast Iron pipes are manufactured in lengths of 2.5 m to 5.5 m. The 
fittings of these pipes are also manufactured in sand molds having 
core boxes. These fittings are also weighed, coated with coal tar and 
finally tested. Cast-Iron pipes are joined together by means of Bell 
and Spigot, Threaded or flanged Joints
Cast Iron Pipes
Conveyance of Water 
Advantages of CI Pipes 
• Ease in jointing the pipes 
• Can withstand high Internal pressure 
• Have a very long design life. (100 years) 
• They are less prone to corrosion.
Conveyance of Water 
Dis-advantages of CI Pipes 
• They are heavy and difficult to transport 
• Length of pipe available as less (2.5 to 5.5m) so more joints are 
required for laying the pipes so chances of leakage also Increases. 
• They are brittle so they break or crack easily.
Conveyance of Water 
Wrought Iron Pipes 
• Wrought Iron Pipes are manufactured by rolling the flat plates of the 
metal to the proper diameter and welding the edges. If compared 
with cast Iron, these are more lighter, can be easily cut, threaded and 
worked, give neat appearance if used in the interior works. But it is 
more costly and less durable than cast iron pipes. These pipes should 
be used only inside the buildings, where they can be protected from 
corrosion. Wrought Iron pipes are joined together by couplings or 
screwed and socketed joints. To Increase the life of these pipes 
sometimes these are galvanized with zinc.
Wrought Iron Pipes
Conveyance of Water 
Steel pipes 
• The Construction of these pipes is similar to wrought iron 
pipes, it is occasionally used from main lines and at such 
places where pressure are high and pipe dia is more. Steel 
pipes are more stronger, have very light weight and can 
withstand high pressure than cast iron pipes. They are also 
cheap, easy to construct and can be easily transported.
Steel pipes
Conveyance of Water 
• The disadvantages of these pipes is that they cannot withstand 
external load, if partial vacuum is created by emptying pipe rapidly, 
the pipe may be collapsed or distorted. These pipes are much affected 
by corrosion and are costly to maintain The life of these pipes is 25 to 
50 years, which is much shorter as compared to cast Iron Pipes Steel 
pipes are not used in distribution system, owing to the difficulty in 
making connections. 
• The joints in steel pipes may be made of welding or riveting, 
longitudinal lap joints are made In riveted steel pipes up to 120 cm 
dia
Conveyance of Water 
Concrete Pipes 
• These pipes may be precast or Cast-in-situ plain concrete 
pipe may be used at such places where water does not flow 
under pressure, these pipes are jointed with Bel &Spigot 
Joints. Plain Concrete pipes are up to 60 cm dia only, above 
it these are reinforced.
Concrete Pipes
Conveyance of Water 
Advantages of R.C.C Pipes 
• Their life is more about 75 years 
• They can be easily constructed in the factories or at site 
• They have least coefficient of thermal expansion than other types of 
pipes . Hence they do not require expansion joints 
• Due to their heavy weight, when laid under water, they are not 
affected by buoyancy, even when they are empty. 
• They are not affected by atmospheric action or ordinary soil under 
normal condition.
Conveyance of Water 
Disadvantages of R.C.C Pipes 
• They are affected by acids, alkalis and salty waters 
• Their repairs are very difficult. 
• Due to their heavy weight, their transportation and laying cost is 
more. 
• It is difficult to make connections in them 
• Porosity may cause them to leak.
Pipe Joints 
• For the facilities in handling, transporting, and placing in position, 
pipes are manufactured in small lengths of 2 to 6 meters. These small 
pieces of pipes are then joined together after placing in position to 
make one continuous length of pipe. 
• The design of these joints mainly depends on the material of the pipe, 
internal water pressure and the condition of the support 
• The bell and spigot joints, using lead as filling material is mostly used 
for cast Iron pipes. For Steel pipes welded, riveted, flanged or screwed 
joints my be used.
Various types of Joints which are mostly used, are 
as follows 
• Spigot and Socket Joints or Bell & Spigot Joints 
• Expansion Joints 
• Flanged Joints 
• Mechanical Joints 
• Flexible Joints 
• Screwed Joints 
• Collar Joints 
• A.C. Pipe Joints
Spigot and Socket Joints 
• This types of joints is mostly used for cast iron pipes 
For the construction of this joint the spigot or normal 
end of one pipe is slipped in socket or bell mouth end 
of the other pipe until contact is made at the base of 
the base of the bell.
Spigot and Socket Joints
Spigot and Socket Joints 
• After this hemp or yarn is wrapped around the spigot end of 
the pipe and is tightly filled in the joint by means of yarning 
iron up to 5 cm depth. The hemp is tightly packed to 
maintain regular annular space and for preventing jointed 
material from falling inside the pipe. After packing of hemp 
& gasket or joint runner is clamped against the outer edge of 
the bell.
Spigot and Socket Joints 
• Sometimes wet clay is used to make tight contact between 
the runner and the pipe so that hot lead may not run out of 
the joint spaces. The molten lead is then poured into V-shaped 
opening left in the top by the clamp joint runner. 
The space between the hemp yarn and the clamp runner is 
removed, the lead which shrink while cooling, is again 
tightened by means of chalking tool and hammer. Now a 
days in order to reduce the cost of lead certain patented 
compounds of sulphur and other materials and other 
materials are filled in these joints.
Expansion Joints 
• This joint is used at such places where pipes expand or contract due 
to change in atmospheric temperature and thus checks the setting of 
thermal stresses in the pipes. In this joints the socket end is flanged 
with cast iron follower ring, which can freely slide on the spigot end 
or plane end of other pipes. An elastic rubber gasket is tightly pressed 
between the annular spaces of socket by means of bolts. In the 
beginning while fixing the follower ring some space is left between 
the socket base and the spigot end for the free movement of the pipes 
under variation of temperature. In this way when the pipe expands 
the socket end moves forward and when the pipe contracts, it moves 
backward in the space provided for it. The elastic rubber gasket in 
every position keeps the joint water tight.
Expansion Joints
Flanged Joint 
• This joint is mostly used for temporary pipe lines, because the pipe 
line can be dismantled and again assembled at other places. 
• The pipe in this case has flanges on its both ends, cast, welded or 
screwed with the pipe. The two ends of the pipes which are to be 
jointed together are brought in perfect level near one another and 
after placing of washer or gasket of rubber, canvas, copper or lead 
between the two ends of flanges is very necessary for securing a 
perfect water-tight joints. These joint cannot be used at places where 
it has to bear vibration of pipes etc..
Flanged Joint
Flexible Joints 
• Sometimes this joint is also called Bell & Socket or Universal Joint. 
This joint is used at such places where settlement is likely to occur 
after the lying of the pipes. This joint can also be used for laying of 
pipes on curves, because at the joint the pipes can be laid at angle. 
This is a special type of joint. The socket end is cast in a spherical 
shape. The spigot end is plain but has a bead at the other end. For the 
assembling of this joints, the spigot end of one pipe is kept in the 
spherical end of the other pipe.
Flexible Joints
Flexible Joints
Flexible Joints 
• After this the retaining ring is slipped which is stretched 
over the bead. Then a rubber gasket is moved which touches 
the retainer high. after it split cast iron gland ring is placed, 
the outer surface of which has the same shape as inner 
surface of socket end. Over this finally cast iron follower 
ring is moved and is fixed to the socket end by means of 
bolts. It is very clear that if one pipe is given any deflection 
the ball shaped portion will move inside the socket, and the 
joint will remain waterproof in all the position.
Flexible Joints
Mechanical Joints 
• This type of joints are used for jointing cast Iron, Steel or wrought 
Iron pipes, when both the ends of the pipes are plain or spigot. There 
are two types of mechanical joints. 
• Dressers- Couplings 
• It essentially consists of one middle ring, two follower rings and two 
rubber gaskets. The two follower rings are connected to-gather by 
bolts and when they are tightened, they pass both the gaskets tightly 
below the ends of the middle ring. These joints are very strong and 
rigid and can withstand vibrations and shocks up to certain limit. 
These joints are mostly suitable for carrying water lines over bridges, 
where it has to bear vibrations.
Mechanical Joints
Mechanical Joints
Mechanical Joints 
Victaulic Joint 
• In this type of joints a gasket or leak-proof ring is slipped over both 
the ends of the pipes. This gasket is pressed from both the sides by 
mean of half iron couplings by bolts. The ends of pipes are kept 
sufficient apart to allow for free expansion, contraction and 
deflection. This joints can bear shocks, vibrations etc.. and used for 
cast-iron, steel or wrought iron pipe lines in exposed places.
Victaulic Joint
Victaulic Joint
Screwed Joints 
• The joint is mostly used for connecting small diameter cast iron, 
wrought iron and galvanized pipe. The end of the pipes have threads 
outside, while socket or couplings has threads on the inner side. The 
same socket is screwed on both the ends of the pipes to join them. For 
making water tight joints zinc paint or hemp yarn should be placed 
in the threads of the pipes, before screwing socket over it.
Screwed Joints
Collar Joint 
• This type of joint is mostly used for joining big diameter concrete and 
asbestos cement pipes. The ends of the two pipes are brought in one 
level before each other. Then rubber gasket between steel rings or 
jute rope socked in cement is kept in the grove and the collar is 
placed at the joint so that it should have same lap on both the pipes. 
Now 1:1 cement mortar is filled in the space between the pipes and 
the collar.
Collar Joint
Joint for A.C. Pipes 
• For jointing small diameter A.C. Pipes the two ends of pipes are 
butted against each other, then two rubber rings will be slipped over 
the pipes and the couplings will be pushed over the rubber rings. The 
rubber rings make the joint water-proof.
Laying of Water Supply Pipes 
• Pipes are generally laid below the ground level, but sometimes when 
they pass in open areas, they may be laid over the ground. The pipes 
are laid in the following way. 
• First of all the detailed map of all roads, streets lanes etc., is prepared. 
On this map the proposed pipe line with all sizes and length will be 
marked. The position of existing pipe line, curb lines, sewer lines etc.. 
will also be marked on it. In addition to this position of valves and 
other pipe specials, stand posts etc.. will also be marked, so that at 
the time of laying there should be no difficulty in this connection.
Laying of Water Supply Pipes 
• After the general planning, the center line of the pipe line will be 
transferred on the ground from the detail plan. The center line will 
be marked by means of stalkes driven at 30 m interval on straight 
lines. On curves the stalkes will be driven at 7 to 15 m spacing. If the 
road or streets have curbs, the distance of center of pipe line fro curb 
will be marked.
Laying of Water Supply Pipes 
• When the center line has marked on the ground the excavation for 
the trenches will be started. The width of the trench will be 30 cm to 
45 cm more than the external diameter of the pipe. At every joint the 
depth of excavation will be 15 to 20 cm more for one meter length 
for easy joining of the pipes. The pipe lines should be laid more than 
90 cm below the ground so that pipe may not break due to impact of 
heavy traffic moving over the ground
Laying of Water Supply Pipes
Laying of Water Supply Pipes 
• After the excavation of trenches the pipes are lowered in it. The pipe 
laying should start from lower level and proceed towards higher 
level with socket end towards higher side. The jointing of pipes 
should be done along with the laying of pipes. 
• After laying the pipe in position, they are tested for water leakage 
and pressure. 
• When the pipe line is tested, the back filings of the excavated 
material will be done. 
• The soil which was excavated is filled in the trenches all around the 
pipes and should be well rammed. All the surplus soil will be 
disposed off and the site should be cleaned.
Laying of Water Supply Pipes
Laying of Water Supply Pipes
Laying of Water Supply Pipes
Hydrostatic Test 
• After laying the new pipe line, jointing & back filling, it is subjected 
to the following tests: 
• Pressure Tests at a pressure of at least double of maximum working 
pressure, pipe joints shall be absolutely water tight. 
• Leakage Test (to be conducted after the satisfactory completion of the 
pressure test) at a pressure as specified by the authority for a 
duration of two hours. 
• In this way error in workman ship will be found immediately and 
can be rectified. Usually the length to be tested is kept up to 500 m.
Laying of Water Supply Pipes
Hydrostatic Test
Hydrostatic Test
Pumps for Lifting Water 
• The function of the pump is to lift the water or any fluid at higher elevation or 
higher pressure. In water works pumps are required under the following 
circumstances. 
• At the source of water to lift the water from rivers, streams, wells etc.. and to 
pump it to the treatment works. 
• At the treatment plant to lift the water at various units so that it may flow in 
them due to the gravitational force only during the treatment of the water. 
• For the back washing of filters and increasing their efficiency. 
• For pumping chemical solution at treatment plants. 
• For filling the elevated distribution reservoirs or overhead tanks 
• To increase the pressure in the pipe lines by boosting up the pressure. 
• For pumping the treated water directly in the water mains for its distribution.
Pumps for Lifting Water
Classification of pumps 
• (i) Classification based on principles of operation 
• Displacement pump 
• Centrifugal pumps 
• Air –lift pumps 
• Impulse pumps 
• (ii) Classification based on type of power required 
• Electrical driven pumps 
• Gasoline engine pumps 
• Steam engine pumps 
• Diesel engine pumps
Classification of pumps 
• (iii) Classification based on the type of services 
• Low lift pumps 
• High lift pumps 
• Deep-well pumps 
• Booster pumps 
• Standby pumps
The selection of a particular type of pumps 
depend upon the following factors 
• Capacity of pumps 
• Number of pump units required 
• Suction conditions 
• Lift (total head) 
• Discharge condition, and variation in the load 
• Floor space requirement 
• Flexibility of operation 
• Starting & priming characteristics 
• Initial cost and running costs
Displacement Pumps 
• In these types of pumps vacuum is created mechanically by 
the movable part of the pumps. In the vacuum first the 
water is drawn inside the pumps, which on the return of 
mechanical part of the pump is displaced and forced out of 
the chamber trough the valve and pipe. The back flow of the 
water is prevented by means of suitable valves.
Displacement Pumps 
• The following are the two main type of displacement pumps 
(i) Reciprocating Pumps 
(ii) Rotary Pumps
Displacement Pumps 
Reciprocating Pump 
• Reciprocating pumps may be of the following types 
• Simple hand-operated reciprocating pump 
• Power operated deep well reciprocating pump 
• Single-acting reciprocating pump 
• Double-acting reciprocating pump
Reciprocating Pump
Displacement Pumps 
Rotary Pump 
(a) Rotary pumps with gear 
(b) Rotary pumps with cams 
• The revolving blades fit closely in the casing and push the water by 
their displacement. The blades revolve in a downward direction at 
the Centre and the water is carried upward around the side of the 
casing. In this way the water is pushed through the discharge pipe 
and partial vacuum is created on the suction side. The intensity of 
vacuum mainly depends on the tightness of the parts.
Rotary Pump
Displacement Pumps 
Advantages of Rotary Pumps 
• They do not require any priming as they are self-primed. 
• The efficiency of these pumps is high at low to moderate heads up-to 
discharge of 2000 l/m 
• These pumps have no valves, are easy in construction and 
maintenance as compared with reciprocating pumps. 
• These pumps give steady and constant flow 
• These pumps are deployed for the individual building water supply 
and for fire protection.
Displacement Pumps 
Disadvantages of Rotary Pumps 
• The initial cost of these pump is high 
• Their maintenance cost is high due to abrasion of their cams and 
gears. 
• They cannot pump water containing suspended impurities as the 
wear and abrasion caused by the impurities will destroy the seal 
between the cans and the casing.
Centrifugal Pumps 
• These pumps work on the principle of centrifugal force, 
therefore, they are called centrifugal pumps. The water 
which enters inside the pump is revolved at high speed by 
means of impeller and is thrown to the periphery by the 
centrifugal force.
Centrifugal Pumps
Centrifugal Pumps 
Advantages and Disadvantages of Centrifugal Pumps 
• The centrifugal pumps have the following advantages 
• Due to compact design, they require very small space. 
• They can be fixed to high-speed driving mechanism 
• They have rotary motion due to which there is low or no noise 
• They are not damaged due to high pressure
Centrifugal Pumps 
Disadvantages of centrifugal pumps 
• They require priming 
• The rate of flow of water cannot be regulated. 
• Any air leak on the suction side will affect the efficiency of the pump. 
• They have high efficiency only for low head and discharge. 
• The pump will run back, if it is stopped with the discharge valve 
open.
Design of Pumps 
• Design of pumps means to find out the capacity of the pump 
required to deliver specific quantity of water against specific head. 
• So design of pumps can be divided into two parts 
• To find the total head against which the pump has to operate. 
• The total power requirement or the capacity of the pump or the size 
of the pump required and also deciding the number of pumps 
required as well as stand by.
Total Head Or Lift Against Which The Pump Has 
To Work 
• The total head or total lift against which the pump has to work 
includes suction lift (or Head), discharge or delivery lift (or Head) 
and total loss of head due to friction, entrance, exit, fitting etc. in 
suction and rising main. 
• If Hs= Suction lift or Head 
• Hd= Delivery or discharge head 
• Hl= Total loss of head then, 
• The total head against which the pump has to work is given by: 
• H= Hs + Hd + H l
Total Head Or Lift Against Which The Pump Has 
To Work 
• Suction lift : It is the difference between the lowest water and the 
pump 
• Discharge lift or delivery Head: It is the difference between the point 
of discharge or delivery and the pump. 
• Generally only the friction losses is considered for the design as 
minor losses are very small if the length of the pipe is greater
Total Head Or Lift Against Which The Pump Has 
To Work
Total Head Or Lift Against Which The Pump Has 
To Work 
• Friction loss can be found out by Darcy Weisbach equation 
• Darcy Weisbach Eqn = Hf= 4 f l v2 = f’ l v2 
2 g d 2g d 
Where , 
l= length of pipe 
d= dia of pipe 
v= velocity of flow 
f= coefficient of friction 
f’= friction factor Value of friction factor varies between (0.02 to 0.075)
Power required by the pump or capacity of 
pump 
• The horse power (H.P.) of the pump can be determined by calculating the 
work done by the pump in raising the water up to the height H. 
• Let the pump raiseW kg of water to height H meter. 
• Then the work done by the pump= W x H (m.kg) 
• = ϒ Q H (m. kg/sec) 
• Where, ϒ = UnitWeight of water 
• Q= Discharge to be pumped in m3 /sec 
• H= Total head in meter 
• Water Horse Power (WHP) = ϒ Q H 
75
Power required by the pump or capacity of 
pump 
• Brake Horse Power (B.H.P) = W.H.P 
Ƞ 
= ϒ Q H 
75 Ƞ
Number of Pumps, size and stand by units 
• Pumping units at water works are generally not operated at full 
capacity for all times. Since the efficiency of pumping unit varies 
with the load, it is a usual practice to design a pumping station that 
some of the pump units can be operated at full capacity, at all the 
time. Hence two, three, or four pumps are installed. The sizes of these 
pumps can be fixed by considering the demand, available storage. 
• Thus, there will always exist some stand by capacity to take care of 
the repairs, breakdowns, etc. Generally 100 % stand-by by capacity 
to take care against average demand and 33.33 to 50 % standby 
capacity against the peak demand is considered sufficient and may 
therefore be provided at the pumping station.
Design of Rising Main 
Design of Rising Main 
• Rising main is the pipe through which the pumped water is sent 
further to the next unit for treatment purpose. Water flows in this 
pipe under high pressure and flow is turbulent. Here the friction loss 
in the pipe is more due to high velocity. Pressure pipes are designed 
such that overall cost of the project should be lowest possible both 
from maintenance and constructional point of view.
Design of Rising Main
Design of Rising Main 
Economic diameter of rising main 
• For pumping a particular fixed discharge of water, there are two options 
• It can be pumped through bigger diameter pipe at low velocity 
• Through lesser diameter pipe at high velocity 
• If the dia of the pipe is increased, it will lead to higher cost of the pipe line on the other 
hand if the pipe diameter is reduced the velocity would increase which will lead to 
higher frictional head loss and will require more Horse Power for pumping, thereby 
increasing the cost of pumping, also cost of fitting will increase. 
• For obtaining the optimum efficiency, it is necessary to design the diameter of the 
pumping main which will be overall most economical in initial cost as well as 
maintenance cost for pumping the required quantity of water. The diameter which 
provide such optimum condition is known as “economic diameter” of the pipe.
Design of Rising Main 
• An empirical formula given by lee is commonly used for determining 
the dia of the pumping or rising main 
• D= 0.97 to 1.22 √Q 
• Where, 
• D= Economic dia of pipe in meters 
• Q= Discharge to be pumped in cumecs
Design of Rising Main 
Head loss in rising main 
• The loss of head in the rising main can be found by using 
• (i) Darcy Weisbach eq 
• (ii) Hazen William’s equation 
• Darcy Weisbach Eqn= Hf= 4 f l v2 = f’ l v2 
2 g d 2g d 
Where , 
l= length of pipe 
d= dia of pipe 
v= velocity of flow 
f= coefficient of friction 
f’= friction factor Value of friction factor varies between (0.02 to 0.075)
Design of Rising Main 
Hazen Williams Equation 
• V= 0.85 CH R 0.63 S 0.54 
• Where, 
• V= velocity of flow 
• S= Slope of H.G.L 
• = Hl = Head Loss 
L Length of Pipe 
R= Hydraulic mean Radius of the pipe = A 
P 
If pipe is running full then 
R= Π/4 d2 = d/4 
Π d 
CH= Hazen William’s coefficient which depends on age, quality and material of pipe.
Examples 
• Find out the head loss due to friction in a rising main from the 
following data: 
• Length of the rising main= 600 m 
• Diameter of pipe= 0.2 m 
• Discharge required to be pumped = 1200 l/min 
• Friction factors= 0.025
Examples 
• Velocity of flow = QA 
Q= 1200 l/min 
= 1200 x 10-3 m3 /sec 
60 
= 0.02 m3 /sec 
V= 0.02 
Π (0.2) 2 = 0.637 m/sec 
4
Examples 
• Hf= f’ lv2 
2gd 
= 0.025 x 600 x (0.637)2 
2 x 9.81 x 0,2 
= 1.551 m
Examples 
• A city with 1.5 lakh population I to be supplied water at 100 lpcd 
from a river 1 km away. The difference in water level of sump and 
reservoir is 30 m. if the demand has to be supplied in 8 hr., 
determine the size of the main and B.H.P of the pumps required. 
• Take f- 0.0075, velocity in the pipe as 2.0 m/sec and efficiency of 
pump as 75 %
Examples 
• Population of a city= 1,50,000 
• Rate of water supply= 100 lpcd 
• Therefore the average demand of the town= 1,50,000 x 100 
• = 15 x 10 6 l/day 
• Maximum daily demand= 1.5 x avg demand 
• = 1.5 x 15 x 10 6 
• = 22.5 x 10 6 l/day 
• = 22.5 MLD
Examples 
• As the full demand is to be supplied through pumps in 8 hrs 
• Discharge required= 22.5 x 10 6 l/ hours 
• 8 
• = 22.5 x 10 6 x 10 -3= 0.781 m3 /sec 
8 x 3600
Examples 
• The maximum velocity in the pipe is given as 2.0 m/sec 
• Therefore Cross sectional area of the pipe required 
• A= Q = 0.781 = 0.39 m 2 
• v 
• If d is the dia of the pipe then 
• Π d 2 = 0.39 
4 
D= 0.704m 
= 0.75 m 
Total lift is given as 30 m
Examples 
• Friction loss hf can be found by using Darcy Weisbash eq n 
• Hf= 4 f l v2 
2 g d 
= 4 x 0.0075 x 1000x (2.0 ) 2 
2 x 9.81 x 0.75 
= 8.155 m
Examples 
• Thus the total lift against which the pump has to work or lift water 
• = 30 + 1.155 
• = 38.155m 
• BHP of the pump= ϒ Q H 
75 Ƞ 
= 1000 x 0.781 x 38.155 
75 x 0.75 
= 526.75 = 530 HP 1 hp(I) = 745.699872W = 0.745699872 kW 
1 W in ... ... is equal to ... 
2 
3 
• 1 kg·m 
/s
Example 
• From a clear water reservoir 3 m deep and maximum water level at 
RL 35 m water is to be pumped to an elevated reservoir at RL 80 m at 
the constant rate of 9 lakh litres per hour. The distance is 2000 m. 
Find the economic diameter of the rising main and the water horse 
power of the pump. Neglect minor losses and take f=0.01
Example 
• The Discharge Q= 9 lakh per hour 
• = 9,00,000 = 0.25 m3 /sec 
1000x 60 x 60 
Economic diameter of rising main can be found by 
D= 1.22 √Q 
= 1.22 √0.25 
= 0.61 m
Example 
• Maximum Suction Head = 3 m ( depth of reservoir) 
• Maximum delivery head = (80- 35)= 45 m 
• (Difference between maximum water level and height of elevated 
reservoir) 
• Suction + Delivery= 3 + 45 = 48 m
Example 
• Friction Head loss can be found by 
• Hf= 4 flv 2 
2 g D 
V= Q = 0.25 = 0.855 m/ sec 
A Π (0.61) 2 
4 
Hf= 4 x 0.01 x 2000 x (0.855) 2 
2 x 9.81 x 0.61 
Hf= 4.886 m 
The total Head = 48 + 4.886 m 
H= 52.886 m
Example 
• Water horse power of Pump= ϒ Q H 
75 
= 1000 x 0.25 x 52.866 
75 
= 176.22 HP
References 
Water Supply Engineering : By Prof S.K. Garg 
Khanna Publishers 
Internet Websites
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Collection and Conveyance of Water

  • 1. Collection & Conveyance of Water Unit-II BTCI05006/ MBCI05006
  • 2. Collection & Conveyance of Water Unit-II
  • 3. Syllabus • Collection and conveyance of water: Types of intake structure, design of intake structure, estimation of fluid flows, engineering requirements of conduits with respect to their performance, types of conveyance system, hydraulic design of conveyance conduits, various materials of pipes, appurtenances, and issues associated with conveyance of water. • Pumps for lifting of water: Types of pumps, selection of pumps, design of pumping main for conveyance of water, economical diameter of pumping main, pumping station
  • 5. Introduction • In any water supply project the first step is to select the source of water from which water is drawn. The device Installed for the purpose of drawing water from the source of water are called Intakes
  • 7. Intake Structure • The basic function of intake structure is to help in safely withdrawing water from the source and then to discharge this water in to the withdrawal conduit, through which it reaches the water treatment plant. • It is constructed at the entrance of the withdrawal conduit and thereby protecting it from being damaged/clogged by ice,debris. • Some times from reservoirs where gravity flow is possible, water is directly transmitted to the treatment through intake structure. • If gravity flow is not possible, water entering intake structure is lifted by pumps and taken to the treatment plant.
  • 10. Selecting Location Of Intake Structure • Site should be near the treatment plant to reduce conveyance cost. • Intake must be located in the purer zone of the source so that best quality water is withdrawn from source to reduce the load on the treatment plant. • Intake must never be located in the vicinity of waste water disposal point. • Intake must never be located near the navigation channels so as to reduce chances of pollution due to waste discharge from ships. • The site should be such as to permit greater withdrawal of water, if required in future.
  • 11. Selecting Location Of Intake Structure
  • 12. Selecting Location Of Intake Structure • Intake must be located at a place from where it can draw water even during the driest period of the year. • The intake site should remain easily accessible during floods and should not get flooded. • In meandering rivers, the intakes should not be located on curves or atleast on sharp curves.
  • 13. Selecting Location Of Intake Structure
  • 14. Intakes for Collecting Surface Water Types of Intakes According to type of source • River Intake • Canal Intake • Reservoir Intake • Lake Intake According to position of Intake • Submerged Intake • Exposed Intake According to presence of water in the tower • Wet Intake • Dry Intake
  • 15. Intakes for Collecting Surface Water According to position of Intake • (a) Submerged Intake • (b) Exposed Intake • The submerged Intake structures are those which are constructed entirely under water. They are less expensive to construct but are difficult to maintain. Such intakes are commonly used to obtain water from lakes • The Exposed intakes is in the form of well or tower constructed near the bank of river or in some cases even away from the bank of river. They are more common due to ease in operation and maintenance
  • 16. Intakes for Collecting Surface Water According to presence of Water in the tower Wet Intake Dry Intake A Wet intake is that type of the Intake tower in which the water level is practically the same as the water level of the source of supply. Such Intakes are also called as JackWell and is most commonly Used In Dry Intake There is no water in the intake tower. Water enters through entry port directly in to conveyance pipes. The dry Intake tower is simply used for the operation of valves.
  • 17. Simple Lake Submerged Intakes • It consists of a simple concrete block or a rock filled timber crib supporting the starting end of the withdrawal pipe. • The intake opening is generally covered by screen so as to prevent the entry of debris, ice etc.. in to the withdrawal conduit. • In lakes, where silt tends to settle down , the intake opening is generally kept at about 2 to 2.5m above the lake bed level to avoid entry of silt. • They are cheap & do not obstruct navigation • They are widely used for small water supply projects drawing water from streams or lakes having a little change in water level through out year. • Limitation is that they are not easily accessible for cleaning & repairing.
  • 19. Rock Filled Timber Crib -Submerged Intake
  • 20. Intakes for Collecting Surface Water River Intake A River Intake is located on the upstream side of the city to get comparatively better quality of water. They are either located sufficiently inside the river so that necessary demand of water can be met in all the seasons of the year. The intake tower permits the entry of water through several entry ports located at various levels to cope with fluctuations in the water levels during different seasons. This are also called as penstocks. The penstocks are covered with suitable design screens to prevent entry of floating impurities.
  • 21. Intake Towers • They are widely used on large water supply projects drawing water from rivers or reservoirs having large change in water level. • Gate controlled openings called Ports are provided at various levels in these concrete towers to regulate the flow. • If the entry ports are submerged at all levels, there is no problem of any clogging or damage by ice or debris etc.. • There are two major types of intake towers: (a)Wet intake towers (b) Dry intake towers
  • 22. Wet Intake Towers • It consist of a concrete circular shell filled with water up to the reservoir level and has a vertical inside shaft which is connected to the withdrawal pipe. • The withdrawal pipe may lie over the bed of the rivers or may be in the form of tunnels below the river bed. • Openings are made in to the outer concrete shell as well as, in to the inside shaft. • Gates are usually placed on the shaft, so as to control the flow of water in to the shaft and the withdrawal conduit. • The water coming out of the withdrawal pipe may be taken to pump house for lift (if treatment plant is at high elevation) or may be directly taken to treatment plant (at lower elevation).
  • 24. Dry Intake Towers • The water is directly drawn in to the withdrawal conduit through the gated entry ports. • It has no water inside the tower if its gates are closed. • When the entry ports are closed, a dry intake tower will be subjected to additional buoyant forces. • Hence it must be of heavier construction than wet intake tower. • They are useful since water can be withdrawn from any selected level of the reservoir by opening the port at that level.
  • 27. Intake • There are two types of intakes as under • (i) Dry Intake Tower • In dry intake tower the entry ports are directly connected with the withdrawal conduit and water inside the tower when gates are in a closed position. Dry Intake tower has a merit that the intake tower being dry is made accessible for inspection and operation besides that the water can be withdrawn from any level by opening the port at that level. • However, dry intake tower is massive in structure, than wet intake to withstand additional buoyant forces to which it is subjected when the port gates are closed.
  • 31. Intake Wet Intake Tower • A wet intake tower has entry ports at various levels and the vertical shaft is filled with water up to reservoir level. It differs from the dry intake tower is that the water enters from the ports into the tower and then into the withdrawal conduict through separate gated openings. As such it consists of a circular shell made of concrete filled with water up to reservoir level, housing another inside shaft directly connected to the withdrawal conduit. It is less costly to construct and is usually not subjected to flotation and certain other stress may not be the consideration.
  • 33. Trash Racks • Trash rack is defined as a screen or grating provided at the entrance of intake to prevent entry of debris. Trash racks usually consists of trash sections 1.5 to 2 m wide and not too long for handling, made up of mild steel flats on edge 5 to 15 cm. Coarse trash racks are provided near the ports to prevent large drift, such as cakes of ice, roots, trees and timber from being drawn into the intake.
  • 34. Trash Racks • In some part of the intake fine trash racks are provided to protect the machine & machine parts through which water flows. In cold region, trash racks is often clogged with fragile ice. Electrical heating for small trash racks are provided to prevent ice formation on the racks. • The floating debris accumulated, as are denied entry into the intake, are removed with the help of power driven rack-rakes.
  • 36. River Intake Structures • They are generally constructed for withdrawing water from almost all rivers. • They can be classified in to two types (1) Twin well type of intake structure (2) Single well type of intake structure
  • 37. Twin Well Type Intakes • They are constructed on almost all types of rivers, where the river water hugs the river bank. • A typical river intake structure consists of 3 components: (a) An inlet well (b) An inlet pipe (intake pipe) (c) A jack well • Inlet well is usually circular in c/s, made of masonry or concrete. • Inlet pipe connects inlet well with jack well. It has a min dia of 45cm, laid at slope of 1 in 200. Flow velocity through it<1.2m/s • Water entering jack well is lifted by pumps & fed into the rising main • Jack well should be founded on hard strata having B.C> 450 kN/m2.
  • 38. Twin Well Type Intakes
  • 39. Single Well Type Intakes • No inlet well & inlet pipe in this type of river intake. • Opening or ports fitted with bar screens are provided in the jack well itself. • The sediment entering will usually be less, since clearer water will enter the off-take channel. • The silt entering the jack well will partly settle down in the bottom silt zone of jack well or may be lifted up with the pumped water since pumps can easily lift sedimented water. • The jack well can be periodically cleaned manually, by stopping the water entry in to the well.
  • 40. Single Well Type Intakes
  • 41. Single Well Type Intakes
  • 43. Canal Intakes • In case of a small town a nearby Irrigation Canal can be used as the source of water. The Intake Well is generally located in the bank of the Canal. Since water level is more or less constant there is no need of providing inlets at different depth. It essentially consist of concrete or masonry intake chamber or well. • Since the flow area in the canal is obstructed by the construction of Intake well, the flow velocity in the canal decreases. So the canal should be lined on the Upstream & Downstream side of the intake to prevent erosion of sides and bed of channel
  • 44. Intakes For Sluice Ways Of Dams
  • 45. Intakes For Sluice Ways Of Dams
  • 46. Intakes For Sluice Ways Of Dams
  • 47. Intakes for Reservoirs • When the flow in the river is not guaranteed throughout the year, a dam is constructed across the river to store the water in the reservoir so formed. • Reservoir Intakes essentially consists of an Intake tower constructed on the slope of Dam at such a place where Intake can draw water in sufficient quantity even in the driest period. Intake pipes are fixed at different levels, so as to draw water near the surface in all variations of water levels.
  • 48. An intake structure constructed at the entrance of conduit and thereby helping in protecting the conduit from being damaged or clogged by ice , trash, debris, etc.., can vary from a simple Concrete block supporting the end of the conduit pipe to huge concrete towers housing intake gates, Screens, pumps, etc.. and even sometimes, living quarters and shops for operating personnel.
  • 49. Lake Intake • Lake Intake are mostly submerged intake. These Intakes are constructed in the bed of lake below the low water level so as to draw water even in dry season. It mainly consist of a pipe laid in the bed of the lake. One end of the pipe which is in middle of the lake is fitted with bell mouth opening covered with a mesh and protected timber or concrete crib. The water enters in the pipe through the bell mouth opening and flows under gravity to the bank where it is collected in a sump well and then pumped to the treatment plant for necessary treatment.
  • 51. Advantages Intakes • No Obstruction to navigation • No danger of floating bodies • No ice trouble
  • 53. Intake • The general requirement of an Intake Structure are: Structural Stability • The Intake structure is stable to resist water and wave thrust besides wind pressure when reservoir is empty as also against the shock of earthquakes. Hydraulic efficiency • There is smooth entry into the water conductor system to ensure gradual transformation of static head to conduct velocity so as to involve hydraulic losses.
  • 55. Intake Velocity Limitation • The velocity through trash rack gates and ports is within economic and safe limits. Operational efficiency • The intake and the equipments are such as to prevent/ minimize ice, floating trash and coarse sediment entering the water conductor system to ensure good operational efficiency.
  • 56. Intake • The main components of an irrigation intake structure are (i) Trash rack and supporting structure (ii) Bell mouth entrance with transition and rectangular circular opening, and (iii) Gate slot closing devices with air vents.
  • 59. Gate slot closing devices with air vents.
  • 60. Intake Function of Intakes • Intake structure serve to permit withdrawal of water in the reservoir over a predetermined range of reservoir levels to the outlet. • The other functions served by an intake are to support necessary auxiliary appurtenances such as trashrack, fish screens and bypass devices, etc.,.
  • 67. Intake Run-of-River Intakes • In a run-of-River plants, intake is apparent to power house and draws water from the river without any appreciable storage upstream of the diversion structure. Characteristics of river flows., the intake is designed to withstand high peaks and short duration flood flows and high sediment loads. The bell mouth entrance is essentially provided with trash racks.
  • 69. Intake Canal Intake • It is also a variant of the run-of-river intake, that is provided adjacent to the diversion weir/ barrages to admit water into the canal. It is designed to function under low heads and the topography and geology permits straight reach suitable for it. Sediment excluder is an essential component of the intake. The crest of the intake is generally raised to prevent entry of coarse fraction of bed load into the canal.
  • 71. Intake Reservoir Type Intakes • Intake tower classified as Submerged, dry and wet intakes fall in this category. (i) Submerged Intake • An Intake Structure which remains entirely under water during its operation is termed as submerged intake. It is provided where the structure serves only as an entrance to the outlet conduct and where ordinarily cleaning of the trash is not required. The conduct intake may be inclined, vertical or horizontal in accordingly with the intake requirements. . An Inclined Intake may be provided with gates and operated on the upstream slopes of a low dam.
  • 74. Intake Intake tower • An Intake tower is used to draw water from the reservoir in which there are huge fluctuations in water level or quality water is to be drawn at the desirable depth or both. It Consist of an elaborate exposed or tower like structure rising above maximum reservoir level and closely located to the dam body or the bank of the stream so as to be approached by a connecting bridge of minimum span.
  • 76. Intake • The Intake tower consist of circular concrete structure provided with openings or ports for water entry fitted with trash racks to prevent the entry of debris and ice large enough to injure the equipment and gates that control the flow through intakes into the feeding conduct outlet. • It has a merit that best quality of water available at different depths at different seasons of the year can be drawn through port openings at different elevations.
  • 77. Design of Intake • An Intake should be designed and constructed on the basis of following points • Sufficient factor of safety should be taken so that intake work can resist external forces caused by heavy waves and currents, Impact of floating and submerged bodies, ice pressure etc.. • Intake should have sufficient self weight, so that it may not float by the up trust of water and washed away by the current • If Intake work is constructed in navigation channels, it should be protected against the impact of the moving ships by cluster of pile around • The foundation of Intake should be taken sufficient deep so that they may not be undermined and current may not overturn the structure.
  • 78. Design of Intake • To avoid the entrance of large and medium objects and fishes screens should be provided on the Inlet, sides • The Inlet should be of sufficient size and should allow required quantity of water. • The positions of Inlet should be such that they can admit water in all seasons near the surface where quality of water is good. • Number of Inlets should be more so that if any one is blocked, the water can be drawn from others. The inlets should be completely submerged so that air may not enter the suction pipe.
  • 80. Design procedure for Intakes Canal Intake • If Population is given and rate of water Supply is given the discharge required by the city/town can be found • Q= Population x Rate of Supply Design of Coarse Screen • Generally the coarse screens are made of vertical bars of 15 to 20 mm dia and are spaced at 20 to 50 mm Centre to Centre • Velocity through the screens is assumed to bearound 0.15 m/sec
  • 82. Design procedure for Intakes • Area of Screens= Discharge Velocity through screens Q= A x V Height of the screen is found assuming that the bottom of the screen is kept 0.15 m above canal bed and also considering the minimum water level in the canal. After finding height, length of the screen opening can be found out. Length of screen = Area Height
  • 84. Design procedure for Intakes • Number of bars required can be found after assuming the diameter and spacing of the bars. • Total length of screen will be length of opening + length occupied by bars . Design of bell mouth entry • To find the area of bell mouth entry first assume thevelocity through bell mouth generally around 0.3 to 0.35 m/sec . After getting the area find the dia of bell mouth
  • 86. Design Procedure for Intakes Design of Intake Conduit • Assume the velocity of flow through conduit, generally 1.0 to 1.5 m/sec • Find , A= Q V Then Using Hazen William formula, find the head loss and the slope required, Charts can be used.
  • 87. River Intake • First Design the Intake Well. Dia is generally between 4 to 7.5 m. Using discharge find the area and the diameter. • If rectangular find length and width after finding the length and width of the screen required. • Design procedure for coarse screen and outlet conduct is almost same as canal Intake.
  • 88. Example • Design a bell mouth canal intake for a city of 70,000 persons drawing water from a canal which runs only for 10 hrs. a day with a depth of 1.6 m. Also calculate the head loss in the intake conduit if the treatment plant is 0.5 km away. Assume average consumption per person= 160 l/d. Assume the velocity through the screens and bell mouth to be 0.15 m/s and 0.3 m/s respectively.
  • 89. Example • Discharge required by the city = 70000 x 160 (Population x rate of supply) = 11,200,000 11.2 MLD (Million litre per day) Since the canal only runs for 10 hrs. a day, this whole daily flow is required to be drain in 10 hrs.
  • 90. Example Therefore the Intake load= 11.2 = 1.12 ML/Hour 10 = 1.12 x 10 6 m3 / hr.... 10 3 1.12 x 10 3 m3 /sec 60 x 60 = 0.311 m3 /sec
  • 91. Example Design of Coarse Screen • Area of Coarse Screen = Discharge Velocity through the screen Velocity through the screen = 0.15 m /sec Area of the coarse screen = 0.311 = 2.075 m 2 0.15 Assume the minimum water level is 0.3 m below the normal water level. The bottom of the screen is kept at 0.15 m above the bed level. The top of screen is kept at minimum level Therefore available height= 1.6 – 0.3- 0.15 = 1.15 m Minimum length of the screen= 2.075 = 1.80 m 1.15
  • 93. Example Assume the clear opening between vertical bars to be 30 mm each we have • Number of opening = 1.8 = 60 0.03 Therefore no of bars= 59 Assume the dia of bar as 20 mm Length occupied by the bar of 20 mm = 59 x 0.02 = 1.18 m Therefore length of screen= 1.8 + 1.18 = 2.98 Say 3 m Hence provide coarse screen of length 3.0 m and height 1.15 in rectangular intake well
  • 95. Example Design of Bell Mouth Entry • Area of Bell mouth entry = Discharge Velocity through the bell mouth = 0.311 0.3 = 1.037 m 2 Diameter d of the bell mouth entry as = Π d 2 = 1.037 4
  • 96. Example • D={ 4 x 1.037} 1/2 Π = 1.15 m If the dia of small holes in the screen is assumed to be 15 mm (10 to 20mm). Then area of each hole= Π x (0.015) 2 4 = 1.767 x 10 -4 Therefore number of holes on the bell mouth = Area of bell mouth Area of one hole = 1.037 1.767 x 10 -4 = 5868.2 Say 5869
  • 98. Example Design of Intake Conduit • Assume Velocity of flow in the conduit as 1.5 m/sec • Area of conduit required = Discharge Velocity = 0.311 = 0.2073 m 2 1.5 Dia of pipe D will be Π D2 = 0.2073 4= 0.514 Say 0.55 m
  • 100. Example • Flow velocity through this 0.55 m dia conduit will be = V = Q = 0.311 = 1.31 m /sec A = Π x (0.55) 2 4 assume velocity of 1.5 m /sec
  • 101. Example • Head loss through the conduit up-to treatment plant is calculated by using Hazen William’s eq n • V= 0.85 CH R 0.23 S 0.54 • Where , • CH= Coefficient of the Pipe • = 130 for Cast Iron Pipe • R= Hydraulic mean depth • = d/4 ( for pipe running full) • = 0.55 = 0.138 m 4 V= Velocity S= Slope
  • 102. Example • Therefore, • 1.5 = 0.85 x 130 x (0.138 ) 0.63 S 0.64 • S 0.54 = 150 0.85 x 130 x (0.138) 0.63 = 0.047 S= (0.047) 1 /0.54 = 3.51 x 10 -3 Or 1 in 284.73 S= HL = Head Loss L Length of Pipe Length of pipe is equal to the distance of Intake from treatment plants 0.5 km = 500 m HL= 3.51 x 10 -3 x 500 = 1.755 m
  • 103. Example • Design a bell mouth canal Intake for a City of 1,00,000 persons drawing water from a canal which runs for 10 hrs.. a day with a depth of 2 m. Also calculate the head loss in the intake conduit if the treatment works are 1 km away. Draw a neat sketch of canal Intake. Assume average consumption per person= 150 l/day. Assume the velocity through the screens and bell mouth to be less than 15 cm/sec and 35 cm/sec
  • 105. Example Discharge through Intake Daily Discharge= 150 x 1,00,000= 15,000,000 l/day • Since the canal runs only for 10 hrs. per day. • Intake Load/hr = 15,000,000 = 15,000,00 lit/hr 10 = 15,00 m3 /hr.... Q= 1500 = 0.4166 m3 /sec 60 x 60
  • 106. Example Area of Coarse Screen I front of Intake • Area of Screen= 0.4166= 2.777 m 2 0.15 Let the area occupied by solid bars by 30 % of the total area Therefore the actual area= 3.96 m 2 Let us assume minimum water level at 0.3 m below normal water level. Also let us keep bottom of the screen at 0.15 m above canal bed and top of screen at the minimum water level. Available height of screen= 2- 0.3-0.15 = 1.55 m Required length of screen= 3.96 = 2.55 m 1.55 Hence provide a length of 2.6 m Hence provide a screen of 1.55 x 2.6 m
  • 107. Example Design of Bell Mouth Entry • Area of Bell mouth Ab= 0.4166 = 1.301 m 2 0.32 Dia db= { 1.301 x 4}1/2 = 1.65 m 3.14 Hence provide a bell mouth of 1.7 m dia
  • 108. Example Design of Intake Conduit • Let us assume a velocity of 1.5 m/sec in the conduit • Dia of conduit D ={ 0.4166 x 4 } 1/2 = 0.35 m 1.5 x 3.14 However, provide 0.5 m dia, conduit, so that actual velocity of flow is V = 0.4166 x 4 = 2.12 m/sec 3.14 x (0.5) 2
  • 109. Example For head loss through the conduit • V= 0.849 C R 0.63 S 0.54 • C= 130 • R= D/4 = 0.5 /4 = 0.125 • Hence Slope S of the energy line, • 2.12 = 0.849 (130) (0.125) 0.63 S 0.54 • S= 7.533 x 10 -3 • S= HL/L • HL= S x L= 7.53 m
  • 111. Conveyance of Water • Water is drawn from the sources by Intakes. After it’s drawing the next problem is to carry it to the treatment plant which is located usually within city limits. Therefore after collection, the water is conveyed to the city by mean of conduits. If the source is at higher elevation than the treatment plant, the water can flow under gravitational force. • For the conveyance of water at such places we can use open channel, aqueduct or pipe line, Mostly it has been seen that the water level in the source is at lower elevation than the treatment plant, In such case water can be conveyed by means of closed pipes under pressure
  • 113. Conveyance of Water • If the source of supply is underground water, usually there is no problem as, these sources are mostly in the underground of the city itself. The water is drawn from the underground sources by means of tube-wells and pumped to the over-head reservoirs, from where it is distributed to the town under gravitational force. Hence at such places there is no problem of conveyance of water from sources to the treatment works.
  • 115. Conveyance of Water • In case of sources of water supply is river or reservoir and the town is situated at higher level, the water will have to be pumped and conveyed through pressure pipes. If the source is available at higher level than the town, it is better to construct the treatment plant near the source and supply the water to the town under gravitational forces only,
  • 117. Conveyance of Water Open Channels • These ae occasionally used to convey the water from the source to the treatment plant. These can be easily and cheaply constructed by cutting in high grounds and banking in low grounds. • The channels should be lined properly to prevent the seepage and contamination of water. As water flows only due to gravitational forces, a uniform longitudinal slope is given. The hydraulic gradient line in channels should not exceed the permissible limit otherwise scouring will start at the bed and water will become dirty. In channel flow there is always loss of water by seepage and evaporation,
  • 119. Conveyance of Water Aqueducts • Aqueducts is the name given to the closed conduit constructed with masonry and used for conveying water from source to the treatment plant or point of distribution. Aqueduct may be constructed with bricks, stones or reinforced cement concrete. In olden days rectangular aqueduct were used, but now a days horse-shoe or circular section are used. These aqueduct are mostly constructed with cement concrete The average velocity should be 1 m/sec
  • 121. Conveyance of Water Tunnels • This is also a gravity conduit, in which water flows under gravitational forces. But sometimes water flows under pressure and in such cases these are called pressure tunnels. Grade tunnels are mostly constructed in horse-shoe cross-section, but pressure tunnel have circular cross-section. In pressure tunnels the depth of water is generally such that the weight of overlying material will be sufficient to check the bursting pressure. Tunnels should be water tight and there should be no loss of water.
  • 123. Conveyance of Water Flumes • These are open Channels supported above the ground over trestles etc.. Flumes are usually used for conveying water across valleys and minor low lying areas or over drains and other obstruction coming in the way. Flumes may be constructed with R.C.C, wood or metal. The common section are rectangular and circular.
  • 124. Flumes
  • 125. Conveyance of Water Pipes • These are circular conduits, in which water flows under pressure. Now a days pressure pipes are mostly used at every places and they have eliminated the use of channels, aqueducts and tunnels to a large extent. These are made of various materials like cast Iron, wrought Iron, steel, cement Concrete, asbestos, cement, timber, etc.. In the town pips are also used for distribution system. In distribution system pipes of various diameter, having many connections and branches are used. Water pipe lines follow the profile of the ground water and the location which is most economical, causing less pressure in pipes is chosen.
  • 126. Pipes
  • 127. Conveyance of Water • The cost of pipe line depends on the internal pressure to bear and the length of pipe line. Therefore as far as possible the hydraulic line is kept closer to the pipe line. In the valley or low points a scour valve is provided to drain the line and removing accumulated suspended matter. Similarly at high points air relief valves are provided to remove the accumulated air. To prevent the bursting of pipes due to water hammer, surge tanks or stand pipes are provided at the end of pipes.
  • 128. Surge Tank or Surge Chamber
  • 130. Surge Tank or Surge Chamber
  • 131. Conveyance of Water The selection of material for the pipes is done on the following points • Carrying Capacity of the pipes • Durability and life of the pipe • Type of water to be conveyed and its corrosive effect on the pipe material. • Availability of funds • Maintenance cost, repair etc.. • The pipe material which will give the smallest annual cost or capital cost will be selected, because it will be mostly economical.
  • 133. Conveyance of Water Following types of pipes are commonly Used • Cast Iron Pipes • Wrought Iron pipes • Steel Pipes • Concrete Pipes • Cement lined Cast Iron Pipes • Plastic or PVC pipes • Asbestos cement pipes • Copper and lead pipes • Wooden pipes • Vitrified Clay pipes
  • 134. Conveyance of Water • Out of the types mentioned, plastic or PVC and Asbestos cement pipes, wooden pipes are not generally used for conveyance of water. They are used in house drainage or water connection within individual house.
  • 135. Cast Iron Pipes • Cast – Iron Pipes are mostly used in water supply schemes. They have higher resistant to corrosion, therefore have long life about 100 years. • Cast Iron pipes are manufactured in lengths of 2.5 m to 5.5 m. The fittings of these pipes are also manufactured in sand molds having core boxes. These fittings are also weighed, coated with coal tar and finally tested. Cast-Iron pipes are joined together by means of Bell and Spigot, Threaded or flanged Joints
  • 137. Conveyance of Water Advantages of CI Pipes • Ease in jointing the pipes • Can withstand high Internal pressure • Have a very long design life. (100 years) • They are less prone to corrosion.
  • 138. Conveyance of Water Dis-advantages of CI Pipes • They are heavy and difficult to transport • Length of pipe available as less (2.5 to 5.5m) so more joints are required for laying the pipes so chances of leakage also Increases. • They are brittle so they break or crack easily.
  • 139. Conveyance of Water Wrought Iron Pipes • Wrought Iron Pipes are manufactured by rolling the flat plates of the metal to the proper diameter and welding the edges. If compared with cast Iron, these are more lighter, can be easily cut, threaded and worked, give neat appearance if used in the interior works. But it is more costly and less durable than cast iron pipes. These pipes should be used only inside the buildings, where they can be protected from corrosion. Wrought Iron pipes are joined together by couplings or screwed and socketed joints. To Increase the life of these pipes sometimes these are galvanized with zinc.
  • 141. Conveyance of Water Steel pipes • The Construction of these pipes is similar to wrought iron pipes, it is occasionally used from main lines and at such places where pressure are high and pipe dia is more. Steel pipes are more stronger, have very light weight and can withstand high pressure than cast iron pipes. They are also cheap, easy to construct and can be easily transported.
  • 143. Conveyance of Water • The disadvantages of these pipes is that they cannot withstand external load, if partial vacuum is created by emptying pipe rapidly, the pipe may be collapsed or distorted. These pipes are much affected by corrosion and are costly to maintain The life of these pipes is 25 to 50 years, which is much shorter as compared to cast Iron Pipes Steel pipes are not used in distribution system, owing to the difficulty in making connections. • The joints in steel pipes may be made of welding or riveting, longitudinal lap joints are made In riveted steel pipes up to 120 cm dia
  • 144. Conveyance of Water Concrete Pipes • These pipes may be precast or Cast-in-situ plain concrete pipe may be used at such places where water does not flow under pressure, these pipes are jointed with Bel &Spigot Joints. Plain Concrete pipes are up to 60 cm dia only, above it these are reinforced.
  • 146. Conveyance of Water Advantages of R.C.C Pipes • Their life is more about 75 years • They can be easily constructed in the factories or at site • They have least coefficient of thermal expansion than other types of pipes . Hence they do not require expansion joints • Due to their heavy weight, when laid under water, they are not affected by buoyancy, even when they are empty. • They are not affected by atmospheric action or ordinary soil under normal condition.
  • 147. Conveyance of Water Disadvantages of R.C.C Pipes • They are affected by acids, alkalis and salty waters • Their repairs are very difficult. • Due to their heavy weight, their transportation and laying cost is more. • It is difficult to make connections in them • Porosity may cause them to leak.
  • 148. Pipe Joints • For the facilities in handling, transporting, and placing in position, pipes are manufactured in small lengths of 2 to 6 meters. These small pieces of pipes are then joined together after placing in position to make one continuous length of pipe. • The design of these joints mainly depends on the material of the pipe, internal water pressure and the condition of the support • The bell and spigot joints, using lead as filling material is mostly used for cast Iron pipes. For Steel pipes welded, riveted, flanged or screwed joints my be used.
  • 149. Various types of Joints which are mostly used, are as follows • Spigot and Socket Joints or Bell & Spigot Joints • Expansion Joints • Flanged Joints • Mechanical Joints • Flexible Joints • Screwed Joints • Collar Joints • A.C. Pipe Joints
  • 150. Spigot and Socket Joints • This types of joints is mostly used for cast iron pipes For the construction of this joint the spigot or normal end of one pipe is slipped in socket or bell mouth end of the other pipe until contact is made at the base of the base of the bell.
  • 151. Spigot and Socket Joints
  • 152. Spigot and Socket Joints • After this hemp or yarn is wrapped around the spigot end of the pipe and is tightly filled in the joint by means of yarning iron up to 5 cm depth. The hemp is tightly packed to maintain regular annular space and for preventing jointed material from falling inside the pipe. After packing of hemp & gasket or joint runner is clamped against the outer edge of the bell.
  • 153. Spigot and Socket Joints • Sometimes wet clay is used to make tight contact between the runner and the pipe so that hot lead may not run out of the joint spaces. The molten lead is then poured into V-shaped opening left in the top by the clamp joint runner. The space between the hemp yarn and the clamp runner is removed, the lead which shrink while cooling, is again tightened by means of chalking tool and hammer. Now a days in order to reduce the cost of lead certain patented compounds of sulphur and other materials and other materials are filled in these joints.
  • 154. Expansion Joints • This joint is used at such places where pipes expand or contract due to change in atmospheric temperature and thus checks the setting of thermal stresses in the pipes. In this joints the socket end is flanged with cast iron follower ring, which can freely slide on the spigot end or plane end of other pipes. An elastic rubber gasket is tightly pressed between the annular spaces of socket by means of bolts. In the beginning while fixing the follower ring some space is left between the socket base and the spigot end for the free movement of the pipes under variation of temperature. In this way when the pipe expands the socket end moves forward and when the pipe contracts, it moves backward in the space provided for it. The elastic rubber gasket in every position keeps the joint water tight.
  • 156. Flanged Joint • This joint is mostly used for temporary pipe lines, because the pipe line can be dismantled and again assembled at other places. • The pipe in this case has flanges on its both ends, cast, welded or screwed with the pipe. The two ends of the pipes which are to be jointed together are brought in perfect level near one another and after placing of washer or gasket of rubber, canvas, copper or lead between the two ends of flanges is very necessary for securing a perfect water-tight joints. These joint cannot be used at places where it has to bear vibration of pipes etc..
  • 158. Flexible Joints • Sometimes this joint is also called Bell & Socket or Universal Joint. This joint is used at such places where settlement is likely to occur after the lying of the pipes. This joint can also be used for laying of pipes on curves, because at the joint the pipes can be laid at angle. This is a special type of joint. The socket end is cast in a spherical shape. The spigot end is plain but has a bead at the other end. For the assembling of this joints, the spigot end of one pipe is kept in the spherical end of the other pipe.
  • 161. Flexible Joints • After this the retaining ring is slipped which is stretched over the bead. Then a rubber gasket is moved which touches the retainer high. after it split cast iron gland ring is placed, the outer surface of which has the same shape as inner surface of socket end. Over this finally cast iron follower ring is moved and is fixed to the socket end by means of bolts. It is very clear that if one pipe is given any deflection the ball shaped portion will move inside the socket, and the joint will remain waterproof in all the position.
  • 163. Mechanical Joints • This type of joints are used for jointing cast Iron, Steel or wrought Iron pipes, when both the ends of the pipes are plain or spigot. There are two types of mechanical joints. • Dressers- Couplings • It essentially consists of one middle ring, two follower rings and two rubber gaskets. The two follower rings are connected to-gather by bolts and when they are tightened, they pass both the gaskets tightly below the ends of the middle ring. These joints are very strong and rigid and can withstand vibrations and shocks up to certain limit. These joints are mostly suitable for carrying water lines over bridges, where it has to bear vibrations.
  • 166. Mechanical Joints Victaulic Joint • In this type of joints a gasket or leak-proof ring is slipped over both the ends of the pipes. This gasket is pressed from both the sides by mean of half iron couplings by bolts. The ends of pipes are kept sufficient apart to allow for free expansion, contraction and deflection. This joints can bear shocks, vibrations etc.. and used for cast-iron, steel or wrought iron pipe lines in exposed places.
  • 169. Screwed Joints • The joint is mostly used for connecting small diameter cast iron, wrought iron and galvanized pipe. The end of the pipes have threads outside, while socket or couplings has threads on the inner side. The same socket is screwed on both the ends of the pipes to join them. For making water tight joints zinc paint or hemp yarn should be placed in the threads of the pipes, before screwing socket over it.
  • 171. Collar Joint • This type of joint is mostly used for joining big diameter concrete and asbestos cement pipes. The ends of the two pipes are brought in one level before each other. Then rubber gasket between steel rings or jute rope socked in cement is kept in the grove and the collar is placed at the joint so that it should have same lap on both the pipes. Now 1:1 cement mortar is filled in the space between the pipes and the collar.
  • 173. Joint for A.C. Pipes • For jointing small diameter A.C. Pipes the two ends of pipes are butted against each other, then two rubber rings will be slipped over the pipes and the couplings will be pushed over the rubber rings. The rubber rings make the joint water-proof.
  • 174. Laying of Water Supply Pipes • Pipes are generally laid below the ground level, but sometimes when they pass in open areas, they may be laid over the ground. The pipes are laid in the following way. • First of all the detailed map of all roads, streets lanes etc., is prepared. On this map the proposed pipe line with all sizes and length will be marked. The position of existing pipe line, curb lines, sewer lines etc.. will also be marked on it. In addition to this position of valves and other pipe specials, stand posts etc.. will also be marked, so that at the time of laying there should be no difficulty in this connection.
  • 175. Laying of Water Supply Pipes • After the general planning, the center line of the pipe line will be transferred on the ground from the detail plan. The center line will be marked by means of stalkes driven at 30 m interval on straight lines. On curves the stalkes will be driven at 7 to 15 m spacing. If the road or streets have curbs, the distance of center of pipe line fro curb will be marked.
  • 176. Laying of Water Supply Pipes • When the center line has marked on the ground the excavation for the trenches will be started. The width of the trench will be 30 cm to 45 cm more than the external diameter of the pipe. At every joint the depth of excavation will be 15 to 20 cm more for one meter length for easy joining of the pipes. The pipe lines should be laid more than 90 cm below the ground so that pipe may not break due to impact of heavy traffic moving over the ground
  • 177. Laying of Water Supply Pipes
  • 178. Laying of Water Supply Pipes • After the excavation of trenches the pipes are lowered in it. The pipe laying should start from lower level and proceed towards higher level with socket end towards higher side. The jointing of pipes should be done along with the laying of pipes. • After laying the pipe in position, they are tested for water leakage and pressure. • When the pipe line is tested, the back filings of the excavated material will be done. • The soil which was excavated is filled in the trenches all around the pipes and should be well rammed. All the surplus soil will be disposed off and the site should be cleaned.
  • 179. Laying of Water Supply Pipes
  • 180. Laying of Water Supply Pipes
  • 181. Laying of Water Supply Pipes
  • 182. Hydrostatic Test • After laying the new pipe line, jointing & back filling, it is subjected to the following tests: • Pressure Tests at a pressure of at least double of maximum working pressure, pipe joints shall be absolutely water tight. • Leakage Test (to be conducted after the satisfactory completion of the pressure test) at a pressure as specified by the authority for a duration of two hours. • In this way error in workman ship will be found immediately and can be rectified. Usually the length to be tested is kept up to 500 m.
  • 183. Laying of Water Supply Pipes
  • 186. Pumps for Lifting Water • The function of the pump is to lift the water or any fluid at higher elevation or higher pressure. In water works pumps are required under the following circumstances. • At the source of water to lift the water from rivers, streams, wells etc.. and to pump it to the treatment works. • At the treatment plant to lift the water at various units so that it may flow in them due to the gravitational force only during the treatment of the water. • For the back washing of filters and increasing their efficiency. • For pumping chemical solution at treatment plants. • For filling the elevated distribution reservoirs or overhead tanks • To increase the pressure in the pipe lines by boosting up the pressure. • For pumping the treated water directly in the water mains for its distribution.
  • 188. Classification of pumps • (i) Classification based on principles of operation • Displacement pump • Centrifugal pumps • Air –lift pumps • Impulse pumps • (ii) Classification based on type of power required • Electrical driven pumps • Gasoline engine pumps • Steam engine pumps • Diesel engine pumps
  • 189. Classification of pumps • (iii) Classification based on the type of services • Low lift pumps • High lift pumps • Deep-well pumps • Booster pumps • Standby pumps
  • 190. The selection of a particular type of pumps depend upon the following factors • Capacity of pumps • Number of pump units required • Suction conditions • Lift (total head) • Discharge condition, and variation in the load • Floor space requirement • Flexibility of operation • Starting & priming characteristics • Initial cost and running costs
  • 191. Displacement Pumps • In these types of pumps vacuum is created mechanically by the movable part of the pumps. In the vacuum first the water is drawn inside the pumps, which on the return of mechanical part of the pump is displaced and forced out of the chamber trough the valve and pipe. The back flow of the water is prevented by means of suitable valves.
  • 192. Displacement Pumps • The following are the two main type of displacement pumps (i) Reciprocating Pumps (ii) Rotary Pumps
  • 193. Displacement Pumps Reciprocating Pump • Reciprocating pumps may be of the following types • Simple hand-operated reciprocating pump • Power operated deep well reciprocating pump • Single-acting reciprocating pump • Double-acting reciprocating pump
  • 195. Displacement Pumps Rotary Pump (a) Rotary pumps with gear (b) Rotary pumps with cams • The revolving blades fit closely in the casing and push the water by their displacement. The blades revolve in a downward direction at the Centre and the water is carried upward around the side of the casing. In this way the water is pushed through the discharge pipe and partial vacuum is created on the suction side. The intensity of vacuum mainly depends on the tightness of the parts.
  • 197. Displacement Pumps Advantages of Rotary Pumps • They do not require any priming as they are self-primed. • The efficiency of these pumps is high at low to moderate heads up-to discharge of 2000 l/m • These pumps have no valves, are easy in construction and maintenance as compared with reciprocating pumps. • These pumps give steady and constant flow • These pumps are deployed for the individual building water supply and for fire protection.
  • 198. Displacement Pumps Disadvantages of Rotary Pumps • The initial cost of these pump is high • Their maintenance cost is high due to abrasion of their cams and gears. • They cannot pump water containing suspended impurities as the wear and abrasion caused by the impurities will destroy the seal between the cans and the casing.
  • 199. Centrifugal Pumps • These pumps work on the principle of centrifugal force, therefore, they are called centrifugal pumps. The water which enters inside the pump is revolved at high speed by means of impeller and is thrown to the periphery by the centrifugal force.
  • 201. Centrifugal Pumps Advantages and Disadvantages of Centrifugal Pumps • The centrifugal pumps have the following advantages • Due to compact design, they require very small space. • They can be fixed to high-speed driving mechanism • They have rotary motion due to which there is low or no noise • They are not damaged due to high pressure
  • 202. Centrifugal Pumps Disadvantages of centrifugal pumps • They require priming • The rate of flow of water cannot be regulated. • Any air leak on the suction side will affect the efficiency of the pump. • They have high efficiency only for low head and discharge. • The pump will run back, if it is stopped with the discharge valve open.
  • 203. Design of Pumps • Design of pumps means to find out the capacity of the pump required to deliver specific quantity of water against specific head. • So design of pumps can be divided into two parts • To find the total head against which the pump has to operate. • The total power requirement or the capacity of the pump or the size of the pump required and also deciding the number of pumps required as well as stand by.
  • 204. Total Head Or Lift Against Which The Pump Has To Work • The total head or total lift against which the pump has to work includes suction lift (or Head), discharge or delivery lift (or Head) and total loss of head due to friction, entrance, exit, fitting etc. in suction and rising main. • If Hs= Suction lift or Head • Hd= Delivery or discharge head • Hl= Total loss of head then, • The total head against which the pump has to work is given by: • H= Hs + Hd + H l
  • 205. Total Head Or Lift Against Which The Pump Has To Work • Suction lift : It is the difference between the lowest water and the pump • Discharge lift or delivery Head: It is the difference between the point of discharge or delivery and the pump. • Generally only the friction losses is considered for the design as minor losses are very small if the length of the pipe is greater
  • 206. Total Head Or Lift Against Which The Pump Has To Work
  • 207. Total Head Or Lift Against Which The Pump Has To Work • Friction loss can be found out by Darcy Weisbach equation • Darcy Weisbach Eqn = Hf= 4 f l v2 = f’ l v2 2 g d 2g d Where , l= length of pipe d= dia of pipe v= velocity of flow f= coefficient of friction f’= friction factor Value of friction factor varies between (0.02 to 0.075)
  • 208. Power required by the pump or capacity of pump • The horse power (H.P.) of the pump can be determined by calculating the work done by the pump in raising the water up to the height H. • Let the pump raiseW kg of water to height H meter. • Then the work done by the pump= W x H (m.kg) • = ϒ Q H (m. kg/sec) • Where, ϒ = UnitWeight of water • Q= Discharge to be pumped in m3 /sec • H= Total head in meter • Water Horse Power (WHP) = ϒ Q H 75
  • 209. Power required by the pump or capacity of pump • Brake Horse Power (B.H.P) = W.H.P Ƞ = ϒ Q H 75 Ƞ
  • 210. Number of Pumps, size and stand by units • Pumping units at water works are generally not operated at full capacity for all times. Since the efficiency of pumping unit varies with the load, it is a usual practice to design a pumping station that some of the pump units can be operated at full capacity, at all the time. Hence two, three, or four pumps are installed. The sizes of these pumps can be fixed by considering the demand, available storage. • Thus, there will always exist some stand by capacity to take care of the repairs, breakdowns, etc. Generally 100 % stand-by by capacity to take care against average demand and 33.33 to 50 % standby capacity against the peak demand is considered sufficient and may therefore be provided at the pumping station.
  • 211. Design of Rising Main Design of Rising Main • Rising main is the pipe through which the pumped water is sent further to the next unit for treatment purpose. Water flows in this pipe under high pressure and flow is turbulent. Here the friction loss in the pipe is more due to high velocity. Pressure pipes are designed such that overall cost of the project should be lowest possible both from maintenance and constructional point of view.
  • 213. Design of Rising Main Economic diameter of rising main • For pumping a particular fixed discharge of water, there are two options • It can be pumped through bigger diameter pipe at low velocity • Through lesser diameter pipe at high velocity • If the dia of the pipe is increased, it will lead to higher cost of the pipe line on the other hand if the pipe diameter is reduced the velocity would increase which will lead to higher frictional head loss and will require more Horse Power for pumping, thereby increasing the cost of pumping, also cost of fitting will increase. • For obtaining the optimum efficiency, it is necessary to design the diameter of the pumping main which will be overall most economical in initial cost as well as maintenance cost for pumping the required quantity of water. The diameter which provide such optimum condition is known as “economic diameter” of the pipe.
  • 214. Design of Rising Main • An empirical formula given by lee is commonly used for determining the dia of the pumping or rising main • D= 0.97 to 1.22 √Q • Where, • D= Economic dia of pipe in meters • Q= Discharge to be pumped in cumecs
  • 215. Design of Rising Main Head loss in rising main • The loss of head in the rising main can be found by using • (i) Darcy Weisbach eq • (ii) Hazen William’s equation • Darcy Weisbach Eqn= Hf= 4 f l v2 = f’ l v2 2 g d 2g d Where , l= length of pipe d= dia of pipe v= velocity of flow f= coefficient of friction f’= friction factor Value of friction factor varies between (0.02 to 0.075)
  • 216. Design of Rising Main Hazen Williams Equation • V= 0.85 CH R 0.63 S 0.54 • Where, • V= velocity of flow • S= Slope of H.G.L • = Hl = Head Loss L Length of Pipe R= Hydraulic mean Radius of the pipe = A P If pipe is running full then R= Π/4 d2 = d/4 Π d CH= Hazen William’s coefficient which depends on age, quality and material of pipe.
  • 217. Examples • Find out the head loss due to friction in a rising main from the following data: • Length of the rising main= 600 m • Diameter of pipe= 0.2 m • Discharge required to be pumped = 1200 l/min • Friction factors= 0.025
  • 218. Examples • Velocity of flow = QA Q= 1200 l/min = 1200 x 10-3 m3 /sec 60 = 0.02 m3 /sec V= 0.02 Π (0.2) 2 = 0.637 m/sec 4
  • 219. Examples • Hf= f’ lv2 2gd = 0.025 x 600 x (0.637)2 2 x 9.81 x 0,2 = 1.551 m
  • 220. Examples • A city with 1.5 lakh population I to be supplied water at 100 lpcd from a river 1 km away. The difference in water level of sump and reservoir is 30 m. if the demand has to be supplied in 8 hr., determine the size of the main and B.H.P of the pumps required. • Take f- 0.0075, velocity in the pipe as 2.0 m/sec and efficiency of pump as 75 %
  • 221. Examples • Population of a city= 1,50,000 • Rate of water supply= 100 lpcd • Therefore the average demand of the town= 1,50,000 x 100 • = 15 x 10 6 l/day • Maximum daily demand= 1.5 x avg demand • = 1.5 x 15 x 10 6 • = 22.5 x 10 6 l/day • = 22.5 MLD
  • 222. Examples • As the full demand is to be supplied through pumps in 8 hrs • Discharge required= 22.5 x 10 6 l/ hours • 8 • = 22.5 x 10 6 x 10 -3= 0.781 m3 /sec 8 x 3600
  • 223. Examples • The maximum velocity in the pipe is given as 2.0 m/sec • Therefore Cross sectional area of the pipe required • A= Q = 0.781 = 0.39 m 2 • v • If d is the dia of the pipe then • Π d 2 = 0.39 4 D= 0.704m = 0.75 m Total lift is given as 30 m
  • 224. Examples • Friction loss hf can be found by using Darcy Weisbash eq n • Hf= 4 f l v2 2 g d = 4 x 0.0075 x 1000x (2.0 ) 2 2 x 9.81 x 0.75 = 8.155 m
  • 225. Examples • Thus the total lift against which the pump has to work or lift water • = 30 + 1.155 • = 38.155m • BHP of the pump= ϒ Q H 75 Ƞ = 1000 x 0.781 x 38.155 75 x 0.75 = 526.75 = 530 HP 1 hp(I) = 745.699872W = 0.745699872 kW 1 W in ... ... is equal to ... 2 3 • 1 kg·m /s
  • 226. Example • From a clear water reservoir 3 m deep and maximum water level at RL 35 m water is to be pumped to an elevated reservoir at RL 80 m at the constant rate of 9 lakh litres per hour. The distance is 2000 m. Find the economic diameter of the rising main and the water horse power of the pump. Neglect minor losses and take f=0.01
  • 227. Example • The Discharge Q= 9 lakh per hour • = 9,00,000 = 0.25 m3 /sec 1000x 60 x 60 Economic diameter of rising main can be found by D= 1.22 √Q = 1.22 √0.25 = 0.61 m
  • 228. Example • Maximum Suction Head = 3 m ( depth of reservoir) • Maximum delivery head = (80- 35)= 45 m • (Difference between maximum water level and height of elevated reservoir) • Suction + Delivery= 3 + 45 = 48 m
  • 229. Example • Friction Head loss can be found by • Hf= 4 flv 2 2 g D V= Q = 0.25 = 0.855 m/ sec A Π (0.61) 2 4 Hf= 4 x 0.01 x 2000 x (0.855) 2 2 x 9.81 x 0.61 Hf= 4.886 m The total Head = 48 + 4.886 m H= 52.886 m
  • 230. Example • Water horse power of Pump= ϒ Q H 75 = 1000 x 0.25 x 52.866 75 = 176.22 HP
  • 231. References Water Supply Engineering : By Prof S.K. Garg Khanna Publishers Internet Websites