design of internal & external water supply

7/30/2019 Design Of Internal & External Water Supply

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E2-E3/Civil Rev date: 01-04-11

BSNL India For Internal Circulation Only Page: 1

E2-E3: CIVIL

CHAPTER-5

DESIGN OF INTERNAL & EXTERNAL

WATER SUPPLY SYSTEM


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Design of Internal & external Water supply System

Quality Of Water

1.0 Absolute pure water is never found in nature. Water f ound in naturecontains a number of impurities in varying amount in the form of salts,

gases, bacteria algae etc.

1.10 Only potable water is to be suppli ed in a water supply scheme. A

potable water is one that is safe to drink, pleasant to the taste, and

usable for domestic purpose. Contaminated water is one that contains

micro-organisms, chemicals, industrial or other waters, or sewage so

that it is unfit for its intended use.

1.20 The following are the standards of water to be used for domesticpurposes.

Physical

Tempera tu re - 10 c to 15.6 c

Odour - 0 to 4 P0 value

Colour - 10 to 20 (platinum cobalt

scale)

Turbidity - 5 to 10 ppm (Silica scale)

Taste - no objectionable taste

Chemical

Total Solids - upto 500 p.p.m.

Hardness - 75 p.p.m. to 115 p.p.m.

(hardness expressed as

caco3 equivalent)

Chlorides - upto 250 p.p.m.

Iron and Manganese - upto 0.3 p.p.m.

PH Value - 6.5 to 8

Lead Arsenic - 0.1 p.p.m.

Sulphate - upto 250 p.p.m.

Carbonate Alkanity - upto 120 p.p.m.

Dissolved Oxygen - 5 to 6 p.p.m.

B.O.D. - Nil

Biological

B- coil - No B- coil in 100 ml.

Most Probable Number

(M.P.N)

- One Number in 100 ml.

Radiological

emitters - 1 c/l iter

emitters - 10 c/liter


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1.30 Regular periodical chemical, physical and bacteriological tests

of water samples shall be got it done through approved laboratory.

Remedial measures based on test results shall be taken.

2.0 Treatment ProcessThe treatment process depends on the impurities present in water. For

removing various types of impurities, the following treatment

processes are used.

-----------------------------------------------------------------------------------

Impurity Process used for removal

-----------------------------------------------------------------------------------

1. Floating matters as leaves, Screening

Dead animals etc.

2. Suspended impurities as silt clay, Plain Sedimentation

Sand etc.

3. Fine suspended matter Sedimentation with

coagulation

4. Micro-organism and Filtration

Colloidal matters

5. Dissolved gases, tastes Aeration and chemical

and odours treatment

6. Softening Permutit method

7. Pathogenic bacteria Disinfections

-----------------------------------------------------------------------------------

We in our department generally use either Municipal water or

ground water. Water received from above sources are usually

clear and may require only disinfection, chemical treatment

softening etc. Therefore discussion is only restricted to the

disinfection of water.

2.2 Methods of Disinfection

The disinfection of water can be done by the following common

methods.

a) By the boiling of water.

b) By ultra-viol et rays.

c) By the use of ozone.

d) By treatment with silver or electro- Katadyn process.

e) By the use of Iodine and Bromine.

f) By the use of excess lime.

g) By using potassium permanganate.

h) By the use of chlorine.


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Methods a.b.c.d. & e are effective but very costly. Therefore these

methods can be used at individual level and cannot be used in water

works.

2.2.1 Disinfection by ChlorineDisinfection by Chlorine is very useful to kill the various Micro-

Organisms present in the water. When Chlorine is dissolved in water, it

hydrolysis immediately as :

Cl2 + H2O HOCL + H+

+ Cl-

( Hypochlorous Acid)

After some time Hypochlorous Acid further ionizes as

HOCL H

+

+ OCL

-

( Hypochlorite Ions)

Two prevailing species HOCL (Hypochlorous Acid) and OCL-

(Hypochlorite Ion) are called Free Available Chlorine and are

responsible for the disinfection of water.

2.2.1.1 Forms of Chlorine

Chlorine is generally available in the following forms

a) In the forms of Liquid Chlorine.b) In the forms of gaseous Chlorine.c) In the form of Chlorine dioxide.d) In the form Chloramines.e) In the form of Bleaching Powder.

Form of Chlorine (a) to (d) require treatment plants and are used in big

water works. For small colonies we commonly use Bleaching Powder

as a source of Chlorine for disinfection.

When Bleaching Powder (Calcium Hypochlorite) is added to the water,

following chemical reaction takes place.

Ca (ocl)2 ----- Ca++

+ 2OCL-

(Calcium Hypochlorite) (Hypochlorite Ions)

Hypochlorite ions obtained further combine with Hydrogen ions

present in water and form hypochlorous Acid as follows

OCl-

+ H+

HOCL

(Hypochlorous Acid)

Hypochlorous Acid and Hypochlorite Ions so formed kill s the bacteria

present in the water.


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2.2.1.2 Dosage of Chlorine

In normal waters that are pre treated with settling and filtration, a

chlorine of about 0.2 to 1 ppm (Particle Per Million) may be

required to obtain the desired results. The commercial bleachingpowder normally contains low values of chlorine which vary 25-30%.

The value of chlorine content continuously decreases if the powder is

exposed to the atmosphere; therefore it should be stored in air tight

container.

The dose of Bleaching Powder should be calculated properly. If the

dose is less, it will not be effective to kill the Bacteria and if it is

more, odour and taste of water will be objectionable and will not be

potable.

3.0 Example

Given Data

Population of Colony = 1,000

Demand of water = 200 litre/Capit a/day

Availability of

Chlorine in Bleaching Powder = 30%

Required dosage of

Chlorine in water at

Water works. = 0.3 p.p.m.

Calculate the Quantity of Chlorine & Bleaching Powder required

Per day?

Solution

Water requirement of = 200 x 1,000

The colony

= 2 x 100000 litre

Chlorine dose required = 0.3 p.p.m.

For disinfection

= 0.3 mg/litr e

Quantity of Chlorine = 0.3 x 2 x 105

mg

Required

= 60 gm/day

Quantity of Bleaching = 60 x 100Powder 30


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= 200 gm.

Demand Requirement and General Principles

1.0 The demand load of water supply system in a building is not

exactly determinable. The number of sanitary fitting varies not only for

different classes of buildings but also in same class of buildings but

depending upon the habits of people. The minimum flow that will be

satisfactory for any part of premises will greatly depend upon

consumer, his standard of living, his professional needs, the size of

family and other ancillary requirements such as gardening air-

conditioning etc. The total daily requirement of the buildings is

calculated on the basis of the population to be served and per

capita rate of supply. Calculate the population on the basis of the five

members per family, and number of dwelling units in the building. The

per capita rate may be taken as 200 lit/head/day as residences are to be

provided with full flushing system. In case of non-residential buildings

the daily consumption per day in liters shall be given table B and the

population to be provided for, shall be as per actual requirements in the

building or as given in table A.

1.1 Requirement of water for Buildings

1. The total expected population of the building should first beworked out with reference to area of the building by using table

A. The total requirement of water per day of this population

should be calculated on the basis of table B. This would give

the figure for storage of general water supply.

1.2 Fire Fighting Requirements

For buildings not greater than 15 m in height, no separate

provision is to be made for firefi ghting purposes.

For buildings greater than 15m, demand of water should be

worked out as per Table E.

2.0 General Guide lines for Underground and Over Head Tank

Where underground tanks are used for the storage of water for

domestic purposes, the following requirements should be compiled

with.

1. The tank should project at least 30 cm above the highest floodlevel. Where this is not possible the manhole cover should be

raised 30 cm above the highest flood level of the locality or

ground level whichever is higher.

2. The design of the tank should be such that water should not beallowed to collect round the tank.


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3. The tank should be perfectly water tight.4. The inner surface of tank should be rendered smooth as for as

possible.

5. The top of tank should be so leveled to prevent water fromaccumulating on it.

6. The tank must be covered by R.C.C. slab leaving a manholeopening provided with iron cover fitted with leak proof cast iron

frame . Where tank is of l arge size,

Adequate number of manholes should be provided.

7. No gap should be allowed around the suction pipe.8. The overflow pipe or vent shafts if provided shall have a wire

gauge cover of 1.5 mm mesh properly screwed tightly to the

opening.

9. The tall building fittings should not be subjected to pressure

greater than 30 Mt. Head. This can be achieved by provision of

intermediate cisterns and pumps or by use of pressure release

values.

2.1 In case of an individual building like telephone exchange. Post

office, or administrative building, the overhead water storage should be

provided over the terrace of the building. For spread out complexes

like the residential colonies, training centers, workshop complexes ,

overhead tank and underground tanks should be located at a high

ground and at the center of the demand. The height of staging ofoverhead tank should be such that the residual water pressure at

consumers tap after allowing for all losses is not less than 3.5 m head

or 0.35 kg/cm2.

2.2 The underground and overhead tank with independent staging

should be designed and constructed for the ultimate requirements of the

building or complex to meet the needs of further expansion.

Whenever temporary overhead water storage tanks are located over the

terrace of a building with a provision for future vertical extension,

such tanks should be designed for 1/3rd daily requirement of existing

phase only. However the underground tank should be designed for

2/3rd of ultimate daily requirement of the building after further

expansion.

3.0 Supply to High Rise Buildings

3.1 General

In the case of high rise or multistoried buildings, the down take systemmay be one or a combination of the foll owing systems;


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i) Overhead storage system

ii) Break pressure tank system

i) The Overhead Storage SystemIn this system the tanks are provided on the terrace of the building. Amain fold down take pipe may be taken out from the storage tanks

which should be designed for peak load demand. A pressure reducing

value shall be provided in the down takes to limit the head to a

maximum of 25 m head in easily accessible places like ducts, cat

walks, etc.

i i) Break Pressure Tank SystemIn this system, the entire building is to be conveniently divided into

suitable zones of 5 to 8 stories each. For each such zone there shall be

a break pressure tank, the capacity of which should be such that it

holds 10 to 15 minutes supply of the floors it feeds below and shall be

not less than 2KL each for flushing and other domestic purposes

separately. The down take from the master- overhead tank feeds into

the pressure tank.

The capacity of the pump should be such as to cope up with the peak

demand. Normally 3 pumps called the lead pump; the supplementary

pump and the stand by pump respectively are provided. The last pumpis preferably diesel driven to serve where there is a power failure.

4.0 Principles and General Guidelines for Planning of External

Water Supply System.

4.1 Distribution

4.1.1 Pipe Work

a) There should be no inter- connection or cross connectionwhatsoever between pipe or fitting for conveying or containing whole

some water and a pipe or fitting for containing impure water, water

liable to contamination or uncertain quality or water which has been

used for any purpose.

b) The design of the pipe work should be such that there is no

possibility of back siphonage or otherwise. Valves cannot be relied on

to prevent such back flow.


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c) All pipe work should be so designed, laid or fixed and

maintained as to be and to remain completely water tight, there by

avoiding waste of water, damage to property and the risk of

contamination of the water conveyed.

d) No piping should be laid in or through any sewer or drain or any

manhole or chamber connected herewith, nor in ground contaminated

by sewage farm yards, stable yards and proximity of cesspools should

be avoided. In designing and planning the layout of the pipe work, due

attention should be given to maximum rate or discharge required ,

economy in labour & material, accessibility, protection against

damage, corrosion and avoidance of airlocks noise in transmission and

unsightly arrangement.

e) To reduce frictional losses, the piping should be as smooth as

possible internally. Methods of jointing should be such as to avoid

internal roughness and projections at joints whether of the jointing

materials or otherwise.

f) Change in diameter and direction should preferably be gradual rather

than abrupt to avoid undue loss of head.

g) Underground piping should be laid at such a depth that is unli kely to

be damaged by traffic loads, or frost and vibrations. Where piping has

to be laid in any ground liable to subsidence then special consideration

should be given to the type of joint to be adopted in order to minimize

risk of damage due to settlement. Where the piping has to be laid

across recently disturbed ground, continuous longitudinal support

should be provided and not merely supporting piers at intervals.

4.1.2 Water Supply Mains

a. Mains should be divided into sections by provisions of sluicevalves (or stop valves if the main i s of 50mm bore or less).

b. Air valves should be provided at summits and washouts at lowpoints between on summits unless adequate provision is made

for the discharge of air and water by pressure of service

connection and fire hydrants.

c. Washouts should not be discharged into drain or sewer or into amain hall or chamber connected there to. Where a washout

discharges into a natural water, the discharge should at all

times be well above the highest possible water level in the

water course.


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d. Mains need not be laid at unvarying gradients but may followthe general contour of the ground. They should however as for

as possible, fall continuously towards the washouts and rise

continuously towards the air valves. They should not rise above

the hydraulic gradient that is to say there should always bepositive presser greater than atmospheric, at every point under

working condition.

e. Provisions should be made at every bend, branch and dead endin a main to resist the hydraulic thrust.

f. Mains should be designed for a rate of flow sufficient tocertified the combined the maximum demand of all the services

to be supplied. All maximum demand of the separate service

may not occur simultaneously and the actual combined

maximum demand may be proportion sum of the separate

maximum demands, which will be determined by the number

and character of services.

4.1.3 General Principles for Arrangements of External Water

Supply Pipe

The distribution pipes consist of supply mains, branches and laterals.

They are normally laid sloping from high level to low level areas to

secure maximum advantage of head available due to gravity. Sluice

valves are placed at intervals on straight runs, at junctions and at

branching of points to control the flow of water in different sections.Drain valves are placed at low spots in the system to drain off the

pipes for carry out any repairs.

5.0 Layout of Distribution System

5.1 Dead End System

Since the distribution pipes are to be laid under the roads in towns,

their layout gets guided by the layout of the roads. Where the roads are

not properly planned, the water supply mains have to follow main roadsand branches are taken off from these at different junction which

usually terminate at a number of dead ends. Each system has also to be

followed in the ribbon development whi ch usually takes place along the

main roads to longer towns, and cities. This system requires less

number of valves to control the flow in the system and also shorter

pipe lengths so that it is cheap and simple but since water can be

reached to any place by only one route, any damage and subsequent

repair to the pipe line result in shutting downs the supply of a large

area ahead. Further the dead ends in the system cause the water in pipe

to remain stagnant which results in the degradation of its quality.


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5.2 Grid Iron System

Where the roads arranged in grid iron pattern the pipe lines are laidsimilarly in the form of net work with number of interconnections.

Water reaches different places through more than one route. Hence the

amounts to be carried frictional losses, and the sizes of the pipe get

reduced. However the system requires more length of pipes and number

of sluice valves to control it. It is also difficult to design and costlier

to construct. But it eliminates all dead ends and because of its different

interconnections the water remains in constant circulation. If repairs

are to be carried out to any pipe, only a small portion in the vicinity

gets affected, since wat er can be supplied ahead by some other route.

5.3 The Ring Main System The capacity of grid iron can be enhanced and the pressure can be

improved by running a looped feeder around the high demand section

and arranging grid over it.


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Table - AThe assessment of the population in occupancies based on plinth area

(clause 6.2.1. part IX Plumbing services section I. Water supply and

clause 7,5 or part IV fire protection as given in * National Building

code of India 1970 *)

S

No.

Type of Building Population

i) Staff Quarters & residence Assume a family of 5

person per quarter or

an area of

12.5m2/person

whichever is more.

ii) Technical buildings such as

Telephone Exchange Buildings,

Telecom Buildings, Factories andworkshop.

10.00m /person

iii) Post offices and Administrative

Buildings

10.00m /person

iv) Dormitories 7 .50m /pe rson

v) Assembly without seating facilities

including Tiffin rooms,dining rooms

canteen etc.

1 .5m /person (*)

vi) Day Schools, Boarding schools and

Hostels

4 .00m /pe rson

vii) Community halls 1 .5 m /person (*)

viii) Institutional 15.00m /person (**)

ix) Stores 30.00m /person

Notes :

*The plinth area shall include, in addition to the main assembly room

or space, any occupied connecting room or space in the same story or

in the storey above or below, where entrance is common to such rooms

and spaces and they are available for use by the occupants of the

assembly place. No deductions shall be made is the plinth area forcorridors, closets or other sub divisions; the area shall include all

space serving the particular assembl y occupancy.

**Occupant load in dormitory portions where sleeping accommodation

is provided, shall be calculated at not less than 7.5m2 plinth area per

person.


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Table B

S.

No.

Building Demand of Water

i) Staff Quarters &residence

200 Liters/ head/ day(Para 5.1.N.B.C. 1983)

ii) Technical buildings such

as Telephone Exchange

Buildings, Telecom,

Buildings, factories

And workshops.

45 liters/ head/ day

(Para 3.2 IS-1172-1971)

iii) Post offices and

Administrative Buildings


(Para 3.2 IS-1172/ 1971)

iv ) Dormitories 135 liters/ head/ day

(para 3.2 IS-1172-1971)

v) Assembly without seating

facilities including Tiffin

rooms, dining rooms

canteen etc.

70 liters/ seat/ day

(Para 3.2 Is. 1172 1971)

vi) School

a) Day Schools,b) Boarding Schools

and Hostels.


135 liters/head/day

vii) Institutions 45 liters/ head/ day

viii) Community halls 15 liter/seat/day

ix) Stores 45 liters/ head/ day

.


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Design of Water Distribution System

1.0Till date no direct methods are available for design of distribution

pipes. While doing the design, diameter of pipes are assumed.

Terminal pressure is calculated, after allowing the losses of head,

when full peak flow discharge is flowing.

The Hazens williams formula is widely used for determining the

velocity through pipes.

V = 0.85 CH.R0 .63

. S0 .54

V = Velocity m/Sec.

S = Slope of the Energy Line.

R = Hydraulic Mean Depth

R = A/P = (Cross section Area/ Perimeter)

CH = Coefficient of Hydraulic Capacity.

For circular conduits, expression becomes

V = 4.567 X 10-3

.CH.d0 .63

.S0 .54

Discharge

Q = 3.1 X 10-4

X CH. d2 .63

. S0 .54

In the above said expression

Q = Discharge in K.L Per day

d = Dia of pipe in mm

S = Slope of Hydraulic Gradient

CH = Coefficient of Hydraulic Capacity.


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1.1 Value of CH for Different Pipes

(Hazens Williams Coefficient)

The value of CH for new conduit materials are as follows:

-----------------------------------------------------------------------------------

Sl. Conduit Value CH for Recommended

Value of CH No. Material New Material for

design purpose

-----------------------------------------------------------------------------------

1. Cast Iron 130 100

2. G.I. for more than

50mm dia 120 100

3. G.I. for less than 50mm 120 55

4. Steel rivetted joints 110 95

5. Steel, welded joints with

cement or bitumen enamel 140 110

6. Steel, welded joints 140 100

7. Concrete 140 110

8. A.C. 150 120

9. P.V.C. 150 120

-----------------------------------------------------------------------------------

1.2 Head Losses due to FrictionHead loss due friction can be determined by the formula

HL = --------------- ---------- X ---------------

HL = Head loss due to friction in M

L = Length of pipe in M.

Head loss in assumed pipe diameter is determined by above

formula. After deduction head loss, the terminal pressure is

determined.

1

0.094

X

Q

CH

1.85 L

D.


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2.0 General Design Guide Lines

2.1 Design PeriodIt is generally taken 30 years for new distribution system.

2.2 Peak FactorCapacity of distribution system should be sufficient to meet the

maximum hourly flow which can be computed by multiplying the

average hourly flow the following peak factors.

For Towns having Population

i) Up to 50,00 = 3.0ii) From 50,000 to 2 lac = 2.5iii) Above 2 lac = 2.0iv)

For Industrial demand = 1.0

2.3 Rate of Water SupplyAs discussed earlier, generally we may assume 200 lit/capita/day

for staff quarters.

2.4 Terminal PressureDistribution system should be designed for following minimum

terminal pressure

i)

Single Stroyed Building = 7.0mii) Double Stroyed Building = 12.0miii) Three Stroyed Building = 17.0m

2.5 Permissible VelocityThe permissible velocity is kept as per follows

---------------------------------------------------------------------------

Diameter of pipe approximate value of the

velocity

(Internal in cm) meter/second

---------------------------------------------------------------------------

10 0.915 1.225 1.5

40 1.8

---------------------------------------------------------------------------

2.0 Design of pipe Network

Since the design of network involves the method of trial and

error by assuming various diameters of the pipes, it is very

tedious and cumbersome job.


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To reduce the tedious calculations, the Hazens Williams

Nomogram is used Hazen s Williams chart for various

materials of pipe are available in Public Health Engineering

departments of the state Govt.

For using the Nomogram, a straight edge is placed on any two

known values, such as discharge and velocity, and the value of

the two other unknowns such l oss of head per thousand meter and

the diameter of pipe can be directly read out.

If the terminal pressure in any particular zone is found to be

more or less than the minimum permissible, than size of pipe can

be suitably decreased or increased. The process is continued on

trial till the terminal pressures are obtained.

4.0 Example

Design a water supply scheme. Various zone and population

shown in plan as Annexure A.

Average requirement of water = 200lit/ capita/ day

Reduced Level of O.H.T. = 120 m

R.L. of Point A = 100m

------do-------- B = 98m

------do-------- C = 96m

------do-------- D = 93m

Length of pipe AB = 700m

------do-------- BC = 500m

------do-------- CD = 600m

Peak Factor = 3

Minimum terminal pressure = 17.00m

________________________


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Annexure A

200 200 500 200 500

O.H.

500

20 0

40 0

30 0

300 300

200

400

A B C D


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O.H.

T.

400

600 300 300 900

50 0

70 0500

A B C D


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S.

N

Li n

e

Population Served Maximum

Demand

3x200xP

24x60x60

Lit./second

Proposed

di a

meter of

pipe in

mm

Loss of head Hydra

ulic

level

in M

Groun

d

level

in M

Termi

na l

Head

in M

Previou

s

Local Total Rate

pe r

1000

M

Lengt

h of

pipe

in M

Loss

in

pipe

in M

1 2 3 4 5 6 7 8 9 10 11 12 13

1. CD ----- 2100 2100 14.58 150 8.0 600 4.8 D =

111.1

D = 93 18.1

O.K

2. BC 2100 800 2900 20.14 200 4.0 500 2.0 C =

115.9

C = 96 19.0

O.K

3. AB 2900 1300 4200 29.17 250 3.0 700 2.1 B =

117.9

B = 98 19.9

O.K

A =

12 0

A =

10 0

20


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Internal Water Supply

1.0 Principle and General Guide for Planning of Internal Water

Supply System

1.1 The maximum rate of demand for water in premises should be

estimated based on number, nature and use of the fittings

provided. If no storage or only small storage for water is

provided in the premises, the service pipe should be capable of

discharging at the rate of maximum demand. Service pipes larger

than necessary to furnish the required supply should not be

installed, except where it is desirable to make provision for

future expansion.

1.2 The pressure of the water in service pipe will depend upon thehead of water in main, or upon the elevation of the over head

tank or upon pumping plant if any, and the appropriate class or

grade of piping of suitable strength should be chosen in

accordance therewith.

1.3 As far as practicable, the underground service pipe should belaid at right angles to the main and in approximately strength

lines to facilities location for repairs.

1.4 A stop valve should be provided in the service pipe in anaccessible position inside the building, as near as practicable to

the point of entry of pipe, so that the supply may be readily shut

off in case of trouble and for repairs. a draining tap should be

provided just above the stop valve to enable the service piping in

the building to be emptied of water when the stop valve is shut.

Where building is divided into flats or other separately occupied

parts which are supplied from common service pipe, there should

be a stop valve to control the supply of each part, fixed inside so

as to be under the sole control of the occupiers. The service pipeshould be so arranged that if does not pass through any such part

of the building on its way to a supply elsewhere, but if it does so

pass through, then instead of stop valve on the service pipe

where it enters there should be stop valve on every branch pipe

of the service pipe in the said part and in addition there should

the building, in a place accessible to all occupies of the building.

Where water is supplied to flats or other separately occupied

parts of a building through a common distributing pipe from


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storage cistern, distributing pipe should be arranged and stop

valves fixed as described above for a common service pipe.

1.5 Where practicable, water for drinking should not pass throughcistern, and there, taps supplying water for these purposes should

be supplied directly from service pipe.

1.6 A service pipe should not be connected (into any distributingpipe. Such connections might permit the backflow in certain

circumstances of water from a cistern into service pipe with

consequent danger of contamination. It might also result in pipes

and fitting being subjected to a pressure higher than that for

which they were designed and in flooding from overflowing

system.

1.7 The services should be designed and installed so as to avoidairlocks and so that piping and fittings can be drained off water

for prevention of damages by frost and to facilitate repairs.

There should be draining taps or dr aw off taps at low points fr om

which the piping should rise continuously to draw off taps, ball

valves cisterns or vents at high points. In a building which is

divided into flats or other separately occupied parts, it should be

possible to drain off the water in any such without interfering

with supply to any other part.

1.8 Service should be designed and installed so as to reduce theproduction and transmission of noise as much as, possible. High

velocity of water in piping and fittings should be avoided. Piping

should be confined as far as possible to rooms where appliances

are fixed. Noise may be reduced by the use of thick walled

piping and choice of pipe material.

1.9 Piping should be so located that it is not unduly exposed toaccidental damage, and fixed so as to avoid accumulations of dirt

and facilitate cleaning.

All pipe work should be planned so that the piping is accessible for

inspection, replacement and repair. To avoid its being unsightly, it is

usually possible to arrange it in or adjacent to cupboards, recesses etc.

provided that there is a sufficient space to work on the piping with

usual tools. Piping should not be buried in walls solid floors. In

suitable cases, piping may be buried for short distances provided that

adequate protection is given against damage by frost, corrosion onexpansion and that no joints are buried. If the piping is laid in ducts or


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chases these should be roomy enough to facilitate repairs. Covers to

ducts and chases or floors boards covering piping should be so fixed as

to be readily removable.


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1.10 Number of Connections Fed from a MainDIA OF

DELIVERY PIPE

DIAMETER OF BRANCH PIPE (MM)

100 90 80 65 50 40 32 25 20 15

100mm 1 1 2 3 6 10 17 32 53 113

90mm - 1 1 2 4 8 13 25 43 88

80mm - - 1 2 6 6 10 18 32 66

65mm - - - 1 2 3 6 11 19 39

50mm - - - - 1 2 3 6 10 20

40mm - - - - - 1 2 3 6 12

32mm - - - - - - 1 2 3 7

25mm - - - - - - - 1 2 4

20mm - - - - - - - - 1 2


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Questions:-

1. What are the different standards of Potable Water?2.

What are the different processes for removal of various impurities inwater?

3. What are the various methods of disinfection of water?4. What is Free Available Chlorine and which compound is responsible

for killing the bacteria of water in Chlorination?

5. What are the various forms of Chlorine?6. Which is the cheap and best source of Chlorine?7. What is the range of dosage of Chlorine for disinfection of water?8. What are the parameters for assessment of population in occupancies

based on plinth area in case of Staff Quarters and Telephone

Exchange Buildings?

9. What is the daily requirement of water for designing water supplysystem in case of Staff Quarters and Telephone Exchange Buildings?

10.What are the merits and demerits of Dead End System, Grid IronSystem and Ring Main System?

11.Which empirical formula is used for calculating the head losses inthe pipe network?

design of internal & external water supply

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