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Transcript of WS Chapter9 Print
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9.0 VALVES & FITTINGS 9.1 DIFFERENT TYPES OF VALVES
1. SLUICE VALVES
Gate valve or stop valves
Cheaper, offer less resistance to flow and less head lossthan other
Provide at every junction and at interval 3-5 Km
The entire distribution system is divided into blocks byproviding these valves at appropriate places
Consists of wedge shaped circular disc which is connected
to wheel above by means of thread spindle Flow is controlled by raising or lowering the handle or
wheel
When the valve is closed, it shuts off water in pipe line to
enable under repair in that particular block6/24/2013 Chapter-7/Water Supply Engineering 1
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SLUICE VALVES
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9.1 DIFFERENT TYPES OF VALVES2. REFLUX VALVE
Check valve or non return valve
Is an automatic device which allows water to flow inone direction only and prevent in reverse direction
Normally after pump component
Consists of a disc which is hinged about pivot and itis kept in open position due to presence of water indirection of flow
When water flow in reverse direction, the disc isautomatically fall down and due to back flowpressure it tightly closed.
Hence, it prevents passage of water in reverse
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9.1 DIFFERENT TYPES OF VALVES3. SAFETY VALVE
Pressure relief valve or automatic cutoff valve Release the high pressure in pipe and save the
pipe from bursting
Consists of disc controlled by a spring which canbe adjusted for any pressure
When pressure is exceeds than desired pressure,
the disc is forced off from seat and excessivepressure is release through cross pipe
After pressure release, the disc is automatically
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3. SAFETY VALVE
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9.1 DIFFERENT TYPES OF VALVES4. AIR VALVE
Sometimes, air is accumulated at summit of
pipelines and block the flow of water due to air lock Air removal is done automatically by means of air
relief valves
Consists of a chamber in which floats are placed
and are connected to pipe lines When there is flow under pressure in the pipe line,
water occupies the float chamber and makes floatto close the outlet
When there is accumulation of air in pipelines, airenters the chamber, makes the float to comedown,thus opening outlet
The accumulated air is released from outlet6/24/2013 Chapter-7/Water Supply Engineering 7
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4. AIR VALVE
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9.1 DIFFERENT TYPES OF VALVES5. DRAIN VALVE
Scour valves or blow off valves or wash outvalves
Manually operated valves placed at all dead
ends and depressions of pipelines to removesand wash out the accumulated silt and sands
After complete removal and washing, the valve
is closed
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5. DRAIN VALVE
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9.2 DIFFERENT TYPES OF PIPE FITTINGS
1. STOP COCK
It is a type of valve. Sometimes called stop taps oreven main plumbing valves.
It is fitted at the end of communication pipe and
it is under the control of water supply authority. The purpose of stop cock is to stop the supply of
water.
In the case of your home it is the main valve thatcontrols the flow of water from the external
water supply to your plumbing system within the
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STOP COCK
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9.2 DIFFERENT TYPES OF PIPE FITTINGS2. WATER TAPS
Generally provided inside the buildings and in
streets for taking water Street stand post should be provided with self
closing tap to prevent undue wastages of water
Water taps are attached at the end of water pipes,from which consumer obtained water
It should be water tight. The leaky water taps are thesource of waste of water.
the table gives the idea of water lost due to leakywater taps in continuous system of water supply.
Therefore it is advisable to repair or replace such
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S.N
.Leakage
Loss of water
in
Lt./ day
1
30 dropsper
minute8
2
60 drops
per
minute 17
3
120
drops
per
minute
36
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9.2 DIFFERENT TYPES OF PIPE FITTINGS
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9.3 PUBLIC STAND POST public stand post is the component of the public water supply system
and is the point from where people collect water at designed rate to
meet their demand for household purpose in rural area
It must be clean, properly designed and aesthetically pleasant
Surplus and washout water should be properly drain off
Location should be appropriate for the local people and non-disputable
One tap for 8-10 houses
Its distance should not greater than 200m horizontal and 50m vertical
from the houses
98% reliability, 80% efficiency and 10 lt./min (Guidelines For Human
Settlement Planning and Design)
one tap required per 25-50 dwellings, maximum number of peopleserved per water point: 300 and maximum number of people served per
tap: 150
All tap stands must constructed as per government agency guidelines
using local material
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PUBLIC STAND POST
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9.3 BREAK PRESSSURE TANK The pipe material must be selected to withstand the
highest possible pressure that can occur in the pipeline
Water reservoirs located in elevated areas ensure water issupplied to outlet points under the influence of gravity
In gravity system, the worst-case scenario is for pressure tobe at its maximum during shut-off conditions (shut-off at
downstream end) when the static pressure is too high. High pressures in transmission pipes occur as a result of
long distances or specific topography
To limit the maximum pressure, break pressure tanks or
chambers is installed along the main. function of such tank is to limit the static pressure by
providing open water surface at certain places along thepipeline and establish new static level
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BREAK PRESSSURE TANK
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9 3 BREAK PRESSSURE TANK
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9.3 BREAK PRESSSURE TANK It consists of a closed chamber with inlet, outlet, overflow
and float valve.
A float is connected inlet pipe to control valve andregulates the water level inside the pressure tank.
As demand decreases, the water level inside the tank rises,causing float to ascend and gradually forces the inlet valveto close.
A sudden demand for water causes the water level insidethe tank to drop and the descending float, which reopensthe control valve of the inlet pipe.
In general BPT are placed every 100-meters change inaltitude.
BPT act similar as pressure release valve.
Reservoir may also act as break pressure tank
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9 4 OPERATION & MAINTENANCE OF
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9.4 OPERATION & MAINTENANCE OF
WATER SUPPLY SYSTEM
Operation and maintenance (O&M): refers to all activitiesneeded to run a water supply entity, except for construction
of new facilities, with aim to improve the performance,efficiency and sustainability.
Operation: refers to the procedures and activities involved inthe actual delivery of services, e.g. abstraction, treatment,pumping, transmission and distribution of drinking water. It
includes the planning and control of the extraction/collection, treatment, conveyance, and delivery of water. Italso covers the management of client and public relations,legal, personnel, commercial and accounting functions.
Maintenance: refers to activities aimed at keeping existing
capital assets in serviceable condition, e.g. by repairing waterdistribution pipes, pumps and public taps. Maintenance dealswith activities that keep the system in proper workingconditions, including management, cost recovery, repairs andpreventive maintenance
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9.4 MAINTENANCE OF WATER SUPPLY SYSTEMObjectives of O&M
Service to the public
Operating efficiency
Service life
Life-cycle cost
maintenance is the repairing of the damage things andprotection is the proper use and supervision of things.
Proper protection reduces maintenances. Properprotection as well as timely maintenance of crack,corrode, clogging pipe and fittings and damagedcomponents which make water supply project sustainable
As per repair works, maintenance can be classified aspreventive, emergency and regular.
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MAINTENANCE OF WATER SUPPLY SYSTEM1. Preventive measures
In rainy season, accumulated sediments may damage
source, pipe may be exposed and broken. In such casesconstruction of protection wall, plantation, construction ofcatch drain is done for protection from further damage,which is called preventive damage
2. Emergency maintenance
During floods, landslide and natural disaster, the source,tank, pipes, valves, other components may get damaged. Insuch cases immediate maintenance is needed for re-supply,which is called emergency maintenance. It may be costlier
3. Regular maintenance
Pipe and valve leakage, clog, tap break, pipe exposure,infrastructure damage etc may occur during regular supplyof water which is called regular maintenance. If damage ismajor it may be costlier
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