WS Chapter9 Print

8/13/2019 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

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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


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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WS Chapter9 Print