Mechanical and Electrical presentation report

           CONTENTS

INTRODUCTION  ..................................................................................................................  2  

WATER  QUANTITY  ............................................................................................................  2  

1.  QUANTITY  FOR  DOMESTIC  USE  ...................................................................................................  2  2.  QUANTITY  FOR  LIVESTOCK  ..........................................................................................................  3  

WATER  QUALITY  ...............................................................................................................  4  

WATER  SOURCES  ...............................................................................................................  4  

WATER  STORAGE  SYSTEM  .............................................................................................  5  

1. CONCRETE-­‐LINED  EARTHEN  RESERVOIR  ................................................................................  5  2.  REINFORCED  CONCRETE  RESERVOIR  ........................................................................................  6  3.  ELEVATED  STEEL  RESERVOIR  .....................................................................................................  6  4.  FERROCEMENT  TANK  ...................................................................................................................  7  

WATER  SUPPLY  DISTRIBUTION  SYSTEM  ..................................................................  8  

1.  PUMPING  SYSTEM  .........................................................................................................................  9  2.  GRAVITY  SYSTEM  ........................................................................................................................  10  3.  DUAL  SYSTEM  ..............................................................................................................................  10  

LAYOUT  OF  DISTRIBUTION  NETWORK  ...................................................................  11  

1.  DEAD  END  SYSTEM  .....................................................................................................................  11  2.  REDIAL  SYSTEM  ..........................................................................................................................  11  3.  GRID  IRON  SYSTEM  .....................................................................................................................  12  4.  RING  SYSTEM  ...............................................................................................................................  13  

WATER  SUPPLY  SYSTEM  OF  A  BUILDING  ...............................................................  13  

1.  COLD  WATER  OR  CLEAN  WATER  PIPE  SYSTEM  ...................................................................  14  a.  Up-­‐Flow  /  Direct  Water  Supplying  System  ................................................................  14  b.  Down  Flow  /  Indirect  Water  Supplying  System;  .....................................................  15  Operation  and  Maintenance  .................................................................................................  16  

2.  HOT  WATER  DISTRIBUTION  SYSTEM  .....................................................................................  17  a.  Gravity  System  .......................................................................................................................  17  b.  Forced  Circulation  System  ................................................................................................  20  Operation  and  maintenance  .................................................................................................  21  

CONCLUSION  ....................................................................................................................  22  

Introduction

Water, a substance essential to human life, has always been used for many

different purposes. The constant demand forced men to create conditions so that it

would be possible to transport it to the necessary locations, thereby creating water

supply systems. Throughout the centuries of existence of the human race, there has

been a constant evolution of these systems, which has allowed current constructions

to include a wide choice of options. This increase of solutions is linked with the

concepts of quality and security which, other than having propelled the plumbing

industry, in pursuit of the raw material which provided the best quality conditions,

economy, safety or concern with the main environment, has also allowed the creation

of regulations, which are nowadays essential in building an effective system.

Water, along with food, is one of the essentials of life. Perhaps because of its

importance and scarcity in many locations, in most societies the use of water is

encompassed by very strong cultural/social precepts. The success of projects aiming

to improve water supply and water quality therefore depends on the full participation

of the village population, in particular the women, as they are the main users of water.

While relatively small quantities will sustain human life, much more is needed

for cooking, personal hygiene, laundry and cleaning. Water for a sanitary system is

desirable, although not essential if it is scarce. Water is also required for livestock and

perhaps for irrigating crops. Types of water required for the farmstead include: (a)

clean water for use in the home; (b) reasonably clean water for livestock; and (c)

water for irrigation.

Water Quantity

1. Quantity for domestic use

Location and convenience are significant factors in determining the

volume of clean water for domestic use, as Table 1 below shows.

The range of consumption given in Table 1 varies by a factor of over 100. It

seems obvious that people adapt their needs to the supply. At the low extreme, the

bare minimum is used for cooking and drinking, while at the upper extreme water is

used with abandon. When there is a shortage, much lower quality water may be used

for personal hygiene and for washing clothes. The suggestions that follow are

intended to improve both the supply and the quality of water.

2. Quantity for livestock

Table 2 gives the estimated water requirements for various classes of

livestock. This can be used to determine the total requirements.

Table 2: Water requirement for life stock.

Table 1: Domestic water consumption

If water for dipping livestock is to be drawn from the same source, 3 litres per

head of livestock per week must be added to the estimated amount needed.

Fish can be raised in a reservoir without any additional volume of water.

Although chickens, pigeons and turkeys can live on used water from the house, ducks

and geese need approximately 1 litre of fresh water a day per bird.

For the production of biogas, a weekly consumption of around 100 litres must

be included in the total requirement of water for livestock.

Water Quality

Water from a protected well is nearly free from harmful bacteria although it

may contain dissolved salts that make it less than desirable for drinking. A protected

well is located upgrade from sources of pollution such as animal yards and privies.

Twenty metres is an adequate distance in areas with fairly heavy type soils, while

double that distance is necessary for light soils and even more in areas with limestone

formations. “Protected” also implies a well head that extends high enough above the

ground level to prevent anything from washing or blowing into the well mouth and

narrow enough to discourage the users from standing on it. The other essential feature

is a concrete apron sloping away from the well on all sides. A sanitary means of

lifting the water is also necessary.

Streams and ponds, whether artificial or natural, are very likely to be

contaminated and should be used for domestic purposes only as a last resort.

When the only water available is turbid (cloudy) and suspected of being

polluted, it should be filtered through a well-designed sand filter. Even then, the

safety of the water for drinking is questionable and boiling or other purification is

recommended for complete safety.

Water Sources

When planning a water supply scheme for an area, the potential sources of

water should first be assessed. Consideration should be given to the quantity of water

available to meet present and future needs in the supply area, as well as to the quality

of the water. Water that is unfit for human consumption will need to be treated before

being distributed.

Water for human settlements can be obtained from one or more of the

following sources:

•Springs;

•Wells and boreholes;

• Rainwater;

• Surface water – rivers and dams; • bulk-supply pipelines; and

• A combination of the above.

Water Storage System

The water storage system can be classified as follow:

— Concrete-lined earthen reservoir; — Reinforced concrete reservoir; — Elevated steel reservoir; — Ferrocement tank.

1. Concrete-lined earthen reservoir

Lined earthen reservoirs can be built in natural depressions, or constructed by

excavating and building a dam around the reservoir. If possible, the quantities of

excavation and refill are kept nearly identical, to minimize the amount of work. The

inner and outer walls of such a reservoir are always sloped, and inlets and outlets are

installed during the earthwork. The

walls and bottom of the reservoir

must be compacted, especially the

parts made by refilling. The inside of

the reservoir is waterproofed by a

lining of concrete, which is usually

poured on-site in large slabs. The

slab size is limited by the ability of

the concrete slab to support its own Figure 1: Concrete-Lined Earthen Reservoir

weight when it is moved into place during const ruction of the reservoir. Once in

place, the slabs are connected by a sealing of waterproof material. More recently,

reservoirs have been constructed using a single slab of concrete, using ferrocement

technology. Linings can also be made of clay, loam or plastic. It is used to store from

a few cubic meters to thousands.

2. Reinforced Concrete Reservoir

Reinforced concrete reservoirs are used to store clean water for release on de-

mand. They are usually made of concrete reinforced with steel bars or steel mesh,

although some low-cost construction techniques use bamboo or other materials to

reinforce the concrete. Reservoirs may also be made of masonry, or ferrocement.

Chemical additives are of- ten mixed with the concrete to make it more impermeable

to water. Reinforced concrete reservoirs are built at the site on a solid foundation. If

the base is not solid enough, another site should be chosen, or arrangements made to

stabilize the construction.

To protect the water from contamination, the reservoir is covered with a roof,

usually made of reinforced concrete, but other materials can be used. In the top of the

tank an aeration pipe with a screen allows fresh air to circulate in the tank, but keeps

rodents and insects out. A manhole in the roof allows access to the tank for cleaning

and repairs. Water flows into the

reservoir through an inlet pipe above the

water level in the reservoir. This prevents

back-flow and allows the water to be

heard entering the tank. At this point, a

chlorine solution is often added for

disinfection. Outlets are built a little

above the floor of the reservoir, which

has a slope pitched down towards one

point with a washout pipe for flushing.

3. Elevated steel reservoir

Elevated steel reservoir stores clean water in a steel tank on a raised stand or

tower. The elevation of the tank provides the water pressure to all points in the

Figure 2: Reinforced Concrete Reservoir

pressure zone of the distribution system. Tanks may be cylindrical, rectangular or any

other convenient shape. For family use, the tank can be made of an old oil drum (duly

coated), and the tower of bamboo. For communal needs, elevated steel tanks are often

constructed from factory-made galvanized steel elements bolted or welded together.

However, even with galvanization, steel tanks are generally more sensitive to

corrosion than concrete reservoirs. On the other hand, steel tanks can be built faster

and the cost of transport- ing the material is generally lower, especially when concrete

aggregates are not locally produced. Several pipes are connected to the tank,

including ones for inlet, outlet, overflow and washout, and a screened vent hole or

pipe maintains atmospheric pressure in the tank. There is also an entryway in the

cover of the reservoir to allow the reservoir to be inspected. The entryway is normally

kept closed with a lid. If an electric

pump is used to pump water into the

reservoir, sensor electrodes in the tank

can regulate the water level in the

reservoir. Alternatively, a float valve

may be used to cut off the inflow when

the maxi- mum level has been reached.

The tanks may be placed on

steel, wooden or reinforced-concrete

towers, and special attention must be

given to the foundation structure. Major

water users, such as agricultural

enterprises and communities, typically

use big elevated steel tanks.

4. Ferrocement tank

Ferrocement water tanks are made of steel mesh and wire, covered on the in-

side and outside with a thin layer of cement-and-sand mortar. The walls may be as

thin as 2.5 cm. The tanks can be used for individual households or for whole

communities, and they provide a relatively inexpensive and easy-to-maintain

Figure 3: Elevated Steel Reservior

storage method. To avoid bending forces in the material, most ferrocement tanks

have curved walls, in the form of a cylinder, a globe or an egg. Compared to concrete

reservoirs, ferrocement tanks are relatively light and flexible. To protect

the water from contamination, the tank is covered with a lid or a roof that can be

made of various materials, but is usually ferrocement. Figure 4.

In this case, an aeration pipe with a screen is needed to allow fresh air to

circulate in the tank, while keeping out rodents and insects. A manhole in the roof

gives access to the tank for

cleaning and repairs. Water

flows into the reservoir through

an inlet pipe, which is normally

above the water level.

Often, a chlorine

solution is adde d to the stored

water for disinfection. Outlets

are built a little above the floor

of the reservoir, which slopes

down towards a washout pipe

for flushing into a drain. The

site is fenced, to keep out cattle

that can damage the thin walls

of the reservoir.

Water Supply Distribution System

Infrastructures for the collection, transmission, treatment, storage, and

distribution of water for homes, commercial establishments, industry and irrigation, as

well as for such public needs as firefighting and street flushing. Of all municipal

services, provision of potable water is perhaps the most vital. People depend on water

for drinking, cooking, washing, carrying away wastes, and other domestic needs.

Figure 4: Ferocement Tank

Water supply systems must also meet requirements for public, commercial, and

industrial activities. In all cases, the water must fulfill both quality and quantity

requirements.

For efficient distribution it is required that water should reach to every

consumers with required rate of flow, quality and pressure. Pressure in pipe is

important and necessary, which should force the water to reach at all the places.

Water Supplying System are classified as:

• Pumping system

• Gravity system

• Dual system

1. Pumping System

o Water is directly pumped in the mains

o Number of pumps are required to work at different time & pressure

rate in a day.

o If the power fails the whole supply will freeze.

o The pressure in pipe is controlling by water pump.

o We use this method when the storage is almost the same level or lower

than supplying area. Figure 5.

Figure 5: Pumping System

2. Gravity System

o When the reservoir and/or storage are sufficiently higher than the

supplied area.

o Water will flow in mains using gravity which pumping system will not

be required. Figure 6.

3. Dual System

o Is also known as combined gravity and pumping system.

o Pump is connected to the mains as well as to the elevated reservoir

o When there is less water demand, water is stored in elevated reservoir.

o With increase in water demand, water will come from both pumping

station as well as reservoir.

o During power failure and fire fighting water stored in the reservoir can

be used. Figure 7.

Figure 6: Gravity System

Figure 7: Dual System

Layout of Distribution Network

The distribution pipes are generally laid below the road pavements, and as

such their layouts generally follow the layouts of the roads. In general there are four

types of pipe networks, and the are as follows:

• Dead end system

• Radial System

• Grid Iron System

• Ring System

1. Dead End System

It is suitable for old towns and cities having no definite pattern of roads.

Figure 8.

Advantages:

• Relatively Cheap

• Determination of discharge and pressure easier due to less number of valves.

Disadvantages

• Due to many dead ends, stagnation of water occurs in pipes.

2. Redial System

The area is divided into different zones and water is puped into the distribution

reservoir kept in the middle of the each zone and the supply pipes are laid radially

ending towards the periphery. Figure 9.

Figure 8: Dead End System

Advantages

• It gives quick service

• Calculation of pipe size is easy.

3. Grid Iron System

It is suitable for cities with rectangular layout, where the water mains and

branches are laid in rectangles. Figure 10.

Advantages

• Water is kept in good circulation due to the absence of dead ends.

• In the cases of breakdown in some sections, water is available from other

directions.

Disadvantages

• Exact calculation of pipe sizes are not possible due to provision of valves on

all branches

Figure 9: Radial System

Figure 10: Grid Iron System

4. Ring System

The supply main is laid all along the peripheral roads and sub mains branch

out from the mains. This system also followed the grid iron system with the flow

pattern similar in character to that of dead end system, so determination of pipe size is

easy. Figure 11.

Advantages

• Water can be supplied to any point from at least two directions

Water Supply System of a Building

Carries water from the water source, street main or a pump to the building and

to the various points of the building were water need to be used.

All water supply systems use a combination of pipes (of different dimensions

and materials), valves and outlets to deliver water to building users. Some water

supply systems also use storage tanks and pumps. Designing a water supply system

involves getting all of these elements right so that clean water is delivered to the user

at the appropriate rate and temperature

Water piping system in a building can be classified as follows:

– Cold water or clean water pipe system for daily use.

– Hot water piping system.

Figure 11: Ring System

– Fire Hydrant piping system.

1. Cold Water or Clean Water Pipe System

In a building this system is classified in to two main parts as:

a. Up-Flow / Direct Water Supplying System

In this system the water comes into the water system tank and flows through

an upper basket and then down a riser tube in the middle of the tank. Once the water

reaches the bottom of the riser tube it is then distributed through a lower basket

attached to the riser tube. The water then flows from the bottom of the tank through

the filter media in a swirling motion. The swirling motion is created by the reaction of

the water coming out of the lower basket coming in contact with the bottom of the

filter tank, which is rounded or curved. An up-flow design eliminates the need for

backwashing on most filters because the filter media is continuously being fluffed

each time the water flows through the tank. Another advantage to an up-flow design is

the amount of contact time the untreated water has with the filter media. An up-flow

design also forces the filter media to swirl which in turn allows the media to have

longer contact time with the water yielding better results.

In the low buildings, cold water can be distributed by the up-flow method in

which at each story plumbing fixtures are served by branch pipes connected to risers

that carry water upward under pressure from the water source.

If the water source pressure is not sufficient to provide adequate water

pressure a pump up-flow distribution system is used. Figure 12.

Figure 12: Direct Water Supply System.

Advantages:

– Saving in pipe works especially in multistory buildings. (This is due to

cold water distribution pipe from the cistern being omitted)

– Cheaper as the storage tank is no need.

– No chance of water growing harmful bacteria.

– Can deal with large demand more easily.

Disadvantages:

– If cold mains fail there wont be any emergency backup supply.

– Cannot always supply cold water as the mains water pressure is low (in

peak hour).

– More system noise as water is under high pressure.

b. Down Flow / Indirect Water Supplying System;

Down-flow systems direct the water in a down-flow direction. The water

comes into the tank through an upper

basket and flows down the tank

around the outside of the distributor

tube through the filter media. The

water then flows through the filter

media and into the lower basket at the

bottom of the riser tube. The water

then flows up the riser tube and out of

the tank. Down flow water systems

require back washing to raise or fluff

the filter media because the direction

of the incoming water presses down

on the filter media compacting it.

Down flow systems can sometimes

have issues with channeling caused Figure 13: Indirect Water Supplying System

when the water makes channels or tunnels in the compacted filter media. When the

water does not reach the other filter media, the effectiveness of the filter can be

weakened. If you are looking to purchase a down-flow water system be sure that it

back washes to avoid channeling. This is not an issue in up-flow designed water

systems. Another benefit to up-flow filters is that most do not require back washing,

drain lines or electricity. Even though most water systems may look the same, it is

always a good idea to understand how the different systems work. In cases like iron

removal using oxidation media like greensand plus or salt system regeneration, down

flow systems may be required to flush out oxidized iron or water hardness. Figure 13.

In buildings that cannot be adequately serviced by an up-feed system, water is

pumped to elevated storage tanks and the water is fed down into the building by

gravity. This gravity system, fed from the upper stories to the lower is called a down-

feed distribution system

Advantages:

– There is no risk of back siphon age.

– There is no tendency of pipe bursting due to the low pressure in pipe

work.

– Adequate store in case of an interruption in the mains supply.

Disadvantages:

– Longer Pipe runs are required

– A larger storage cistern is necessary

– Fresh drinking water is only available at the kitchen sink (or single

point)

Operation and Maintenance

• Collecting bacteriological samples

• Testing the chlorine residuals

• Finding and repairing leaks

• Testing system pressure at various locations on a systematic basis

• Flushing the main lines at least once a year

• Inspecting fire hydrants twice a year

• Locating and exercising in-line valves at least once a year

• Cleaning the storage reservoir once a year

• Inspecting the storage reservoir,, valves, once a year

• Replacing pilot valves and altitude valves once a year

2. Hot Water Distribution System

In hot-water heating systems, the water is heated at a central source and

circulated through pipes to radiators, convectors, or unit heaters. There are two

general types of low-temperature, hot-water heating systems. The first type is a

gravity system in which water circulation depends upon the weight difference

between the hot column of water leading to the radiators and the relatively cooler,

heavier column of water returning from the radiators. The second type is the forced-

circulation system in which water is circulated by a power-driven pump.

a. Gravity System

The distribution systems and piping for hot-water heating systems and for

domestic hot-water supply systems are simpler in design than those for steam because

there are no traps, drips, or reducing valves. Several items, such as supports,

insulation, and some valves and fittings, are the same for steam and hot-water

distribution.

Gravity hot-water distribution systems operate because of the gravitational

pull on the heavier cool water, which sinks as the heated water becomes lighter and

rises. At this point, some of the types of gravity systems that are currently used are

discussed.

One-Pipe, Open-Tank System

The one-pipe, open-tank gravity distribution system shown in figure 14

consists of a single distribution pipe that carries the hot water to all of the convectors

or radiators and returns it to the boiler. This system is easy to install and moderate in

cost.

The water that flows into the radiators at the end of the system has a lower

temperature than the water

entering the first radiators. A

system of this type should be

designed so the water

reaching the last convector is

not too much cooler than the

water reaching the first drop

in the distribution system,

convector radiators should be

installed at the end of the

system to equalize the

amount of heat radiation per

radiator. It is difficult to get

enough circulation by gravity to give the system small convector temperature drops;

consequently, we do not recommend the one-pipe, open-tank gravity system.

Two-Pipe, Open-Tank System

Many hot-water gravity distribution systems are two-pipe, open-tank systems,

as shown in figure 15. This heating system is constructed with separate water mains

for supplying hot water and returning cold water. The radiators are connected in

parallel between the two mains. In the two-pipe, open-tank gravity system, the

distributing supply mains are either in the basement with upfeed to the radiators or in

the attic. When the system is in the attic, it has overhead downfeed supply risers. The

return mains are in the basement. Return connections for the two-pipe system are

Figure 14: One pipe, Open Tank System

usually made into a gravity return, which pitches downward to the return opening in

the heating boiler. The water temperature is practically the same in all radiators,

except for the allowance to be made for the temperature drop in the distribution

supply mains occurring between the boiler and the end of the circuit. Water

temperatures are the lowest at the end of the circuit. The amount of temperature drop

between the beginning and the end of the line depends upon the length of the main

and upon the heating load.

A tank with its vent open to the atmosphere is installed in the system above

the highest radiator for water

expansion. The water level in the

expansion tank rises and falls, as the

system is heated and cooled, and the

system is full of water and free from

air at all times. In the open-tank

gravity hot-water heating system,

the expansion tank is installed on a

riser directly above the boiler, so the

air liberated from the boiler water

enters the tank and is not retained in

the system.

One-Pipe, Closed-Tank System

A one-pipe, closed-tank gravity hot-water distribution system, as shown in

Figure 16, is similar to the one-pipe,

open-tank gravity hot-water heating

system, except the expansion tank is a

pneumatic compression tank not open to

the atmosphere. When the water in a

closed-tank system is heated, it. expands

into the pneumatic compression tank.

This action permits system operation at a

much higher water temperature, without

Figure 15: Two Pipe, Open Tank System

Figure 16: One Pipe, Closed Tank System

boiling, than the temperature in the one-pipe, open-tank gravity system. This also

results in higher heat emission from the radiators.

b. Forced Circulation System

Forced-circulation hot-water distribution systems have several advantages.

They permit the use of smaller pipe sizes and allow the installation of radiators at the

same level as the boiler, or below, without impairing water circulation. By using a

circulation pump, a positive flow of water is assured throughout the system. In larger

installations, especially where more than one building is served, forced circulation is

almost invariably used. With the development of a circulation pump of moderate cost,

the forced-circulation system is being used more in small heating installations.

Even as in gravity systems, forced-circulation systems can consist of a one-

pipe or a two-pipe, upfeed or downfeed, and can be equipped with a direct or a

reversed return. Although these systems usually have closed expansion tanks, they

may have open tanks.

One-Pipe, Closed-Tank System

The general arrangement of a one-pipe, closed-tank, forced-circulation system

shown in figure 17, is similar to the one-pipe gravity system, but with the addition of

a circulating pump.

The circulation to individual radiators is improved by special supply and

return connecting tees. These tees, by an ejecting action on the distribution supply

main and an ejecting action on the return, combine to use a portion of the velocity

head in the main to increase circulation

through the radiators. Tees of this type also

aid stratification of hot and cold water

within the distributing main. They are

designed to take off the hot-test water from

the top of the main and to deposit the colder

water on the bottom of the main.

Figure 17: One Pipe, Closed Tank System

Two-Pipe, Closed-Tank System

The general arrangement of the piping and radiators for the two-pipe, forced-

circulation distribution system is the same as that for the two-pipe gravity system. The

relative locations of the compression tank relief valve and the circulating pump are

shown in figure 18.

Operation and maintenance

Hot-water heating systems require little maintenance other than periodic

checks to make certain that all air is out of the system and all radiators are full of

water. The circulating pumps should be oiled regularly according to the

manufacturer's instructions, and the pressure-relief valves should be checked

periodically.

Operator maintenance on the electrically driven feed pump consists mostly of

cleaning the pump and motor. However, the pump motor is lubricated according to

the manufacturer's specifications. Remember that not using enough lubricant can

result in the bearings running dry or seizing on the motor shaft. But, too much

lubricant causes the motor to become dirty, and it can result in the motor windings

becoming saturated with oil and burning out.

When a water leak develops around the pump shaft, tighten the packing-gland

nuts or repack the stuffing box as necessary. The strainer, installed between the pump

Figure 18: Two-Pipe, Closed Tank System

and the condensate receiver, should be kept clean to avoid any restriction of the flow

of water to the pump.

The maintenance of feed-water heaters and economizers normally includes

removing solid matter that accumulates in the unit; stopping steam and water leaks;

and repairing inoperative traps, floats, valves, pumps, and other such associated

equipment.

Conclusion

All water supply systems use a combination of pipes (of different dimensions

and materials), valves and outlets to deliver water to building users. Some water

supply systems also use storage tanks and pumps. Designing a water supply system

involves getting all of these elements right so that clean water is delivered to the user

at the appropriate rate and temperature

The purpose of water distribution system is deliver water to consumers with

appropriate quality, quantity and pressure. Distribution system is used to describe

collectively the facilities used to supply water from its source to the point of usage. A

good water distribution should have the following characteristics:

1. Water quality should not get deteriorated in the distribution pipes.

2. It should be capable of supplying water at all the intended places with

sufficient pressure head

3. It should be capable of supplying the requisite amount of water during fire

fighting.

4. The layout should be such that no consumer would be without water

supply, during the maintenance or repairing session of the system.

5. All the distribution pipes should be preferably laid one meter away or

above sewer pipelines.

6. It should be fairly water-tight as to keep losses due to leakage to the

minimum.