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INDEX

Unit – I .............................................................. 3

Lesson – 1: Water Supply .................................. 4

Lesson – 2: Drainage ....................................... 21

Unit – II .......................................................... 42

Lesson – 3: Thermal Insulation ...................... 43

Lesson – 4: Acoustics and Sound Insulation ... 61

Unit –III .......................................................... 77

Lesson –5: Air-conditioning ............................ 78

Unit - IV ........................................................ 129

Lesson – 6: Fire Protection ........................... 130

Unit - V .......................................................... 154

Lesson – 7: Lifts and Elevators ...................... 155

Lesson – 8: Escalators .................................. 168

Suggested Reading........................................ 177

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Unit – I

Water Supply and Drainage

Lesson-1: Water Supply Lesson-2: Drainage

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Lesson – 1: Water Supply

Objective: To look into the importance of building services

and why it is imperative for a designer to have a very good understanding of the various services

provided in a building.

To study in detail the principles of sanitation and plumbing in building construction.

Structure: 1.1 Introduction

1.2 Technical Terms

1.3 Water Distribution System 1.4 Types of Pipes

1.5 Taps, Valves and Cocks

1.6 Service Connection

Storage Tanks in Buildings

1.1 Introduction

The origin of all sources of water is rainfall. As it rains water can be collected from roof before it falls

on ground or as it flows on surface it gets collected

in the form of ponds, lakes, streams, river or sea.

Water that percolates or seeps into the ground gets stored as ground water which can be tapped in the

form of springs, shallow wells, deep wells, artesian

wells, etc. Adequate supply of potable water is essential for the occupants of buildings.

The municipal corporations or the municipalities are

responsible for providing public water supply system which includes collection of water from the source of

supply, giving necessary treatment to the water to

make it hygienically safe and potable and finally

distribution of water through a network of piping

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work (trunk mains, street mains etc). Water from

the street main is supplied to the individual

buildings through a service connection. Within the

building, water" is distributed to different fixtures through pipes which may run on the surface or be

concealed in walls or below flooring. Water thus

supplied may be used for bathing, cooking, flushing of W.C., washing clothes/utensils/floors etc. In this

manner the potable water gets converted into

wastewater which is drained out into a sewer or

other suitable disposal system like septic tank etc.

Plumbing is a general term which broadly includes

the system, materials, fittings and fixtures used in a

building in connection with supply of water, removal of used water with other liquid and water borne

wastes including connected ventilation system as

well as drainage of storm water. The various types of fittings and fixtures used In plumbing are termed

as plumbing fixtures.

1.2 Technical Terms

Some of the technical terms used in connection with drainage system are as under

Soil Pipe: A pipe which carries discharge from

W.C., urinal, or any other soil appliances

Waste Appliance: This includes washbasins, sinks,

bath tubs washing trough, drinking water fountain

etc.

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Waste Pipe: A pipe which carries waste water from

kitchen, bathroom, floor traps, nahani trap or by other waste appliance.

Rain Water Pipe: This is a pipe provided to carry

rainwater.

Ventilation Pipe: Also known as vent pipe is a pipe

which ventilates drainage system. This pipe is open

at the top and it is connected to a soil pipe or waste pipe at its bottom. This pipe is extended above the

roof of the building to permit exit of foul gases into

the atmosphere. This pipe only ventilates the

system and does not carry any discharge from soil, waste or rainwater pipe.

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WASTE PIPE AND VENT PIPEs

Stack: It is a term used for any vertical pipeline of

a drainage system.

Drain: Also known as house drain, is a system of

underground horizontal pipes used for drainage of discharge from soil pipes waste pipes etc. , of a

single property. Since the drain is laid within the

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private boundary, the responsibility of Its

maintenance rests with the owner of the property

Sewage: It is a combination of discharge from soil

pipe, waste pipes, vent pipes, sewers, septic tanks etc (iii) ire system of storm water including

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collection and carrying of rain water (from roofs,

paved areas and ground surface) to a public storm

water drain or to a pond or river etc

1.3 Water Distribution System

There are two distinct systems of supply of water to

a building from the mains. Direct system and

Indirect system.

Direct system. In direct system also known as

upward distribution system, the supply of water is

given to various floors in a building directly from the

mains which has sufficient pressure to feed all the floors and water fittings at the highest part of the

building. Indirect system, In indirect system also

known as down take supply or downfall distribution system, the water supply from the mains may be

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drawn either by Feeding water directly into the

overhead storage tank provided at the roof of the

building from where the water is supplied to

different floors by gravity or Feeding the water into an underground water storage tank. The water from

the underground tank is pumped to an overhead

storage from where the water is supplied by gravity.

1.4 Types of Pipes

Following types of pipes are commonly used in

water supply system.

(1) Cast Iron Pipes: Cast iron (C.I) pipes are extensively used in water distribution mains

because they are comparatively cheaper in cost, highly resistant to corrosion and have

very long life.

CAST IRON PIPES CAST IRON FITTINGS

Steel Pipes: Steel pipes are recommended for use in

water mains in situations where the pipe is

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subjected to very high pressure (i.e. above 7

kg/cm2) and the diameter of pipe required in large

in cement mortar or cement concrete are called

Hume Steel Pipes Galvanised Iron Pipes: Galvanised Iron (G.I.)

pipes are wrought steel pipes provided with zinc

coating. G.I pipes are most commonly used for water supply work inside the buildings. They are

also invariably used in service connections. Mostly

screw and socket joints are used for G.I. pipe

connections. Copper Pipes: Copper pipes are used in hot water

supply installations. They have high tensile strength

and can therefore have thin walls and they can be bent easily. To enhance their appearance copper

pipes are sometimes chromium plated to match with

the chromium plated water supply fittings.

STEEL PIPES, GALVANISED IRON PIPES AND

COPPER PIPES

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Polythene Pipes: Polythene and P.V.C. pipes are

being used increasingly these days for supply of cold

water in external and internal plumbing work. They

are light in weight, non-corrosive, lower in cost and do not require any threading for connections.

Asbestos cement (A.C.) pipes, Reinforced Concrete (R.C.C) Pipes. Prestressed reinforced concrete

(P.S.C.) pipes are among the other commonly used

pipes for supply work. The choice of the type of pipe to be used for any work is made keeping in view the

requirement of design, availability of material, cost

and other similar factors

1.5 Taps, Valves and Cocks

The term taps, valves and cocks are used to name

different types of fittings required to control the flow

of water either along or at the end of a pipeline.

Valves: Valve is a fitting commonly used to control

the flow of water along a pipeline. With the

introduction of valve it is possible to isolate any section of pipeline for the purposes of inspection,

repair of a leak, of addition/alteration to the already

functioning water supply system. Following types of

valves are commonly used in domestic water supply system.

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Globe Valve: This is the most commonly used

type of valve for manually controlling or

completely closing the flow of water in domestic

water installation. This type of valve is normally made of brass. Globe valve as such, or in some

modified form is used to control flow of water to

wash basins, shower, kitchen sink etc. In its simplest form it consists of a disc which is forced

down by a screw against a circular seat. The disc

and screw form a single moving part which is

operated by a wheel head. This type of valve is normally used for high pressure system where it

may be necessary to shut off the water supply

completely.

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Gate Valve: This type of valve is used to control

flow of water or for completely stopping the flow

of water in pipe line. This type is normally used

in low-pressure system and it offers much less resistance to flow of water as compared with

Globe valve. Gate valve is used for controlling

the discharge to the outlet from a storage tank.

Float Valve Or A Ball Valve: Float valve is used to supply water to storage tank or flushing

cistern and to automatically shut off supply when

the pre-determined level is reached. The valve is

operated by a float which allows the valve to be fully open when it is in lower position. As the

water level rises, the float also rises which

gradually closes the valve and shuts off the supply of water as soon as the water reaches the

full supply level mark.

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GATE VALVE AND BALL VALVE

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Taps and Stop Cock. Taps are used at the end

of a pipeline for draw off purposes. Taps are also

called Bibcock or Bib tap. A stopcock is a valve used in pipeline for controlling or completely

stopping the flow of water to o fixture. Taps and

stop cocks are two most extensively used type of

fittings in domestic water supply system. They are normally of screw down type and open in

anti-clockwise direction.

STOPCOCK AND BIBCOCK

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1.6 Service Connection

Service connection is a water connection given by

the local body (municipal corporation or municipality

etc.) from city water distribution mains to a consumer. The consumer may be the owner of a

single house, a multi-storeyed apartment, a planned

block development or a water district buying water wholesale. A domestic service connection comprise

of the following components:

1. Brass or Bronze Ferrule: Ferrule is a special

type of appliance made UP of brass or bronze. It has a vertical inlet for screwing on to the water

main and a horizontal outlet to be connected to

service pipe The water main which is usually under pressure is drilled and tapped and the

ferrule is screwed in without shutting own the

mains, The normal size of the ferrule to be used

is usually half the size of the service pipe.

2. Goose Neck: This is a 40 to 50 cm long flexible

curved pipe made up of brass, copper or lead

inserted between the ferrule and the service pipe. The goose-neck is provided to

accommodate the possible movement I

displacement or settlement that may take place between the water main and the service pipe due

to water pressure and prevent damage to the

connection.

3. Stop Cock: This is provided before the water meter in a chamber with a cover to cut off the

supply of water from the street main to the

building for repairs to the plumbing system within the building.

4. Water Meter: Water meter is installed in a

chamber provided with a cover for the purpose of measuring the quantity of water used by the

consumer. The local body raises water bill to the

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consumer based on consumption recorded by the

water meter.

1.7 Storage Tanks in Buildings

Water supply to a building from city mains could be

either continuous on intermittent. Normally due to continuously increasing demand and shortage of

water the local authority plan distribution of water in

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different city zones in two or three shifts (i.e.,

morning, evening and sometimes in afternoon) Even

in areas where continuous supply of water is

available the pressure of water in the mains may not be adequate to raise the water to upper floors.

Thus provision of storage tank is made in a building

to ensure availability of water during non-supply hours or when the municipal supply is stopped. In

case of multi-storeyed buildings, besides meeting

demand of water for domestic consumption, it is

mandatory to make provision of adequate overhead storage of water for fire fighting requirements. As

explained earlier in case the pressure in the mains is

not sufficient to feed all floors directly, it becomes necessary to feed from mains to an underground

storage tank. There after the water from the

underground tank is pumped to overhead tank for distribution to various floors by gravity. The storage

tanks can be made from brick or stone masonry, G.I

sheets, pressed M.S. plates, P.V.C. or R.C.C.

Normally underground tanks are made from masonry or R.C.C. Overhead flushing tanks or tanks

of small capacities ore made of G sheets, pressed

steel plates or P.V.C. Overheads tanks of large capacities are always made of R.C.C. The various

accessories connected with water storage tanks are

given below. The figure below shows arrangement of various accessories in an overhead water storage

tank

Ball valve with float -This is provided at the

inlet to the tank to control the flow of water in the tank and to automatically shut off the supply

when correct level has been reached

Inlet pipe -The pipe supplying water to the tank is termed as inlet pipe

Outlet pipe -This pipe is installed at 3 to 5 cm

above the floor of the tank. The pipe is always

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provided with a stop valve to stop supply of

water to down take pipes

Over flow pipe -This pipe is provided a little

above the inlet pipe to allow the incoming water to overflow in case the ball valve assembly does

not function properly and it is not able to shut of

the incoming supply of water. This pipe is provided with mosquito proof netting to prevent

entry of mosquitoes, flies etc. into the tank,

Scour pipe -Also known as drain pipe, it is

provided at the floor of the tank for cleaning the tank.

Cover -The manhole cover on the roof of the

tank should be of tight fitting type to prevent entry of dust mosquitoes etc. in the tank.

Assignment:

Students to study the importance of services in a

building like water supply and drainage, electrical supply, HCAV (heating, cooling and ventilation)

security and communication systems etc.

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Lesson – 2: Drainage

Objective:

To study in detail the drainage system of a

building and it‟s various components. To understand the use of traps.

To look into the various types of sanitary fittings

used in a building and their function.

Structure:

2.1 Introduction

2.2 Drainage below the ground

2.3 Drainage above the ground

2.4 Traps

2.4.1 Essentials of a good trap

2.4.2 Causes of loss or breaking of water seal

2.5 Type of Traps

2.6 Sanitary Fittings

2.6.1 Wash Basin

2.6.2 Sink

2.6.3 Bath Tub

2.6.4 Urinals

2.6.5 Water Closets

Flushing Cistern

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2.1 Introduction

As explained earlier, potable water supplied to a

building is distributed to various areas like kitchen,

both, W.C. etc. through a network of pipes provided with plumbing or sanitary fittings at their terminal

ends. Adequate arrangements are required to be

made for quick collection, conveyance and disposal of used water from the fittings without any risk to

the health of the occupants. It is also essential that

the rain or storm water from the roof paved areas of

building and the ground surface is suitably collected and discharged without flooding the area. The term

drainage or sewerage includes the system of

removal of sullage or waste water (from floor traps, kitchen, bath, and wash basin), soil water (from

W.C. and urinals) and storm water from buildings

and conveying the same upto its ultimate point of

treatment and disposal. The system of drainage can be broadly divided in two parts.

2.2 Drainage below the ground:

This comprises of a system of under ground house drain, inspection chamber, main drain or sewer,

manholes, ventilation shafts etc. provided for

conveying the sanitary sewage (soil water and waste water) and storm water for final treatment or

disposal. Underground drainage can be divided into

the following three systems:

I. Combined system. II. Separate system.

III. Partially combined system.

1. Combined system: In this system the storm water is completely mixed with the sanitary sewage

and conveyed through a single drain or sewer.

2. Separate system: In this system the storm

water is not allowed to get mixed with sanitary sewage. Two separate drains are provided. One

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for sanitary sewage and other for drainage of storm water.

3. Partially combined system: In this system a

part of storm water (usually run off from roofs,

paved yards and streets etc is mixed with sanitary sewage and conveyed through sewer

and the remaining storm water is conveyed

through separate surface drains.

2.3 Drainage above the ground:

This consists of a system of vertical stacks,

horizontal branches, floor traps etc provided for

conveying sanitary sewage (soil water and waste water) storm water (rain water) etc. to the

underground drainage system for final disposal. This

system is also known as house or building drainage system.

2.4 Traps

A trap is providing a fitting in a drainage system to

prevent entry of foul air or gases from the sewer or drain into the building. The barrier to the passage of

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foul air is provided by the seal in the trap. In its

simplest form a trap is merely a double bend or loop in the sanitary fitting, the depth of water seal being

the distance between the top 01 the first bend and

the bottom of the second. The deeper the seal the

more efficient is the trap. Depending upon the design of the trap, the depth of the water seal vary

from 40mm to 75mm. The trap should always be

fitted close to the waste or soil fitting unless the trap form an integrated part of the fitting as in case

of the European W.C. (siphon type).

2.4.1 Essentials of a good trap:

A good trap should have the following

characteristics:

1. It should maintain an efficient water seal under

all conditions of flow; both during the water flow as well as in absence of water flow.

2. It should be self-cleansing.

3. It should not have any internal projections, angles or contractions so as to permit

unobstructed flow through it.

4. It should have a smooth inner surface so that

each part is automatically scoured by flow of water and there is the possibility of dust, dirt etc.

getting struck to it.

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5. It should be provided with suitable means of

access for cleaning purposes.

2.4.2 Causes of loss or breaking of water

seal:

The primary object of providing a trap is lost, in

case it is not possible to retain water seal. The

water seal in a trap may break due to the following

causes:

1. Evaporation of water in the trap caused on

account of not using the appliance for a long

time.

2. Use of defective trap, defective installation of

trap or development of crack in trap after

installation.

3. Creation of partial vacuum caused due to

discharge of another fitting connected to the

same stack leading to emptying of the water of

the seal by induced siphonage.

4. Pressure on seal of trap due to sudden discharge

of water in large quantity into the fitting (bucket

full of water into a W.C.) forcing the seal to beak due to self siphonage.

5. Build up of backpressure of sewer gas in the

drain forcing up the water of the trap seal.

6. Due to capillary action caused by piece of some

porous material getting struck at the outlet of

the trap in such a manner that one end of the

piece remains in water of the seal and the other end of the piece remain hanging over the outlet

2.5 Type of Traps:

Traps can be made in different shapes and they are normally named after the shape of the letter they

resemble. Out of the different shapes, the trap

resembling the letter, P (or P-Trap), Q (Q-Trap) and

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S (S-Trap) are more common. The traps are

normally made of cast iron glazed stoneware.

Depending upon the use and location, the various

types of traps can be broadly summarised as under:

1. Floor Trap Or Nahani Trap: Trap provided in

floors to collect used water from floors of

bathroom, kitchen or washing floor etc, are known as floor or Nahani traps, This type is

made of iron and it is provided with a removable

grating on top. The grating intercepts dust or

other solid matter and prevents blockage of trap. The depth of water seal of floor trap should not

be less than 40mm.

2. Gully Trap: Gully trap is a deep seal trap which is provided on the external face of wall for

disconnecting the waste water flowing from

kitchen, bath, wash basin & floors from the main drainage system. The deep water seal forms a

barrier for preventing the passage of foul air

from house drain to the inside of the building, It

is made of cast iron or glazed stoneware. The Stoneware Gully trap has a top square in plan

where as the top of cast iron trap is normally

circular, it is fitted in a small masonry enclosure to meet the requirements of invent levels of

waste pipes discharging into the gully trap.

Grating is provided on top of the trap to intercept and retain all solid matter and prevent it from

flowing into the drain. The bars of the grating

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should not be more than 10 mm apart.

FLOOR TRAP, GULLY TRAP AND INTERCEPTING

TRAP

3. Intercepting Trap: This trap is provided at the junction of house drain (inspection chamber) and

street sewer to prevent entry of foul gases from

sewer into the house drain. The intercepting trap is thus provided to disconnect the house drain

from the street sewer. The trap is made of

glazed stoneware and has a opening at top

(known as clearing eye), The opening is kept closed with a tight fitting plug which Is taken out

only during cleaning of the trap. It has a deeper

seal than normal traps (not less than 100 mm).

4. Grease Trap: Grease traps are provided in large

hotels, restaurants or other industries producing

large quantity of greasy waste with the primary aim of removing the grease content of waste

water before discharging the same into drain If

the greasy or oily matter is not removed, being

sticky in nature, it will induce deposition of solids in the drain which can cause obstruction to the

flow of water in the drain and may finally result

in blockage of drain. Grease trap is a small masonry or cast chamber with a T or bent pipe

to serve as the outlet. The velocity of wastewater

flow gets reduced on entering the grease trap

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(because of sudden increase in area of holding of

waste water) and this results in separation of oily

or greasy matter from the waste water. The

greasy matter appears as floating (in the trap), which is removed periodically with the help of a

mild steel tray.

5. Silt Trap: Silt traps are provided only in situations where the wastewater carries large

amount of silt, sand, coarse particles etc. It is a

masonry chamber which functions like grit

chamber where the silt, sand etc. settle down before the waste water Is discharged into the

drainage system.

SILT TRAP

2.6 Sanitary Fittings

The fittings or appliance used for collection and discharge of soil or waste matter is termed as

sanitary fittings. Different types of sanitary fittings

are required in building to perform different type of

functions. Sanitary fittings are glazed chinaware. The fittings are so designed and shaped that they

have non-absorbent surface which can be cleaned

easily. The different type of sanitary fittings normally used in buildings are as under:

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2.6.1 Wash Basin:

A washbasin is used for washing hands, face etc

made of porcelain vitreous enamelled steel, or

plastic and it is available in various patterns and sizes. The type of wash basin normally used in a

house has an oval shaped bowl with an overflow slot

at top. The wash basin has a flat back and has provision for making holes for installing one, two or

even three taps. Normally two pillar taps are

provided one for cold water and the other for hot

water. It has a circular waste hole for draining out wastewater from the basin. A metallic strainer is

provided in the waste hole which is connected to a

waste pipe either directly or through a bottle trap

for discharge of waste water into the floor trap. The

basin is normally mounted on 2 angle irons fixed in the wall. The top of the washbasin should be kept at

a height of about 75 to 80 cm from the floor.

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2.6.2 Sink.

Sink is commonly used in kitchen, hospitals and

laboratories Sink is made of glazed fire clay,

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stainless steel, plastic, marble and R.C.C (finished

with terrazzo finishing). Sink may be made with or

without overflow arrangement. In hospitals and

laboratories only vitreous sinks are preferred. It has a circular waste hole for fixing the metallic strainer

to which the waste pipe is attached for conveying

the discharge from sink to the floor trap. The kitchen sink is invariably provided with a drain hole

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2.6.3 Bath Tub:

A shower is considered to be a more efficient and

hygienic means of taking bath and as such is widely

used in bathrooms by most of the people. However, some people prefer to use bathtub as they find it to

be more comfortable and relaxing. Use of bathtub is

restricted to certain class of hotels and private

residences. Bath tubs are made of enamelled steel

gel coated fibre glass, reinforced enamelled porcelain, reinforced concrete finished with

terracotta or marble finishes etc. Bathtubs are

provided with holes for fixing hot and cold-water

connections and have provision for over flow and waste water pipes. The length of bath tubs varies

from 75 m to 85 m width varies between 0.7 m to

0.75 m and its depth near the waste pipe varies between 0.43 to 0.45 m

2.6.4 Urinals:

Urinals fall under the category of soil appliance and

as such the discharge from urinals is connected to soil pipe either directly or through a trap provided

with gun-metal or bass domed shaped removable

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grating. From hygienic consideration it is desirable

to provide glazed tiles on walls of urinal preferable

upto door height. Following types of urinals are

commonly used

1. Bowl Type. This is a one piece construction with

integral flushing box rim having 12 hole suitably

distributed for proper flushing. The urinal has an outlet horn at bottom for connecting. to the trap

and an outlet pipe. In another pattern of bowl

type urinal, the appliance has a porcelain trap

inbuilt with the pan as a single piece. In case number of urinals is required to be installed in a

row, it is necessary to provide vertical partition

between two urinals from consideration of privacy.

2. Slab Or Stall Type: The type of urinal is

manufactured either as single unit or as a range of two or more units. In case of single unit the

width of stall should not be less than 75 cm. The

flushing of urine is normally carried out through

automatic flushing cistern which operates at regular intervals of 10 to 15 minutes. The

discharge from the series of stalls in a row is

usually carried through a glazed semi circular drain which has a sharp fall towards the trap

from where it is discharged into the soil pipe

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2.6.5 Water Closets (W.C.):

Water closet is a sanitary appliance provided for collection and discharge of human excreta into the

soil pipe through a trap. The W.C. is connected to a

flushing cistern to flush the excreta from the pan.

W.C. is made of glazed earthen ware, fire clay or white vitreous china ware. The types of W.Cs

commonly used are as under:

1. Indian Or Squatting Type W.C: This type of W.C. Is used in squatting position The W.C

consists of two pieces, i.e. Porcelain pan and a P

or S trap. The W.C, pan along with the trap is

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fixed flush with the floor. Two footrests are

provided on either side of the pan. The pan has

an inbuilt flushing rim having a number of holes

through which the flushing water from the cistern is discharged. The flushing cistern is

normally kept 1.8 to 2 m above the floor level.

The contents of the pan are removed by the gravity flush of water. When the pan and

footrests are made as integral single piece, the

appliance is termed as Orissa Pattern. In this

type while using the W.C. the excreta does not fall directly into the trap and in case the flushing

is not proper, the matter remains struck to the

pan which is considered unhygienic. Special care is to be taken to maintain cleanliness of the pan.

2. European Type W.C: This type of W.C. is used

in sitting position over a plastic seat hinged to the appliance. This is a pedestal type of

appliance with the pan and trap in a single piece.

The pan is shaped in the form of a short inverted

cone with an almost vertical back and providing minimum fouling area. The main advantage of

this type of W.C. is that by virtue of the

design/shape of pan, the excreta falls almost directly in the water in the trap and chances of

the same getting struck to the sides of the pan

are less. The flushing rim of the pan is attached to the cistern which may be of high level type

(installed at a height of 1 .8 to 2 m from floor) or

low level type (30 cm above the top of W.C. seat

or resting just at the level of W.C. seat) for getting flushing water. Following two types of

European type W.C. are used:

Wash-down type of European W.C: This is the most commonly used pattern in which the content of the

pan are removed by the gravity flush of water

discharged into the pan through the flushing rim of the pan. For ground floor, normally the W.C. having

S-trap (with outlet pointing vertically down) is used

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whereas for installation on upper floors W.C. ending

up with a P-trap is preferred

a) Siphonic type: In this type, the contents of the

pan are removed by siphonic action when the cistern is flushed and water passes through the

pan. The special type of trap inbuilt with the pan

is so shaped as to set up siphonic action when the flushed water passes over the pan. Due to

siphonic action the entire water along with the

content get emptied from the pan into the soil

pipe. The W.C. has small after-flush chamber inbuilt in the appliance, water from which re-

seals the trap. Siphonic type W.C. may have a

single trap (single-trap type siphonic W.C) or two trap (Double trap type siphonic W.C.) The two

trap type W.C. has larger area of water seal and

is more efficient and silent as compared with. single trap siphonic or wash down type of

European W.C.

1. Anglo-Indian type: This type of W.C can be

used both in squatting position as well as in sitting position and hence it is named as Anglo-Indian Type

W.C. It is a pedestal type appliance with inbuilt trap.

The top of the W.C. pan is flared out to provide for footrest to permit it to be used in squatting position.

When it is desired to use the appliance as European

type W.C the plastic seat hinged to the closet is turned on the top of the pan to use it in sitting

position. In this the design is such that the fouling

area of pan is less and the excreta falls in the water

of trap and it is flushed out in manner similar to European type W.C.

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2.6.6 Flushing Cistern:

A flushing cistern is used for storage and discharge

of water for flushing of contents from a W.C. or

urinal. Cistern is made of cast iron vitreous china or pressed steel plates or plastic the capacity of

flushing cistern varies from 10 to 15 litres. When

the cistern is fixed at a height of 1.8 to 2 m from floor level it is termed as high-level cistern made of

cost iron. The European type W.C is normally

provided with low level cistern made up of porcelain.

The low level operates at a height not more than 30 cm between top of pan and under side of cistern.

Flushing cisterns are of three types:

I. Valveless siphonic type or Bell type

II. Valve fitted type or piston type

III. Automatic flushing type

The valveless type of bell type of flushing cistern is

used only as high level cistern whereas the piston type can be used both as high level as well as low

level cistern. The components of a bell type cistern

which is most widely used for Indian type W.C. are as under:

I. A cast iron box having a storage capacity

of 10 to 5 litres.

II. A central outlet stand pipe covered by a

bell or dome shaped cast iron vessel.

III. A lever arrangement attached with a long

chain.

IV. A float valve with a float.

V. Inlet, outlet and overflow pipes.

In this case the bell shaped vessel is connected to a chain through a level arrangement. The float valve

provided with a ball float closes the water supply to

the cistern as soon as the pre-fixed level is reached.

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For flushing the cistern, when the chain is pulled

due to lever arrangement the heavy bell 15 thrown

over the top of the inner tube (Central outlet stand

pipe) resulting In setting up the siphonic action which causes the entire stored water to get

discharge into the flush pipe attached below.

Working of Flushing cistern

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Assignment:

Students to know the function of drainage and its

various systems.

Discuss the various types of traps used in a drainage system.

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Summary:

It is very important for a designer to have a very

good understanding of the various services provided

in a building and to study in detail the principles of sanitation and plumbing in building construction.

Entire system of water supply and distribution pipes

and entire system of drainage are important aspects to be considered in plumbing. Also , the

entire system of storm water – its collection and

disposal to a public storm water or drain is also a

part of plumbing.

Revision Points:

Water Distribution System

Types of Pipes Taps, Valves and Cocks

Traps

Sanitary fittings

Key Words:

Plumbing

Stack

Vent pipe Valve

Traps

In Text Questions:

1. Explain the two systems of water distribution.

2. What is drainage? Explain in detail the various

systems of drainage.

Terminal Exercises:

1. What are valves? Explain in detail the various

types of valves used.

2. Explain with the help of sketches the various

components of a domestic service connection.

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3. What is the need of a water storage tank in a

building? Explain with the help of a sketch the

various parts of a water tank.

4. What are the essentials of a good trap? Explain in detail the causes of breakage in water seals.

5. Explain with the help of sketches the various

types of traps.

6. What are sanitary fittings? Explain in detail any

five types of sanitary fittings used in a house.

Suggested Reading:

1. Building Construction by S.K Sharma

2. Building Construction by Sushil Kumar

3. Time Savers Standards For Buildings Types

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Unit – II

Lesson-3: Thermal Insulation Lesson-4: Acoustic and Sound

Insulation

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Lesson – 3: Thermal Insulation

Objective: To understand various ways in which heat

transfer takes place. To know about various types and requirements

of good heat insulating materials.

To understand general methods of thermal insulation.

To study means by which thermal insulation of

roofs, walls, exposed doors and windows can be

done.

Structure:

3.1 Introduction

3.2 Heat Transfer: Basic Definitions 3.3 Heat insulating Materials

3.4 Requirements of Heat Insulating Materials

3.5 Classification and description of Heat

Insulating Materials 3.5.1 Cork

3.5.2 Glass Wool

3.5.3 Rock Wool 3.5.4 Slag Wool

3.5.5 Asbestos

3.5.6 Thermocole 3.5.7 Reflecting Paper

3.5.8 Reflecting Paper

3.5.9 Aluminium foils

3.10 General Methods of Thermal Insulation 3.10.1Thermal Insulation of Roofs

3.10.2Thermal Insulation of Exposed Walls

Thermal Insulation of Exposed Doors and Windows

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3.1 Introduction

When there is difference in temperature of inside of

a building and outside atmosphere, heat transfer

takes place from areas of higher temperature to those of lower temperature. In colder regions, when

the buildings are internally heated where outside

atmosphere is very cool, it is necessary to check this heat loss from the building. Similarly, in very

hot regions, when the buildings are internally cooled

and the outside atmosphere is unbearably warm, it

is essential to check the entry of heat from outside into the building. The term thermal insulation is

used to indicate the construction or provisions by

way of which transmission of heat from or in the room is retarded. The aim of thermal insulation is to

minimise the transfer of heat between outside and

inside of the building. Advantages or thermal

insulation

The following advantages derived from thermal

insulation:

1. Comfort: Thermal insulation keeps the room cool in summer and hot in winter. This results in

comfortable living.

2. Fuel saving: Since heat transfer is minimised due to thermal insulation, less fuel is required to

maintain the desired temperature in the room.

3. Prevention of condensation: Use of thermal

insulating materials inside a room results in prevention of condensation (or moisture

deposition) on interior walls and ceilings etc.

4. Use of thermal insulating materials prevents the freezing of water taps in extreme winter, and

heat loss in case of hot water system.

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3.2 Heat Transfer: Basic Definitions

Heat transfer can take place by the following ways:

1. Conduction: Conduction is the direct

transmission of heat through a material. The amount of heat transfer by conduction depends

upon

i. Temperature difference, ii. Thickness of solid medium,

iii. Area of exposed surface,

iv. Time for which heat flow takes place, v. Conductivity of the medium, and

vi. Density of the medium.

2. Convection: Heat is transmitted by convection

in fluids and gases, as a result of circulation. Air movement causes the heat insulator; it is

preferable to ensure that excessive air change is

avoided.

3. Radiation: Heat is transferred by radiation

through space in the form of radiant energy.

When the radiation strikes an object, some of the energy is absorbed and transformed into heat.

One of the ways of reducing heat absorption

from radiation is to introduce a suitable reflecting

surface.

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3.3 Heat insulating Materials

General Aspects

The function of a thermal or heat insulator is to

resist the flow of heat through its body.

The heat insulating materials are required to grant protection against heat and cold. It may

also be employed to prevent either the flow of

heat from a heat furnace to the surrounding atmosphere, or the ingress of heat from the

environment to the plant operating at lower

temperature.

These materials are generally porous and their properties are governed not only by their

porosity but also by nature of pores, their

distribution, size and whether they are open or closed. The materials with a great number of

fine, closed and air-filled pores are the best heat

insulating materials.

The bulk density of heat insulating materials is

usually below 7000 N/m and their coefficient of

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thermal conductivity does not exceed 0.75 kJ per

in hr0C.

The heat insulating materials should be protected

against moisture (since the coefficient of thermal conductivity of water is about 25 times higher

than that of air)

3.4 Requirements of Heat Insulating

Materials

The main requirements of good heat insulating

materials are:

1. Thermal stability

2. Chemical Stability

3. Physical stability 4. Low thermal conductivity

5. Resistance to moisture

6. Low specific heat 7. Low specific gravity

8. Odourless

9. Resistance to vibration and shock

10.Non in flammability 11.Porous and fibrous texture

12.Economical in its initial cost

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3.5 Classification and description of Heat

Insulating Materials

The heat insulating materials may be classified as

follows:

Organic Insulators are enumerated below:

a) Wool

b) Cattle Hair

c) Eelgrass

d) Cotton Wool

e) Corkboard

f) Silk

g) Wood pulp

h) Sugarcane fibre

i) Saw dust

j) Cardboard (corrugated)

k) Paper etc.

Inorganic insulators include

1. Air (steel)

2. Slag wool

3. Mineral Wool

4. Glass wool

5. Aluminium Foil

6. Diatomaceous earth (powder)

7. Charcoal

8. Wood ashes

9. Gypsum (powder)

10.Slag

11.Asbestos etc.

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Some important heat insulating materials are

described below:

3.5.1 Cork:

It is derived from the bark of oak trees. It is ground, sized and baked in moulds. When ground and

baked, the natural resin in the cork binds the

materials into homogeneous mass which can be pressed into flexible sheets or boards etc. It is

available in the form of granulated cork, slab cork,

and regranulated baked cork.

The structure of cork consists of an aggregation of minute air vessel, provided with thin, strong wall, so

that if material is compressed it behaves more like a

gas than an elastic solid; unlike the behaviour of spring, which exerts a pressure proportionate to the

linear amount of compression. Cork, when

compressed, exerts a pressure which increases in a

more rapid manner and varies, approximately, inversely as the volume.

Properties: Following are the properties of cork:

a) Light in colour

b) Porous in structure

c) Specific gravity is about 0.24

d) Not affected by moisture

e) Thermal conductivity is low

f) Can be easily compressed

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g) Resilient and reasonably elastic when dry

Uses: Following are the uses of cork:

a) Cork sheets and boards are used for insulating

walls and ceilings, both against heat and cold and also as a sound insulator.

b) Used as a non-conducting covering for pipes

carrying steam or hot water.

c) Used as non-conducting material for scientific

apparatuses.

d) Used in refrigeration and cold storage insulation

e) Also used for bottle stoppers, vibration pads and floats for rafts and fishnets.

3.5.2 Glass Wool

Glass wool is produced by blowing high-pressure jets of steam or air on molten streams of glass at a

high temperature. Molten glass is violently scattered

in all directions, to give this product.

Glass wool is a form of fibrous glass with short and fine fibres, scattered in various directions. It is

available in the form of loose fibres, mats, rigid

quilts, or semi-rigid slabs or blocks etc.

Properties:

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a) Fibrous in structure

b) Light in weight

c) Has good tensile and dielectric strength

d) Low thermal conductivity e) Quite durable

f) Acts as an excellent insulating material because

of the presence of large pockets of air in it. g) Not affected by low temperatures and has been

used successfully at temperatures as low as

212C

Characteristics: Glass fibres have the following characteristics:

a) Does not catch fire

b) Not easily affected by heat c) Not spoiled by insects and moisture

Uses:

a) Mostly used for insulation of pipes, bends, valves etc.

b) Used for panel insulation for all types of

industrial equipment

c) Can be used for thermal and sound insulation of aircrafts.

d) Glass wool blocks can be used the construction

of partition walls for thermal insulation purposes. e) Used in boilers, ovens, cylinder or pipe insulation

3.5.3 Rock Wool: It is produced form flint rock containing some

calcareous matter. In the absence of such a natural rock, flint and lime are mixed in the requisite

proportions and melted in a furnace at temperature

of about 1700C. This molten material is then formed into small globules by means of steam jet. These

globules are then drawn into very fine fibres by

hurling them in a large container. These fibres of wool are then formed into boards or blankets (to be

used as insulators). It can also be pressed, rolled

and secured between fabric of wire-netting of brass

or copper.

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It is available in the form of loose fibres,

mattresses, mats, boards or felts, rigid or semi-rigid

slabs, quilts.

Properties a) Soft and flexible

b) Resilient and woody consistency

c) Heat and sound proof (due to the presence of millions of minute dead air cells)

d) Specific gravity is about 0.48

Uses:

a) Employed for heat and sound insulation purposes.

b) Also used as an electric insulator

3.5.4 Slag Wool:

a) It is an aggregate of fine filaments of slag

produced by blowing air through a stream of

blast furnace slag.

b) It is available in the form of loose fibres.

Uses: It is used for heat insulation in high

temperature furnaces.

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3.5.5 Asbestos:

Asbestos is a mineral fibre composed of hydrous

silicate of magnesia with a small amount of iron

oxide and alumina.

Asbestos sheets or boards consist of natural

asbestos fibres mixed with a binding agent (usually

cement) and then rolled in the form of sheets or boards. There are available in the market under the

trade name „Salamander‟.

Properties:

a) White, grey or brown in colour b) Flexible and can resist high temperature

c) Fire-proof

d) Unaffected by acids and fumes e) Resistant to corrosion and vermin effect

f) Excellently resists heat and electricity

Uses: Employed for heat and sound insulation of

buildings. Also used for insulation of furnaces.

3.5.6 Thermocole:

Thermocole is one of the trade names of polystrene.

This product was developed (in USA) during Second World War. It was made by direct extrusion of the

foam form raw materials.

Properties:

a) It has a very attractive, natural, snow white

colour

b) Very light in weight (density: 150 to 3000 N/m)

the form is very light because it contains over 9% (by volume) air, trapped in 3 to 6 millions

closed cells per litre.

c) Compressive strength = 0.07 to 0.1 MN/m cross breaking strength = 0.14 to 0.18 MN.

d) Very low value of thermal conductivity

e) Highly resistant to moisture

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f) Odourless, chemically stable and assistant to

fungus attack.

ASBESTOS SHEETS AND THERMOCOLE ICE

BOXES

a) Fully resistant to water, salt, soaps, bleaching

agents and HCI (35%), HNO3 (upto 50%), H2SO4

(upto 95%) caustic soda, caustic potash, strong ammonia, alcohols and silicon oil.

b) Not resistant to organic solvents like benzene,

paint thinners and saturated aliphatic

hydrocarbons like petroleum and gasoline.

c) Very good shock-protecting properties.

d) Ability of being moulded into well fitting

contoured cases.

Uses:

a) Thermocole (with operational range of 200C to

80C) is an excellent material for cold insulation in refrigerators, cold storages, air conditioning,

chilled pipelines and chemical processes.

b) It is used for industrial insulation and insulation

for buildings, against extremes of Climate.

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c) In the form of specially made flexible sheets,

thermocole can be used on intermediate concrete

floors in multi-storey buildings, to reduce impact

sound transmission. d) It is used for packing electronic goods like

transistor, radios, tape recorders and calculating

machines, clock, medicine bottles, cameras etc. e) It is also used for airdropped packaging,

decorative and gifts packaging and edge

protecting packaging.

3.5.7 Reflecting Paper Reflecting paper (also known as building paper) is a

strong tough paper which is lined with aluminium or

copper foil on the exposed side, which reflects back heat waves coming from a source and this keeps the

walls and the enclosed rooms cool.

Something, reflecting coatings of varnishes,

paraffins, gums or synthetic resins and applied to various grades of paper of fibrous materials.

Properties:

a) Strong and tough in nature

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b) Heat resistant

c) Possesses adequate dielectric strength.

d) Uses: Used for heat insulation purposes.

3.5.8 Gypsum:

It is hydrated sulphate of calcium (CaSO4 2H2HO)

occurring in monoclisnic crystals. It seldom occurs in

nature in pure state; contains impurities such as alumina, calcium carbonate, magnesium carbonate

and silica upto 6 percent.

When it is burnt in kilns, „Plaster of Paris‟ is

obtained. After mixing with asphalt and casting into slabs, it burnt in a kiln to form very strong sheets

which possess very good insulating properties.

Properties:

a) Crystalline and fibrous in structure

b) Controls the setting time of cement

c) Gypsum boards are good insulators of heat.

Uses: Employed for heat insulation purposes. Ceiling panels made of gypsum are used for

suspended ceilings.

3.5.9 Aluminium foils:

These are very thin foils or sheets of aluminium and

are also known as „Alfoils‟. These are available in the

form of paper backed foils, separated layers of foils and some rigid materials faced with foils.

Properties

a) Light in weight

b) Low thermal conductivity

c) Posses smooth and shining surface

d) Low emissivity (which decreases the radiation

losses)

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e) Resistant to ordinary atmospheric gases.

Uses: Used as heat insulator in refrigerators.

3.10 General Methods of Thermal

Insulation

Apart from providing thermal insulating materials on

walls, roofs, doors etc., thermal insulation can also

be achieved by the following methods:

1. Heat Insulation by Orientation: the orientation of a building with respect to the sun

has a very important bearing on its thermal

behaviour. For optimum orientation, there are usually conflicting requirements. Minimum

transfer of solar heat is desired during the day in

summer, while maximum heating of rooms by solar heat is required during winter.

2. Heat insulation by shading: While shading of

roof brings down the surface temperature, it is

very difficult to achieve this effect in practice, especially when the altitude angle of the sun is

quite high during the period of peak heat gain in

afternoons, between 1100 h and 1500 h. Raising the parapet walls can help only when the altitude

angle of the sun is low, but the cost may not be

commensurate with the effect obtained.

3. Heat insulation by proper height or ceiling:

While the surface temperature of the ceiling does

not vary with its height, the intensity of long

wave radiation, emitted by the ceiling decreases as it travels downwards. The effect of vertical

gradient of radiation intensity is not significant

beyond 1 to 1.3 m. Hence it should be adequate to provide ceiling at a height of about 1 to 1.3 m

above the occupant.

3.10.1Thermal Insulation of Roofs

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Adopting the following methods may reduce heat

gain through roofs:

1. Application of heat insulating materials. Heat

insulating materials may be applied externally or internally to the roofs. In case of external

application, heat-insulating material may be laid

over the roof but below a waterproof course. In case of internal application, heat-insulating

material may be fixed by adhesive or otherwise

on the underside of roofs from within the rooms.

False ceiling of insulating material may be provided below the roof wit air gaps in between

2. For flat roofs, external insulation may also be

done b~ arranging asbestos cement sheets or corrugated galvanised iron sheets on bricks.

3. Shining and reflecting materials may be fixed on

the top of the roof.

4. Roofs may be flooded with water in the form of

sprays or otherwise. Loss due to evaporation

may be compensated by make up arrangements.

5. Roofs may be whitewashed before on-set of each summer.

6. Top exposed surface of roof may be covered by

2.5 cm thick layer of coconut pitch cement concrete. Such a concrete is prepared by mixing

coconut pitch with cement and water. After

laying, it is covered with an impermeable layer and then allowed to dry for 20 to 30 days.

3.10.2 hermal Insulation of Exposed Walls

Heat insulation of exposed walls may be achieved

by the following ways:

1. The thickness of wall may be increased.

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2. Cavity wall construction may be adopted for

external walls.

3. The wall may be constructed out of suitable hear insulating material provided structural

requirements are met.

4. Heat insulating materials may be fixed on the

inside or outside of the exposed wall, in such a way that the value of overall thermal

transmittance is brought within a desired limits.

In the case of external application, overall waterproofing is essential.

5. Light-coloured white-wash or distemper may be

applied on the exposed side of the wall.

3.10.3Thermal Insulation of Exposed Doors and Windows

In dealing with heat insulation of exposed windows

and doors, suitable methods should be adopted to reduce:

a) Reduction of incidence of solar heat. This may be

achieved by anyone of the following means:

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i. External shading, such as louvered shutters,

sun breakers chhajjas, and

ii. Internal shading, such a curtains and

venetian blinds.

b) Reduction of heat transmission. Where glazed

windows and doors are provided, reduction of

heat transmission may be achieved by providing insulating glass or double glass with air space or

by any other suitable means.

Assignment:

Students to be familiar with the different heat insulating materials available in the market and

their respective cost.

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Lesson – 4: Acoustics and Sound Insulation

Objective:

To understand the meaning of acoustics.

To study characteristics of audible sound. To know the behaviour of sound in enclosed

spaces.

To understand various types of sound absorbents.

To study common sound defects found in

buildings.

Structure:

4.1 Introduction

4.2 Characteristics of Audible Sound

4.3 Behaviour of Sound in Enclosures

4.4 Reflection of Sound

4.5 Defects due to reflected sound

4.5.1 Echoes

4.5.2 Reverberation

4.6 Absorption

4.7 Absorbents

4.8 Common Acoustical Defects

4.1 Introduction

'Acoustics' is the science of sound, which deals with

origin, propagation and auditory sensation of sound,

and also with design and construction of different building units to set optimum conditions for

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producing and listening speech, music, etc. The

knowledge of this science is necessary for the

proper functional design of theatres, cinema halls,

auditoriums, conference balls, hospitals, etc. so that unwanted sound is excluded or insulated.

Sound is generated in the air when a surface is

vibrated. The vibrating surface sets up waves of compression and rarefaction in the air and these set

the ear drum vibrating. The movements of the

eardrum are translated by the brain into sound

sensation. When the sound waves are periodic, regular and long continued, they produce a pleasing

effect; such a sound is known as musical sound. On

the contrary, when the sound wave is non-periodic, irregular and of very short duration, it produces

displeasing effect; such sound is known as noise. A

noise is an abrupt sound of complex character with an irregular period and amplitude originating from a

source of non-periodic motion.

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4.2 Characteristics of Audible Sound

Sound is transmitted in the form of waves which are

a series of compressions and rarifications created in

the medium through which it travels. The sound waves are longitudinal waves and hence each

particle of the medium through which sound wave is

proceeding, moves backwards and forwards along a line in the direction in which sound is travelling. The

velocity of sound depends upon the nature and

temperature of the medium through which it travels.

It travels much faster in solids and liquids than in air. The velocity of sound in air depends upon

moisture in air and temperature of air. The velocity

of sound in atmospheric air at 200C is 343 m/sec. The velocity of sound in pure water is 1450 m/sec

while that in bricks and concrete is 4300 and 4000

m/sec respectively. Sound cannot travel in vacuum.

For the sound to be audible, the sound source and ear must be connected by an uninterrupted series of

portions of elastic matter.

There are three characteristics of sound:

1. Intensity and loudness of sound

Intensity of sound is defined as the amount or flow

of wave energy crossing per unit time through a unit area taken perpendicular to the direction of

propagation. Mathematically, the energy of a wave

and hence the intensity at a point is proportional to

the square of the amplitude of vibration of the point. But the distinction between the physical quantity

called intensity and the meaning to be understood

by the term loudness must be clearly noted. Loudness of a sound corresponds to the degree of

sensation depending on the intensity of sound and

the sensitivity of ear drums, and does not increase proportionally with intensity but more nearly to its

logarithm. It is know as Weber and Fechner's law

which states that the magnitude of any sensation is

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proportional to the logarithm of the physical

stimulus that produces it. Thus, intensity of sound is

purely a physical quantity which can be accurately

measured, and which is independent of ear of listener. Loudness, on the other hand, is the degree

of sensation which is nm wholly physical but partly

subjective and does depend upon the ear and the listener. It may also happen that the same listener

might give different judgements about the loudness

of sounds of the same intensity but of different

frequencies as the response of the ear is found to vary with the frequency of vibration.

2. Frequency and pitch of sound

Frequency or Pitch is defined as the number of cycles which a sounding body makes in each unit of

time. It is a measure of the quality of a sound. It is

that characteristic by which a shrill sound can be distinguished from a grave one, even though the

two sounds may be of the same intensity. The

sensation of pitch depends upon the frequency with

which the vibrations succeed one another at the ear, the greater the frequency the higher the pitch and

the lesser the frequency the lower the pitch. The

frequency scale covers a wide range varying from 20 cycles per second to 1500 cycles per second.

3. Quality or Timbre

The quality of a sound is that characteristic which enables us to distinguish between two notes of the

same pitch and loudness played on two different

instruments or produced by two different voices. A

study of vibration curves of various musical instruments has shown that the notes emitted by

them are seldom pure. They contain some

fundamental tones of frequency n and additional tones of (of frequencies 2n, n, 4n, etc.) called

overtones. The quality of a note is determined by its

complex structure and depends upon the presence

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or absence of a certain number of overtones, on

their relative strengths and pitches. It is to be noted

that it is the memory of this tonal quality which

enables us to recognise a large number of different sounds. Among these are the voices of friends and

acquaintances, the various sounds employed in

speech and familiar musical instruments and the cries of animals.

4.3 Behaviour of Sound in Enclosures

When sound is generated in a room, the distance

between the source and the walls is so small that there is little or no reduction due to distance. When

the sound waves strike the surfaces of a room,

three things happen:

i. Some of the sound is reflected back in the

room.

ii. Some of the sound energy is absorbed by the

surfaces and listeners. iii. Some of the sound waves set on the walls,

floors and ceiling vibrating and are thus

transmitted outside the room. The amount of sound reflected or absorbed depends

upon the surfaces, while the sound transmitted

outside the room depends upon sound insulation properties of the surfaces.

4.4 Reflection of Sound

Sound waves get reflected from a large uniform

plane surface in the same manner as that of light waves, the angle of incidence being equal to angle

of reflection, as shown in Fig. 28.1. The reflection of

sound has certain virtues in acoustics such as the enhancement of loudness and enrichment of total

quality of sound. The following characteristics of

reflection of sound waves are noteworthy:

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1. Reflection of sound waves follow practically the

same laws as reflection of light. However, this

may not be true in some exceptional cases, hence great caution should be exercised while

applying these laws.

2. The reflected wave fronts from a flat surface are

also spherical and their centre of curvature is the image of source of sound Fig. 28.2 (a).

3. Sound waves reflected at a convex surface are

magnified and are considerably bigger Fig. 28.2 (b). They are attenuated and are therefore

weaker. Convex surfaces may be used with

advantage to spread the sound waves throughout the room.

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4. The sound waves reflected at a concave surface

are considerably smaller Fig. 28.2 (c). The waves

are most condensed and therefore amplified. The

concave surfaces may be provided for the concentration of reflected waves at certain

points.

4.5 Defects due to reflected sound

The behaviour of reflected sound plays very important role in the acoustical design of an

enclosed space. The following are two main defects

that may be caused due to reflection of sound waves:

(a) Echoes

(b) Reverberation

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4.5.1 Echoes

An echo is produced when the reflected sound wave

reaches the ear just when the original sound from

the same source has been already heard. Thus, there is repetition of the sound. The sensation of

sound persists for 1/10th of a second after the

source has ceased. Hence in order that an echo may be distinguished as separate, it must reach the ear

1/10th of a second after the direct sound. Taking the

velocity of sound as 340 m/sec, it means that sound

must come after traversing a distance of 34 m, i.e., the minimum distance of the obstacle from the

source must be half of this, i.e., 17 m. If, however,

the distance of the reflecting surface is less than this, the sound will appear to be draw out. Near

echoes, sufficient to cause blurring, occur when the

distance of the reflecting surface is between 8 and 17 m. Multiple echoes may be heard when a sound

is reflected from a number of reflecting surfaces

suitably placed, such as two parallel cliffs. The

rumbling and rolling of a thunder is due to successive reflections of a peel of thunder from a

number of reflecting surfaces such as clouds,

mountains, rocks and surfaces of separation between atmospheric currents and various strata of

air.

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4.5.2 Reverberation

It has been generally noticed that in public halls and

auditoriums, the sound persists even after the

source of sound has ceased. This persistence of sound is called reverberation. It is due to multiple

reflections in an enclosed spare. Reverberation is a

familiar phenomenon in Cathedrals and new halls/rooms without furniture, where, even after

sound source stops the reverberation is heard even

upto 10 seconds. A certain amount of reverberation

is desirable, specially for giving richness to music,

but too much reverberation is undesirable.

The time during which the sound persists is called

the reverberation time of sound in the hall. It is the lime taken by the reverberant sound to decay to its

one-millionth of the sound intensity level existing al

the time the source of sound slopped. In other

words, it is the period of time in seconds, which is required for sound energy to decay or diminish by

60 dB after the sound source has stopped.

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4.6 Absorption

When a sound wave strikes a surface, a part of its

energy is absorbed by friction. The sound generated

in an auditorium or hall is absorbed in four ways:

a) In the air

b) By the audience

c) In the furniture and furnishings

d) At the boundary surfaces such as floors,

ceilings, walls etc.

Absorption in Air

The absorption of sound in the air is mainly due to the friction between the oscillating molecules when

sound wave travels through it. However, this

absorption is extremely small.

Absorption by the audience

Sound energy absorbed by the clothing of the

audience. Room acoustics change perceptibly by the

number of audience present. Also, absorption is more in winter, than in summer, because of heavy

clothing.

Absorption in furniture and furnishings

Furniture, curtains, carpets, etc. also absorb sound

energy to a fair extent.

Absorption by boundary surface

When sound waves strike the boundary surfaces

such as walls, floors, ceilings (treated or otherwise),

absorption takes place due to the following factors:

(a) Penetration of sound into porous materials, causing resonance within air pockets in the pores

until energy is dissipated; (b) Resonant vibration of

panel materials; (c) Molecular damping in soft absorbing materials; and (d) Transmission through

structures.

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4.7 Absorbents

Special materials used on boundary surfaces to

increase absorption are known as absorbents.

Ceiling is generally more exposed to direct sound waves than are other surfaces, and is usually the

largest single area available for treatment.

Absorbents can be broadly classified as following:

a) Porous materials

Absorption in porous materials is mainly due to the

frictional losses which occur when the sound waves

cause to and fro movement of the air contained in the material. However, these materials absorb

sound mainly in the higher frequencies. Their

efficiency depends upon porosity, the resistance to air flow through the materials and the thickness.

Examples of absorbents under this category are rock

wool, glass silk, wood wool, curtains and other soft

furnishings, drilled fibre boards and acoustic plasters.

b) Resonant panels

These panels absorb the sound by damping the. sympathetic vibrations in the panels, caused by

sound pressure waves bf appropriate: frequency, by

means of air space behind the panel. These panels absorb sound only at lower frequencies, over a

comparatively narrow frequency band ranging from

50 to 200 cycles. The frequencies at which panels

vibrate depend upon their weight and depth of air spaces behind them.

c) Cavity resonators

A cavity resonator is virtually a container with a small opening, and it functions by the resonance of

air in it. They can be designed to absorb sound of

any frequency.

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d) Composite absorbers

These are a comparatively recent development,

combining the functions of all the above three

absorbents. It consists of a perforated panel fixed over an air space containing porous absorbent. The

perforations in the panel should form at least 10 per

cent of the total area to allow the porous materials to absorb sound at higher frequencies.

4.8 Common Acoustical Defects

Perfect acoustical conditions in a big room, hall or

auditorium etc. are achieved when there is clarity of sound in every part of the occupied space. For this,

the sound should rise to suitable intensity

everywhere with no echoes or near echoes or distortion of the original sound; with correct

reverberation time. Following are the common

defects which are encountered and which require

special attention of the designer for proper treatment:

1. Reverberation.

We have already seen that reverberation is the persistence of sound in the enclosed space, after the

source of sound has stopped. Reverberant sound is

the reflected sound, as a result of improper absorption. Excessive reverberation is one of the

most common defects, with the result that sound

once created prolongs for a longer duration resulting

in confusion with the sound created next. However, some reverberation is essential for improving quality

of sound. Thus, optimum clarity depends upon

correct reverberation time which can be controlled by suitably installing the absorbent materials.

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2. Formation of echoes

Echoes are also formed due to reflection of sound when the reflecting surfaces are situated at a

distance greater than about 17 m and when the

shape of the hall /auditorium/room is curved with

smooth character. This defect can be removed by selecting proper shape of the hall and by providing

rough and porous interior surfaces to disperse

energy of echoes.

3. Sound foci

As indicated in Fig. 28.2 (c), reflecting concave

surfaces cause concentration of reflected sound waves at certain spots, creating a sound of large

intensity. These spots are called sound foci.

Geometrical designed shapes of the interior faces,

including ceilings, and providing highly absorbent materials on focussing areas, can remove this

defect.

4. Dead spots

This defect is an outcome of the formation of sound

foci. Because of high concentration of reflected

sound at sound foci, there is deficiency of reflected sound at some other points. These points are known

as dead spots where sound intensity is so low that it

is insufficient for hearing. This defect can be

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removed by installation of suitable diffuser so that

there is even distribution of sound in the hall.

5. Insufficient loudness.

This defect is caused due to lack of sound reflecting flat surface near the sound source and excessive

sound absorption treatment in the hall. The defect

can be removed by providing hard reflecting surface near the source, and by adjusting the absorption of

the hall so as to get optimum time of reverberation.

When the length of the hall is more, it may be

desirable to install loud speakers at proper places.

6. External noise.

External noise from vehicles, traffic engines,

factories, cooling plants etc. may enter the hall either through the openings (such as doors,

windows, ventilators etc.) or through even walls and

other structural elements having improper sound insulation. This defect can be removed by proper

planning of the hall with respect to its surroundings

and by proper sound insulation of exterior walls.

Assignment:

Students to visit an auditorium or a theatre and

study its acoustical design.

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Summary:

Due to difference in temperature inside and outside

the built environment , it becomes necessary .a

comfortable living inside. By using thermal insulating materials, we can resist the flow of heat

outside and maintain comfortable living conditions

inside.

Noise causes annoyance, interference with speech

and results in efficiency of work performance. Good

planning and constructional measures have to be

adopted for noise control, sound insulation and to eliminate common defects due to sound reflection

such as echo and reverberation.

Revision points:

1. Methods of Heat transfer

2. Classification of heat insulating materials

3. Characteristics of audible sound.

4. Behaviour of sound in enclosed spaces.

5. Common acoustical defects.

Key words:

1. Conduction

2. Convection

3. Radiation

4. Acoustics

5. Echo

6. Reverberation

In text questions:

1. What is thermal insulation? What are the advantages derived from thermal insulation?

2. What is acoustics? Explain in detail the

characteristics of audible sound.

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3. What are the requirements of a good heat

insulating material?

Terminal exercises:

1. Explain in detail the various ways in which heat transfer takes place.

2. Explain in detail any seven types of heat

insulating materials.

3. Explain in detail the general methods of thermal

insulation.

4. How will you provide thermal insulation for the

following structural components:

Roofs

Walls

Doors and windows

1. How does sound behave in enclosed spaces?

Explain in detail.

2. Explain in detail the various types of sound

absorbents.

3. Discuss in detail the common sound defects

found in buildings.

Suggested reading:

1. Building Construction by Sushil Kumar

2. Building Construction by Dr. B.C. Punmia

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Unit –III

Lesson-5: Air - Conditioning

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Lesson –5: Air-conditioning

Objective:

To understand the basic concept of air

conditioning. To understand parts of an air conditioner.

To study various types of air conditioning.

To study the air distribution system.

Structure: 5.1 Introduction

5.2 How Is Cooling Made Possible?

5.3 Equipment Used To Produce Cooling 5.3.1 The Compressor

5.3.2 The Condenser

5.3.3 The Evaporator 5.4 Airconditioning Capacity -The 'Ton'

5.5 Heat Load Estimation

5.6 Types of Airconditioning Systems

5.7 Non-Ducted Products 5.7.1 Room Airconditioners

5.7.2 Split Airconditioners

5.7.3 Types of Split Airconditions 5.8 Drainage of Condensate Water

5.9 Packaged Airconditioning Systems

5.9.1 Air-Cooled Ductable Splits

5.9.2 Floor Standing Packaged Units 5.10 Types of Compressors Used In Window

Split and Packaged Airconditioners

5.10.1Sealed Reciprocating Compressors 5.10.2Sealed Scroll Compressors

5.10.3Sealed Rotary Compressors

5.11 Mounting of Outdoor Units 5.12 Mounting, Safety and Serviceability

5.13 Coastal Installations

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5.14 Installation Practices for Air-Cooled Units 5.15 Length of Interconnecting Piping

5.16 Refrigerant Pipe Insulation

5.17 Direct Expansion and Chilled Water

Systems 5.18 Compressors Used In Vapour Compression

Central Plants

5.19 Packaged Chillers 5.20 Packaged Chillers Installation Tips

5.21 Air Cooled Chillers

5.22 Water Cooled Chillers 5.23 Introducing the Condenser

5.23.1How the Condenser Is Cooled

5.23.2How the Air Cooled Condenser Is Cooled

5.23.3How the Water Cooled Condenser Is Cooled

5.24 Cooling Towers

5.25 Air Handling Units 5.26 Fan Coil Units

5.27 Ducts, Grilles & Diffusers

5.28 Co-Ordination between Designer and Airconditioning Engineer

5.29 Modern Trends in Design and Fabrication

of Ducts

5.30 Fresh Air 5.31 Sick Building Syndrome

5.32 Changes in Fresh Air Requirement over

the Years 5.33 Filtration and Filters

5.34 Pleated Panel Type Filter

5.35 Noise & Noise Control in Airconditioning 5.36 Saving Energy on Airconditioning

5.37 Building Design

5.38 Energy Efficient Airconditioning Equipment

5.39 Effective Maintenance and Utility Management

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5.1 Introduction

Airconditioning is defined as a process, which cools

(or heats), cleans, circulates, freshens air and

controls its moisture content simultaneously. Most often airconditioning is about removing heat. Now

that we have defined airconditioning let us get to

know the nature of 'Heat'. There are two types of 'Heat': "Sensible Heat" and "Latent Heat" 'Sensible

heat' is any heat that raises the temperature but not

the moisture content of the substance. This is our

regular and familiar every day heat. Because it raises the temperature it can be detected by the

senses and this in fact is why it is called Sensible

Heat.

'Latent Heat' is the tricky one. When we talk of

Latent Heat we mean 'Latent Heat of Vaporisation.

It is that heat required to transform a liquid to

vapour. Take water for example. Water can be heated to its boiling point of 100°C. If more heat is

added at this point the temperature of the water

does not increase. The water continues to boil and becomes steam. So where does all the heat go?

Well, the heat goes into changing the water into

steam. The latent heat of vaporisation in this instance is the heat required to change water from

liquid at 100°C to vapour at the same temperature.

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Latent heat plays an important part in Refrigeration

and Airconditioning. It explains the principle of refrigeration and also is a component of Heat Load.

Human beings generate Latent Heat by way of

moisture (perspiration) on their skin. This

perspiration requires to be dried; therefore, a change of its state from liquid to vapour is required.

Fresh air which is added into the air system, very

often brings in plenty of moisture with it. Removal of this additional moisture also involves latent heat

removal. A portion of the airconditioning heat load is

therefore in the form of latent heat, for example in an office 10% of the airconditioning heat load could

be in the form of Latent Heat. This goes up to

around 25% in a restaurant and around 33% in a

movie theatre.

5.2 How Is Cooling Made Possible?

Now that we have discussed 'Heat let us talk about

the principle at work in airconditioning, the core concept to understand is Evaporation. Remember

how cold your skin felt when dabbed by liquid spirit

at a doctor's clinic before an injection? It felt cold

A refrigerant is a gas with special

characteristic that make it suitable for Refrigeration. It is possible to liquefy it

even ambient temperatures when the

pressure is raised R-22 is the most commonly used refrigerant in air-

conditioning. Recent studies indicate

that Refrigerants when leaked into the

atmosphere cause damage to the ozone layer. By international consensus

today‟s refrigerants may be replaced by

new ozone friendly refrigerants over the next three or four decades.

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because the spirit evaporated (changed from liquid

state to the vapour state) very rapidly. And when it

evaporated it needed heat to change its state.

Where did this heat come from? It came from the liquid itself and your skin with which it was in

contact.

In the refrigeration cycle this principle is put to work by causing a liquid Refrigerant to evaporate in a

cooling coil (evaporator), This refrigerant is a

specially chosen substance which has the property

of evaporation at very low temperatures. (For example, the commonly used refrigerant, R-22,

would start evaporating at -40°C even under normal

atmospheric pressure). The cooling coil, in which the refrigerant evaporates, is in contact with the air (or

water in chilled water systems) surrounding it,

thereby cooling that as well. Once cooled, this air (or water) is then directed to the spaces which

require cooling.

5.3 Equipment Used To Produce Cooling:

Now that we have seen the process by which cooling takes place, and examined the nature of heat and

humidity, let us briefly look at the main equipment

used to produce the effect we require.

5.3.1The Compressor:

Under atmospheric temperature and pressure the

refrigerant is in gaseous form. We learnt that the

cooling takes place when liquids evaporate to become gas. Therefore we must first transform the

refrigerant gas into the liquid form. Most gasses can

be made into the liquid form by raising its pressure (and cooling it, which is handled by the condenser).

The equipment that increases the pressure of the

gas by compressing it, is called the Compressor.

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5.3.2 The Condenser:

During compression however the refrigerant

becomes hot. This is because of two reasons:

a) Because of the work done on it (remember how

warm the hand pump became when pumping air

into your bicycle tires?) and

b) Because the refrigerant is converted from gas to

liquid releasing its latent heat.

This heat has to be removed to enable the gas to

condense into a liquid easily. The equipment that removes the heat is called the Condenser.

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5.3.3 The Evaporator ('Cooling Coil'):

From the condenser we now have the liquid refrigerant ready to go to work. This refrigerant can

remove heat when it starts evaporating. The liquid

refrigerant from the condenser is injected through a metering device called the capillary or expansion

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valve into the cooling coil which is a bundle of

tubes.

Inside the cooling coil the pressure is low, because

of the metering/ throttling device on one side and the compressor suction on the other side. In the low

pressure, the liquid refrigerant starts evaporating

rapidly. While evaporating it needs sensible heat to transform itself from the liquid to the gas state. So

it soaks up heat from the surrounding tubes, and

from the air, with which the tubes are in contact.

This is what causes the cooling.

End of Cycle and Beginning of the Next One:

Having done this the refrigerant is back into the

gaseous form. It is sucked into the compressor where it will be compressed again for the next

refrigeration cycle.

5.4 Airconditioning Capacity -The 'Ton'

Most of us have heard about the Ton' In connection with heat Load or capacity of airconditioning

equipment. The Ton (TR)- in Refrigeration &

Airconditioning is a unit indicating a certain Quantity of heat. This "Quantity of Heat" is different from

temperatures which only says how hot the

substance is but not how much heat it contains.

The two most common units for stating the heat

quantity are the British thermal unit (Btu) and the

Calorie (cal). The Btu is the quantity of heat needed

to raise the temperature of 1 Ib of water by 1 Fahrenheit. The Calorie is the metric unit of heat

quantity. It is the heat needed to raise the

temperature of a gram of water by 1 Celsius. Since a calorie is a very small measurement, It is practical

to use thousand calories as the unit for

airconditioning and it is expressed as Kilo Calorie (K Cal), 1 Ton Refrigeration = 12000 Btu or 3000 K Cal

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5.5 Heat Load Estimation

In warm countries the primary aim of

airconditioning is to bring the temperature down

within the conditioned space.

We know temperatures can be brought down by

removing heat airconditioning systems are

employed to pump out this heat from within the space.

It is important to select the right airconditioning

equipment to do the job. A system that is too large

for the requirement would not only cost more, but also be a waste of capacity. On the other hand, a

system with low capacity would not be able to

satisfy the comfort needs of the occupants. Further, being of low capacity, the system would have to run

for a longer time thereby being prone to abnormal

wear and tear

It stands to reason therefore, that in order to select the equipment of the right capacity, one must know

the quantity of heat that is to be removed from the

conditioned space. This 'quantity of heat' is calculated using certain formulas and this process is

referred to as Heat Load Estimation

The heat within the space comes from various sources both external and Internal. The sun brings

in external heat into the space through the walls,

roof and glazing. Fresh air brought into the

conditioned space from outside, contribute substantially to the heat load. The Internal heat

comes from electrical equipment, machinery lighting

and from the occupants themselves Humans dissipate heat into the space and their perspiration

adds to the humidity and therefore to the Latent

heat. The quantum of heat added by the occupants depends on their level of activity. People at rest will

contribute less heat load than those doing more

physical activity.

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Calculating heat loads has evolved over the years to

become very precise. An airconditioning engineer

relies on certain checklist-like form or special

computer software to estimate the heat load

5.6 Types of Airconditioning Systems

Over the years, Airconditioning Systems have

evolved to suit different needs. The emergence of new technologies, environment conditions and the

availability of space have all played a part in

shaping the airconditioning system of today. Though

many types of airconditioning systems are available it is convenient to first classify them broadly as

follows:

Basic Branches of Airconditioning

The basic branches of airconditioning are Non-

Ducted products and Ductable System. Ductable

System can then be divided into Packaged

Airconditioners and Central Plants. Further subdivisions appear in subsequent pages.

Non-Ducted Products and Ductable Systems

By Non-Ducted Products we mean those airconditioners that do not use any air ducting to

cool the conditioned space. Window mounted 'Room

Airconditioners' and the 'Non-Ducted Split Airconditioners' fall into this category. These

products are suitable where air throw is limited to

around 4 metres (13 feet) and small spaces are

involved. Where large spaces are involved, multiple units are used to distribute the air. Alternatively in

order to distribute the air uniformly using fewer

units, ductable systems are preferred.

Ductable systems can be further subdivided into

Packaged airconditioners and Central plants. The

term 'Ductable' implies any airconditioning system suitable for ducting. The design engineer may prefer

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not to use ducting by employing Fan coil Units

instead.

5.7 Non-Ducted Products

The basic branches of airconditioning can be divided into Non-Ducted Products and Ducted Systems. Let

us first explore the branches under Non-Ducted

products:

5.7.1 Room Airconditioners

Room Airconditioners are familiar to most of us. These ubiquitous machines can be seen mounted in

windows and therefore, also referred to as 'Window

Airconditioners'. In Window Airconditioners the compressor, condenser-fan, condenser and

evaporator are all enclosed in a single cabinet. The

unit is to be installed in a wooden frame either in a window or in a hole in the wall. The air being blown

through the condenser must pass freely through

without restriction. We must therefore, make sure

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that the condenser is not obstructed (for example

by a neighbouring wall).

These air conditioners come in cooling capacities of

0.5,0.75, 1, 1.5 and 2 tons, adequate for a room between 5 and 20 square metres in size. Larger

spaces may be handled by using multiple units of

this type. While Window Airconditioners are

economical and most convenient to install they could be noisy for some applications.

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5.7.2 Split Airconditioners

As the name implies, the Split Airconditioner is split

into two basic components, the Indoor unit and the

Outdoor unit. These two units are connected by refrigeration tubing and electrical wires that can

pass through a hole in the wall barely 10cms in

diameter. Because the relatively g noisy components, such as the compressor and condenser

fan, are in the outdoor unit, the conditioned space

tends to be quite. There are situations where it is

not possible to mount a window airconditioner because of obstructions from neighbouring walls or

non availability "of a suitable window. In such cases

the Spilt Airconditioner is used because the outdoor unit can be mounted on the roof or on a ledge some

distance away from the room to be airconditioned.

Though Split Airconditioners are more expensive

than the Window Mounted type they are preferred for their low noise levels.

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The outdoor unit houses the compressor, condenser

and the condenser fan. The indoor unit consists of

the evaporator Cooling coil: and the evaporator

blower. Since the noisier components are outside the building the conditioned space is much quieter.

5.7.3 Types of Split Airconditions

Indoor Units:

While the outdoor units of split airconditioners are

all similar the indoor units are available in different

types to suit the needs of the airconditioned space.

The types of indoor units are:

Floor Mounted: The indoor unit of this

Airconditioner is typically kept on the floor against

the wall of the space to be air-conditioned. This type is ideal for living rooms or office rooms where

adequate floor space is available. Since the air

throw is from the top, the space above the indoor

unit must be free from obstructions.

High Wall Mounted: This unit is fixed to the wall at

height of about 2.5 metres usually below the false ceiling. The controls are generally operated either

by a corded or cordless remote control unit, because

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it is mounted on the wall it is preferred for rooms

having less floor space. This model is widely used

for domestic and commercial applications.

Ceiling Mounted: Split airconditioners are equipment designed to be suspended from the main

ceiling. They are available in three models:

a) Ceiling Mounted (Exposed): These units are fixed directly to the ceiling and are visible. The

unit is similar to the Floor mounted (exposed)

type. They are easy to mount and are preferred

in commercial areas or offices that do not have a false ceiling.

b) Ceiling Mounted (Hide-Way): These units are

also mounted at the ceiling but are designed for being hidden. They are generally concealed by a

panelled box or false ceiling. These units are

suitable for commercial areas where the interior design requires the airconditioning equipment to

be concealed so as not to interfere with the

aesthetics. You will find such units working in

restaurants and offices.

CEILING MOUNTED AND HIGH WALL MOUNTED

c) Cassette Type: Cassette type indoor units are

mounted above the false ceiling in such a way

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that the outlet grill of the units is flush with the

bottom of the false ceiling. While the other types

of indoor units provide for condensate draining

by gravity the same is not possible for the cassette type. To overcome this problem a small-

motorised pump is employed to drain out the

condensate.

5.8 Drainage of Condensate Water

When the air around the evaporator is cooled, the moisture in the air accumulates as water under the

evaporator. This happens because the cold air

cannot hold as much water vapour as it held when it was warmer. You experience the same phenomenon

when a small puddle of water accumulates under a

chilled glass of water.

This water referred to as 'condensate' is collected in a pan under the evaporator and must be removed

from the conditioned space. Therefore, wherever

indoor units are mounted, there must be a gently sloping drain tube to carry this condensate water

away from the room. If the water is not drained out

properly it may collect in the drain pan until it overflows and drips into the room.

5.9 Packaged Airconditioning Systems

Packaged Airconditioning systems can be broadly

classified as:

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Air-cooled Ductable Splits and

Floor standing packaged Airconditioners

5.9.1 Air-Cooled Ductable Splits:

The indoor portion of these units are located above the false ceiling and connected to the ducting.

Consequently they do not occupy floor space.

Currently in India they are available in 3.5 and 7.5 ton capacities. Since the indoor units is located

above the false ceiling the space available limits the

capacity to 7.5 tons per unit.

However, great care must be taken to select the location of the indoor units. Ideally, they must be

located in corridors, above lofts, etc. where

accessibility is not a problem. If the units are located in the conditioned area, attending to the

machines can cause disturbance to the working

area. False ceilings in the decorated interior areas

may also get shabby due to maintenance handling by mechanics

5.9.2 Floor Standing Packaged Units

These are shaped like cupboards and are typically placed in a small enclosure adjacent to the

conditioned area. Inside this 'cupboard' like

enclosure is housed the Compressor, Evaporator and the Evaporator blower. Though these units are

typically used with ducting they can also be placed

directly in the room to be conditioned whereby the

cooled air is thrown directly into the rooms without ducting. Currently in India these units come in

capacities of 5, 7.5, 10 and 15 tons machines.

Higher capacities (20 tons and above) can be expected in the coming years.

These floor standing packaged airconditioners come

in both the Air- cooled and the Water-cooled models

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Water-Cooled Units require water. This water is

used to cool the refrigerant in the condenser. Water

is pumped through the shell and tube condenser, which is a part of the packaged unit. This water is

then sent into a „cooling tower' outside the air-

conditioned room where the heat is dissipated to the

atmosphere. Water cooled units give higher capacity and are more power efficient due to lower operating

pressure.

Air-Cooled Models are especially suitable for places where water is space or of 'hard' quality, or where

there is no space for installing a cooling tower. The

heat is removed by way of an air-cooled condenser with a fan blowing through it. This condensing Unit

is mounted outside the building on a sunshade or a

terrace Air-cooled.

Though they require a small plant room, floor mounted packaged units offer some clear

advantages.

They are service friendly because of easy accessibility.

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They can handle longer ducts by virtue of having

more powerful fans.

Large tonnages can be handled with fewer units

by using 10 TR OR 15 TR units.

Interiors are clean and undisturbed since the

machines are located in a separate plant room

5.10 Types of Compressors Used In Window

Split and Packaged Airconditioners

As mentioned earlier the outdoor unit encloses the

compressor and the condenser. The compressors

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used in Window, Split and Packaged Air-conditioning

are typically Hermetically Sealed compressors. A

Hermetically sealed compressor is a gas tight steel

shell within which is housed an electrical motor and the compressor unit. These compressors may be of

the Reciprocating type, the Scroll type or the Rotary

type. Let us take a brief look at these compressors and how they work.

5.10.1Sealed Reciprocating Compressors

These compressors typically have one or two pistons

mounted on the crankshaft extension of the motor. As the motor turns the crankshaft, the piston moves

up and down in the cylinder. On the top of the

cylinder is mounted a valve plate assembly with a

suction and discharge valve. Each time the piston

moves down, the suction valve opens and the gas is sucked into the cylinder. When the piston moves up

the gas is pushed against the discharge valve which

opens to let the compressed gas out. These

compressors are available from very small fractional ton capacities up to 10-ton units.

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5.10.2 Sealed Scroll Compressors:

Scroll compressors are a recent innovation in use

since the mid eighties. These compressors are very

efficient and are gaining acceptance among several leading manufacturers as an option to the

reciprocating compressors. Scroll compressors use

two interlocked spiral-shaped members which enclose the refrigerant gas in pockets between

them. One of the spiral-shaped members is fixed

and the other rotates causing the refrigerant to be

squeezed into ever decreasing pockets until it reaches the centre from where it is discharged.

These compressors are currently available in small

capacities of upto 10 tons. The advantages include high reliability, low maintenance, low noise &

vibration and high efficiency.

5.10.3 Sealed Rotary Compressors:

This type of compressor has a turning rotor eccentric to the cylinder housing, and blades which

slide to form a continuous seal for the refrigerant

gas. At the beginning of the stroke a volume of refrigerant gas enters the chamber. As the stroke

progresses the nature of eccentricity squeezes the

gas thereby compressing it. Rotary compressors are considered unsuitable for areas with high ambient

temperatures and limited to use in window

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airconditioners and small split airconditioners. These

compressors are not repairable and are generally

replaced when they become defective

5.11 Mounting Of Outdoor Units

All types of split units are connected to a box like

cabinet placed outside the conditioned space. This

'box' is the 'Outdoor Unit' (ODU) through which the heat from the conditioned space is dissipated into

the atmosphere. If we look inside the outdoor unit,

we will find a Compressor, a Finned- Coil Condenser

and a Fan Motor with a fan blade used for blowing or sucking air through the finned coil. We would also

find some electrical components and cables. The

outdoor unit is typically mounted on an external wall, the roof, and sunshade or skirting around the

building. The airconditioning engineer is careful

about how and where the outdoor unit is mounted.

Let us take a brief look at some of the key points.

5.12 Mounting, Safety and Serviceability

When the unit is wall mounted, we must ensure

that the wall to which the ODU support framework is grouted, is structurally sound and

is capable of supporting the load of the ODU.

This applies to any other structure on which the ODU is mounted.

We should also make sure that the ODU support

framework is properly designed, with a catwalk

to permit servicing and

A Safety Railing Must Be Provided Around The

Structure.

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5.13 Coastal Installations

Special care must be taken while installing ODUs on

the seacoast. We must ensure that

The condenser fan outlet is not facing the sea wind. This is done to reduce the risk of the fan

not running at all or losing speed while working

against the wind

The ODUs are not located near ground level,

close to the beach since sand can clog the

condenser coils

Care is taken to give the supporting framework a good quality anti corrosive paint treatment

(epoxy or chlorinated rubber paint) and

The isolator switch and electrical components are properly protected from moisture.

5.14 Installation Practices for Air-Cooled

Units

Copper Standards for Piping

We know that the Indoor Unit (IDU) of any Split

airconditioner is connected with the Outdoor unit

through refrigerant piping. Most often imported copper pipe is used for this purpose.

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Soft Drawn Copper Tubing is used for single

phase Non Ducted split airconditioners

Hard Drawn, L-Grade Copper Tubing is used for

3 Phase Ducted Splits/Packaged units

5.15 Length of Interconnecting Piping

We must always ensure that the right distance is

maintained between the IDU and ODU. There are limits to the distance between them imposed by the

equipment design. As the distance between the

units increases the following happens:

The refrigerant pressure drops, resulting in

decreased cooling capacity.

The lubricating oil does not return to compressor

damage (it is a good idea to the compressor

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provide an oil trap every 3 meters or so on the

suction line. This helps to return the lubricant to

the compressor along with the return gas easily,

leading to and The extra refrigerant required by long tubing can

lead to un-evaporated liquid refrigerant flowing

into the compressor thereby damaging it.

5.16 Refrigerant Pipe Insulation Refrigerant Piping carrying gas from evaporator

(cooling coil) to the compressor is known as Suction

line, and the piping carrying liquid refrigerant from the condenser to the evaporator is known as Liquid

line. The insulation requirement will depend on

where the metering device, usually a capillary or a expansion valve, is located.

If the metering device is located in the ODU the

Suction and liquid lines must be separately insulated

and gap maintained between the two lines. If however the device is located in the IDU, the

Suction and discharge lines must be insulated

together. CENTRAL PLANTS

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5.17 Direct Expansion and Chilled Water

Systems

Central Plants are usually large airconditioning

plants assembled at the site. These plants are used for big buildings such as hotels, theatres, hospitals,

large office complexes and factories. They are

designed for accurate control of all the parameters of comfort. As the name implies the Central Plant is

housed in a central location usually in a plant room.

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This plant room could be in a basement or adjacent

to the building to be airconditioned

Though the Central Plant can look quite complex

with large compressors pumps, gauges, miles of piping, ducts and cables, the basic components are

the same as smaller plants. Central plants comprise

of Compressors, condensers, Air-Handling Units, Water Chillers and cooling Towers.

As we see in the tree diagram for Central Plants, the

main divisions are those that use Direct Expansion

(DX) and those that use Chilled Water.

Direct Expansion (DX) System: In this system air

is cooled and conditioned in the plant room. This

treated air is then pumped to various parts of the building. The air returning from the airconditioned

area is sucked through a coil-fin arrangement by a

fan. Refrigerant inside the coil picks up heat from this air and evaporates. The cold air is then pumped

back to the airconditioned space. In DX plants the

place where this heat exchange takes place is called

an Air Handling Unit (AHU). This type of system typically uses ducting passing through the structure

to various parts of the building to be conditioned.

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Chilled Water System: Where Refrigerant and

water interaction takes place the system is called a -

Chilled Water System. The refrigerant in the shell

(or tube, depending on the design) of a shell & tube heat exchanger evaporates by picking up the heat

from the water which is in the other portion of the

heat exchanger. This chilled water, is then circulated to various water-air heat exchangers called Fan Coil

Units/ Air Handling Units. The system is also

preferred where multiple zones are to be cooled like

a hotel or hospital.

5.18 Compressors Used In Vapour

Compression Central Plants:

As we saw in the tree diagram for Central Plants, the main division were those that use the Direct

Expansion (DX) system and those that use Chilled

Water. Referring again to the diagram you will see

that the next level is divided into system using vapour compression units and those vapour

absorption system.

While the Vapour Absorption system uses a chemical reaction to produce low temperature/ the

Vapour Compression System uses a Compressor to

compress the refrigerant gas. These compressors are driven by an external motor. While smaller

central plants use one or two compressors, large

plants depend on a bank of such machines.

Generally two compressors are provided in tandem so that even when one is being serviced the other

one keeps working. Compressors are truly

remarkable machine built for extreme reliability and efficiency.

The type of compressors most widely used in

Central Plants are the Reciprocating type the Screw

Type and the Centrifugal type.

The Reciprocating Compressor: The reciprocating

compressor is similar to the two-stroke motorbike

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engine. It employs a crankshaft to drive

reciprocating pistons which compress the

refrigerant. These compressors are the most

common type of compressors used in India today are as well suited for application ranging from less

than a ton to 120 tons of airconditioning.

The Screw Type Compressor: The objective of any compressor is to reduce the volume of the

gaseous refrigerant. The screw type compressors

does it by using a pair of helical l shaped screws

which mesh while rotating and compress the volume of refrigerant gas as it travels from the inlet to the

discharge port. Screw compressors are popular in

capacities over 100 TR.

The Centrifugal Compressors: Centrifugal force is

that force which pushes you to the right of your car

when you are taking a sharp left turn. Or vice versa.

The centrifugal compressor employs one or more

rapidly spinning disks to force the refrigerant gas

from it's centre to its extremity thereby increasing pressure. These compressors are typically used for

application requiring tonnage ranging from 150 TR

to several thousand tons.

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5.19 Packaged Chillers

Many large airconditioning applications require

Chilled Water and depend on "Packaged Chillers" to

provide the chilled water. These chillers are typically mounted on a frame and comprises a compressor

with it's drive motor, a condenser (air or water

cooled) and a shell & tube heat exchanger. Depending on the type of compressor used these

chillers can be classified as a Reciprocating Chiller, a

Screw Chiller or a Centrifugal Chiller. Where the

absorption system is used the chillers are called Absorption Chillers.

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5.20 Packaged Chillers Installation Tips

A few precautions are to be taken when installing

Chillers

5.21 Air Cooled Chillers

Do not have obstruction on top of chillers (for

top discharge units)

Have at least 1-meter clearance on all sides adjacent to the chillers.

Support chiller weights on reinforced building

structure and not on slabs

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Ensure all electrical switch gear are in weather

proof enclosures.

Provide adequate vibration isolation between

chiller and building by using vibration absorbing

pads or springs.

5.22 Water Cooled Chillers

Have at least 1 to 1.5 meters clearance between

units

Leave space equal to condenser length for tube

cleaning

Air & Water Cooled Systems

5.23 Introducing the Condenser

Now that we have been introduced to the

compressor let us discuss the Condenser. If we

pause to think about it, we will notice that the airconditioning process is a series of heat transfers.

The heat from the conditioned space is transferred

via the refrigerant, the condenser and the cooling tower to the outside air.

In the air cooled system the heat from the

conditioned area is transferred to the cold

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refrigerant warming it up. This warm refrigerant

then sheds the heat to the air outside in the Air

Cooled Condenser.

In the water-cooled system the heat from the conditioned area is transferred to the cold

refrigerant warming it up. This warm refrigerant

transfers the heat to water in the Water Cooled Condenser thereby warming the water. This warm

water in turn transfers the heat to the atmosphere

through the cooling tower cooling tower.

5.23.1How the Condenser Is Cooled

There are two ways in which the condenser is

cooled:

By blowing or sucking Air through it in an Air cooled condenser and

By pumping water through in a Water Cooled

Condenser

5.23.2 How The Air Cooled Condenser Is

Cooled:

An air cooled condenser consists of a set of finned

copper tubes and a fan to blow or blow the air

through this finned coil arrangement. The hot gas flows through the condenser inside the tubes while

air is blown or sucked through the condenser inside

the tubes arrangement by a fan. The air which is normally at a temperature 10°C to 12°C lower than

the gas, picks up the heat from the gas making it

condense inside the tube. Air cooled condensers are

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very common for windows, split and packaged

airconditioners and are now becoming popular for

central plants also.

However, because of their superior efficiency, water-cooled plants are preferred, where adequate

water is available

5.23.3 How The Water Cooled Condenser Is Cooled:

In water cooled condenser water is pumped through

the tubes of a shell & tube condenser using a water

pump and the refrigerant is passed through the shell. This condenser is also called 'Heat Exchanger'

because this is where the refrigerant and water

exchange heat with each other. On giving away some of it's heat to the water, the refrigerant

condenses in the shell. The water, which gains some

heat in the heat exchanger travels to the „cooling

tower‟ where part of the water evaporates on contact with air, cooling the remaining water, which

is once again circulated through the heat exchanger.

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5.24 Cooling Towers

We learnt that in the water cooled air-conditioning

system the heat from the room is transferred to the

condenser, and from the condenser to the cooling water, which finally transfers the heat into the

atmosphere

In the Cooling Tower the water is sprayed through

nozzles into the air. The water becomes small droplets and evaporates thereby losing heat and

becoming cool. This cool water falls into a sump

tank at the bottom of the cooling tower from where it is pumped into the shell & tube condenser and the

cycle repeats again. The typical types of Cooling

Towers are:

Atmospheric or Natural Draft Towers. In these towers the water is sprayed into the tower and the

droplets of water cools in the natural air currents

passing through the cooling tower.

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Forced Draft Towers. These towers use a motor

and fan to pull or push a constant volume of air

through the tower, water is sprayed through nozzles

evaporating rapidly and cooling the rest of the water. The quality of water is very important for the

performance of the airconditioning system, hard

water causes scaling, thereby decreasing the efficiency of heat transfer in the condenser. Some

water is required to make up for the water which

evaporates and also the portion of the water that is

blown away by the wind. This is referred to as 'Make-up water‟. Water cooled condensers and

cooling towers are normally used where water is

available in plenty.

5.25 Air Handling Units

The Air Handling Unit (AHU) is a centrifugal type fan

that pumps air. The fan is usually located in the Air

Handler/Water Coil Cabinet. Its purpose is to create a pressure differential so that the air from the

conditioned space is drawn to the unit. The air is

passed through a filter first to remove dust particles

and then over the cooling coils or chilled water

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tubes where the heat is rejected. This cooled and

dehumidified air is then drawn into the suction side

of the fan and discharged back into the conditioned

space. A damper arrangement in the suction side of the AHU is kept a little open to draw in fresh air.

The typical AHU is a steel sheet cabinet which

houses the Cooling Coil and the blower fan. The motor is mounted on the outside of the cabinet and

drives the blower by pulley-belt arrangements.

Depending on their application, AHUs vary in size

from small/medium sized packaged units to large

walk-in models.

There are two types of AHUs, the 'single skinned'

and the 'double skinned' type.

The 'single skinned' AHUs are widely used. They

have a single layer cabinet and are usually placed

inside an AHU room. It is advisable to insulate the

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room so that the air in the AHU does not pick up

heat from the outside warm air. Keeping the AHU in

an insulated room also reduces the sound levels in

the conditioned space.

The 'double skinned' type has an inner cabinet and

the outer cabinet. A layer of thermal insulation is

sandwiched between the two cabinets. Though these AHUs are more expensive than the single

skinned type, they have the following advantages:

Because of the Insulation, the cool air inside

does not gain heat from the surrounding air thereby improving the efficiency of the plant.

They are more silent because the thermal

Insulation also acts like an acoustic insulation.

They do no „sweat' on the outside and can be

kept in the non- airconditioned space thereby

saving on the cost of a separate plant / AHU room.

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5.26 Fan Coil Units

The Fan Coil Unit (FCU) is a sheet metal cabinet that

houses a Chilled Water Coil constructed out of

copper tubes and aluminium fins, a Blower with motor and an Air Filter, Fan Coil Units are generally

used where multiple areas (example, hotel rooms)

are to be cooled independently using a central airconditioning plant.

The water is chilled centrally and pumped to various

parts of the building through insulated pipes. The

chilled water enters the FCU where exchange takes place between the room air and the chilled water in

the coil. Air is passed over the coils using a three-

speed blower motor, mounted in the FCU. The air speed can be controlled by choosing the blower

motor speed, from a selector switch, in the

conditioned space.

A thermostat is also mounted in the airconditioned space. The thermostat controls a solenoid valve that

closes when the desired temperature is reached,

thereby shutting off the flow of chilled water into the FCU water coil. Once the temperature in the room

rises the thermostat activates the solenoid valve

which opens allowing the chilled water to flow into the coil again

5.27 Ducts, Grilles & Diffusers

Ducts are usually Galvanised Sheet Steel or

aluminium sheets shaped into rectangular boxes or

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round tubes. They are used to distribute the cool air

from the Air Handling Unit (AHU), uniformly

thorough out the building to be airconditioned. They

start at the AHU, or the packaged airconditioner, and travel to the spaces to be conditioned carrying

the cool air.

Diffusers And Grilles: The conditioned supply air arrives through the ducts at the supply air diffusers

and enters the conditioned space. Most diffusers are

attached to the false ceiling and a variety of

diffusers are available for different air spreading needs. For well distributed cooling, an airflow

pattern needs to be created in the conditioned

space. The design engineer takes care to separate the supply air diffusers and the return air grilles to

prevent short circuiting of the air. Return air usually

flows into the plenum or return air box through grilles placed in the false ceiling.

Return Air: Since a substantial amount of energy

goes into cooling the air in the first place, it is a

practice to recycle the air. The air is therefore brought back to the AHU, or the packaged

airconditioned, using return air ducts. It is common

to route the return air through the gap between the false ceiling and the main ceiling, a space referred

to as a 'plenum'. It is desirable wherever possible to

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pass the supply air duct through the return air

plenum, because this works like a heat exchanger,

thereby improving the efficiency of the plant.

Sometimes a separate system of return air ducts/boxing is employed to carry the return air

instead of using the plenum. Where the supply air

ducts do not pass through the plenum they are usually insulated so that cool air does not pick up

heat from the warmer surroundings.

Fresh Air Intake: A certain volume of fresh, outside air is sucked into the building near the AHU

This air is usually drawn in through a, damper'

which is adjusted to allow the specified volume of

air into the building, This keeps the air pressure within the building a little higher than the outside air

pressure. This prevents dusty, moist or any

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undesirable external air from infiltrating into the

building.

5.28 Co-Ordination between Designer and

Airconditioning Engineer

The vertical and horizontal distribution of air supply

system is a major design issue requiring co-

ordination between the architect and the engineer.

It would be advisable to select the basic system during the early phase of building design. This is

because ducting requires taking the optimum route

in the space between the false ceiling and the main ceiling avoiding obstructions such as beams,

columns and partition walls

5.29 Modern Trends in Design and

Fabrication of Ducts

Most contractors fabricate the ducting on site

according to drawings provided by design engineers.

In recent times however I computer aided design of ducting is being used to determine the optimum

duct dimensions.

Modern facilities are being set up to manufacture

machine made ducts These ducts are pre-fabricated and shipped to the site for quick and convenient

assembly, Though these pre-fabricated ducts cost

more than the hand made ones, they have the following advantages:

Least disturbance at site because ducts come

ready made

Less space required for storage of pre-fabricated

sections

Minimum leakage and vibration noise

Better designed reinforcement

Consistent quality because of standardised

material at factory

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5.30 Fresh Air

Freshening The Air: One of the most important

factors in delivering comfort is the freshness of the

conditioned air. If the same air was circulated over and over again it would become 'stale' and make

the occupants very uncomfortable. Ideally an

airconditioning system would induce plenty of fresh air into the air system. However this outside air

brings with it moisture and heat from outside. This

causes the heat load on the airconditioning system

to go up thereby requiring a larger and consequently more expensive plant.

Substantial research has been done to determine

the optimum requirement of fresh air for different application and the airconditioning engineer designs

the plant accordingly. Usually the fresh air

requirements are stipulated as cubic feet per minute

(cfm) per person or minimum air changes per hour. A guide on recommended Fresh Air requirements is

given below:

5.31 Sick Building Syndrome

Airconditioning systems must do more than provide

immediate comfort conditions. They must also be

designed to prevent hidden negative affects on the occupants over a period of time. Indoor Air Quality

(AIQ) is becoming an important concern and one

hears the term 'Sick Building Syndrome' (SBS)

frequently these days. The effects of IAQ are usually non-specific symptoms rather than clearly defined

illness. Symptoms attributed to IAQ problems

include headache, nausea, shortness of breath, sinus congestion, cough and eye-nose & throat

irritation. The solution often lies in improvement of

the air quality by introducing plenty of fresh clean

air into the building and reducing the noise of air-flow and machinery.

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5.32 Changes in Fresh Air Requirement

Over The Years

It is interesting to see how the specified fresh air

requirements changed over the years. In 1824 the recommendation was 4 cubic feet per minute (cfm)

per person. In 1893 The American Society of

Heating Refrigeration and Airconditioning Engineers

(ASHRAE) changed the specification to 30 cfm. In 1936 it went down to 10 cfm which was considered

the threshold level for detecting human body

odours. In the early seventies with the energy crisis forcing the world into fuel economy the figure went

way down to 5 cfm. Then in the Eighties the growing

concern about indoor air quality prompted the society to raise the quantity of fresh air to 15 cfm

5.33 Filtration and Filters In order to clean the air it is passed through filters

that remove the airborne dust particles and ensure

delivery of clean air to the conditioned spaces. We

have seen how important the quality of air is in the

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airconditioning system and filters play an important

part in delivering good air quality. The filters keep

the cooling coils from clogging thereby maintaining

the efficiency of heat transfer. Without a good air filtration system the diffusers in the rooms 'streak'

and fluorescent lamps gather a film of dust that cuts

illumination. Dust choked filters interfere with the performance of the air system. It is therefore very

important to clean or replace the filters periodically.

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5.34 Pleated Panel Type Filter

The typical filter in use is the Pleated Panel type also

known as the Synthetic Media Etended Surface type

filter. The pleated panel type filter consists of a

porous fabric like material folded like an accordion (to Increase the surface area) and fitted into a

frame

5.35 Noise & Noise Control in Airconditioning

Sound is a result of vibration of air. When sound is

unpleasant it is referred to as' Noise In an

airconditioning system sound emanates from the machinery such as fans, fan motors, compressors,

pumps, air flow through ducts and diffusers, pipes &

tubes and cooling tower fans The solutions are a) to reduce the original source of the sound by using

well designed equipment; b) enclose the source in

acoustically insulated space; and c) to absorb the sound using sound tower fans.

It is a practice to mount vibration-producing

machinery on anti- vibration mounts such as

cork, rubber, springs and 'cushioned feet‟. Plant rooms are acoustically insulated to prevent

machinery sound from permeating into the

airconditioned space.

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Ducts are fitted with sound attenuators which

work somewhat like the mufflers in the exhaust

pipe of a car. In addition, acoustic insulation is

used on some portions of the duct, near the AHU discharge, where it is most prone to making

noise.

Pipes are insulated from the wall it passes through so that the vibrations are not passed

into the structure.

Cooling towers using Axial Fans are a little more

noisy than those using Centrifugal fans. In the induced draft cooling tower the sound is higher

at the fan discharge side of the tower desirable

to arrange the fan discharge side in such a way that windows do not overlook it.

Inside the conditioned space, some noise can

make an entry through the diffusers. Carpets and curtains inside the space help to dampen

sound.

Locating the plant room properly will help reduce

noise levels within the conditioned space.

5.36 Saving Energy on Airconditioning

In any commercial airconditioned building the

airconditioning system generally consumes the maximum power. Taking a little care to minimise

energy consumption will result in substantial savings

in the long run Energy savings can be made by

Adopting an energy-efficient building design

Using energy-efficient airconditioning systems

and

Regular maintenance and effective utility management.

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5.37 Building Design:

rientation of the building plays a key role In the

structure's airconditioning requirement. Excessive

use of glass especially on the western side adds high airconditioning heat loads. Using materials such

as foam concrete, double wall glazing, hollow

concrete blocks, or foam insulated roofing will help improve the insulation of the building and save

energy.

5.38 Energy Efficient Airconditioning

Equipment:

It is advisable to go In for equipment with the best

Energy Efficieny Ratio (EER). Though initial capital

may be higher, the user will save energy

continuously thereby saving expenses in the long run. Packaged airconditioners/Ducted Splits are

available with Reciprocating Compressors as well as

Scroll Compressors. Scroll Compressors are capable of higher EER and hence save on energy. For higher

tonnages Screw and Centrifugal equipment are most

preferred because of low operating costs. Where heat source such as steam or hot water is available

as a by product or economically, Absorption type

units are a good energy saving choice.

5.39 Effective Maintenance and Utility Management:

Regular maintenance will ensure efficient

performance. Cleaning of filters, de-scaling of the heat exchanger, lubricating friction points, such as

fans, motors and shafts, should be done regularly.

Prudent utility management will save substantial

energy on the airconditioning. Simple measures like isolating areas of the building not in use, setting

indoor temperatures in the highest point acceptable

to the largest segment of occupants, and shutting off the system when not in use will save energy.

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Assignment:

Discussion and case studies with respect to types of

air conditioning – split , central.

Students to prepare schematic plans for various air-conditioning systems used in different working

environments such as a small office, drawing room

of a residence etc.

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Summary: Air-conditioning deals with various types of heats

and the process is a series of heat transfers. The

heat from the conditioned space is transferred via the refrigerant, the condenser and the cooling tower

to the outside air.

Over the years, different Air conditioning Systems have evolved to suit different needs. The emergence

of new technologies, environment conditions and

the availability of space have all played a part in

shaping the air conditioning system of today. Many types of air conditioning systems are available – the

ductable and the non ductable systems.

Further, the air distribution systems , namely the ducts , grills , diffusers etc. are used to distribute

cool air throughout the building. Regular

maintenance of the above is a must to ensure

efficient performance.

Revision points: 1. What is air-conditioning

2. Various types of heats 3. The cooling cycle of air-conditioning.

4. Various typess of air-conditioning systems

5. The air distribution systems

Key words: 1. Air-conditioning

2. Sensible heat and latent heat

3. Ton 4. A.H.U.

In text questions: 1. What is air conditioning? Explain in detail the

various types of heats. 2. What is heat load estimation?

3. What are air-handling units?

4. Define the following: 5. Cooling tower

6. A.H.U.

7. Grills and diffusers. 8. Split A.C.

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Terminal exercises: 1. Explain with the help of a sketch the cooling

cycle of an air conditioner.

2. Explain in detail the various types of split air conditioners.

3. What are ductable airconditioning systems?

Explain in detail. 4. Explain in detail the various types of

compressors in a window AC.

5. What points would you keep in mind while

installing a split air conditioner? 6. What are central plants? Explain in detail the

various types of central types.

7. How is the condenser cooled in an airconditioning system?

8. Write a detailed note on the types of grills and

diffusers available in the market today.

9. What kind of airconditioning systems would you recommend for the following areas. Give reasons

for your choice.

10.Drawing room of a residence 11.A hotel suite

12.Restaurant

13.A small office 14.How do you control noise in an air-conditioned

environment?

Suggested reading:

1. Time Savers Standards For Buildings Types 2. Time Savers Standards For Interior design and

Space Planning.

3. Building Construction by S.K Sharma

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Unit - IV

Lesson-6: Fire Protection

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Lesson – 6: Fire Protection

Objective:

To study major causes of fire in a building.

To understand the aspects of fire safety and

important characteristics of fire resistant

materials.

To be familiar with fire extinguishing

equipments.

Structure:

6.1 Introduction

6.2 Causes of fire

6.3 Characteristics of Fire Resisting Materials

6.4 Fire-Resisting Properties of Common Building

Materials

6.5 General Fire Safety Requirements for

Buildings

6.6 Fire Resistant Construction

6.6.1 Walls and columns

6.6.2 Floors and roofs

6.6.3 Wall Openings

6.6.4 Escape Elements

6.6.5 Strong room construction

6.7 Fire Alarms

6.8 Fire Extinguishing Equipments

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6.1 Introduction

No building material is perfectly fire proof. Every

building contains some materials (such as furniture,

clothing, eatables etc.) which can either easily catch fire or which are vulnerable to fire. However, the

endeavour of the architects and engineers should be

to plan, design and construct the building in such a way that safety of occupants may be ensured to the

maximum possible extent in the event of outbreak

of fire in the building due to any reason whatsoever.

The technical interpretation of fire safety of building is to convey the fire resistance of buildings in tern

IS of hours when subjected to fire of known

intensity. It should have structural time interval so that adequate protection to the occupants is

afforded. A wider interpretation of fire safety may

be deemed to cover the following aspects:

a) Fire prevention and reduction of number of outbreaks of fire,

b) Spread of fire, both internally and externally,

c) Safe exit of any and all occupants in the event of an out-break of fire, and

d) Fire extinguishing apparatus.

6.2 Causes of fire

Most fires are caused by carelessness. Common

instances of carelessness are:

a) Careless discarding of lighted ends of cigarettes,

cigars, matches and tobacco,

b) Smoking in unauthorised places.

c) Indifferent maintenance of machinery including

overloading and under or over lubricating of bearings,

d) General indifference to cleanliness,

e) Incorrect storage of materials,

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f) Faulty workmanship and inattention to electrical

installations (this is particularly evident by the

fires which occur during the monsoon),

g) Un-approved equipment and layout,

h) Inattention of persons concerned with inspection

and patrol of the premises under their

jurisdiction, and

i) Inattention of fire safety regulations, etc.

In case of an outbreak of fire, the danger is from

fire, smoke and panic. The provision of suitable

means of escape should be in relation to these dangers and the number of persons affected. The

chances of damage due to panic can be reduced;

the escapes should be located in such a way that they remain unobstructed by smoke or fumes. The

means of escapes from fire should be easily

accessible, unobstructed and clearly defined.

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6.3 Characteristics of Fire Resisting

Materials

An ideal fire resisting material should possess the

following characteristics:

1. The material should not disintegrate under the

effect of great heat.

2. The expansion of the material due to heat should

not be such that it leads to instability of the structure of which it forms a part.

3. The contraction of the material due to sudden

cooling with water (during fire extinguishing process) after it has been heated to a high

temperature should not be rapid.

In relation to fire, building materials can be divided into two types:

a) Non-combustible materials: Non-combustible

materials are those which if decomposed by heat

will do so with absorption of heat (i.e. endothermically) or if they do oxidise, do so with

negligible evolution of heat. These materials do

not contribute to the growth or spread of fire, but are damaged and decomposed when high

temperatures are reached. Examples of non-

combustible materials are: stones and bricks, concrete, clay products, metal, glass etc.

b) Combustible materials: Combustible materials

are those which, during fire, combine

exothermically with oxygen, resulting in evolution of lot of heat and giving rise to flame

or glow. Such materials burn and also contribute

to the growth of fire. Examples of these materials are: wood and wood products,

fibreboard, straw board etc.

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6.4 Fire-Resisting Properties of Common

Building Materials

1. Stone: Stone is a non-combustible building

material and also a bad conductor of heat and does not contribute to the spread of fire.

However, it is a bad fire-resisting material since

it is liable to disintegrate into small pieces when

heated and suddenly cooled, giving rise to failure of structure. Granite, on exposure to severe

heat, explodes and disintegrates. Limestone is

the worst, since it is easily crumbled even under ordinary fire. Sand stone of compact composition

(fine grained) can, however, stand the exposure

to moderate fire without serious cracks. In general, the use of stone in a fire-resisting

construction should be restricted to a minimum.

2. Bricks: Brick is a poor conductor of heat. First

class bricks moulded from good clay can stand

exposure to fire for a considerable length of time, upto temperatures of about 1200°C. Brick

masonry construction, with good mortar and

better workmanship, is the most suitable for safeguarding the structure against fire hazards.

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3. Concrete: The behaviour of concrete during

exposure to heat varies with the nature of coarse

aggregate and its density, and the quality of

cement. It also depends upon the position of steel in concrete. Aggregates expand on heating

while ordinary cement shrinks on heating. These

two opposite actions may lead to spalling of the concrete surface. Aggregates obtained from

igneous rocks containing higher calcareous

content, tend to crack more while the aggregates

like foamed slag, cinder and bricks are better. The cracks formed in concrete generally extend

to a depth of about 25 mm. Hence reinforced

concrete fire-resistant construction should have greater cover. In general, concrete offers a much

higher resistance to fire than any other building

material. Reinforced concrete structures can withstand fire lasting for several hours with a

temperature of 1000°C without serious damage.

4. Steel: Though steel is non-combustible, it has

very low fire resistance, since it is a good conductor of heat. During fire, it gets heated

very soon, its modulus of elasticity reduces and

it looses its tensile strength rapidly. Unprotected steel beam sags and unprotected columns or

struts buckle, resulting in the collapse of

structures. If the surface paint on these steel components is not fire resistant structure, it is

essential to protect structural steel members

with some coverings of insulating materials like

brick, terra-cotta, concrete etc. Fixing of steel in plate or sheet form to the structural steel

framework is also effective in resisting the

passage of flame. Such construction is widely used in making fire-resisting doors and windows.

5. Glass: Glass is poor conductor of heat, and its

thermal expansion is also less. When it is heated and then suddenly cooled, cracks are formed.

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These cracks can be minimised if glass is

reinforced with steel wire netting. Thus,

reinforced glass is more fire resistant, and can

resist variations in temperature without serious cracks. Rein- forced glass has higher melting

point. Even if cracks are formed, the embedded

wires hold the cracked portion in position. Reinforced glass is therefore commonly used for

fire-resisting doors, windows, done skylights,

etc.

6. Timber: Timber is a combustible material. It ignites and gets rapidly destroyed during fire, if

the section is small. However, if timber is used in

thick sections, it possesses the properties of self-insulation and slow burning. During exposure to

fire, timber surface gets charred; this charred

portion acts as protective coating to the inner portion. However, if the temperatures are higher

than 500°C, timber gets dehydrated under

continued exposure, giving rise to combustible

volatile gases which readily catch fire. In order to make timber fire-resistant, the following

measures are adopted:

i. Use of thicker sections at wider spacing than thinner sections at closer spacing, especially

in case of floor joints.

ii. Reducing number of comers and area of exposed surfaces to a minimum.

iii. Coating timber surface with chemicals like

ammonium phosphate and sulphate, borax

and boric acid, zinc chloride,

iv. Painting timber surfaces with asbestos or

ferrous oxide paints, if painting is necessary.

Painting these with oil paints or varnish should not be done since these paints catch

fire.

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7. Cast-iron and wrought iron: Cast iron

behaves very badly in the event of fire. On

sudden cooling, it gets contracted and breaks

down into pieces or fragments, giving rise to sudden failure. Hence it is rarely used in fire-

resistant building unless suitably covered by

bricks, concrete etc. Wrought iron behaves practically in the same way as mild steel.

8. Asbestos cement: It is formed by combining

fibrous asbestos with Portland cement. It has low

coefficient of expansion and has property of incombustibility. It has, therefore, great fire-

resistance. Asbestos cement products are largely

used for construction of fire-resistant partition walls, roofs, etc. It is also used as protective

covering to other structural members.

9. Aluminium: It is very good conductor of heat. It has very poor fire-resistant properties. Its use

should be restricted to only those structures

which have very fire risks.

10.Plaster or mortar: Plaster is non-combustible. Hence it should be used to protect walls and

ceilings against fire risk. Cement plaster is better

than lime plaster since the latter is likely to be calcined during fire. Using it in thick layers or

reinforcing it with metal laths can increase the

fire-resistance of plaster. Gypsum plaster, when used over structural steel members, makes them

better fire-resistant.

6.5 General Fire Safety Requirements for

Buildings

In order that the fire hazards (i.e. personal hazard,

internal hazard and exposure hazards) are

minimised, it is recommended that the buildings

shall conform to the following general requirements:

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1. All buildings and particularly buildings having

more than one storey shall be provided with

liberally designed and safe fire- proof exits or

escapes.

2. The exits shall be so placed that they are always

immediately accessible and each is capable of

taking all the persons on that floor, as alternative escape routes may be rendered

unusable and/or unsafe due to fire.

3. Escape routes shall be well ventilated as persons

using the escapes are likely to be overcome by smoke and/or fumes which may enter from the

fire.

4. Fire-proof doors shall conform rigidly to the fire safety requirements.

5. Where fire-resisting doors are employed as cut-

offs or fire breaks, they shall be maintained in good working order so that they may be readily

opened to allow quick escape of persons trapped

in that section of the building, and also, when

necessary, prompt rescue work can be expeditiously carried out.

6. Electrical and/or mechanical lifts, while reliable

under normal conditions may not always be relied on for escape purposes in the event of a

fire, as the electrical supply to the building itself

may be cut-off or otherwise interrupted, or those relying on mechanical drive may not have the

driving powder available.

7. Lift shafts and stairways invariably serve as flues

or tunnels thus increasing the fire by increased drought and their design shall be such as to

reduce or avoid this possibility and consequent

spread of fire.

8. False ceiling, either for sound effects or air-

conditioning or other similar purpose shall be so

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constructed as to prevent either total or early

collapse in the event of fire so that persons

underneath are not fatally trapped before they

have the time to reach the exits; this shall apply to cinemas, and other public or private buildings

where many people congregate.

9. To a lesser extent, the provisions of clause (8) above shall apply to single-storey buildings

which may be used for residence or an

equivalent occupancy. Whatever be the class or

purpose of the building, the design and construction shall embody the fire retardant

features for ceilings and/or roofs.

10.Floors. Floors are required to withstand .the effects of fire for the full period stated for the

particular grading. The design and construction

of floors shall be of such a standard that shall obviate any replacement, partial or otherwise,

because experience shows that certain types of

construction stand up satisfactorily against

collapse and suffer when may first be considered as negligible damage, but in practice later

involves complete stripping down and either total

or major replacement. This consideration shall also be applied to other elements of structure

where necessary.

11.Roofs. Roof for the various fire-grades of the buildings shall be designed and constructed to

withstand the effect of fire for the maximum

period for the particular grading, and this

requires concrete or equivalent construction. It is, however, important that maximum endurance

is provided for as stated above.

12.Basements. Where basements are necessary for a building and where such basements are used

for storage, provision shall be made for the

escape of any heat arising due to fire and for

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liberating and smoke which may be caused. It is

essential that fire resistance of the basement

shall conform to the highest order and all

columns for supporting the upper structures shall have a grading not less than laid down in types 1

to 3.

13.Smoke extraction from basements: The following requirements shall be provided for

smoke extraction:

a) Unobstructed smoke extracts having direct

communication with the open air shall be provided in or adjoining the external walls and in

positions easily accessible for firemen in an

emergency.

b) The area of smoke extracts shall be distributed,

as tar as possible, around the perimeter to

encourage flow of smoke and gases where it is impracticable to provide a few large extracts, for

example, not less than 3 m2 in area, a number

of small extracts having the same gross area

shall be provided.

c) Covers to the smoke extracts shall, where

practicable, be provided in the stall board and/or

pavement lights at pavement level, and be constructed of light cast iron frame or other

construction which may be readily broken by

fire-men in emergency. The covers shall be suitably marked.

d) Where they pass through fire resisting

separations, smoke extracts shall in all cases be

completely separated from other compartments in the building by enclosures of the appropriate

grade of fire resistance. In other cases, steel

metal ducts may be provided.

e) Where these are sub-basements, the position of

the smoke extracts from sub-basements and

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basements shall be suitably indicated and

distinguished on the external faces of the

building.

6.6 Fire Resistant Construction

In a fire resistant construction, the design should be

such that the components can withstand fire as an

integral member of structure, for the desired period. We shall consider the construction of the following

components:

6.6.1 Walls and columns:

The following points should be observed for making walls and columns fire-resistant:

i. Masonry walls and columns should be made

of thicker section so that these can resist fire for a longer time, and can also act as barrier

against spread of fore to the adjoining areas.

ii. In the case of solid load-bearing walls, bricks

should be preferred to stones.

iii. If walls are to be made of stone, granite and

limestone should be avoided.

iv. In the case of building with framed structure, R.C.C. should be preferred to steel.

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v. If steel is used for the framed structure, the

steel structural components should be

properly enclosed or embedded into concrete,

terracotta, brick, gypsum plaster board or

any other suitable material, as illustrated in the figure below:

vi. If the framework is of R.C.C., thicker cover

should be used so that the members can resist fire for a longer time. It is

recommended to use 40 to 50 mm cover for

columns, 35 to 40 mm cover for beams and

long span slabs and 25 mm for short span slabs.

vii. Partition walls should be of fire-resistant

materials such as R.C.C., reinforced brick work, hollow concrete blocks, burnt clay tiles,

reinforced glass, asbestos cement boards or

metal laths covered with cement plaster.

viii. Cavity wall construction has better fire

resistance.

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ix. All walls, whether load bearing or non-load

bearing, should be plastered with fire-

resistive mortar.

6.6.2 Floors and roofs:

The following points are note-worthy for fire-

resistant floors and roots:

i. For better fire resistance, slab roof is preferred to sloping or pitched roofs.

ii. If it is essential to provide sloping roof,

trusses should either be of R.C.C. or of

protected rigid steel with fireproof covering.

iii. For better fire resistance, the floor should be

either of R.C.C. or of hollow tiled ribbed floor

of concrete jack arch floor with steel joists embedded in concrete.

iv. If floor is made of timber, thicker joists at a

greater spacing should be used, and fire stops

or barriers should be provided at suitable interval.

v. The flooring materials like concrete tiles,

ceramic tiles, bricks etc. are more suitable for fire resistance.

vi. If cast iron, wrought iron, cork carpet, rubber

tiles etc. are to be used, these should be protected by a covering of insulating

materials like ceramic tiles, plaster,

terracotta, bricks etc.

vii. Ceiling, directly suspended from floor joists should be of fire resistant materials like

asbestos cement boards, fibre boards, metal

lath with plaster etc.

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6.6.3 Wall Openings

i. From the point of view of fire spread,

openings in the walls should be a bare

minimum.

ii. Openings serve means of escape. Hence

these should be properly protected by

suitable arrangements, in case of fire.

iii. Doors and windows should be made of steel.

Fire- resistant doors can be obtained by fixing

steel plates to both the sides of the door.

iv. Wire-glass panels are preferred for windows.

v. Rolling shutter doors should be used for

garages, godowns, shops etc.

vi. In case of timber doors, minimum thickness of door leaf should be 4 cm. and that of door

frame as 8 to 10 cm.

vii. All escape doors should be such as to provide

free circulation to the persons in passages, lobbies, corridors, stairs etc., and should be

made of fire proofing material.

6.6.4 Escape Elements

i. All escape elements, such as staircases,

corridors, lobbies, entrance etc. should be

constructed of fire-resistant materials.

ii. These escape elements should be well

separated from the rest of the building.

iii. Doors to these escapes should be fire proof.

iv. Staircases should be located next to the outer wall and should be accessible from any floor

in the direction of flow towards the exits from

the building.

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v. Fireproof doors to the emergency staircases

should be fixed in such a way as to make

them close from inside only.

vi. The lift shafts connecting various floors should be surrounded with the enclosure

walls of fire-resisting materials.

vii. Lift shafts should be vented from top to permit escape of smoke and hot gases.

viii. An emergency ladder should be provided in

the fire- resisting building. This ladder should

be at least 90 cm wide, constructed of fire-resistant materials.

ix. All escape routes over roofs should be

protected with railings, balustrades or parapets not 1ess than one metre in height.

6.6.5 Strong room construction:

A strong mom construction is found to be useful in

case of safe deposit vaults in banks, Following are the important features of construction:

i. The walls, doors and ceilings of a strong room

are made of atleast 30 cm thick cement concrete. If thin R.C.C. walls are used, they

should have a covering of bricks or terra cotta

and then suitably plastered with fire-resistant plaster.

ii. Doors and windows are well anchored to

concrete walls by large number of steel

holdfasts longer in length.

iii. Doors and windows should be fireproof. It is

preferable to have double fireproof door.

iv. Windows and ventilators should be covered by special grills made of 20 mm steel square

bars. These grills should be well fixed to

concrete walls by means of long steel holdfasts.

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6.7 Fire Alarms

Fire alarms are installed to give an alarm and to call

for assistance in event of fire. The fire alarms give

enou2h time to the occupants to reach to a safe place. Fire alarms call be either manual or

automatic.

1. Manual alarms: These are of a hand-bell type or similar other sounding device, which can emit

distinctive sound when struck. These are

sounded by watchmen and the occupants are

thereby warned to have safe exit in shortest possible time. Manually operated alarms shall be

provided near all main exits and in the natural

path of escape from fire, at readily accessible points which are not likely to be obstructed.

2. Automatic alarms: These alarms start sounding

automatically in the event of fire. It is used in

large industrial buildings which may remain unoccupied during nigh1. The automatic fire

alarm sends alarm to the nearest control point.

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MANUAL ALARMS AND AUTOMATIC ALARMS

The system can also perform the function of sending message to the nearest fire brigade station.

6.8 Fire Extinguishing Equipments

Each building should have suitable fire extinguishing

arrangements, depending upon the importance of the building and the associated fire hazards.

Following are usual equipments required for fire

extinction.

1. Manual fire extinguishing equipment: These

devices are useful for extinguishing fire as soon

as it starts. They are not so useful when once the fire ha~ spread. Under this category comes

the portable extinguishers of carbon-dioxide type

or foam generation type etc. The discharge from

a portable fire extinguisher lasts only for a short duration of 20 to 120 seconds. In some cases,

especially in small buildings buckets of water,

sand and asbestos blanket may be kept ready at

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all times to extinguish fire. These buckets are

installed at convenient locations for taking care

of fire of minor size.

2. Fire hydrants: These fire hydrants are provided

on a ring main of 150 mm dia. in the ground

around the building periphery. The ring main gets water from underground tank with pressure,

so that available pressure at each hydrants is of

the order of about 3.5 to 4 kg/cm.

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3. Wet riser system: The system consists of

providing 100 to 150 mm dia. vertical G.I. pipes

(risers) at suitable locations in the building. A

fire pump is used to feed water from underground tank to these pipes, to ensure a

pressure of 3 kg/cm2 at uppermost outlet.

4. Automatic sprinkler system: This

arrangement is adopted for important structures

like textile mills, paper mills etc. The system consists of a network of pipes 20 mm dia. fixed

to the ceiling of the room. These pipes are

spaced at 3 m centre to centre. Heat actuated sprinkler heads are fixed to these pipes at

regular interval. The pipes get supply from a

header.

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5. Each sprinkler head is provided with fusible plug.

In the event of fire, the fusible plug in the

sprinkler nearest to the wire melts due to rise of temperature, and water gushes out of the

sprinkler head. The fire is thus brought under

control in a short period.

Assignment:

Students to do a case study / survey related

to various fire extinguishing and fire fighting

equipment.

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Summary:

Safety of the occupants in the event of outbreak of

fire is a major concern for designers. Thus

maximum use of non combustible materials should be encouraged and the construction should be fire

resistant. In addition to this, particularly in multi-

storeys, it is obligatory to make provision of fire detection and fire extinguishing systems.

Revision Points:

Major causes of fire

Fire-Resisting Properties of Common Building Materials

Fire resistant construction

Fire extinguishing equipment.

Key Words:

Fire alarms

Fire hydrants

Combustible materials

In Text Questions:

1. What are the aspects of fire safety?

2. Write down the fire resisting properties of the

following materials:

i. Bricks

ii. Glass

iii. Stone

iv. Timber

v. Concrete

Terminal Exercises:

1. Explain in detail the major causes of fire in a

building.

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2. What are the characteristics of a fire resistant

material? Explain in detail.

3. What are the general fire safety requirements of

a building? Explain in detail.

4. What is fire resistant construction? Explain in

detail the various ways in which you can make a

building fire resistant.

5. Explain in detail the various types of fire alarms

and fire extinguishing equipment.

Suggested Reading:

1. Building Construction by Sushil Kumar

2. Building Construction by Dr. B.C. Punmia

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Unit - V

Lesson-7: Lifts

Lesson-8: Escalators

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Lesson – 7: Lifts and

Elevators

Objective:

To understand the brief history of vertical

transportation.

To study various types of lift and the design

considerations for a lift

Structure:

7.1 Introduction

7.2 Types of lifts

7.2.1 Observation lift

7.2.2 Double-deck lift

7.2.3 Sky lobby

7.2.4 Freight lifts

7.2.5 Residential lifts

7.3 Design Considerations

7.3.1 Number of Lifts and Capacity

7.3.2 Positioning of Lift

7.3.3 Shape and Size of Lift Car

Positioning of Machine Room

7.1 Introduction

The need for vertical transport is as old as

civilisation. Over the centuries, mankind has employed ingenious forms of lifting. The earliest lifts

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used man, animal and water power to raise the

load. Lifting devices relied on these basic forms of

power from the early agricultural societies until the

dawn of the Industrial Revolution. In ancient Greece, Archimedes developed an

improved lifting device operated by ropes and

pulleys, in which the hoisting ropes were coiled around a winding drum by a capstan and levers.

By A.D. 80, gladiators and wild animals rode crude

lifts up to the arena level of the Roman Coliseum.

Medieval records contain numerous drawings of hoists lifting men and supplies to isolated locations.

Among the most famous is the hoist at the

monastery of St. Barlaam in Greece. The monastery stood on a pinnacle approximately 61 metres (200

ft) above the ground. Its hoist, which employed a

basket or cargo net, was the only means up or down.

At an abbey on the French seacoast, a hoist was

installed in 1203 that used a large tread wheel. A

donkey supplied the lifting power. The load was raised by a rope wound on a large drum.

By the 18th century, machine power was being

applied to the development of the lift. In 1743, a counterweighted personal lift was commissioned by

Louis XV in France for his personal chambers in

Versailles. By 1833, a system using reciprocating rods raised and lowered miners in Germany‟s Harz

Mountains. A belt-driven lift called the “teagle” was

installed in an English factory in 1835. The first

hydraulic industrial lift powered by water pressure appeared in 1846. As machinery and engineering

improved, other powered lifting devices quickly

followed. Lifts are a mechanism for moving people from floor

to floor in a multi-storied building. Electric lifts

consist of an enclosed cab (lift car), fastened to one end of steel cables. The cables go up and over a

grooved drive wheel (sheave) and down to a

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counterweight of cast iron blocks that

counterbalance the weight of the car. An electric

motor supplies power to move both car and

counterweight guided between steel guide rails in an enclosed shaftway. Button controls in the lobby or

floor bring the lift to the rider. Push button controls

inside the car allow the riders to select the desired floor. Hydraulic lifts use a plunger that moves up

and down to operate the lift car instead of steel

cables, by a motor pumping hydraulic oil in and out

of the plunger cylinder. The car and hall push buttons on both types of lifts do the same function.

For multi-storeyed buildings the installation of lifts is

a must to avoid fatigue in climbing up the stairs and for quick vertical circulation between different floors.

The provision of lifts in a building is a highly

specialised job. However certain provisions are required to be made in the building layout and

structures for accommodating lifts and other

accessories such as operating devices. A vertical

shaft with openings at the floor level is provided. The shaft is located at a suitable place e.g. by the

side of the stair or within the open well of a stair. It

may have sides built in masonry or concrete or metallic cage with suitable doors. The shaft extends

below the ground floor or the basement floor, as the

case may be, to accommodate the spring buffers for slow speed lifts and hydraulic buffers for high-speed

lift. Usually a machine room is located at the top of

the lift shaft for housing equipment and accessories.

However it can also be at the bottom, by the side or at the base of the shaft. The size or the machine

room is normally 4 m X 3 m X 2.5 to.3 m. Its floor

should be suitably designed to 8upport the weight of the lift car, equipment, passengers, the balancing

weight and the weight of motor with the winch

arrangement. Floors of machine room should be designed to carry a load of not less than 500 kg/m2

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plus the load imposed by the equipment or any

reaction from such equipment.

The shaft for the lift should be able to accommodate

the lift car, balancing weight, and vertical guides for them. Previously collapsible doors were provided

both for the lift door or cage and for the opening in

the shaft in the floor level. Now a days flush doors of sliding type are provided. The doors at the floor

level are fitted with electro-mechanical safety

looking devices with special emergency lock release.

7.2 Types of lifts 7.2.1 Observation lift The observation lift puts the cab on the outside of

the building. Glass-walled lift cars allow passengers to view the cityscape or the building‟s atrium as

they travel. By eliminating the hoistways, the

observation lift also offers owners, architects and

builders valuable space-saving advantages.

7.2.2 Double-deck lift Double-deck lifts save time and space in high-

occupancy buildings by mounting one car upon another. One car stops at even floors and the other

stops at the odd floors. Depending on their

destination, passengers can mount one car in the

lobby or take an escalator to a landing for the alternate car.

OBSERVATION LIFTS

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DOUBLE DECK LIFTS

7.2.3 Sky lobby

In very tall buildings, lift efficiency can be increased

by a system that combines express and local lifts.

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The express lifts stop at designated floors called sky

lobbies. There, passengers can transfer to local lifts

that will take them to their desired floor. By dividing

the building into levels served by the express lifts, the local lifts can be stacked to occupy the same

shaft space. That way, each zone can be served

simultaneously by its own bank of local lifts.

7.2.4 Freight lifts

These lifts are specially constructed to withstand the

rigors of heavy loads. Standard capacities range

from 1360 kilograms (3000 lb) up to 5440 kilograms (12,000 lb). These lifts are rated

according to load categories, with Class “A” being

for hand trucks, Class “B” for carrying automobiles and Class “C1” for lifts with the capacity to carry a

commercial truck.

7.2.5 Residential lifts

Residential lifts use modern hydraulics to produce a smooth, quiet ride while occupying a minimum

amount of space. These hydraulic systems are

quiet, producing about the same amount of sound as a typical refrigerator, which makes them well

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suited for residential use. They can be operated at

any hour without causing disturbance. The compact

design allows the lift to be installed in the amount of

space required for an average-sized closet.

7.3 Design Considerations

7.3.1 Number of Lifts and Capacity:

Two basic considerations, namely, the quantity of

service required and the quality of service required, determine the type of lifts to be provided in a

particular building. Quantity of service gives the

passenger handling capacity of the lifts during the peak periods and the quality of service is measured

in terms of waiting time of passengers at various

floors. Both these basic factors require proper study into the character of the building, extent and

duration of peak period, frequency of service

required, type and method of control, type of

landing doors, etc.

The number of lifts, their capacity and speed

required for a building is governed by such

considerations as number of the floors to be served, number of passengers to be handled, floor area and

floor heights. In large buildings, the provision of a

battery of lifts is advisable wherever feasible. Consideration should also be given to leaving space

for additional lift installation to cater for future

traffic development.

Quantity 0f Service: The quantity of service is a measure of the passenger handling capacity of a

vertical transportation system. It is measured in

terms of the total number of passengers handled during each five-minute peak period of the day. A

five-minute base period is used as this is the most

practical time over which the traffic may be

averaged. The passenger handling capacity (H) for different occupancies expressed in percent of the

estimated population that has to be handled in the

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building in the five minute peak period should be

approximately as follow:

Class of Occupancy H (percent)

Diversified (mixed) office occupancy

10-15

Single purpose office

occupancy 15-26

Residential 5

Quality of Service

The quality of service is generally measured by the

passenger waiting time at the various doors. The

following is the guiding factor for determining this aspect:

Acceptable Interval Quality of Service or

Rating

20 - 25 seconds Excellent

30 - 35 seconds Good

35 - 40 seconds Fair

40 - 45 seconds Poor

Over 45 seconds Unsatisfactory

The round trip time can be decreased not only by

increasing the speed of the lift but also by improving the design of the equipment related to opening and

closing of the landing and oar doors, acceleration,

deceleration, levelling and passenger movement.

These factors are given below:

a) The most important factor in shortening the time

consumed between the entry and exit of the

passengers to the lift car is the correct design of the doors and the proper car width. It has been

proved that the ideal door width is that of 100

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cm and that of the ideal car width is

approximately 200 cm. Under these conditions,

the car can comfortably hold four people,

shoulder to shoulder, in a straight line, permitting the two central located persons to

make an exit without disturbing the rest of the

passengers.

b) The utilization of centre opening doors has been

a definite factor in improving passengers transfer

time, since when using this type of door the

passengers; as a general rule, obtain to move before the doors have completely opened. On

the other hand with a side-opening door the

passengers tend to wait until the door has completely opened before moving. The utilization

of centre opening door also favours the doors

opening and closing time periods. Given the same door speed, the centre opening door is

much faster than the side opening type. It is

beyond doubt that the centre-opening door

represents an increase in transportational capacity in the operation of a lift.

7.3.2 Positioning of Lift

A thorough investigation shou1d be made for assessing the most suitable position for lift(s) while

planning the building. It should take into account

future expansions, if any. Though each building has

to be considered individually for purposes of location of lifts, factors influencing the locations of passenger

and goods lifts are given below.

The location of lifts may also conform to the travel distance requirements.

Arrangement of Lifts

The lifts should be easily accessible from all entrances to the building. For maximum efficiency,

they should be grouped near the centre of the

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building. It is preferable not to have all the lifts out

in straight line and, if possible, not more than three

lifts should be arranged in this manner. It bas to be

kept in mind that the corridor should be wide enough to allow sufficient space for waiting

passengers as well as for through passengers.

In some cases when there are more than three lifts, the alcove arrangement, is recommended. With this

arrangement, the lift alcove leads off the main

corridor so that there is no interference by traffic to

other groups or to other parts of the ground floor. This arrangement permits the narrowest possible

corridors and saves space on the upper floors.

Walking distance to the individual lift is reduced and passengers standing in the centre of the group can

readily see all the lift doors and landing indicators.

The ideal arrangement of the lifts depends upon the particular layout of the respective building and

should be determined in every individual case.

Passenger Lifts

Low and Medium Class Flats: Where a lift is arranged to serve two, three or four flats per floor,

the lift may be placed adjoining a staircase, with the

lift entrances serving direct on to the landings. Where the lift is to serve a considerable number of

flats having access to balconies or corridors, it

maybe conveniently be placed in a well ventilated tower adjoining the building.

Office buildings, Hotels and High Class Flats: It

is desirable to have at least a battery of two lifts at

two or more convenient points of a building. If this is not possible, it is advisable to have lit least two

lifts side by side at the main entrance and one lift

each at different sections of the building for intercommunication. When two- lifts are installed

side by side, the machine room shall be suitably

planned with sufficient space for housing the

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machine equipment. The positioning of lifts side by

side gives the following advantages:

a) All machines and switch gear may be housed in

one machine room

b) The lifts can be inter-connected more

conveniently from an installation point of view,

and

c) Greater convenience in service owing to the

landing openings on each floor being adjacent.

Shops and Departmental Stores: Lifts in shops

and store& should be situated so as to secure convenient and easy access at each Floor.

Hospitals: It is convenient to place the passenger

lifts near the staircases.

Goods Lifts: The location of lifts in factories,

warehouses and similar buildings should be planned

to suit the progressive movement of goods throughout the bui1dings, having regard to the

nature of processes carried out in the building, the

position of the loading platforms, railway sidings,

etc. The placing of a lift in a fume or dust laden atmosphere or where it may be exposed to extreme

temperatures, should be avoided wherever possible.

Where it is impossible to avoid installing a lift in an adverse atmosphere, the electrical equipment

should be of suitable design and construction to

meet the conditions involved.

Hospital Bed Lifts

Hospital Bed Lifts should be situated conveniently

near the ward and operating theatre entrances.

There shall be sufficient space near the landing door for easy movement of stretcher.

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7.3.3 Shape and Size of Lift Car

The shape and size of the passenger lift car bears a

distinct relation to its efficiency as a medium of

traffic handling. The width of the lift well entrance is, in reality the basic element in the determination

of the best proportion. The width of the car is

determined by the width of the entrance and the

depth of the car is regulated by the loading. Centre opening doors are the most practicable and the

most efficient entrance units for passenger lifts.

7.3.4 Positioning of Machine Room

The machine room should as far as possible, be placed immediately above the lift well as this has

several advantages, such as reduced load on the

building, lower capital cost of the lift, a smaller lift well for a given size lift car and reduced power

consumption compared with a machine room in the

basement, renewal of suspension ropes is less frequent and the cost of such renewals is less

because shorter ropes are required and time taken

for fitting them is less.

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If a machine room on the lift well is impracticable

for architectural or other reasons, the machine room

may be placed below the lift well or in the

basement, but guidance of a lift engineer should be followed on each instance, to minimize the

disadvantage of its being so placed.

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Lesson – 8: Escalators

Objective:

To know about escalators and its various parts

To study several standard layout configurations of escalators.

Structure:

8.1 Introduction

8.2 Capacity of Escalators

8.2.1 Theoretical Capacity

8.2.2 Practical Capacity

8.3 Terminology

8.4 Essential Requirements

Layout Configuration

8.1 Introduction: Escalators are deemed essential where the movement of people in large numbers at a

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controlled rate in a controlled space, is involved for

example, airports etc. In exhibitions, big

departmental stores and the like, escalators

encourage people to circulate freely and conveniently.

As the escalators operate at a constant speed, serve

only two levels and have a known maximum capacity, the traffic study is rather easy. Provided

the population to be bandied in a given time is

known, it is easy to predict the rate at which the

population can be handled.

For normal peak periods, the recommended

handling capacities for design purposes should be

taken as 3200 to 6400 persons per hour depending upon the width of the escalator.

8.2 Capacity of Escalators

Escalators are capable of moving a huge number of

people. There are 3 widths of Escalator, which are available. The handling capacity of an Escalator is

dependant on the number of people that you can

accommodate on a step.

The person loading that is used for capacity

calculations are as follows:

The persons per step assumes the passengers are

standing facing the direction of travel. The most

popular escalator widths are 800mm and 1000mm, with very little cost difference between the two.

8.2.1 Theoretical Capacity

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All capacity calculations assume a step speed of 0.5

meters per second. The table below details the

theoretical capacity:

These calculations assume full loading on every step.

8.2.2 Practical Capacity

Passengers will leave small gaps between other

passengers before entering the Escalator. In

addition to this some passengers may hesitate slightly at entrance and egress from the Escalator.

Hence the assumption of full capacity on every step

is realistically unachievable. Therefore a Load Factor to calculate the Practical Capacity has been

developed.

Dependent on the environment, the usage is classed as Light, Medium and Heavy and the suitable factor

applied accordingly.

With this factor applied, the Practical Capacity is as

follows:

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1.3 Terminology

The below annotated picture highlights the terminology used for the main features of an

Escalator.

8.4 Essential Requirements

1. Angle of inclination shall not be in excess of 300

from the horizontal excepting that with an

escalator having a vertical rise not exceeding 6 m an angle up to 35° may be permitted.

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2. The width between balustrades shall be

measured on the incline up to a point 68.5 cm

vertically above the nose line of the steps and

shall not be less than the width of the step. It shall not exceed the width of the step by more

than 33 cm with a maximum of 16.5 cm on

either side of the escalator.

3. Escalators shall be provided on each side with

solid balustrades. On the step side the

balustrades shall be smooth and substantially

flush except for protective moulding parallel to the run of the steps and properly bevelled

vertical mouldings projecting not more than 6.5

mm, that cover joints of panels.

a) There shall be no abrupt changes in the width

between the balustrades on the two sides of the

escalator. Where a change in width is unavoidable, such change shall not exceed 8

percent of the greatest width. In changing the

direction of the balustrades resulting from a

reduction in width the maximum allowable angle of change in balustrades shall not exceed 15

degrees from the line of the escalator travel.

b) The clearance on either side of the steps between the steps and the adjacent skirt guard

shall be not be more than 5 mm and the sum of

the clearances on both sides shall be not more than 6 mm.

c) A solid guard shall be provided in the intersecting

angle of the outside balustrade (deck board) and

the ceiling or soffit except where the intersection of the outside balustrade (deck board) and the

ceiling or soffit is more than 60 cm from the

centre line of the handrail. The vertical face of the guard shall project at least 36 cm –

horizontally from the apex of the angle.

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1. Handrails.

a) Each balustrade shall be provided with a handrail

moving in the same direction and at substantially

the same speed as the steps. b) Each moving handrail shall extend at normal

handrail height not less than 30 cm beyond the

line of points of comb-plate teeth at the upper and lower landings.

c) Hand or finger guards shall be provided at the

point where the handrail enters the balustrade.

d) The horizontal distance between the centre lines of two handrails measured on the incline shall

not exceed the width between the balustrades by

more than 15 cm, with a maximum of 7.0 cm on either side of the escalator.

2. Step Treads

e) The depth of any step tread in the direction or

travel shall not be less than 40 cm and the rise between treads shall be not be more than 22 cm.

The width of a step tread shall be not less than

40 cm or more than 102 cm. f) The maximum clearance between step treads on

the horizontal run shall be 4 mm.

g) The tread surface of each step shall be slotted in a direction parallel to the travel of the steps.

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Each slot shall be not more than 6.5 mm wide

and less than 9.5 mm deep; and the distance

from centre to centre of adjoining slots shall be

not more than 9.5 mm. 3. Landing: Landing shall be made out of anti-slip

material.

4. Comb-plates: There shall be a comb-plate at the entrance and at the exit of every escalator.

The comb-plate teeth shall be meshed with and

set into the slots in the tread surface so that the

points of the teeth are always below the upper surface of the treads. Comb-plates shall be

adjustable vertically.

1. Trusses Or Girders: The truss or girder shall be

designed to safely sustain the step and running gear in operation. In the event of failure of the

track system it shall retain the running gear in

its guides. 2. Step Wheel Tracks: This shall be designed to

prevent displacement of steps and running gear

if a step chain breaks.

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3. Driving Machine, Motor and Brake

a) The driving machine shall be connected to the

main drive shaft by toothed gearing, a

coupling, or a chain. b) An electric motor shall not drive more than

one escalator.

c) Each escalator shall be provided with an electrically released, mechanically applied

brake capable of stopping the up or down

travelling escalator with any load up to rated

load. This brake shall be located either on the driving machine or on the main drive shaft.

d) Where a chain is used to connect the driving

machine to the main drive shaft, a brake shall be provided on this shaft. It is not required

that this brake be of the electrically released

type if an electrically released brake is provided on the driving machine.

4. Speed Governor: Speed governor shall be

provided, the operation of which shall cause the

interruption of power to the driving machine should the speed of the steps exceed a

predetermined value which shall be not more

than 40 percent above the rated speed.

8.5 Layout Configuration

There are several standard layout configurations.

The layout is a key element in the traffic flow

through the building. The layout configurations are:

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Summary:

Both lifts and escalators are mechanical ways of

vertical transportation. The location of lifts, their

installation, design, type and arrangement – are all important areas to be studied.

Escalators are more common where the movement

of people in large numbers at a controlled rate in a controlled space is involved for example, airports

etc. In exhibitions, big departmental stores and the

like.

Revision points:

1. Types of lifts

2. Design considerations for a lift

3. Parts of an escalator.

Key words:

1. Sky lobby

2. Lift shaft

3. Comb plates

4. Speed governor

5. Driving machine

In text questions:

1. Give a brief history of vertical transportation.

2. What are the various types of lifts?

3. What are escalators?

Terminal exercises:

1. What are the design considerations for a lift?

Explain in detail

2. Explain in detail the various parts of an escalator.

3. How do you work out the capacity of an

escalator? Explain in detail.

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Suggested Reading

1. Building Construction by S.K Sharma

2. Building Construction by Sushil Kumar

3. Time Savers Standards For Buildings Types