Ventilation (Chapter 1)

8/10/2019 Ventilation (Chapter 1)

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DEFINITION

The air change and movement within buildings for thepurpose of comfort and processes used in the enclosedspace.

The provision of a supply of outdoor air to a room orspace by natural or mechanical means, in a quantitysufficient for the needs of the occupants.


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PRINCIPLE OF VENTILATION

Comfort

COMBINATION OF

CorrectOxygen

Content ( 21% of airvolume)

CorrectRelative

Humidity (30%- 70% RH)

Correct AirMovement (air

velocitycondition0.15m

0.5m/sec.)

CorrectTemperature

(5C lowerthan room

temperature )


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VENTILATION METHODS

NATURAL MECHANICAL

Components integralwith construction

Bricks

Louvres

Openable Windows

Electrically DrivenFans


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REASONS FOR MECHANICAL VENTILATION

1. In densely populated space

Inadequate air supplyInadequate quality air

Difficulty in controlling natural ventilation

2. Natural ventilation is impossible

3. Heat Liberation

4. Moisture Liberation

5. Removal of odours

6. Removal of poisonous fumes

7. High heat of moisture gain

8. Need a clean atmosphere


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MECHANICALVENTILATION

SYSTEMS

Mechanical Inlet and ExtractCombined

Natural Inlet and MechanicalExtract

Mechanical Inlet and NaturalExtract


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NATURAL INLET ANDMECHANICAL EXTRACT

Principle

The stale air is extracted with the use ofexhaust fan and fresh air replace the stale

air naturally
http://localhost/var/www/apps/conversion/tmp/scratch_6/VIDEO%20VENTILATION.WMVhttp://localhost/var/www/apps/conversion/tmp/scratch_6/VIDEO%20VENTILATION.WMV


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Extract Ventilation to a Lecture Theatre


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COMMERCIAL RESIDENTIAL

KITCHENHOOD
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EXHAUSTFAN IN THE

TOILET
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MECHANICAL INLET ANDNATURAL EXTRACT

Principle

The air being forced in by the inlet fanwhich create a positive pressure within thespace, the existing stale air will be forced

out through the openings.


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CLINIC

Supply Fan

Window

Mechanical Inlet


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Diffuser

Filter

Supply Fan

Fresh Air Distribution System


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MECHANICAL INLET

Advantage

The fan greater power of the inlet to shapethe character of the ventilation or shaping

the airflow pattern through a space.


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MECHANICAL INLET AND

EXTRACT COMBINED

Use both intake

and extract fan

Optimum

controlled of air -distribution


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MECHANICAL INLET ANDEXTRACT COMBINED

Principle

Such systems are said to be balanced inthat the relative powers of the intake and

extract fans are adjusted to give a slightpositive or negative pressure in the space.


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MECHANICAL INLET AND

EXTRACT COMBINED

Extract Fan

Window

SupplyFan

HOSPITAL

Application for the Hospital Ward


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Application for an Office Space

Supply Fan

Window

ExtractFan OFFICE


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A Fan Room for the Ventilation of a Basement Parking Area

Air Supply toBasementParking Area

Grille

Ducting

Electric Motor Airflow

Filter

(Ductwork to distribute the supply air)


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Internal Pressure

Adjusted

Ratio of incoming and extracted air is beingcontrolled.


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Example Extract system is higher for the kitchenand washing area

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HOSPITAL WARD

Activities produce odour

or polluted air.Negative pressurerequired within thespace.

Extract system 10% to20% higher than thesupply system.
http://rds.yahoo.com/S=96062857/K=hospital+ward/v=2/SID=w/TID=MUD_200/l=II/R=1/SS=r/OID=54582ce1175daa80/;_ylt=A9G_Rq.FH0NEqwoAQvCJzbkF;_ylu=X3oDMTBwOWFubDZzBHBvcwMxBHNlYwNzcgR2dGlkA01VRF8yMDA-/SIG=1d4kjbtcs/EXP=1145336069/*-http%3A//images.search.yahoo.com/search/images/view?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3Dhospital%2Bward%26ei%3DUTF-8%26fr%3DFP-tab-img-t%26x%3Dwrt%26vm%3Dr&w=977&h=693&imgurl=www.camp-of-the-woods.org%2Fardill%2FVVF_files%2Fward.jpg&rurl=http%3A%2F%2Fwww.camp-of-the-woods.org%2Fardill%2FVVF.htm&size=486.1kB&name=ward.jpg&p=hospital+ward&type=jpeg&no=1&tt=10,149&ei=UTF-8


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VENTILATION REQUIREMENTS

Type of Space Recommended m/hour per person

FactoryOpen-plan office Shops Department store Supermarket Theatre Cafeteria

Dance hall Hotel bedroomLaboratories Private offices Residential Cocktail bar Function room Luxury residential Restaurant/commercial dining room BoardroomExecutive office Conference room

18-30

30-43

43-65

65-90

Recommended m/hour per m of floor area

CorridorsDomestic kitchen Commercial kitchen Sanitary accommodation

5 36 72 36

Air Volume Requirements


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VENTILATION REQUIREMENTS

Air Change Rate

Accommodation Air Changes per hour

Offices above ground Offices below ground Factories large, open Factories/industrial units Workshops with unhealthy fumes Fabric manufacturing/processing Kitchens above ground Kitchens- below ground Public lavatories Boiler accommodation/plant rooms Foundries Laboratories Hospital operating theatres Hospital treatment rooms

Restaurants Smoking rooms Storage/warehousing

Assembly halls Classrooms Domestic habitable rooms Lobbies/corridors Libraries

2-6 10-20

1-4 6-8

20-30 10-20 20-40 40-60 6-12

10-15 8-15

10-12


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VENTILATION RATE

Influencing Factors

Air Movement Pollution

Body Odour


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MECHANICAL VENTILATIONEQUIPMENT

FAN

FILTERS DUCTWORK

DIFFUSERS


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FAN

TYPES

Propeller Axial Flow Centrifugal


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Axial-flow Fan


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Centrifugal Fan


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FAN SELECTION

Depend on factors:

The volume of air to be handled.

The resistance to the blades during rotation

The permittable noise level

The comfortable level of the ventilated area

The implications to the design of the ductwork dependon the capability of a fan.


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FILTERS

PURPOSE

TO REMOVESUSPENDEDPARTICLES

SUSPENDEDCONTAMINANTS

ODOURS


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DUCTWORK

MATERIALS

GALVANISED STEEL (mostcommon material)

ALUMINIUM

FLEXIBLEFABRICS

POLYPROPYLENE

uPVC

RESIN-BANDEDGLASS FIBRE

Other Metals (e.g.Copper)


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DUCTWORK

CROSS-SECTIONSSHAPECIRCULAR

SQUARE

RECTANGULAR

More efficient less frictionalresistance to

airflow

Moreconvenience

easily fittedinto building

fabric


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Ventilation (Chapter 1)

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