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Questions and Answers
What is the primary operational mechanism of a centrifugal fan?
What is the primary operational mechanism of a centrifugal fan?
Which type of fan is most suitable for exhausting air in a car park setting?
Which type of fan is most suitable for exhausting air in a car park setting?
What advantage does an axial fan have over a centrifugal fan?
What advantage does an axial fan have over a centrifugal fan?
What is a disadvantage of using a propeller fan?
What is a disadvantage of using a propeller fan?
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Which advantage is associated with centrifugal fans?
Which advantage is associated with centrifugal fans?
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What maintenance necessity does a filter fulfill in an air distribution system?
What maintenance necessity does a filter fulfill in an air distribution system?
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What is a notable disadvantage of axial fans regarding their motor location?
What is a notable disadvantage of axial fans regarding their motor location?
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In terms of airflow dynamics, what characteristic distinguishes centrifugal fans from axial and propeller fans?
In terms of airflow dynamics, what characteristic distinguishes centrifugal fans from axial and propeller fans?
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What is the primary purpose of the inlet fan in a fire situation?
What is the primary purpose of the inlet fan in a fire situation?
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Which of the following statements about mechanical inlet and extract systems is true?
Which of the following statements about mechanical inlet and extract systems is true?
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What is one requirement for basement carparks regarding ventilation?
What is one requirement for basement carparks regarding ventilation?
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What happens if the exhaust system in a carpark fails?
What happens if the exhaust system in a carpark fails?
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What is the minimum ventilation rate required in a basement carpark?
What is the minimum ventilation rate required in a basement carpark?
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What is a primary advantage of mechanical ventilation over natural ventilation?
What is a primary advantage of mechanical ventilation over natural ventilation?
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At what height should the exhaust air be extracted from in a carpark?
At what height should the exhaust air be extracted from in a carpark?
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Which statement best describes the mechanical inlet -- natural extract method of ventilation?
Which statement best describes the mechanical inlet -- natural extract method of ventilation?
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In the natural inlet -- mechanical extract system, what happens to the air pressure in the ballroom area when the exhaust fan operates?
In the natural inlet -- mechanical extract system, what happens to the air pressure in the ballroom area when the exhaust fan operates?
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What is one requirement for the exhaust discharge in a mechanical ventilation system?
What is one requirement for the exhaust discharge in a mechanical ventilation system?
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Why is maintaining negative pressure important in a basement carpark?
Why is maintaining negative pressure important in a basement carpark?
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What type of fan is typically used in a mechanical extract system for toilets?
What type of fan is typically used in a mechanical extract system for toilets?
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How does mechanical ventilation allow for determination of a specific air change rate?
How does mechanical ventilation allow for determination of a specific air change rate?
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What can be installed at the mechanical extract to improve air quality?
What can be installed at the mechanical extract to improve air quality?
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Which is NOT a characteristic of mechanical ventilation systems?
Which is NOT a characteristic of mechanical ventilation systems?
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What is a key consideration in the design of a mechanical ventilation system?
What is a key consideration in the design of a mechanical ventilation system?
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What is one of the key advantages of mechanical ventilation over natural ventilation?
What is one of the key advantages of mechanical ventilation over natural ventilation?
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In the natural inlet - mechanical extract system, what effect does the mechanical exhaust fan have on the kitchen area?
In the natural inlet - mechanical extract system, what effect does the mechanical exhaust fan have on the kitchen area?
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What happens to the air pressure in adjacent areas when a mechanical extract fan operates?
What happens to the air pressure in adjacent areas when a mechanical extract fan operates?
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What is a characteristic of the mechanical inlet - natural extract method?
What is a characteristic of the mechanical inlet - natural extract method?
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Which component might be included at the mechanical extract to improve air quality?
Which component might be included at the mechanical extract to improve air quality?
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What purpose does the mechanical exhaust fan serve in a toilet ventilation system?
What purpose does the mechanical exhaust fan serve in a toilet ventilation system?
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What is a potential disadvantage of mechanical ventilation systems?
What is a potential disadvantage of mechanical ventilation systems?
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Which system is NOT a method of mechanical ventilation?
Which system is NOT a method of mechanical ventilation?
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What is one of the key disadvantages of a centrifugal fan?
What is one of the key disadvantages of a centrifugal fan?
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Which type of fan is known for operating quietly and providing smooth air flow?
Which type of fan is known for operating quietly and providing smooth air flow?
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What is a characteristic advantage of axial fans?
What is a characteristic advantage of axial fans?
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What type of fan is specifically designed for low pressure development?
What type of fan is specifically designed for low pressure development?
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How do propeller fans differ from centrifugal and axial fans in terms of installation?
How do propeller fans differ from centrifugal and axial fans in terms of installation?
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What is a potential disadvantage of axial fans in terms of their motor placement?
What is a potential disadvantage of axial fans in terms of their motor placement?
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Which type of fan is often used for removing air from large volumes of dusty or corrosive environments?
Which type of fan is often used for removing air from large volumes of dusty or corrosive environments?
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What is the main function of filters in an air distribution system?
What is the main function of filters in an air distribution system?
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Which of the following types of air filters is best for removing very fine particles?
Which of the following types of air filters is best for removing very fine particles?
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What is a characteristic of AC induction motors?
What is a characteristic of AC induction motors?
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Which type of air filter works by forcing air through changes in direction to separate grease?
Which type of air filter works by forcing air through changes in direction to separate grease?
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What maintenance task is crucial for ensuring the proper functioning of motors?
What maintenance task is crucial for ensuring the proper functioning of motors?
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What distinguishes DC motors from AC induction motors?
What distinguishes DC motors from AC induction motors?
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Which component in an AC motor is responsible for producing the magnetic field?
Which component in an AC motor is responsible for producing the magnetic field?
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What is a downside of electrostatic filters?
What is a downside of electrostatic filters?
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Which type of dry fabric filter can be cleaned or disposed of?
Which type of dry fabric filter can be cleaned or disposed of?
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What environmental condition does the inlet fan create in the stairwell during a fire emergency?
What environmental condition does the inlet fan create in the stairwell during a fire emergency?
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What is the primary purpose of the mechanical inlet and mechanical extract system?
What is the primary purpose of the mechanical inlet and mechanical extract system?
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Why must each section of a mechanical ventilation system for basement carparks operate independently?
Why must each section of a mechanical ventilation system for basement carparks operate independently?
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How far from openings must the exhaust discharge be to prevent re-entry of harmful substances?
How far from openings must the exhaust discharge be to prevent re-entry of harmful substances?
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What is the minimum air change rate required in a basement carpark?
What is the minimum air change rate required in a basement carpark?
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What happens if the exhaust section fails in a mechanical ventilation system for basement carparks?
What happens if the exhaust section fails in a mechanical ventilation system for basement carparks?
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What should the natural ventilation opening be at least to act as a substitute for the mechanical supply part?
What should the natural ventilation opening be at least to act as a substitute for the mechanical supply part?
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What ensures the basement carpark remains under negative pressure?
What ensures the basement carpark remains under negative pressure?
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Study Notes
Mechanical Ventilation Systems
- Mechanical ventilation uses electrically powered fans, offering advantages over natural ventilation
- Systems are differentiated by equipment involved and their associated methods
- Advantages of mechanical over natural ventilation include independence from wind conditions, adjustable air changes, and filtration capabilities
Introduction to Mechanical Ventilation
- Mechanical ventilation is driven by electrically powered fans
- Several advantages over natural ventilation:
- Independent of wind conditions
- Defined air change rates (ventilation rates) possible
- Air filtration possible
- Enables positive pressure environments
Mechanical Ventilation Methods
- Natural inlet - mechanical extract
- Mechanical inlet - natural extract
- Mechanical inlet - mechanical extract
Natural Inlet - Mechanical Extract System
- Common in bathrooms, workshops and kitchens to prevent odors from adjacent rooms
- Creates negative pressure in the source area (e.g., kitchen)
- Exhaust fan draws air out; creating positive pressure in the area receiving the exhaust.
- Ensures room will be positive pressure or have a negative pressure difference
Mechanical Extract Systems
- Forms - fixed across window openings, or within ductwork
- Filters- may be situated at the mechanical extract point.
Mechanical Inlet - Natural Extract System
- Used in areas requiring positive pressure (e.g., fire escapes)
- Automatically activates upon fire; creating positive pressure in the stairwell to contain smoke
- Prevents smoke from escaping into the stairwell allowing occupants to escape
Mechanical Inlet - Mechanical Extract
- This is the most common system across applications
- Allows pressure regulation in a space, whether positive or negative
- Used in basement carparks, where natural inlets and extracts are impractical
Special Requirements for Basement Carparks
- System must consist of an exhaust and a supply part; each with two sections (at least 2 inlets/2 outlets)
- Each section should provide half the air changes required.
- Sections may share ductwork
- Exhaust and supply systems are electrically interlocked, such that failure of one shuts down the corresponding part.
- Systems are connected to an alternate supply (e.g. a back-up generator)
- Natural ventilation can be substituted (if at least 2% of the floor area)
- Exhaust must be sufficiently far from other openings
Mechanical Ventilation Equipment
- Three types of fans:
- Centrifugal
- Axial
- Propeller
Centrifugal Fan
- Throws air outwards from the center
- Can have 1 or 2 outlets
- Motor can be separate or integrated within the unit
Axial Fan
- Air that flows parallel to the axis of the fan
- Used commonly as exhaust fans
- Easily installed
Propeller Fan
- Made with two or more blades
- Low pressure, usually exhaust fans
- Can be used without ductwork (e.g. windows)
Filters
-
Used to remove contaminants from the air, such as dust, dirt, etc.
-
Prevents building up of dirt
-
Prevents dirt on equipment, and staining of property
-
Types of filters
- Dry fabric
- Electrostatic
- Grease filters (e.g., baffles)
Motor Types
-
AC induction motors are the most common for building service equipment; offering
- Ruggedness
- Simplicity
- Reliability
- Low cost
-
DC motors are sometimes used in variable speed HVAC applications
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Description
This quiz explores the fundamentals of mechanical ventilation systems, highlighting their advantages over natural ventilation. Participants will learn about various methods of ventilation and the situations in which they are most beneficial. Understanding these systems is crucial for optimizing air quality and efficiency in various environments.
