Ventilation Method - Mitsubishi Electric Lossnay LGH-15RX3 Technical Manual

3. Ventilation Method

3.1 Ventilation class and selection points
An appropriate ventilation method must be selected according to the purpose.
Ventilation is composed of "Supply air" and "Exhaust air" functions. These functions are classified according to natural flow or
mechanical ventilation using a fan (forced ventilation).
Classification of ventilation (according to Building Standards Law)
Supply
Class 1 Mechanical
Class 2 Mechanical
Class 3 Natural
Class 4 Natural
Classification of mechanical ventilation
1. Class 1 ventilation
Fresh outdoor air is mechanically
brought in and simultaneously the
stale air in the room is mechanically
discharged.
Fresh
outdoor
air
2. Class 2 ventilation
Fresh outdoor air is mechanically
brought in and the exhaust air is
discharged from the exhaust air
outlet (natural).
Exhaust
fan
3. Class 3 ventilation
The stale air in the room is
mechanically discharged and
simultaneously fresh outdoor air is
mechanically introduced from the
supply air diffuser (natural).
Supply
air
diffuser
Exhaust
Mechanical
Natural
Mechanical
Mechanical & natural
Ex. of application
• Ventilation of air
conditioned rooms.
(buildings, hospitals,
etc.)
• Ventilation of room
not facing an outer
wall. (basement,
etc.)
• Ventilation of large
room. (office, large
Stale
conference room,
air
hall, etc.)
Exhaust
fan
• Surgery theatre.
• Clean rooms.
• Foodstuff processing
factories.
Exhaust
air
outlet
• Local ventilation in
kitchens.
• Ventilation of hot
exhaust air from
machine room, etc.
• Ventilation of humid
exhaust air from
indoor pools, bath-
rooms, etc.
• General simple
ventilation.
Exhaust
fan
CHAPTER 1 G Ventilation for Healthy Living
Ventilation volume
Random (constant)
Random (constant)
Random (constant)
Limited (inconstant)
Design and construction
System effect
By changing the • An ideal design in which
balance of the supply the supply air diffuser
fan and exhaust fan's and exhaust air outlet
air volumes, the position relation and air
pressure in the room volume, etc., can be set
can be balanced freely is possible.
freely, and the • A system which adjusts
interrelation with the temperature and
neighboring spaces humidity of the supply
can be set freely. air diffuser flow to the
room environment can
be incorporated.
• The supply and
exhaust volume can be
set freely according to
the changes in
conditions.
As the room is • The position and
pressurized, the flow shape of the supply
of odors and dust, air diffuser can be
etc., from neighboring set.
areas can be • The temperature and
prevented. humidity of the
supply air diffuser
flow can be set
accordingly, and
dust can be removed
as required.
The exhaust air is • Effective exhausting
removed from a local of dispersed stale air
position in the room, generation sites is
and dispersion of the possible from a local
stale air can be exhaust air outlet.
prevented by applying • Ventilation in which
an entire negative the air flow is not felt
pressure. is possible with the
supply air diffuser
setting method.
Room pressure
Random
Positive pressure
Negative pressure
Negative pressure
Selection points
properties
• Accurate supply air
diffuser can be
maintained.
• The room pressure
balance can be
maintained.
• The supply air
diffuser temperature
and humidity can be
adjusted and dust
treatment is
possible.
• The pressure is
positive.
• The supply air diffuser
temperature and
humidity can be
adjusted, and dust
treatment is possible.
• The positional relation
of the exhaust air
outlet to the supply air
diffuser is important.
• The room pressure
is negative.
• Local exhaust is
possible.
• Ventilation without
dispersing stale air is
possible.
• Ventilation with
reduced air flow is
possible.
• The positional relation
of the exhaust air
outlet to the supply air
diffuser is important.
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