3
2. The standards for minimum room volume are as
follows.
(1) No partition (shaded portion)
(2) When there is an effective opening with the adja-
cent room for ventilation of leaking refrigerant gas
(opening without a door, or an opening 0.15% or
larger than the respective floor spaces at the top
or bottom of the door).
(3) If an indoor unit is installed in each partitioned
room and the refrigerant tubing is interconnected,
the smallest room of course becomes the object.
But when mechanical ventilation is installed inter-
locked with a gas leakage detector in the smallest
room where the density limit is exceeded, the vol-
ume of the next smallest room becomes the object.
3. The minimum indoor floor space compared with the
amount of refrigerant is roughly as follows: (When
the ceiling is 2.7 m high)
Check of Density Limit
The room in which the air conditioner is to be
installed requires a design that in the event of
refrigerant gas leaking out, its density will not
exceed a set limit.
The refrigerant (R410A), which is used in the air condi-
tioner, is safe, without the toxicity or combustibility of
ammonia, and is not restricted by laws imposed to pro-
tect the ozone layer. However, since it contains more
than air, it poses the risk of suffocation if its density
should rise excessively. Suffocation from leakage of
refrigerant is almost non-existent. With the recent
increase in the number of high density buildings, how-
ever, the installation of multi air conditioner systems is
on the increase because of the need for effective use
of floor space, individual control, energy conservation
by curtailing heat and carrying power, etc.
Most importantly, the multi air conditioner system is
able to replenish a large amount of refrigerant com-
pared to conventional individual air conditioners. If a
single unit of the multi air conditioner system is to be
installed in a small room, select a suitable model and
installation procedure so that if the refrigerant acci-
dentally leaks out, its density does not reach the limit
(and in the event of an emergency, measures can be
made before injury can occur).
In a room where the density may exceed the limit,
create an opening with adjacent rooms, or install
mechanical ventilation combined with a gas leak
detection device. The density is as given below.
Total amount of refrigerant (kg)
Min. volume of the indoor unit installed room (m
3
)
≤
Density limit (kg/m
3
)
The density limit of refrigerant which is used in multi air con-
ditioners is 0.3 kg/m
3
(ISO 5149).
1. If there are 2 or more refrigerating systems in a sin-
gle refrigerating device, the amount of refrigerant
should be as charged in each independent device.
For the amount of charge in this example:
The possible amount of leaked refrigerant gas in rooms
A, B and C is 10 kg.
The possible amount of leaked refrigerant gas in rooms
D, E and F is 15 kg.
NOTE
Outdoor unit
Refrigerant tubing
Indoor unit
e.g., charged
amount (10 kg)
Outdoor unit
Indoor unit
Room A Room B Room C Room D Room E Room F
e.g., charged
amount (15 kg)
Refrigerant tubing
Outdoor unit
Very
small
room
Indoor unit
Small
room
Medium
room
Large room
Mechanical ventilation device – Gas leak detector
40
35
30
25
20
15
10
5
0
10
20
30
Total amount of refrigerant
Min. indoor floor space
m
2
kg
Range below the
density limit
of 0.3 kg/m
3
(countermeasures
not needed)
Range above
the density limit
of 0.3 kg/m
3
(countermeasures
needed)
