ii
2. The standards for minimum room volume are as fol-
lows.
(1) No partition (shaded portion)
(2) When there is an effective opening with the adjacent
room for ventilation of leaking refrigerant gas (open-
ing 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 interlocked
with a gas leakage detector in the smallest room
where the density limit is exceeded, the volume 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 8.8 ft. high)
Check of Density Limit
The room in which the air conditioner is to be
installed requires a design that in the event of refrig-
erant gas leaking out, its density will not exceed a set
limit.
The refrigerant (R410A), which is used in the air con-
ditioner, is safe, without the toxicity or combustibility of
ammonia, and is not restricted by laws imposed to protect
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 num-
ber of high density buildings, however, 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 compared 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 pro-
cedure so that if the refrigerant accidentally 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 (lbs)
Min. volume of the indoor unit installed room (ft.
3
)
<
Density limit (oz/ft.
3
)
The density limit of refrigerant which is used in multi air
conditioners is 0.3 oz/ft.
3
(ISO 5149).
NOTE
1.If there are 2 or more refrigerating systems in a single
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 353 oz.
The possible amount of leaked refrigerant gas in
rooms D, E and F is 529 oz.
Outdoor unit
Refrigerant tubing
Indoor unit
e.g., charged
amount (353 oz)
Outdoor unit
Indoor unit
Room A Room B Room C Room D Room E Room F
e.g., charged
amount (529 oz)
Refrigerant tubing
Outdoor unit
Very
small
room
Indoor unit
Small
room
Medium
room
Large room
Mechanical ventilation device – Gas leak detector
0 0
57
114
170
227
284
341
398
454
0
500
1000
1500
2000
2500
3000
3500
4000
400 200 600 800 1000 1200
Total amount of refrigerant
Min. indoor volume
Min. indoor floor area
(when the ceiling is 8.8 ft. high)
ft.
3
ft.
2
oz
Range above
the density limit of
0.3 oz/ft.
3
(countermeasures
needed)
Range below
the density limit of
0.3 oz/ft.
3
(countermeasures
not needed)
