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SMMS Concealed Duct High Static Pressure Type
Warnings on Refrigerant Leakage
Check of Concentration 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 concentration will not exceed a set limit.
The refrigerant R410A which is used in the air conditioner is safe, without the toxicity or combustibility of ammonia,
and is not restricted by laws to be imposed which protect the ozone layer. However, since it contains more than
air, it poses the risk of suffocation if its concentration should rise excessively. Suffocation from leakage of R410A
is almost non-existent. With the recent increase in the number of high concentration 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 with
conventional individual air conditioners. If a single unit of the multi conditioner system is to be installed in a small
room, select a suitable model and installation procedure so that if the refrigerant accidentally leaks out, its
concentration 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 concentration may exceed the limit, create an opening with adjacent rooms, or install
mechanical ventilation combined with a gas leak detection device.The concentration is as given below.
Min. volume of the indoor unit installed room (m
The concentration limit of R410A which is used in multi air conditioners is 0.3 kg/m
▼ NOTE 1
If there are 2 or more refrigerating systems in a single refrigerating device, the amounts of refrigerant should be as
charged in each independent device.
e.g., charged amount (10 kg)
Room A
Room B
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 2
The standards for minimum room volume are as follows.
1) No partition (shaded portion)
45-EN
Total amount of refrigerant (kg)
3
)
≤ Concentration limit (kg/m
3
)
3
.
Outdoor unit
e.g., charged amount (15 kg)
Indoor unit
Room C
Room D
Room E
Room F
Installation Manual
SMMS Concealed Duct High Static Pressure Type
– 23 –
2) When there is an effective opening with the adjacent 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 piping is interconnected, the
smallest room of course becomes the object. But when a 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.
▼ NOTE 3
The minimum indoor floor area compared with the amount of refrigerant is roughly as follows:
(When the ceiling is 2.7 m high)
Important
Outdoor unit
Refrigerant piping
Indoor unit
Refrigerant piping
Very small room
Medium
Small
Large room
room
room
Mechanical ventilation device - Gas leak detector
40
Range below the
2
35
m
density limit of
0.3 kg/m
3
30
(countermeasures
not needed)
25
20
Range above the
15
density limit of 0.3 kg/m
(countermeasures
10
needed)
5
0
10
20
30
Total amount of refrigerant
Installation Manual
Outdoor unit
Indoor unit
3
kg
46-EN
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