‒
44
‒
44-EN
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
fl
oor 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.
Total amount of refrigerant (kg)
Min. volume of the indoor unit installed room (m
3
)
≤
Concentration limit (kg/m
3
)
The concentration limit of R410A which is used in
multi air conditioners is 0.3 kg/m
3
.
T
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)
Outdoor unit
e.g., charged
amount (15 kg)
Indoor unit
Room A Room B Room C Room D Room E Room F
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.
T
NOTE 2
The standards for minimum room volume are as
follows.
(1) No partition (shaded portion)
(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
fl
oor spaces at the
top or bottom of the door).
Outdoor unit
Refrigerant piping
Indoor unit
(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.
Very
small
room
Small
room
Medium
room
Large
room
Mechanical ventilation device - Gas leak detector
Indoor unit
Outdoor
unit
Refrigerant piping
T
NOTE 3
The minimum indoor
fl
oor area compared with the
amount of refrigerant is roughly as follows: (When the
ceiling is 2.7 m high)
40
35
30
25
20
20
15
10
10
20
30
0
5
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)
Total amount of refrigerant
kg
Min. indoor
fl
oor
area
m
2
WARNINGS ON REFRIGERANT LEAKAGE
