Toshiba MMK-UP0051DHPL-E(TR) Service Manual page 141

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 R32 or 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 R32 or 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.
Total amount of refrigerant (kg)
Min. volume of the indoor unit installed room (m³)
≤ Concentration limit (kg/m³)
The concentration limit of R32 or R410A which is used in
multi air conditioners is 0.3 kg/m³.
▼ 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 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.
▼ 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
(3) If an indoor unit is installed in each partitioned
Very
small
room
▼ NOTE 3
Outdoor unit
The minimum indoor floor area compared with the
e.g., charged
amount of refrigerant is roughly as follows: (When the
amount (15 kg)
ceiling is 2.7 m high)
Indoor unit
- 141 -
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).
Outdoor unit
Refrigerant piping
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.
Refrigerant piping
Small Medium
room room
Mechanical ventilation device - Gas leak detector
40
Range below
35
m²
the density limit
of 0.3 kg/m³
30
(countermeasures
not needed)
25
20
15
10
5
0
10 20
Total amount of refrigerant
Indoor unit
Outdoor
unit
Indoor unit
Large
room
Range above
the density limit
of 0.3 kg/m³
(countermeasures
needed)
30
kg