Toshiba MMD-AP0481HF2UL Service Manual page 112

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.
Total amount of refrigerant (lbs (kg))
Min. volume of the indoor unit installed room (ft³ (m³))
≤ Concentration limit (lbs/ft³ (kg/m³))
The concentration limit of R410A which is used in multi
air conditioners is 0.019 lbs/ft³ (0.3kg/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
(22 lbs (10 kg))
Room A Room B Room C Room D Room E
For the amount of charge in this example:
The possible amount of leaked refrigerant gas in
rooms A, B and C is 22 lbs (10kg).
The possible amount of leaked refrigerant gas in
rooms D, E and F is 33 lbs (15kg).
Outdoor unit
e.g.,
charged amount
(33 lbs (15 kg))
Room F
Indoor unit
Important
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 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.
Very
small
room
Small Medium
room room
Mechanical ventilation device - Gas leak detector
NOTE 3 :
The minimum indoor floor area compared with the
amount of refrigerant is roughly as follows:
(When the ceiling is 8.9 ft (2.7m ) high)
Range below the
48
density limit of
d²
0.019 lbs/ft³ (0.3 kg/m³)
42
(countermeasures not
36
needed)
30
24
18
12
6
0
22
Total amount of refrigerant
Outdoor unit
Refrigerant piping
Indoor unit
Refrigerant piping
Outdoor unit
Indoor unit
Large room
Range above the density
limit of
0.019 lbs/ft³ (0.3 kg/m³)
(countermeasures needed)
44 66
lbs