MXZ-SM36NAMHZ Service Manual
147
OCH789
10-2. PRECAUTIONS AGAINST REFRIGERANT LEAKAGE
10-2-1. Introduction
R410A refrigerant of this air conditioner is non-toxic and non-flammable but leaking of large amount from an indoor unit into
the room where the unit is installed may be deleterious.
To prevent possible injury, the rooms should be large enough to keep the
R410A concentration specified by ISO 5149-1 as follows.
Note:
When the air conditioning system consists of several independent refrigerant system, figure out the total refrigerant
amount by each independent refrigerant system.
Follow (1) to (3) to confirm the R410A concentration and take appropriate treatment, if necessary.
(1) Calculate total refrigerant amount by each refrigerant system. Total refrigerant amount is recharged
refrigerant at ex-factory plus additional charged amount at field installation.
(2) Calculate room volumes (m
3
) and find the room with the smallest volume
The part with represents the room with the smallest volume.
If the calculation results do not exceed the maximum con-
centration, perform the same calculations for the larger
second and third room, etc., until it has been determined
that nowhere the maximum concentration will be exceeded.
Indoor unit
All refrigerant of this system will leak out to this
room if there is leakage at this indoor unit.
Direction
of refrigerant flow
Outdoor unit
Branching header
Maximum concentration
Maximum refrigerant concentration of R410A of a room is
0.44kg/K accordance with ISO 5149-1.
To facilitate calculation, the maximum concentration is
expressed in units of kg/K [lbs/ft³] (kg [lbs] of R410A per K [ft³])
(ISO 5149-1)
Maximum concentration of R410A: 0.027 lbs/ft³ [0.44 kg/K]
10-2-2. Confirming procedure of R410A concentration
(b) There are partitions, but there are openings that allow
the effective mixing of air.
(c) If the smallest room has mechanical ventilation apparatus that is linked to a household gas detection and alarm
device, the calculations should be performed for the second smallest room.
Total refrigerant in the refrigerating unit (lbs [kg])
[
Maximum concentration(lbs/ft³ [kg/K])
The smallest room in which an indoor
unit has been installed (ft³ [
K
])
Maximum concentration of R410A:0.027 lbs/ft³
[0.44kg/
K
]
(a) Situation in which there are no partitions
(3) Use the results of calculations (1) and (2) to calculate the refrigerant concentration:
Indoor unit
The smallest
room
The second
smallest room
Outdoor unit
Ventilation apparatus
Indoor unit
Opening
Wall
Outdoor unit
(Situation in which there
are no door openings or
in which there are open-
ings above and blow
doors that occupy at
least 0.15% of the floor
area)
Indoor unit
Outdoor unit