Mitsubishi Electric CITY MULTI PUMY-P112VKM6 Service Manual page 122

12 REFRIGERANT PIPING TASKS
12-1. Refrigerant piping system
Refer to installation manual "Pipe length and height difference" for refrigerant piping system.
12-2. PRECAUTIONS AGAINST REFRIGERANT LEAKAGE
12-2-1. 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.
■ Maximum concentration of R410A: 0.44 kg/m
Maximum refrigerant concentration of R410A of a room is 0.44kg/m
To facilitate calculation, the maximum concentration is expressed in units of kg/m
Outdoor unit
12-2-2. Confirming procedure of R410A concentration
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 precharged refrigerant be-
fore shipment plus additional charged amount at field installation.
Note:
• When the air conditioning system consists of several independent refrigerant system, figure out the total refrigerant
amount by each independent refrigerant system.
2. Calculate room volumes (m
The part with
2-1. Situation in which there are no partitions
Branch box
Indoor unit
2-2. There are partitions, but there are openings that allow the effective mixing of air.
Branch box
Indoor unit
Opening
Wall
2-3. 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.
Ventilation apparatus
The
smallest
room
3. Use the results of calculations 1 and 2 to calculate the refrigerant concentration.
Total refrigerant in the refrigerating unit (kg [lbs])
The smallest room in which an indoor
unit has been installed (m
3-1. If the calculation results do not exceed the maximum concentration, perform the same calculation for larger rooms
until it has been determined that nowhere exceeds the maximum concentration.
OCH790 _122
Direction of refrigerant flow
Branch box
Indoor unit
All refrigerant of this system will leak out to this
room if there is leakage at this indoor unit.
3
) and find the room with the smallest volume.
represents the room with the smallest volume.
Outdoor unit
Outdoor unit
Situation in which there are no door openings or
in which there are openings above and below
doors that occupy at least 0.15% of the floor area
Branch box
Outdoor unit
Indoor unit
The second
smallest
room
≤ Maximum concentration (kg/m
[ft ]) *Maximum concentration of R410A: 0.44kg/m
3 3
3 3
[0.027 lbs/ft ] (ISO 5149-1).
3 3
[0.027 lbs/ft ] in accordance with ISO 5149-1.
3
[lbs/ft
[lbs/ft ])*
3 3
[0.027lbs/ft
3
3
] (kg [lbs] of R410A per m
]
3
3 3
[ft ])