Refrigerant Piping Tasks - Mitsubishi Electric MXZ-SM72TAM-U1 Service Manual

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: 0.027 lbs/ft
Maximum refrigerant concentration of R410A of a room is 0.027 lbs/ft
To facilitate calculation, the maximum concentration is expressed in units of lbs/ft
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 (ft
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.
OCH800A_121
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 3
[m ]) 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
3 3
(0.44 kg/m ) (ISO 5149-1)
3 3
(0.44kg/m ) in accordance with ISO 5149-1.
3
[kg/m
3 3
] (lbs [kg] of R410A per ft [m
3
])