Mitsubishi Electric PLA-RP-BA Technical Data Manual page 91

<Table 10>
permitted
Outdoor unit
pipe length
RP200
120m or less
RP250
When length exceeds 70 m
When the total length of the piping exceeds 70 m, calculate the amount of additional charge based on the following requirements.
Note: If the calculation produces a negative number (i.e. a "minus" charge), or if calculation results in an amount that is less than the
"Additional charge amount for 70 m,"perform the additional charge using the amount shown in "Additional charge amount for 70 m."
Main piping:
Amount of additional Liquid line size
=
charge [12.7 overall length
0.12
Additional charge amount
RP200 3.6 kg
for 70 m
RP250 4.8 kg
1. Perform refrigerant piping connections for the indoor / outdoor unit while the outdoor unit's stop valve is completely
closed (Initial setting), and then vacuumize the refrigerant lines through the service port of the outdoor unit.
2. Open the stop valves of the outdoor unit completely.
This will completely connects the refrigerant circuits of the indoor and outdoor units.
Stop valve opening method is shown on the outdoor unit's installation manual.
Note :
· Apply refrigerating machine oil over the flare seat surface. Do not apply to the threaded portion.
(It will cause the flare nut to loosen.)
· Use 2 wrenches to tighten piping connection.
· Use leak detector or soapy water to check for gas leaks after connections are completed.
· For the insulation of the connection at the indoor side, make sure to use the attached insulation materials and
thoroughly follow the instruction shown in the manual.
· Always use a non-oxidizing brazing material when brazing the pipes.
Adjusting the amount of refrigerant
Check additional refrigerant charging amount referring to the procedure 2 below when the liquid pipe diameter of the main
piping A is larger than the standard size.
1 When the standard diameter pipe is used for the main piping A, calculate the additional refrigerant amount by
referring to <Table 2> as well as the 1:1 system.
2 When the liquid pipe diameter of the main piping A is one size larger than the standard size:
· When the extension pipe length (main piping + branch piping) does not exceed 20m, adjustment of the
refrigerant is not necessary (charge-less).
· When the extension pipe length (main piping + branch piping) exceeds 20m, charge the amount of refrigerant
that is obtained by the formula shown in <Table 7>.
If the calculation produces a negative number (i.e. a "minus" charge), additional charging is not necessary.
Note: Apply 0 to L , L , L
1 2
Correcting the capacity value
When calculating the lowered capacity by the extension pipe length, use the longest length between the indoor and the outdoor
units.
At time of shipping
(kg)
30 m and less
6.5
No additional
charge necessary
7.1
Main piping:
Liquid line size
+
[9.52 overall length
0.09 (Gas line:[28.58)
and L which correspond to the liquid pipe size that are not used.
3 4
A+B+C+D
Amount of additional refrigerant charge (kg)
31-40 m and less 41-50 m and less 51-60 m and less 61-70 m and less 71-120 m and less
0.9 kg 1.8 kg
1.2 kg 2.4 kg
Branch piping: Liquid
line size
+
[9.52 overall length
0.06 (Gas line: [15.88)
91
2.7 kg 3.6 kg
3.6 kg 4.8 kg
Branch piping: Liquid
line size
+
–
[6.35 overall length
0.02 (Gas line: [15.88)
The additional charge
amount is obtained by
the following formula.
3.6 (kg)