Mitsubishi Electric CITY MULTI PEFY-P22VMS-E-S Data Book page 335

3. Piping Design
3-3. Refrigerant charging calculation
Sample connection(with 8 indoor units)
OU
A
Amount of refrigerant to be charged
Refrigerant for extended pipes (field piping) is not factory-charged to the outdoor unit. Add an appropriate amount of refrigerant
for each pipe on site.
Record the size of each liquid pipe and the amount of refrigerant that was charged on the outdoor unit for future reference.
Calculating the amount of refrigerant to be charged
The amount of refrigerant to be charged is calculated with the size of the on-site-installed liquid pipes and their length.
Calculate the amount of refrigerant to be charged according to the formula below.
Round up the calculation result to the nearest 0.1kg. (i.e., 16.08 kg = 16.1 kg)
<Amount of refrigerant to be charged>
Calculating the amount of refrigerant to be charged
Total length of ø19.05
Total length of ø15.88
liquid pipe x 0.29 liquid pipe x 0.2
+
(m)x0.29(kg/m) (m)x0.2(kg/m)
Amount of factory-
charged refrigerant
Outdoor unit model Charged amount
P300 model
9.0kg
P350 model
P400 model
11.5kg
P450 model
Note1. No Joint after Header; Piping direct to Indoor Unit from Header;
Note2. If the A/C system is designed to use Cooling mode under outside temperature 10°C, H'(OU under IU)
Note3. As bents cause pressure loss on transportation of refrigerant, fewer bents design is better;
Piping length needs to consider the actual length and equivalent length which bents are counted.
Equivalent piping length (m)=Actual piping length+"M" x Quantity of bent.
B C
a
1st Joint
IU
1 : P50 2 : P200
E F
e
IU
5 : P100 6 : P32
Total length of ø12.7 Total length of ø9.52
liquid pipe x 0.12 liquid pipe x 0.06
+ +
(m)x0.12(kg/m) (m)x0.06(kg/m)
Sample calculation
Indoor
A : ø15.88 15m 1:P50
B : ø12.70 2m
2:P200
C : ø9.52 2m 3:P20
D : ø9.52 1m
4:P20
E : ø9.52 10m 5:P100
F : ø9.52 10m
6:P32
G : ø9.52 5m 7:P20
8:P25
Total length for
each pipe size : ø15.88 A=15m
ø12.70 B=2m
ø9.52 C+D+E+F+G+b+e=2+1+10+10+5+15+5=48m
ø6.35 a+c+d+f+g+h=15+5+5+5+5+5=40m
This yields the following result : =15x0.2+2x0.12+48x0.06+40x0.024+4.5
=11.58kg
=11.6kg
SYSTEM DESIGN
D
b c d
IU IU IU
3 : P20 4 : P32
G
g h
f
IU IU IU
7 : P20 8 : P25
Total length of ø6.35
liquid pipe x 0.024
+ +
(m)x0.024(kg/m)
a : ø6.35 15m
b : ø9.52 15m
c : ø6.35 5m
d : ø6.35 5m
e : ø9.52 5m
f : ø6.35 5m
g : ø6.35 5m
h : ø6.35 5m
C7-R Rev.
< =
4m
Total capacity of connected Charged amount
indoor units
~80 2.0kg
81~160 2.5kg
3.0kg
161~330
3.5kg
331~390
391~480 4.5kg
5.0kg
481~630
6.0kg
631~710
8.0kg
711~800
9.0kg
801~890
891~1070 10.0kg
12.0kg
1071~1250
14.0kg
1251~
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