Refrigerant Charge; Refrigerant Charge Amount - Hitachi RASC-4HNPE Service Manual

3 Piping work and refrigerant charge

Refrigerant charge

3.4 Refrigerant charge

3.4.1 Refrigerant charge amount

Although refrigerant has been charged into this unit, the adequate refrigerant charge depends on the piping length.
• The adequate refrigerant quantity should be determined according to the following procedure.
• Record the adequate refrigerant quantity in order to facilitate maintenance and servicing activities.
!
C A U T I O N
• When charging or removing refrigerant, measure the amount precisely. Overcharging or undercharging of refrigerant may cause
compressor problems.
• In case of actual piping length less than 5 m, consult your distributor.
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Refrigerant charge before shipment (W
W is the RASC unit refrigerant charge before shipment explained before, and it's shown in the following table:
0
Refrigerant charge before shipment
Model
RASC-4HNPE
RASC-5HNPE
RASC-6HNPE
RASC-8HNPE
RASC-10HNPE
(1): Needs to be calculated.
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Calculation method for the additional refrigerant charge
Calculate the additional refrigerant charge amount according to the following steps:
Step 1: Additional refrigerant charge calculation for liquid piping (W
RASC units have been charged with refrigerant for 30 m of actual piping length. In systems with longer actual piping
length, an additional refrigerant charged is required.
For RASC-(4-6)HNPE units
Use the following formula:
L: Total piping length (m)
P: Additional refrigerant charge (kg/m) (Refer to the
For RASC-(8/10)HNPE units
The additional refrigerant charge for RASC-(8/10)HNPE units must be calculated by multiplying the total piping length of
each diameter per its calculation factor according to the following table. The result is the additional refrigerant charge for
liquid piping W .
1
(*): For RASC-(8/10)HNPE units ,add 0.030 kg/m (instead of 0.065 kg/m) when there are 5 or more indoor units connected to the RASC
unit.
48 SMGB0091 rev.2 - 11/2015
(kg))
0
Additional refrigerant charge
(W (kg))
0
4.1
4.2
4.2
5.7
6.2
W = (L-30) x P
1
"Refrigerant charge before shipment (W0 (kg))"
Additional refrigerant charge
Pipe size (mm)
Ø15.88
Ø12.7
Ø9.52
Ø6.35
Maximum additional charge
(P (g/m))
60
60
60
(1)
(1)
(kg))
1
factor (kg/m)
x 0.19
x 0.12
x 0.065
x 0.065 (*)
(kg)
3.9
3.9
3.9
6.3
8.1
section)