Hitachi CENTRIFUGAL VRF Serie Bedienungsanleitung Seite 22

REFRIGERANT PIPING & REFRIGERANT CHARGE
8.4 REFRIGERANT CHARGE PROCEDURE
!
C A U T I O N
• Use refrigerant R410A in the refrigerant cycle. Do not charge oxygen,
acetylene or other flammable and poisonous gases into the refrigerant
cycle when performing a leakage test or an air-tight test.
• These types of gases are extremely dangerous and can cause an
explosion. It is recommended that compressed air, nitrogen or
refrigerant be used for these types of tests.
• Check to ensure that no pressure exists inside the stop valve before
removing the flange.
8.5 CAUTION OF THE PRESSURE BY CHECK JOINT
When the pressure is measured, use the check joint of gas stop
valve (A), and use the check joint of liquid piping (B) in the figure
below.
At that time, connect the pressure gauge according to the
following table because of high pressure side and low pressure
side changes by operation mode.
Check joint for gas stop
valve "A"
Check joint for piping "B"
Check joint for liquid stop
valve "C"
8.6 REFRIGERANT CHARGE QUANTITY
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.
W is the RASC unit refrigerant charge before shipment
0
explained before, and it's shown in the following table:
Refrigerant
charge before
Model
shipment
(W (kg))
0
RASC-4HNPE 4.1
RASC-5HNPE 4.2
RASC-6HNPE 4.2
RASC-8HNPE 5.7
RASC-10HNPE 6.2
(1) needs to be calculated.
12 PMML0399B rev.1 - 07/2016
Cooling Heating
Operation Operation
Low pressure High pressure
High pressure Low pressure
Exclusive for vacuum pump and
refrigerant charge
Additional Maximum
refrigerant additional
charge charge
(P (g/m)) (kg)
60 3.9
60 3.9
60 3.9
(1) 7.1
(1) 8.1
• Insulate the liquid piping completely to avoid a decrease of
performance; if not, it will cause sweating on the surface of the pipe.
• Charge refrigerant correctly. Overcharging or insufficient charging
could cause a compressor failure.
• Check for refrigerant leakage in detail. If a large refrigerant leakage
occurred, it would cause difficulty with breathing or harmful gases
would occur if a fire were being used in the room.
• If the flare nut is tightened too hard, the flare nut may crack after a
long time and cause refrigerant leakage.
?
N O T E
Be careful that refrigerant and oil do not splash to the electrical parts at
removing the charge hoses.
B

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 (kg))
1
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:
W
1
L: Total piping length (m)
P: Additional refrigerant charge (kg/m).
Right side
C a
= (L-30) x P