Hitachi YUTAKI RAS-2WHVRP1 - Brazing Work Precautions; Refrigerant Charge Procedures; Refrigerant Charging Quantity; Pressure Check Joint Precautions

8.3 BRAZING WORK
! CAUTION
• Use nitrogen gas for blowing during pipe brazing. If oxygen, acetylene
or uorocarbon gas is used, it will cause an explosion or poisonous
gas.
• A lot of oxidation lm will occur inside of tubes if no nitrogen gas
blowing is performed during brazing work. This lm will be ecked
off after operation and will circulate in the cycle, resulting in clogged
expansion valves, etc. This will cause bad inuence to the compressor.
• Use a reducer valve when nitrogen gas blowing is performed during
brazing. The gas pressure should be maintained within 0.03 to
0.05MPa. If a excessively high pressure is applied to a pipe, it will
cause an explosion.
8.4 REFRIGERANT CHARGE
! CAUTION
• Do not charge OXYGEN, ACETYLENE, or other ammable and
poisonous gases into the refrigerant because an explosion can occur.
It is recommended that oxygen free nitrogen be charged for these
types of tests cycle when performing a leakage test or an airtight test.
These types of gases are extremely dangerous.
• Insulate the unions and are-nuts at the piping connection part
completely.
• 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 insufcient charging
could cause a compressor failure.
• Check for refrigerant leakage in detail. If a large refrigerant leakage
occurred, it would cause difculty with breathing or harmful gases
would occur if a re were being used in the room.
• If the are nut is tigthened too hard, the are nut may crack after a
long time and cause refrigerant leakage.
8.5 REFRIGERANT CHARGING QUANTITY
In case of the actual piping length is more than the specied length, the additional refrigerant quantity should be charged according
to the table below:
Outdoor unit refrigerant
charge (kg)
Chargeless length (m)
Additional refrigerant
charge (P) (g/m)
Max additional charge
(kg)
RAS-2WHVRP1 1.2
10
15 0.6
RAS-2.5WHVRP1 1.3 15 0.6
RAS-3WHVRP1 1.3 30
<27m= 0.51
>27m=0.90
1 Determine an additional refrigerant quantity and charge it into the system.
2 Record the additional refrigerant quantity to facilitate service activities thereafter.
! CAUTION
• When charging refrigerant accurately measure refrigerant to be charged.
• Overcharging or undercharging of refrigerant can cause compressor trouble.
• Refer to indoor unit installation manual for refrigerant charge and minimum oor requirements.
8.6 CAUTION OF THE PRESSURE BY CHECK JOINT
When the pressure is measured, use the check joints of the gas
stop valve and liquid stop valve.
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.
Cooling
operation
Heating
operation
Check joint for gas stop valve Low pressure High pressure
Check joint for liquid stop
valve
Exclussive for vacuum pump and
refrigerant charge
? NOTE
Be careful that refrigerant and oil do not splash to the electrical parts at
removing the charge hoses.
Stop valve (liquid)
Stop valve (gas)
REFRIGERANT PIPING & REFRIGERANT CHARGE
PMML0576 rev.0 - 06/2021
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