Hitachi UTOPIA RAS-4HVRP2E Installations- Und Betriebshandbuch Seite 42

Refrigerant piping & refrigerant charge
Do not work with two
spanners here.
Refrigerant leakage
shall occur
Use two spanners here
for pipe connection
8.3 BRAZING WORK
!
C A U T I O N
• Use nitrogen gas for blowing during pipe brazing. If oxygen, acetylene
or fluorocarbon gas is used, it will cause an explosion or poisonous
gas.
• A lot of oxidation film will occur inside of tubes if no nitrogen gas
blowing is performed during brazing work. This film will be flecked
off after operation and will circulate in the cycle, resulting in clogged
expansion valves, etc. This will cause bad influence to the compressor.
8.4 REFRIGERANT CHARGE
!
C A U T I O N
• Do not charge OXYGEN, ACETYLENE, or other flammable 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 flare-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.
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"
?
N O T E
Be careful that refrigerant and oil do not splash to the electrical parts at
removing the charge hoses.
11 PMML0545 rev.2 - 04/2021
Cooling Heating
operation operation
Low pressure High pressure
High pressure Low pressure
Exclusive for vacuum pump and
refrigerant charge
!
C A U T I O N
• At the test run, fully open the spindle and ball stop valve.
• If not fully opened, the devices will be damaged.
• Do not attempt to turn service valve rod beyond its stop.
• Do not loosen the stop ring. If the stop ring is loosened, it is dangerous
since the spindle will hop out.
• An excess or a shortage of refrigerant is the main cause of trouble
to the units. Charge the correct refrigerant quantity according to the
description of label at the inside of service cover.
• Check for refrigerant leakage in detail. If a large refrigerant leakage
occurs, it will cause difficulty with breathing or harmful gases would
occur if a fire was being used in the room.
• 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.
• 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.
B
C
A
There may be gas
trapped at the "O-ring
screw" part, which may
produce a sound when
released upon removal
of the cap.
However, this is not a
gas leakage.