18
ENGLISH
Leak test
Leak test should be made by pressurizing nitrogen gas to 3.8
MPa(38.7kgf/cm
2
). If the pressure does not drop for 24 hours, the
system passes the test. If the pressure drops, check where the
nitrogen leaks. For the test method, refer to the following figure.
(Make a test with the service valves closed. Be also sure to pressurize
liquid pipe, gas pipe and high/low pressure common pipe)
The test result can be judged good if the pressure has not be reduced
after leaving for about one day after completion of nitrogen gas
pressurization.
Indoor unit
Nitrogen gas
cylinder
To Heat Exchanger Module
To Indoor Unit
Liquide pipe
Gas pipe
Liquide pipe
Gas pipe
Liquid side
Gas side
Close
Close
Close
Close
NOTE
!
If the ambient temperature differs between the time when pressure is
applied and when the pressure drop is checked, apply the following
correction factor
There is a pressure change of approximately 0.1 kg/cm
2
(0.01 MPa) for
each 1°C of temperature difference.
Correction= (Temp. at the time of pressurization – Temp. at the time
of check) X 0.1
For example: Temperature at the time of pressurization
(3.8 MPa) is 27 °C
24 hour later: 3.73 MPa, 20°C
In this case the pressure drop of 0.07 is because of
temperature drop And hence there is no leakage in pipe
occurred.
CAUTION
To prevent the nitrogen from entering the refrigeration system in
the liquid state, the top of the cylinder must be at higher position
than the bottom when you pressurize the system.
Usually the cylinder is used in a vertical standing position.
!
WARNING
Use a vacuum pump or Inert(nitrogen) gas when doing leakage test
or air purge. Do not compress air or Oxygen and do not use
Flammable gases. Otherwise, it may cause fire or explosion.
- There is the risk of death, injury, fire or explosion.
!
Vacuum
Vacuum drying should be made from the service port provided on the outside
unit’s service valve to the vacuum pump commonly used for liquid pipe, gas
pipe and high/low pressure common pipe. (Make Vacuum from liquid pipe, gas
pipe and high/low pressure common pipe with the service valve closed.)
* Never perform air purging using refrigerant.
• Vacuum drying: Use a vacuum pump that can evacuate to -100.7kPa
(5 Torr, -755mmHg).
- Evacuate the system from the liquid and gas pipes with a vacuum
pump for over 2 hrs and bring the system to -100.7kPa. After
maintaining system under that condition for over 1 hr, confirm the
vacuum gauge rises. The system may contain moisture or leak.
- Following should be executed if there is a possibility of moisture
remaining inside the pipe.
(Rainwater may enter the pipe during work in the rainy season or over
a long period of time)
After evacuating the system for 2 hrs, give pressure to the system to
0.05MPa(vacuum break) with nitrogen gas and then evacuate it again
with the vacuum pump for 1hr to -100.7kPa(vacuum drying). If the
system cannot be evacuated to -100.7kPa within 2 hrs, repeat the
steps of vacuum break and its drying. Finally, check if the vacuum
gauge does not rise or not, after maintaining the system in vacuum
for 1 hr.
Scale
Use a graviometer.
(One that can measure
down to 0.1kg). If you
are unable to prepare
such a high-precision
gravimeter you may use
a charge cylinder.
Vacuum
pump
Indoor unit
To Heat Exchanger Module
To Indoor Unit
Liquide pipe
Gas pipe
Liquide pipe
Gas pipe
Liquid side
Gas side
Close
Close
Close
Close
NOTE
!
Always add an appropriate amount of refrigerant. (For the refrigerant
additional charge)
Too much or too little refrigerant will cause trouble.
To use the Vacuum Mode
(If the Vacuum mode is set, all valves of Indoor units and Outside units will be
opened.)
WARNING
Use a vacuum pump or Inert(nitrogen) gas when doing leakage test
or air purge. Do not compress air or Oxygen and do not use
Flammable gases. Otherwise, it may cause fire or explosion.
- There is the risk of death, injury, fire or explosion.
!
WARNING
When installing and moving the air conditioner to another site,
recharge after perfect evacuation.
- If a different refrigerant or air is mixed with the original
refrigerant, the refrigerant cycle may malfunction and the unit
may be damaged.
!
Leak Test and Vacuum drying
www.lgcomfortcooling.co.uk
