LG ARUB80LT2 Installation Manual page 40

Refrigerant piping installation
Leak Test and Vacuum
(1) Leak test
Leak test should be made by pressurizing nitrogen gas to
3.80MPa(38.7 kgf/cm
ure. (Make a test with the service valves closed. Be also sure to pres-
surize low pressure gas pipe and liquid pipe simultaneously)
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 pres-
surization.
* When charging of refrigerant is needed due to a defect of outdoor
unit, pressurize after opening the service valves.
During this test, please using the Vacuum Mode. (Refer to p77)
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
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
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.
(2) Vacuum
Vacuum of the pipe and the indoor units should be made from the port of the outdoor unit's service valve
with the service valve closed. Vacuum should be made from the high pressure gas pipe and the liquid pipe
simultaneously with a vacuum pump including a vacuum gage. (The low pressure gas pipe becomes vacu-
um via the HR unit.) After the degree of vacuum gets to 5 Torr, keep vacuum for more than an hour.
* Never perform air purging by using refrigerant.
During this test, please using the Vacuum Mode. (Refer to p77)
• Vacuum drying : Use a vacuum pump that can evacuate to -
100.7kPa (5 Torr, -755mmHg).
1. Evacuate the system from the liquid pipes and the high pres-
sure gas pipes with a vacuum pump for over 2 hours and
bring the system to -100.7kPa. After maintaining system
under that condition for over 1 hour, confirm the vacuum
gauge rises. If it rises, the system may contain moisture or
leak.
2. Following should be executed if there is a possibility of mois-
ture remaining inside the pipe.
(Rainwater may enter the pipe during work in the rainy sea-
son or over a long period of time)
After evacuating the system for 2 hours, give pressure to the
system to 0.05MPa(vacuum break) with nitrogen gas and
then evacuate it again with the vacuum pump for 1 hour to
-100.7kPa(vacuum drying). If the system cannot be evacuat-
ed to -100.7kPa within 2 hours, repeat the steps of vacuum
break and its drying. Finally, check if the vacuum gauge rise
or not, after maintaining the system in vacuum for 1 hour.
40 Outdoor Unit
2 ). For the test method, refer to the following fig-
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.
High pressure gas pipe
2 (0.01 MPa) for each 1°C of temperature difference.
High pressure gas pipe
Liquid pipe
Low pressure gas pipe
Liquid pipe
Low pressure gas pipe