LG ARUB100LT3, Installation Manual

Page: 48 / 133

Pipe connections between indoor and outdoor unit
Leak Test and Vacuum drying
Indoor unit
Nitrogen gas
cylinder
Nitrogen gas
cylinder
Slave 1 outdoor unit Master outdoor unit
High Pressure
Gas pipe
High Pressure
Gas pipe
Liquide pipe Liquide pipe
Low Pressure
Gas pipe
Low Pressure
Gas pipe
Liquid side
Gas side
Close
Close
Close
Close
Close
Close
HR unit
(1) 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,
Low Pressure Gas pipes, High Pressure Gas pipe)
The test result can be judged good if the pressure has not be reduced after leaving for about one day after com-
pletion of nitrogen gas pressurization.
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.
48 Outdoor Unit