42
Outside Unit
Leakage test and vacuum
Leakage test and vacuum
Leak Test and Vacuum
(1) Leak test
Leak test should be made by pressurizing nitrogen gas to
3.80MPa(38.7 kgf/cm
2
). For the test method, refer to the following
figure. (Make a test with the service valves closed. Be also sure to
pressurize 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 nitro-
gen gas pressurization.
* When charging of refrigerant is needed due to a defect of out-
door unit, pressurize after opening the service valves.
During this test, please using the Vacuum Mode. (Refer to p77)
(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 pressure 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
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 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
evacuated 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.
Low pressure
gas pipe
Liquid pipe
High pressure
gas pipe
A
C
E
D
J
I
F
H
G
B
High pressure
gas pipe
Liquid pipe
Low pressure
gas pipe
A
B
C
H
D
F
E
G
I
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.
