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PIPE CONNECTIONS BETWEEN INDOOR AND OUTDOOR UNIT
46
Leak Test and Vacuum drying
Leak test
Leak test should be made by pressurizing nitrogen gas to 3.8 MPa(38.7 kgf/cm
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.
Nitrogen gas
cylinder
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.
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.
Slave 1 outdoor unit
Master outdoor unit
Close
Close
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.
Close
Close
2
(0.01 MPa) for each 1 °C of temperature difference.
2
). If the pressure
Liquid side
Indoor unit
Gas side
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