ENGLISH
Installation Manual 37
Refrigerant Piping
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.
Leak Test and Vacuum Drying
Nitrogen gas
cylinder
Liquide pipe
Gas pipe
1. Leak test
Leak test should be m
ade by pressurizing nitrogen gas to 38.7 kgf/cm
2
(551 psi). 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 com-
pletion of nitrogen gas pressurization.
During this test, set DIP switch as Vacuum Mode.
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 kgf/cm
2
(1.4 psi) for each 1°C(2°F) 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 (38.7 kgf/cm
2
(551 psi)) is 27°C(81°F)
24 hour later: (38.0 kgf/cm
2
(541 psi)) is 20°C(68°F)
In this case the pressure drop of 0.07 is because of temperature drop
And hence there is no leakage in pipe occurred.
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