Installation
30
Leak Test and Vacuum Drying
Nitrogen gas
cylinder
Liquide pipe
Gas pipe
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 nitro-
gen 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.
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 pres-
sure 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 sys-
tem. Usually the cylinder is used in a vertical standing position.
Summary of Contents for AHNW166T0
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