Si39-303 Installation
General Information 29
3.2.5 Air Tight Test
!
Operational steps
Essential Points
of Testing
(Maintaining
Pressure Over a
Period)
The key to successful testing is strict adherence to the following procedure:
a) The liquid and gas piping in each refrigerant system should be pressurized in turn in accordance with
the following steps. (Nitrogen gas must be used.)
∗
Increasing the system pressure to 3.80MPa does not guarantee the identification of minor leaks if
pressure is maintained for only a short time. It is therefore recommended that the system remain
pressurized in accordance with Step 3 above for at least 24 hours.
Note:
The pressure must on no account be increased beyond 3.80MPa.
b) Check for pressure drop
If there is no drop in pressure then the test is deemed a success.
If the pressure drops then the leak must be located. See following page.
However, if there is a change in the ambient temperature between the pressurizing stage and the time
when you check for a drop in pressure then you will have to adjust your calculations accordingly since a
change of 1°C can account for a pressure change of approximately 0.01MPa.
Compensating adjustment value:
(temperature at time of pressurizing – temperature at time of checking) × 0.01
Example:
Time of pressurizing: 3.80MPa 25°C
24 hours later: 3.75MPa 20°C
The pressure drop in such a case is deemed to be zero (successful test).
Complete
refrigerant pipe
installation work
Pressurize Check for pressure drop Success
Locate and repair leaks
(V0987)
!
Step 1: increase pressure to 0.3MPa for 3
minutes or more
Indicates existence of major leaks
!
Step 2: increase pressure to 1.5MPa for 3
minutes or more
Indicates existence of minor leaks
!
Step 3: increase pressure to 3.80MPa for
approx. 24 hours
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