LG Multi F A2UW14GFA0 Engineering Product Data Book page 322

2. Guideline for each installation process
2.6.2 Essential points of testing
The key to successful testing is strict adherence to the following procedure:
1) 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.)
Step 1: increase pressure to 0.3MPa for 3 minutes or more
Step 2: increase pressure to 1.5MPa for 3 minutes or more
Step 3: increase pressure to 3.8MPa for approxmate 24 hours
Increasing the system pressure to 3.8MPa 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
Piping should not be pressured more than 3.8MPa.
2) 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 pres-
sure change of approximately 0.01MPa.
Compensating adjustment value:
(temperature at time of pressurizing – temperature at time of checking) x 0.01
Example:
During of pressurizing: 3.8MPa 25˚C
24 hours later: 3.75MPa 20˚C
Although the gauge pressure is dropped from 3.8MPa to 3.75MPa, it can be safely assumed that there is no leakage
because the gauge pressure can also drop due to the change in outdoor temperature.
27 _
Heat pump 50Hz/R410A
(MPa)
3.8MPa x 24min
3.8
3.5
3.0
2.5
2.0
1.5MPa x 5min
1.5
1.0
0.5
0.3MPa x 3min
0
5 minutes
3 minutes
Major leaks indicate
Minor leaks indicate
Step 3
3.75
25
20
15
Step 2
Step 1
(Time)
24 hours