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7. Pressure testing
After pipe installation, perform pressure testing
WARNING
Refrigerant leaks may cause oxygen defi ciency.
After pipe installation, perform pressure testing before insulation work. For the pressure testing, use
pressure that is at least as high as the set pressure for the whole of chilling system and no higher than
the set pressure for the condensing unit.
[The design pressure for the condensing unit (DP) is written on the condensing unit name plate.]
Condensing unit design pressure (DP)
High pressure unit
(MPa)
4.15
(1) Close the condensing unit service valves before the pressure test.
(2) Perform the following procedures without the pressure increasing to the test pressure.
(Always pressurise both the liquid and gas pipes.)
1. Pressurise to 0.5 MPa, then stop pressurisation, wait at least 5 minutes, then check for any drop in
pressure.
2. Pressurise to 1.5 MPa, wait at least fi ve minutes again, and then check for any drop in pressure.
3. Afterward, increase the pressure to the test pressure and note the ambient temperature and
pressure.
(3) Leave for approximately one day and night at the defi ned values. The test is passed if no drop in
pressure occurs.
• temperature change of 1°C causes a change in pressure of approximately 0.01 MPa, and thus
requires adjustment.
After welding (brazing), pressurise before the pipe temperature decreases, then lower the pressure
after cooling.
Also, note that changes in the outside air temperature may cause fl uctuations in pressure.
(The air pressure within the vessel is for absolute temperature comparison)
(example)
(measured value, absolute pressure) = (absolute pressure on pressurisation) × {(273 + temperature
on measuring) / (273 + temperature on pressurisation)}
(4) A drop in pressure indicates a leak. Be sure to perform repairs and check for leaks again.
* Do not use fl uorocarbon, oxygen, or fl ammable gases as the pressurising gas.
Low pressure unit
(MPa)
2.2
High pressure switch operation pressure
Operation pressure
(MPa)
+0
4.15
-0.3
19
Recovery pressure
(MPa)
3.2 ±0.2
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