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Vacuumizing
Prerequisites
- Before vacuumizing, check that the refrigerant pipe system has passed the air tightness test and does not leak.
- Before vacuumizing, ensure that all connectors on the device are tightened.
- System high pressure may occur if the system is not vacuumed or is not thoroughly vacuumed. Therefore, ensure that the system is thoroughly vacuumed.
Procedure
- Check whether a low temperature component is installed on the outdoor side.
- If no low temperature component is installed on the outdoor side, connect the pressure gauge and vacuum pump at the low-pressure and discharge pipe needle valves to vacuumize the system simultaneously, as shown in Figure 6-1.
- If a low-temperature component is installed on the outdoor side, connect the pressure gauge and vacuum pump at the low-pressure, exhaust pipe, and liquid pipe needle valves to vacuumize the system simultaneously, as shown in Figure 6-2.
- In the beginning, the vacuum pump makes loud noises and exhausts white gas from the exhaust vent. After 10 minutes, if it still exhausts white gas, observe it for another 10 minutes because the cooling system may not be sealed properly or there may be too much residual refrigerant or water in the cooling system.
- After 20 minutes, the pressure gauge pointer should be in the negative area and the vacuum pump makes small noise. Close and open the pressure gauge alternatively for several times. The position of the pressure gauge pointer and the sound made by the vacuum pump do not obviously change. Otherwise, the cooling system may not be sealed properly.
- Vacuumize the cooling system for at least 80 minutes after checking that the cooling system does not leak. The pressure displayed on the vacuum pump should be less than or equal to 60 Pa (absolute pressure). When the pressure stops dropping, vacuumize for another 10 minutes, after which the sight glass should display green, a sign of dryness.
- After vacuumizing is complete, close all valves of the pressure gauge and the vacuum pump without disconnecting the pump, and preserve the pressure for 10 minutes. Ensure that the pressure of the cooling system does not exceed 90 Pa (absolute pressure).
- If the minimum reading of the pressure gauge is greater than 60 Pa (absolute pressure), ensure that the pointer stays at the smallest scale of the pressure gauge in vacuumizing and preserve the pressure for 1 hour. Then check that the pressure does not rise evidently.
