Midea VC Pro Series Engineering Data page 172

VC Pro VRF 50/60Hz
5.9.3 Leak detection
Notes for installers
The general methods for identifying the source of a leak are as follows:
1. Audio detection: relatively large leaks are audible.
2. Touch detection: place your hand at joints to feel for escaping gas.
3. Soapy water detection: small leaks can be detected by the formation of bubbles when soapy water is applied to a
joint.
4. Refrigerant leak detection: for leaks that are difficult to detect, refrigerant leak detection may be used as follows:
a) Pressurize the piping with nitrogen at 0.3MPa.
b) Add refrigerant into the piping until the pressure reaches 0.5MPa.
c) Use a halogen refrigerant detector to find the leak.
d) If the leak source cannot be found, continuing charging with refrigerant to a pressure of 4MPa and then search
again.
5.10 Vacuum Drying
5.10.1 Purpose
Vacuum drying should be performed in order to remove moisture and non-condensable gases from the system. Removing
moisture prevents ice formation and oxidization of copper piping or other internal components. The presence of ice particles
in the system would cause abnormal operation, whilst particles of oxidized copper can cause compressor damage. The
presence of non-condensable gases in the system would lead to pressure fluctuations and poor heat exchange performance.
Vacuum drying also provides additional leak detection (in addition to the gastightness test).
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