After finishing connection of refrigerant pipe, it shall perform air tightness test.
The air tightness test adopts nitrogen tank to give pressure according to the pipe connection mode as
the following figure shown.
The gas and liquid valve are all in close state. In order to prevent the nitrogen entering the circulation
system of outdoor unit, tighten the valve rod before giving pressure (both gas and liquid valve rods).
Outdoor
Completely tightened
Completely tightened
Flare part
Outdoor units
Mainhole
Discharging valve
3-way valve totally closed
(Gas side)
Low pressure gauge
High pressure gauge
Meter separator
Dropping valve
2-way valve totally closed
(Liquid side)
Nitrogen tank
VL
VH
Indoor units
Indoor
Flare part
Air discharging method
First step: 0.3MPa (3.0kg/cm
2
g) pressurize over 3 minutes.
Second step: 1.5Mpa (15kg/cm
2
g) pressurize over 3 minutes. Large leakage will be found.
Third step: 3.0 MPa (30kg/cm
2
g) pressurize about 24 hours. Little leakage will be found.
From the first to third steps, if the pressure drops, check the leakage in each joint by the sense of
hearing, feeling or soap water, etc. to find the leaking point.
After confirming the leaking point, welding it again or tighten the nut tightly again.
Checking the leaking point
After pressurizing for 24 hours, each 1 C difference of ambient temperature
will result in 0.01MPa(0.1kg/cm
2
g) pressure change. It shall be corrected during test.
Check if the pressure drops
If the pressure does not drop, the unit is passed
If the pressure drops, please check the leaking point.
Use vacuum pump to perform vacuumizing. It is strictly forbidden to use the refrigerant to remove
the air inside the system.
After air tightness test and discharging all the nitrogen, connect the vacuum pump as the following
figure shown.
Piping and indoor unit vacuumizing
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