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It shall use the vacuum pump of (lower than -755mmHg)high vacuum degree and large air
discharging (over 40l/min).
The vacuumizing time depends on the length of the connecting pipe, generally is 1~2 hours.
When vacuumizing, it shall be confirmed both gas and liquid side valves are closed.
If after 2 hours vacuumizing, it cannot reach the vacuum degree below -755mmHg, it can be
vacuumized for other 1 hour.
If after 3 hours vacuumizing, it still cannot reach the vacuum degree below -755mmHg, check
if there is any leaking point and repair the them.
If after over 2 hours vacuumizing, the vacuum degree is below -755mmHg, close the V
L and
V
H
on the meter separator and stop vacuumizing. 1 hour later to confirm if the vacuum degree changes.
If changes,it indicates there is leaking point in the system. Check the leaking point and repair.
After finishing the above vacuumizing, change the vacuum pump into refrigerant pump to charge
the refrigerant.
2-way valve totally closed
(Liquid side)
Indoor units
Indoor
Outdoor
Completely tightened
Completely tightened
Outdoor units
Vacuum pump
Discharging valve
3-way valve totally closed
(Gas side)
Low pressure gauge
High pressure gauge
Meter separator
V L
VH
Flare part
Flare part
P
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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