Haier HBU-18CF03 Service Manual page 20

Commercial air conditioning
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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.
Check if the pressure drops
If the pressure does not drop, the unit is passed
If the pressure drops, please check 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.
Checking the leaking point
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.
Piping and indoor unit vacuumizing
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.
Indoor
Completely tightened
Completely tightened
Indoor units
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.
20
Commercial Air Conditioner
3-way valve totally closed
(Gas side)
Outdoor
Flare part
Flare part
2-way valve totally closed
(Liquid side)
Model: HBU-18CF03
HDU-42CF03/H HPU-42HF03
Low pressure gauge
V L VH
Discharging valve
P
Vacuum pump
Outdoor units
High pressure gauge
Meter separator

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