LG Multi V PRHR033 Installation Manual page 30

30
Leak Test and Vacuum drying
Leak test
Leak test should be made by pressurizing nitrogen gas to 3.8 MPa
(551.1 psi). If the pressure does not drop for 24 hours, the system
passes the test. If the pressure drops, check where the nitrogen leaks.
For the test method, refer to the following figure. (Make a test with
the service valves closed. Be also sure to pressurize liquid pipe, gas
pipe and high/low pressure common pipe)
The test result can be judged good if the pressure has not be reduced
after leaving for about one day after completion of nitrogen gas
pressurization.
Series Installation (Heat Recovery)
Slave 1 outdoor unit
Nitrogen
Close
gas Close
cylinder
Close
Nitrogen
gas
cylinder
Series Installation (Heat Pump)
Slave 1 outdoor unit
Nitrogen
Close
gas Close
cylinder
Close
WARNING
!
Use a vacuum pump or Inert(nitrogen) gas when doing leakage
test or air purge. Do not compress air or Oxygen and do not use
Flammable gases. Otherwise, it may cause fire or explosion.
- There is the risk of death, injury, fire or explosion.
NOTE
!
If the ambient temperature differs between the time when
pressure is applied and when the pressure drop is checked, apply
the following correction factor
There is a pressure change of approximately 0.01 MPa (1.5 psi) for
each 1.8 °F (1 °C) of temperature difference.
Correction= (Temp. at the time of pressurization – Temp. at the
time of check) X 0.1
For example: Temperature at the time of pressurization
3.8 MPa (551 psi) is 80.6 °F (27 °C)
24 hour later: 3.73 MPa (541 psi), 68 °F
(20 °C)
In this case the pressure drop of 0.07
MPa (10 psi) is because of temperature
drop And hence there is no leakage in
pipe occurred.
Master outdoor unit
When inserting
nitrogen gas of
Close
high pressure, it
must be used with
Close
Close
regulator.
Liquid side
Indoor unit
HR unit
Gas side
Master outdoor unit
When inserting
nitrogen gas of
Close
high pressure, it
must be used with
Close
Close
regulator.
Liquid side
Indoor unit
Gas side
CAUTION
!
To prevent the nitrogen from entering the refrigeration system in
the liquid state, the top of the cylinder must be at higher position
than the bottom when you pressurize the system.
Usually the cylinder is used in a vertical standing position.
Vacuum
Vacuum drying should be made from the service port provided on the outdoor
unit's service valve to the vacuum pump commonly used for liquid pipe, gas pipe
and high/low pressure common pipe. (Make Vacuum from liquid pipe, gas pipe and
high/low pressure common pipe with the service valve closed.)
* Never perform air purging using refrigerant.
• Vacuum drying: Use a vacuum pump that can evacuate to -100.7 kPa
(-14.6 psi, 5 Torr, -755 mmHg).
- Evacuate the system from the liquid and gas pipes with a vacuum
pump for over 2 hrs and bring the system to -100.7 kPa (-14.6 psi). After
maintaining system under that condition for over 1 hr, confirm the
vacuum gauge rises. The system may contain moisture or leak.
- Following should be executed if there is a possibility of moisture
remaining inside the pipe. (Rainwater may enter the pipe during work in
the rainy season or over a long period of time)
After evacuating the system for 2 hrs, give pressure to the system to
0.05 MPa (7.3 psi) (vacuum break) with nitrogen gas and then evacuate
it again with the vacuum pump for 1hr to -100.7 kPa (-14.6 psi)(vacuum
drying). If the system cannot be evacuated to -100.7 kPa(-14.6 psi)
within 2 hrs, repeat the steps of vacuum break and its drying. Finally,
check if the vacuum gauge does not rise or not, after maintaining the
system in vacuum for 1 hr.
Series Installation (Heat Recovery)
Slave 1 outdoor unit
Vacuum
pump
Close
Close
Close
Vacuum
pump
Scale
Use a graviometer. (One that can
measure down to 0.1kg). If you are
unable to prepare such a
high-precision gravimeter you may use
a charge cylinder.
Series Installation (Heat Pump)
Slave 1 outdoor unit
Vacuum
pump
Close
Close
Close
Scale
Use a graviometer. (One that can
measure down to 0.1kg). If you are
unable to prepare such a
high-precision gravimeter you may use
a charge cylinder.
Master outdoor unit
Close
Close
Close
Liquid side
Indoor unit
HR unit
Gas side
Master outdoor unit
Close
Close
Close
Liquid side
Indoor unit
Gas side