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(3) Pressurize the system up to 4.15 MPa (42 kgf/
2
cm
G) with dry nitrogen gas and close the cylinder
valve when the gauge reading reaches 4.15 MPa
(42 kgf/cm
2
G). Then, test for leaks with liquid soap.
GB
CAUTION
FR
DE
(4) Do a leak test of all joints of the tubing (both
indoor and outdoor) and both gas and liquid
IT
service valves. Bubbles indicate a leak. Wipe off
the soap with a clean cloth after a leak test.
(5) After the system is found to be free of leaks,
relieve the nitrogen pressure by loosening the
PT
charge hose connector at the nitrogen cylinder.
When the system pressure is reduced to normal,
disconnect the hose from the cylinder.
GR
8-2. Evacuation
Be sure to use a vacuum pump that includes a func-
tion for prevention of back-flow, in order to prevent
back-flow of pump oil into the unit tubing when the
ES
pump is stopped.
●
Perform vacuuming of the indoor unit and tubing.
Connect the vacuum pump to the gas tube valve
and apply vacuum at a pressure of –755 mmHg
(5 torr) or below.
Continue vacuum application for a minimum of 1
hour after the pressure reaches –755 mmHg.)
(1) Attach the charge hose end described in the
preceding steps to the vacuum pump to evacuate
the tubing and indoor unit. Confirm that the "Lo"
knob of the manifold valve is open. Then, run the
vacuum pump.
(2) When the desired vacuum is reached, close the
"Lo" knob of the manifold valve and turn off the
vacuum pump. Confirm that the gauge pressure is
under –101 kPa (–755 mmHg, 5 Torr) after 4 to 5
minutes of vacuum pump operation.
CAUTION
DC̲Inverter̲Eng.indd 60
DC̲Inverter̲Eng.indd 60
To avoid nitrogen entering
the refrigerant system in a
liquid state, the top of the
cylinder must be higher than
the bottom when you pres-
surize the system. Usually,
the cylinder is used in a ver-
tical standing position.
Use a cylinder specifically
designed for use with R410A.
Manifold valve
Pressure
Lo
Hi
gauge
Open
Gas
tube
Liquid
tube
Fig. 8-4
60
Vacuum pump
Close
Outdoor unit
Close
2007/07/25 13:21:47
2007/07/25 13:21:47
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