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1-123
1. Specifications
(3) Pressurize the system up to 4.15 MPa
(42 kgf/cm
2
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.
CAUTION
To avoid nitrogen entering the
refrigerant system in a liquid
state, the top of the cylinder
must be higher than the bottom
when you pressurize the
system. Usually, the cylinder is
used in a vertical standing
position.
Fig. 1-125
CAUTION
Use a cylinder specifi cally
designed for use with R410A.
(4) Do a leak test of all joints of the tubing (both
indoor and outdoor) and both gas and liquid
service valves. Bubbles indicate a leak. Wipe
off the soap with a clean cloth after the leak test.
(5) After the system is found to be free of leaks,
relieve the nitrogen pressure by loosening the
charge hose connector at the nitrogen cylinder.
When the system pressure is reduced to normal,
disconnect the hose from the cylinder.
2. Evacuation
Be sure to use a vacuum pump that includes a
function for prevention of back-fl ow, in order to
prevent back-fl ow of pump oil into the unit tubing
when the 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 –101kPa ( –755
mmHg, 5 Torr) or below.
Continue vacuum application for a minimum of 1
hour after the pressure reaches –101kPa ( –755
mmHg, 5 Torr).
(1) Attach the charge hose end described in the
preceding steps to the vacuum pump to evacuate
the tubing and indoor unit. Confi rm 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. Confi rm that the gauge pressure is
under –101kPa ( –755 mmHg, 5 Torr) after 4 to 5
minutes of vacuum pump operation.
Manifold valve
Pressure
gauge
Lo Hi
Vacuum pump
Outdoor unit
Liquid
tube
Gas
tube
Close
Close
Open
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