10
English
L
H
Fig. 8-1
Indoor units
Outdoor unit
Unit
A
Unit
B
Unit
C
Unit A
Unit B
Unit C
8. Air Purging
Air and moisture remaining in the refrigerant system have
undesirable effects as indicated below.
●
pressure in the system rises
●
operating current rises
●
cooling (or heating) efficiency drops
●
moisture in the air circuit may freeze and block the
capillary tubing
●
water may lead to corrosion of parts in the refrigerant
system
■
Air Purging with a Vacuum Pump (for Test Run)
Preparation
Check that each tube (both narrow and wide tubes) between
the indoor and outdoor units have been properly connected and
all wiring for the test run has been completed. Remove the
valve caps from both the wide and narrow tube service valves
on the outdoor unit. Note that both narrow and wide tube
service valves on the outdoor unit are kept closed at this stage.
Air Purge
For leak testing the indoor units (A, B, C), there are two
methods; using nitrogen gas or outdoor unit's gas according
to the installation site conditions. The respective procedures
are described below.
1) Using Nitrogen Gas (Unit A)
a) Leak test
(1) With the service valves on the outdoor unit remaining
closed, remove the valve cap on the wide and wide
tube service valve. (Save the valve cap for reuse.)
(2) Connect a manifold valve (with pressure gauges) and
dry nitrogen gas cylinder to this service port with charge
hose. (Fig. 8-1)
(3) Pressurize the system to no more than 10 kg/cm
2
with
dry nitrogen gas and close the cylinder valve when the
gauge reading reaches10 kg/cm
2
. Next, test for leaks
with liquid soap.
Be sure to use a manifold valve for
air purging. If it is not available, use
a stop valve for this purpose. The
"Hi" knob of the manifold valve
must always be kept closed.
CAUTION
!
To avoid nitrogen entering the
refrigerant system in a liquid state,
the top of the cylinder must be
higher than its bottom when you
pressurize the system. Usually, the
cylinder is used in a vertical
standing position. (Fig. 8-1)
CAUTION
!
Nitrogen gas cylinder
(in a vertical standing
position)
Charge hose
Manifold
valve
