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10. PIPING WORK AND REFRIGERANT CHARGE
Completion
of Ref.
Piping
Repairing
of Leakage
Part
Check of
Pressure
Decrease
Applying
Nitrogen
Gas
Pass
Procedure
10.3 Air tight test
Do use nitrogen when performing air-tight test.
Connect the gauge manifold using charging hoses with a nitrogen cylinder to the check joints of the
liquid line and the gas line stop valves. Perform the air-tight test. Don't open the gas line stop
valves. Apply nitrogen gas pressure of 550 psig (3.8MPa). Check for any gas leakage at the flare
nut connections, or brazed parts by gas leak detector or foaming agent. It is OK if gas pressure
does not decrease. After the air tight test, release nitrogen gas.
Air tight procedure
10.4 Additional refrigerant charge
Although refrigerant has been charged into this unit, additional refrigerant charge is
required according to the piping length.
The additional refrigerant precharge quantity should be determined and charged into the system
according to the following procedure.
Record the additional refrigerant quantity in order to facilitate maintenance and servicing activities.
Refrigerant charge before shipment (W0 (oz.))
W0 is the outdoor unit refrigerant charge before shipment
Xg is additional refrigerant outdoor unit needed to charge according to piping length during
installation.
Model
Refrigerant
precharged before
shipment (oz.)
Total refrigerant pipe length
0ft.25ft.
Long than 25ft.
24K
70.5
0
Xg = 0.38oz/ft ×( Total pipe length(ft.) -25)
3
6K
98.7
0
Xg = 0.38
oz
/
ft
×
(
T
otal
pi
pe length(ft.)
-
25)
60K
142.9
0
Xg = 0.60oz/ft ×( Total pipe length(ft.) -25)
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