Hitachi Set Free mini-HNRQ1 Series, Руководство по обслуживанию

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19
INSTALLATION
(7) Cautions for Brazing Work
(A) For piping connections, complete non-oxidation brazing with a nitrogen charge. If brazing the pipes
without the nitrogen substitution, a large amount of oxidized scaling will be generated in the piping. This
oxidized scaling can cause clogging inside the expansion valve, solenoid valve, accumulator, and com-
pressor, which can damage the unit.
Do not use field-supplied antioxidant which can corrode pipes and degrade the refrigerant oil.
Notes:
● Make sure to use nitrogen. Nitrogen gas pressure shall be 0.02 MPa or less.
● Make sure to use the pressure-reducing valve.
● Do not use field-supplied antioxidant.
(B) Use a type of flux with a low chlorine concentration.
(C) Washing the weld joints to remove all flux completely after completing brazing work.
Note:
To avoid oxidation and scaling, perform brazing at the appropriate temperature.
(D) To prevent gas leakage at the brazing connection, refer to the table for the insertion depth and the gap
for joint pipe.
Unit: mm
Diameter(ΦD)
Min. Insertion
Depth (B)
Gap (A - D)
5≤ D <8 6
0.05 - 0.35
8≤ D <12 7
12≤ D <16 8
0.05 - 0.45
16≤ D <25 10
(8) Cautions for Flaring Work
(A) Perform the flaring work as shown below:
Unit: mm
Diameter
(Φd)
A +0
-0.4
R410A
6.35 9.1
9.52 13.2
12.7 16.6
15.88 19.7
19.05 (*)
(*): It is impossible to perform flaring work with hard temper pipe. Use an accessory pipe with a flare.
Piping Connection on-site
Brazing Part
Nitrogen Gas
Valve Pipe
Note:
Do not cover the outlet. if the inner
pressure exceeds atmospheric pressure,
a pinhole will result and refrigerant gas
will leak from the brazed fitting.
Cover the gap with
tape or a rubber plug
to prevent air from entering
the pipe interior.
Nitrogen
Gas
Nitrogen Gas Pressure
≤2.9 psi (0.02 MPA)
Pressure Reducing Valve
(Stop Valve)
B
D A
f
f
a5
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