Flared Pipes; Selection Of The Connection With Flare Fitting - Hitachi UTOPIA R32 Series Installation And Operation Manual

Therefore, all work carried out on the copper pipes for refrigerant must follow the three principles
described below:
Principle Cause of the fault
Water infiltration due to
insufficient protection on the
ends of the pipes.
Absence of
Condensation on the inside of
humidity
the pipes.
Insufficient vacuum.
Dust or other elements
entering the ends of the pipes.
Film of rust formed during
brazing without nitrogen
Cleaning
injection.
Insufficient nitrogen wash after
brazing.
Brazing fault.
Flaring fault and insufficient
Absence of
torque.
leaks
Insufficient torque on
compressor connectors.
(*) One gram of water becomes approximately 1000 l of steam at 1 Torr. (1 Torr = 1 mmHg = 133.32 Pa). Therefore, a
long time must be spent on vacuum work using a small pump.

5.3 Flared pipes

5.3.1 Selection of the connection with flare fitting
If it is not possible to perform the widening operation, use a connection with flare fitting.
Distance between sides -B- of the nut -A-
Diameters (mm)
Ø6.35
Ø9.52
Ø12.7
Ø15.88
Ø19.05
Check that there are no scratches, adhered grinding swarf, deformation or surface unevenness at
the flaring part.
PMEN0654 rev.0 - 12/2023
Possible fault
Ice on the inside of the pipe,
on the expansion valve (water
obstruction)
+
Absorption of oil humidity and
oxidation
↓
Filter clogging, insulation and
compressor fault
Expansion valve, Capillary tube
and filter clogging, Oil oxidation
↓
Compressor fault, insufficient
cooling or heating
Lack of refrigerant, Drop in
performance, Compressor fault,
Oil oxidation
↓
Compressor overheating
-B- (mm)
17
22
A
26
29
36
Preventive measure
Seal the ends of the pipes.
Protect and insulate the ends of
the pipes.
↓
Wash
↓
Vacuum dry (*)
Fit caps to the ends of the pipes.
Protect and insulate the ends of
the pipes.
↓
Wash
Carry out basic brazing →
Flaring → Connection work
carefully
↓
Airtight test
↓
Preserving of vacuum
B
5
15