Hitachi UTOPIA R32 Series - 5.2 Three Principles on Work with Refrigerant Pipes; 5.3 Flared Pipes

15
PMEN0654 rev.0 - 12/2023
5
FLARED PIPES
REFRIGERANT PIPING AND REFRIGERANT CHARGE
Therefore, all work carried out on the copper pipes for refrigerant must follow the three principles
described below:
Principle Cause of the fault Possible fault Prevenve measure
Absence of
humidity
Water inltraon due to
insucient protecon on the
ends of the pipes.
Condensaon on the inside of
the pipes.
Insucient vacuum.
Ice on the inside of the pipe,
on the expansion valve (water
obstrucon)
+
Absorpon of oil humidity and
oxidaon
↓
Filter clogging, insulaon and
compressor fault
Seal the ends of the pipes.
Protect and insulate the ends of
the pipes.
↓
Wash
↓
Vacuum dry (*)
Cleaning
Dust or other elements
entering the ends of the pipes.
Film of rust formed during
brazing without nitrogen
injecon.
Insucient nitrogen wash aer
brazing.
Expansion valve, Capillary tube
and lter clogging, Oil oxidaon
↓
Compressor fault, insucient
cooling or heang
Fit caps to the ends of the pipes.
Protect and insulate the ends of
the pipes.
↓
Wash
Absence of
leaks
Brazing fault.
Flaring fault and insucient
torque.
Insucient torque on
compressor connectors.
Lack of refrigerant, Drop in
performance, Compressor fault,
Oil oxidaon
↓
Compressor overheang
Carry out basic brazing →
Flaring → Connecon work
carefully
↓
Airght test
↓
Preserving of vacuum
(*) One gram of water becomes approximately 1000 l of steam at 1 Torr. (1 Torr = 1 mmHg = 133.32 Pa). Therefore, a
long me must be spent on vacuum work using a small pump.
5.3 Flared pipes
5.3.1 Selecon of the connecon with are ng
If it is not possible to perform the widening operaon, use a connecon with are ng.
Distance between sides -B- of the nut -A-
Diameters (mm) -B- (mm)
Ø6.35 17
Ø9.52 22
Ø12.7 26
Ø15.88
29
Ø19.05 36
B
A
Check that there are no scratches, adhered grinding swarf, deformaon or surface unevenness at
the aring part.