Copper Refrigerant Pipe; Three Principles On Work With Refrigerant Pipes - Hitachi RCI-1.0FSN4 Service Manual

3 Piping work and refrigerant charge

Copper refrigerant pipe

3.4 Copper refrigerant pipe

3.4.1 Three principles on work with refrigerant pipes

The basic refrigerant pipe installation work must be carried out paying particular attention to avoid the infiltration of
humidity or dust while working with the refrigerant piping. Otherwise, rust may appear inside the system or the units and
cause serious faults.
Therefore, all work carried out on the copper pipes for refrigerant must follow the three principles described below.
Principle
insufficient protection on the ends
1. Absence of humidity
Ensure the atmosphere
Condensation on the inside of the
remains totally dry
Dust or other elements entering
2. Cleaning
Absence of dust on the
inside of the piping
Insufficient nitrogen wash after
3. Absence of leaks
There must be no leaks
(*) 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.
100 SMGB0099 rev.0 - 12/2016
Cause of the fault
Water infiltration due to
of the pipes.
pipes.
Insufficient vacuum.
the ends of the pipes.
Film of rust formed during
brazing without nitrogen
injection.
brazing.
Brazing fault.
Flaring fault and insufficient
torque.
Insufficient torque on
compressor connectors.
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
↓
Compressor fault, insufficient
cooling or heating
Lack of refrigerant
Drop in performance
Compressor fault
Oil oxidation.
↓
Compressor overheating
Preventive measure
Pipe protection:
1. Seal the ends of the pipes.
2. Protect and insulate the ends
of the pipes.
↓
Wash
↓
Vacuum dry
(*)
Pipe protection:
1. Fit caps to the ends of the
pipes.
2. Protect and insulate the ends
of the pipes.
↓
Wash
Carry out basic brazing work
carefully
↓
Carry out basic flaring work
carefully
↓
Carry out basic connection work
carefully
↓
Airtight test
↓
Preserving of vacuum in the
installation