Flared Connection Mounting; Refrigerant Gas Pipe Insulation - Hitachi RCI Service Manual

Indoor units system free series & complementary systems
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3 Piping work and
refrigerant charge

3.4.7 Flared connection mounting

Line up the end of the flared pipe to face the fitting to which it is to
be threaded.
Gently rest the female cone on the male cone and check that the measurement is correct. Keep the connection lined up
with one hand and gently thread on the flare nut with the other.
Tighten the connection to the corresponding tightening torque indicated in the table below.
Nominal diameter
mm
Ø6.35
Ø9.53
Ø12.7
Ø15.88
Ø19.05
Ø22.20
Ø25.40
Ø28.60
C A U T I O N
Secure the fixed connection with a suitable wrench and use a torque wrench to tighten the flare nut on the
threaded connections.
Do not exceed the torque value indicated in the table. The fitting can become misshapen and the connection
may leak.

3.4.8 Refrigerant gas pipe insulation

The gas refrigerant circulates through the pipes at a very low temperature (several degrees below zero, depending on the
time of year and the installation). The difference in temperature with the ambient air is extremely large and causes two
significant phenomena to be taken into account:
Cold irradiation along the entire pipe.
Condensation of the humidity in the surrounding air.
Actually, cold irradiation is the temperature gain experienced by the gas, as when it circulates under pressure and at such
low temperatures along the inside of the pipes, it is actually liquid and obtains the outdoor temperature (boiling at a very
low temperature) to turn into gas.
As a result of the temperature gain (although it is actually perceived as cold emission), the gas loses its capacity to cool
and the system does not perform as expected. Furthermore, the humidity in the surrounding air condenses on the pipe and
the greater the temperature difference and the longer the pipe, the more water is produced.
In view of this, the gas refrigerant pipes must be fitted with a suitable insulation system that prevents the increase in
temperature of the gas refrigerant and the subsequent loss of energy and the condensation of water along the entire pipe.
87
SMGB0063 rev. 1 - 10/2010
Inches
1/4
3/8
1/2
5/8
3/4
7/8
1
1-1/8
Tightening torque
20 Nm
40 Nm
60 Nm
80 Nm
100 Nm
3

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