Mitsubishi Electric PU(H)Y-P250YGM-A Service Handbook page 4

Precautions for handling units for use with R410A
CAUTION
Do not use the existing refrigerant piping.
A large amount of chlorine that may be contained in the re-
sidual refrigerant and refrigerating machine oil in the exist-
ing piping may cause the refrigerating machine oil in the
new unit to deteriorate.
R410A is a high-pressure refrigerant and can cause the
existing pipes to burst.
Use refrigerant pipes made of phosphorus deoxidized cop-
per. Keep the inner and outer surfaces of the pipes clean
and free of such contaminants as sulfur, oxides, dust, dirt,
shaving particles, oil, and water.
These types of contaminants inside the refrigerant pipes
may cause the refrigerant oil to deteriorate.
Store the pipes to be installed indoors, and keep both ends
of the pipes sealed until immediately before brazing. (Keep
elbows and other joints wrapped in plastic.)
Infiltration of dust, dirt, or water into the refrigerant system
may cause the refrigerating machine oil to deteriorate or
cause the unit to malfunction.
Use a small amount of ester oil, ether oil, or alkylbenzene to
coat flares and flanges.
Infiltration of a large amount of mineral oil may cause the re-
frigerating machine oil to deteriorate.
Charge liquid refrigerant (as opposed to gaseous refriger-
ant) into the system.
If gaseous refrigerant is charged into the system, the com-
position of the refrigerant in the cylinder will change and
may result in performance loss.
Use a vacuum pump with a reverse-flow check valve.
If a vacuum pump that is not equipped with a reverse-flow
check valve is used, the vacuum pump oil may flow into the
refrigerant cycle and cause the refrigerating machine oil to
deteriorate.
Prepare tools for exclusive use with R410A. Do not use the
following tools if they have been used with the conventional
refrigerant (gauge manifold, charging hose, gas leak detec-
tor, reverse-flow check valve, refrigerant charge base, vac-
uum gauge, and refrigerant recovery equipment.).
If the refrigerant or the refrigerating machine oil left on
these tools are mixed in with R410A, it may cause the re-
frigerating machine oil to deteriorate.
Infiltration of water may cause the refrigerating machine oil
to deteriorate.
Gas leak detectors for conventional refrigerants will not de-
tect an R410A leak because R410A is free of chlorine.
Do not use a charging cylinder.
If a charging cylinder is used, the composition of the refrig-
erant will change, and the unit may experience power loss.
Exercise special care when handling the tools for use with
R410A.
Infiltration of dust, dirt, or water into the refrigerant system
may cause the refrigerating machine oil to deteriorate.
Only use refrigerant R410A.
The use of other types of refrigerant that contain chlorine
(i.e. R22) may cause the refrigerating machine oil to deteri-
orate.