Mitsubishi Electric PUHY-HP72 Service Handbook page 7

Use refrigerant piping and couplings that
meet the applicable standards. For refriger-
ant pipes, use pipes made of phosphorus
deoxidized copper. Keep the inner and out-
er surfaces of pipes and couplings clean
and free of such contaminants as sulfur, ox-
ides, dust, dirt, shaving particles, oil, and
moisture. Failure to follow these directions
may result in the deterioration of refrigerant
oil or compressor damage.
Store the piping materials indoors, and
keep both ends of the pipes sealed until im-
mediately before brazing. Keep elbows and
other joints in plastic bags. Infiltration of
dust, dirt, or water into the refrigerant cir-
cuit may cause the refrigerant oil to deterio-
rate or damage the compressor.
Apply ester oil, ether oil, or a small amount
of alkyl benzene to flares and flanges. The
use and accidental infiltration of mineral oil
into the system may cause the refrigerant
oil to deteriorate or damage the compres-
sor.
To reduce the risk of oxidized film from en-
tering the refrigerant pipe and causing the
refrigerant oil to deteriorate or damaging
the compressor, braze pipes under nitrogen
purge.
Do not use the existing refrigerant piping. A
large amount of chloride that is contained in
the residual refrigerant and refrigerant oil in
the existing piping may cause the refriger-
ant oil in the new unit to deteriorate or dam-
age the compressor.
Charge refrigerant in the liquid state. If re-
frigerant is charged in the gas phase, the
composition of the refrigerant in the cylin-
der will change, compromising the unit's
performance.
Do not use a charging cylinder. The use of a
charging cylinder will change the composi-
tion of the refrigerant, compromising the
unit's performance.
Charge the system with an appropriate
amount of refrigerant in the liquid phase.
Refer to the relevant sections in the manu-
als to calculate the appropriate amount of
refrigerant to be charged. Refrigerant over-
charge or undercharge may result in perfor-
mance drop or abnormal stop of operation.
To reduce the risk of power capacity short-
age, always use a dedicated power supply
circuit.
To reduce the risk of both the breaker on the
product side and the upstream breaker from
tripping and causing problems, split the
power supply system or provide protection
coordination between the earth leakage
breaker and no-fuse breaker.
Have a backup system, if failure of the unit
has a potential for causing significant prob-
lems or damages.
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