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Mitsubishi Electric PURY-HP72 Service Handbook page 7

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To reduce the risk or malfunction, turn on
the power at least 12 hours before starting
operation, and leave the power turned on
throughout the operating season.
Recover all refrigerant in the units, and dis-
pose of it properly according to any applica-
ble laws and regulations.
To reduce the risk of deterioration of refrig-
erant oil and compressor malfunctions
caused by a refrigerant that contains chlo-
ride, such as R22, only use R410A.
Provide a maintenance access to allow for
the inspection of pipes above the ceiling or
the buried pipes.
Take appropriate measures against electri-
cal noise interference when installing the air
conditioners in hospitals or facilities with
radio communication capabilities. Inverter,
high-frequency medical, or wireless com-
munication equipment as well as power
generators may cause the air conditioning
system to malfunction. Air conditioning
system may also adversely affect the opera-
tion of these types of equipment by creating
electrical noise.
To reduce the risk of damage to the unit,
leave the valves on the unit closed until re-
frigerant charging is completed.
Place a wet towel on the refrigerant service
valve before brazing the pipes to keep its
temperature from rising above 120ºC and
damaging the surrounding equipment.
Direct the blazing torch flame away from the
adjacent cables and sheet metal to keep
them from being overheated and damaged.
Prepare tools for exclusive use with R410A.
Do not use the following tools if they have
been used with the conventional refrigerant
(R22): gauge manifold, charging hose, re-
frigerant leak detector, check valve, refrig-
erant charge spout, vacuum gauge, and
refrigerant recovery equipment. R410A
does not contain chloride, so leak detectors
for use with older types of refrigerants will
not detect an R410A leak. Infiltration of the
residual refrigerant, refrigerant oil, or water
on these tools may cause the refrigerant oil
in the new system to deteriorate or damage
the compressor.
To reduce the risk of the vacuum pump oil
backflowing into the refrigerant cycle and
causing the refrigerant oil to deteriorate,
use a vacuum pump with a check valve.
Have a set of tools for exclusive use with
R410A. Consult your nearest Mitsubishi
Electric Dealer.
Keep dust, dirt, and water off charging hose
and flare tool. Infiltration of dust, dirt, or wa-
ter into the refrigerant circuit may cause the
refrigerant oil to deteriorate or damage the
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-
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
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

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