Mitsubishi Electric R410A Service Handbook page 7

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.
Use dedicated R410A tools. Tools specifi-
cally for R410A are required. Contact your
nearest dealer or customer support.
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
compressor.
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 pipes indoors and keep both ends
sealed until immediately before the brazing
or flare connection work. Store joints in
plastic bags. There is a risk of deterioration
of the refrigerant oil or a compressor failure
if dust, dirt, or moisture enters the refriger-
ant circuit.
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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