Addison RCA051, Installation, Operation And Maintenance Manual

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16
LEAK TESTING AND EVACUATION
Charge system with R-410A trace gas and dry nitrogen.
Pressurize to 150 PSIG.
Check inside unit, and interconnecting piping with suitable
leak detector. Recommend GEH10 or equivalent to be used
for trace gas.
Release testing charge and connect a good vacuum pump
to the gauge connections.
Do not open any other valves at this time.
Connect a micron gauge to the vacuum pump.
A deep vacuum of at least 500 microns is required.
Wait at least 15 minutes, if there is no rise on the micron
gauge the system is sealed.
!
CAUTION: On units with optional Hot Gas Reheat. It
is necessary to take some additional steps to ensure a
complete evacuation of the system. The use of two suction
points will be required due to the complexity of the
refrigerant circuitry. It is recommended that a suction
manifold be used at the vacuum pump for evacuation of
these systems.
Leaks
Leaks occur at incorrectly made joints. Very small scratches
or particles of dirt in a joint can cause a refrigerant leak.
The leak may be so small that it is difficult to detect on a
Halide leak detector. Leaks can develop even years after
the joint is made unless flux and solder specifically
developed for refrigerant work are used. Any improperly
made joint will cause trouble in time, as it will eventually
leak enough refrigerant to reduce capacity of the system.
Moisture
Moisture in the refrigeration system will combine with
fluorine in the refrigerant and form hydrofluoric acid which
will corrode and pit the system. Hydrofluoric acid also
decomposes the compressor lubrication oil causing sludge.
Great care should be exercised in keeping moisture out of
the refrigeration system when installing tubing, because an
extremely small amount can cause trouble. For this reason,
except on large sizes, only refrigeration grade, seamless
annealed sealed copper tubing should be used. This tubing
is available at refrigeration supply stores which have been
dehydrated and cleaned inside and sealed at each end.
Exposure of the inside of the tubing to the atmosphere must
be kept to a minimum. Do not use tubing that has been
exposed.
Dirt
Dirt and metal chips must be kept out of the refrigeration
system, since they will accumulate at strainers and clog
them, restricting the flow of refrigerant.
Compressor Oil
Factory includes compressor oil for the first twenty pounds
of R410A refrigerant. Compressor oil for change in excess
of twenty pounds must be provided and added into the
system in the field.
The compressor manufacturer stipulates that:

For 100% outside air split systems, one additional
ounce of oil should be added for every two pounds of
R410A refrigerant charge over the base charge of
twenty pounds.

For recirculating split systems, one
additional ounce of
oil should be added for every five lbs of R410A
refrigerant charge over the base charge of twenty
pounds.
It is recommended that the additional POE oil be added
while the system is being charged and handling
practices be carefully followed to prevent the absorption
of moisture. Interconnecting piping must follow sound
practices for oil management and be designed so that
the minimum suction line velocity is at least 1200 fpm
and the minimum velocity in the liquid line at least 150
fpm.