Application Engineering
B U L L E T I N
AE4-1374 R1
compressor. This results in pressures equalizing through
the compressor which can cause the compressor to
slowly rotate backwards until the pressures equalize.
This condition does not affect compressor durability
but can cause unexpected sound after the compressor
is turned off.
Low Ambient Cut-Out
A low ambient cut-out is not required to limit air-to air
heat pump operation. Air-to-water heat pumps must
be reviewed since this configuration could possibly run
outside of the approved operating envelope (Figure 7)
causing overheating or excessive wear.
Oil Type
Mineral oil is used in the ZR*K5 compressors. Sonneborn
Suniso 3GS or Chevron Texaco Capella WF32 should
be used if additional oil is needed in the field.
Polyolester (POE)oil isused in theZR*K5E compressors.
See the compressor nameplate for the original oil
charge. A complete recharge should be approximately
four fluid ounces (118 ml) less than the nameplate value.
Copeland
™ Ultra 32-3MAF, available from Emerson
Wholesalers, should be used if additional oil is needed
in the field. Mobil Arctic EAL22CC, Emkarate RL22,
Emkarate 32CF and Emkarate 3MAF are acceptable
alternatives.
CAUTION! POE must be handled carefully and the
proper protective equipment (gloves, eye protection,
etc.) must be used when handling POE lubricant. POE
must not come into contact with any surface or material
that might be harmed by POE, and spills should be
cleaned up quickly with paper towels, soap and water.
Contaminant Control
Copeland Scroll
compressors leave the factory with a
miniscule amount of contaminants. Manufacturing
processes have been designed to minimize the
introduction of solid or liquid contaminants. Dehydration
and purge processes ensure minimal moisture levels in
the compressor and continuous auditing of lubricant
moisture levels ensure that moisture isn
’t inadvertently
introduced into the compressor.
It is generally accepted that system moisture levels
should be maintained below 50 ppm. A filter-drier is
required on all R-407C and POE lubricant systems
to prevent solid particulate contamination, oil
dielectric strength degradation, ice formation, and
oil hydrolysis, and metal corrosion. It is the system
designer
’s responsibility to make sure the filter-drier is
adequately sized to accommodate the contaminants
© 2013 Emerson Climate Technologies, Inc.
Printed in the U.S.A.
from system manufacturing processes that leave
solid or liquid contaminants in the evaporator coil,
condenser coil, and interconnecting tubing plus any
contaminants introduced during the field installation
process. Molecular sieve and activated alumina are
two filter-drier materials designed to remove moisture
and mitigate acid formation. A 100% molecular sieve
filter can be used for maximum moisture capacity. A
more conservative mix, such as 75% molecular sieve
and 25% activated alumina, should be used for service
applications.
Long Line Sets/High Refrigerant Charge
Some system configurations may contain higher-than-
normal refrigerant charges either because of large
internal coil volumes or long line sets. If such a system
also contains an accumulator then the permanent
loss of oil from the compressor may become critical.
If the system contains more than 20 pounds (9 kg)
of refrigerant, it is our recommendation to add one
fluid ounce of oil for every 5 pounds (15 ml/kg) of
refrigerant over this amount. If the system contains
an accumulator the manufacturer of the accumulator
should be consulted for a pre-charge recommendation.
Other system components such as shell and tube
evaporators can trap significant quantities of oil and
should be considered in overall oil requirements.
Reheat coils and circuits that are inactive during part
of the normal cycle can trap significant quantities of
oil if system piping allows the oil to fall out of the
refrigerant flow into an inactive circuit. The oil level must
be carefully monitored during system development,
and corrective action should be taken if compressor oil
level falls below the top of the lower bearing bracket
for more than two minutes. The lower bearing bracket
weld points on the compressor shell can be used as a
low-oil-level marker.
Discharge Mufflers
Flow through Copeland Scroll compressors is semi-
continuous with relatively low pulsation. External
mufflers, where they are normally applied to piston
compressors today, may not be required for Copeland
Scroll compressors. Because of variability between
systems, however, individual system tests should be
performed to verify acceptability of sound performance.
Whenno testing isperformed,mufflersare recommended
in heat pumps. A hollow shell muffler such as the
Emerson Flow Controls APD-1 or APD-054 will work
quite well. The mufflers should be located a minimum of
six inches (15 cm) to a maximum of 18 inches (46 cm)
from the compressor for most effective operation. The
farther the muffler is placed from the compressor within
these ranges the more effective it may be. If adequate
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