Retrofit Summary for HFC
Refrigerants
Select the Retrofit Checklist from the Appen-
dix for the refrigerant you are replacing.
1. Establish baseline performance with
CFC/HCFC.
2. Drain mineral oil or alkylbenzene (MO/
AB) from the system and measure the
volume removed. Leave the CFC/HCFC
refrigerant in the system.
3. Add POE lubricant; use the same volume
as removed in Step 2. Start up system and
operate for at least 24 hours, or more if
system has complex piping.
4. Drain POE, and repeat steps 2 and 3 at
least two more times. Continue flushing
until MO/AB is less than 5% by weight
or as recommended by compressor
manufacturer.
5. Recover the CFC/HCFC charge into a
proper recovery cylinder.
6. Replace the filter/drier.
7. Evacuate system and check for leaks.
8. Charge with Suva
®
refrigerant. Remove
liquid only from charging cylinder for
Suva
®
HP62 or Suva
®
507. Typical
charge is 75–90% by weight of
CFC/HCFC charge.
9. Start up system, adjust charge size. Label
system for the refrigerant and lubricant
used.
Retrofit Complete
Retrofit of R-12 Systems to
Suva
®
134a
The following detailed discussion is the recom-
mended procedure for retrofitting R-12 systems
to Suva
®
134a.
1. Establish baseline performance with CFC.
Collect system performance data while the
R-12 is in the system. Check for correct refrig-
erant charge and operating conditions. The
baseline data of temperatures and pressures at
various points in the system (evaporator,
condenser, compressor suction and discharge,
superheat and subcool, etc.) at normal operating
conditions will be useful when optimizing
4
operation of the system with the Suva
®
refriger-
ant. A System Data Sheet is included at the
back of this document to record baseline data.
2. Drain mineral oil or alkylbenzene from the
system and measure the volume removed.
Leave the CFC refrigerant in the system.
If mineral oil or alkylbenzene is the existing
lubricant, it will have to be drained. This may
require removing the compressor from the
system, particularly with small hermetic com-
pressors that have no oil drain port. In this case,
the lubricant should be drained from the suction
port on the compressor after the R-12 has been
properly recovered. For an effective flush, it is
important to remove at least 50% of the lubri-
cant in all cases. Larger systems may require
drainage from additional points in the system,
particularly low spots around the evaporator.
In systems with an oil separator, any lubricant
present in the separator should also be drained.
In all cases, measure the volume of lubricant
removed from the system. Record this informa-
tion on the Retrofit Checklist (see Appendix).
Compare this volume with the compressor/
system specifications to ensure that the majority
of lubricant has been removed. Consult the
compressor manufacturer for recommendations
on allowable residual MO/AB in POE lubricant.
If poor system performance is noted on start-up,
an additional lubricant change may be required.
3. Add POE lubricant; use the same volume
as removed in Step 2. Start up system and
operate for at least 24 hours, or more if
system has complex piping. Charge the com-
pressor with the same volume of new lubricant
as the amount you removed from the system in
step 2. Use a lubricant viscosity and grade
recommended by the compressor manufacturer
for the Suva
®
refrigerant you are using; or use a
similar viscosity to the oil you
removed if compressor information is not
available. A typical viscosity is 150 SUS or
ISO 32 for many compressors.
4. Drain POE, and repeat steps 2 and 3 at least
two more times. Continue flushing until MO/
AB is less than 5% by weight or as recom-
mended by compressor manufacturer. For
an HFC refrigerant to operate properly in a
retrofitted system, the residual MO/AB concen-
tration must be very low. Repeatedly removing
and replacing the POE will flush the old oil
from the refrigeration system, providing that
enough time is allowed with each change to
circulate oil through the entire system.
