of the system with the Suva
®
refrigerant. 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 R-22 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 compressors that have no
oil drain port. In this case, the lubricant should
be drained from the suction port on the com-
pressor after the R-22 has been properly
recovered. For an effective flush, it is important
to remove at least 50% of the lubricant in all
cases. Larger systems may require drainage
from additional points in the system, particu-
larly 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 MO/AB 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
recommended 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.
5. Recover the R-22 charge into a proper
recovery cylinder. Use normal service prac-
tices. If the correct charge size is not known,
weigh the amount of refrigerant recovered.
6. Replace the filter/drier. It is routine practice to
replace the filter/drier following system mainte-
nance. Replacement driers are available that are
compatible with Suva
®
refrigerants. See page 2
of this manual for additional information on
driers.
7. Evacuate system and check for leaks. To
remove air or other noncondensables in the
system, evacuate the system to near full vacuum
(29.9 inHg vacuum [500 microns] or less than
10 kPa).
8. Charge with Suva
®
refrigerant. Remove
liquid only from charging cylinder. The
proper cylinder position for liquid removal is
indicated by arrows on the cylinder and
cylinder box. Once liquid is removed from the
cylinder, the refrigerant can be charged to the
system as liquid or vapor as desired. Use the
manifold gauges or a throttling valve to flash
the liquid to vapor if required.
In general, the refrigeration system will require
less weight of the Suva
®
refrigerant than of R-
22. The optimum charge will vary depending on
the system design and operating conditions, but
for most systems the best charge size will be
75–90% by weight of the original charge.
For best results:
• It is recommended that the system be initially
charged with about 75% by weight of the
original charge.
• Add the initial charge of Suva
®
refrigerant to
the high-pressure side of the system (com-
pressor not running) until the system and
cylinder pressures equalize. Then connect to
the low-pressure side of the system, start the
compressor, and load the remainder of the
refrigerant slowly to the suction side of the
system. You should be removing liquid from
the charging cylinder, and therefore should
charge slowly to allow the refrigerant to flash
(vaporize) before entering the compressor
suction and avoid compressor damage.
7
