Manitowoc QD0202A, Руководство по обслуживанию

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Refrigeration System Section 7
7-60
Part No. 80-1100-3
HFC REFRIGERANT QUESTIONS AND ANSWERS
Manitowoc uses R-404A and R-134A HFC refrigerants
with ozone depletion potential (ODP) factors of zero
(0.0). R-404A is used in ice machines and reach-in
freezers and R-134A is used in reach-in refrigerators.
1. What compressor oil does Manitowoc require for
use with HFC refrigerants?
Manitowoc products use Polyol Ester (POE) type
compressor oil. It is the lubricant of choice among
compressor manufacturers.
2. What are some of the characteristics of POE oils?
They are hygroscopic, which means they have the
ability to absorb moisture. POE oils are 100 times
more hygroscopic than mineral oils. Once moisture
is absorbed into the oil, it is difficult to remove, even
with heat and vacuum. POE oils are also excellent
solvents, and tend to “solvent clean” everything
inside the system, depositing material where it is not
wanted.
3. What do these POE oil characteristics mean to me?
You must be more exacting in your procedures. Take
utmost care to prevent moisture from entering the
refrigeration system. Refrigeration systems and
compressors should not be left open to the
atmosphere for more than 15 minutes. Keep oil
containers and compressors capped at all times to
minimize moisture entry. Before removing the
system charge to replace a faulty component, be
sure you have all of the needed components at the
site. Remove new system component plugs and
caps just prior to brazing. Be prepared to connect a
vacuum pump immediately after brazing.
4. Are there any special procedures required if a POE
system is diagnosed with a refrigerant leak?
For systems found with positive refrigerant system
pressure, no special procedures are required.
For systems found without any positive refrigerant
pressure, assume that moisture has entered the
POE oil. After the leak is found and repaired, the
compressor oil must be changed. The compressor
must be removed and at least 95% of the oil drained
from the suction port of the compressor. Use a
“measuring cup” to replace the old oil with exactly
the same amount of new POE oil, such as Mobil
EAL22A.
Remember, care must be taken to prevent moisture
from getting into the refrigeration system during
refrigeration repairs.
5. How do I leak-check a system containing HFC
refrigerant?
Use equipment designed for HFC detection. Do not
use equipment designed for CFC detection. Consult
leak detection equipment manufacturers for their
recommendations. Also, standard soap bubbles will
work with HFC refrigerants.
6. Does Manitowoc use a special liquid line filter-drier
with HFC refrigerants?
Yes. Manitowoc uses an ALCO “UK” series filter-
drier for increased filtration and moisture removal.
During a repair, Manitowoc recommends installing
the drier just before hooking up a vacuum pump.
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