Manitowoc J-1300, Руководство по обслуживанию

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Section 7 Refrigeration System
7-57
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. 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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