54
Refrigeration System
Section 7
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.
Continued on next page...
Summary of Contents for Marine Q 1000
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