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Section 6Refrigeration System

6-24

HFC REFRIGERANT

Manitowoc uses R-404A and R-134A HFC

refrigerants with ozone depletion potential

(ODP) factors of zero (0.0). R-404A is used in

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.

Refrigeration systems and compressors

with POE oil should not be left open to

the atmosphere for more than 15

minutes.

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 we will assume

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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