Suva
®
HP81 offers the highest efficiency versus
R-502, with slightly better capacity. However, the
higher HCFC-22 content results in compressor
discharge temperatures in the range of 14°C (25°F)
higher than that of R-502, which makes Suva
®
HP81 most suited for medium-temperature systems
such as ice machines.
Suva
®
404A (HP62) offers the best overall proper-
ties when compared with R-502. Capacity and effi-
ciency values should be equivalent to R-502, and
compressor discharge temperatures may be up to
9°C (14°F) lower than R-502, which may equate to
longer compressor life and better lubricant stability.
In addition, the heat transfer characteristics of
all the Suva
®
HP products appear to be better than
R-502, so any loss of compression efficiency may
be offset by improvements in heat transfer.
Due to the differences in operating characteristics
described above, Suva
®
HP80 and HP81are typi-
cally selected for different applications. Suva
®
HP81 is preferred where higher energy efficiency
and capacity are needed and where the higher dis-
charge temperatures will not create operating diffi-
culties. Both Suva
®
HP80 and Suva
®
404A (HP62)
are full-range R-502 replacements, with Suva
®
HP80 preferred for retrofitting of existing systems,
and Suva
®
404A (HP62) preferred for new equip-
ment. Suva
®
404A (HP62) can also be used for
retrofitting existing equipment where HFCs are
desired.
Table 2
shows markets that currently use
each of these refrigerants.
Table 2
DuPont™ Suva
®
HP Refrigerant
Market Applications
Product
Medium Temperature
Low Temperature
Suva
®
HP81
Ice Machines
To Be Determined
Food Service
Vending
Supermarket
Suva
®
HP80
Supermarket
Supermarket
Transport
Transport
Food Service
Suva
®
404A
(HP62)
All
Physical Properties
General physical properties of the Suva
®
HP refrig-
erants are shown in
Table 3
. Pressure-enthalpy dia-
grams for the Suva
®
HP refrigerants are shown in
Figures 1–6
.
Additional physical property data may be found
in other DuPont publications. Bulletin ART-18
contains viscosity, thermal conductivity, and heat
capacity data for saturated liquid and both saturated
and superheated vapor. ART-18 also contains heat
capacity ratios for saturated and superheated vapor.
Thermodynamic tables in English and SI units are
available in Bulletins T-HP80-ENG, T-HP80-SI,
T-HP81-ENG, T-HP81-SI, T-HP62-ENG, and
T-HP62-SI for Suva
®
HP80, Suva
®
HP81, and
Suva
®
404A (HP62).
Chemical/Thermal Stability
Stability with Metals
Stability tests for refrigerant with metals are typi-
cally performed in the presence of refrigeration
lubricants. Results of sealed tube stability tests
available for R-502/mineral oil and alkylbenzene
lubricants have shown long-term stability in contact
with copper, steel, and aluminum in actual refrig-
eration systems. Mineral oils, alkylbenzene, mix-
tures of mineral oil/alkylbenzene and polyol esters
(POE) are all possible candidates for use with
Suva
®
HP80 and HP81; POE are proposed lubri-
cants for use with Suva
®
404A (HP62).
The method followed was generally the same as
ASHRAE 97 with several minor modifications. A
3-mL volume of refrigerant/lubricant solution was
heated in the presence of copper, steel, and alumi-
num coupons in an oven for 14 days at 175°C
(347°F). Both the neat lubricant and a mixture of
lubricant and refrigerant (50/50 volume ratio) were
tested. Visual ratings were obtained on both the
liquid solutions and the metal coupons after the
designated exposure time. The visual ratings range
from 0 to 5, with 0 being best.
After the visual ratings were obtained, sample tubes
were opened and the lubricant and refrigerant (if
present) were analyzed. The lubricant was typically
checked for halide content and viscosity, while the
refrigerant was examined for the presence of de-
composition products.
Table 4
summarizes typical
data for Suva
®
HP refrigerants. Visual ratings are
listed for the neat lubricant, the lubricant/refriger-
ant solution, and the three metals that were present
in the lubricant/refrigerant solutions. Viscosity was
determined on the unused lubricant, the tested neat
lubricant, and the lubricant tested in the presence
of refrigerant. Decomposition products were deter-
mined in some cases. Typical measurements for
decomposition products is in the low parts per
million (ppm) range.
Suva
®
HP81 tests with various lubricants indicate it
has adequate chemical stability with these lubri-
cants. In addition, we believe that HP80 will have
similar behavior due to the same refrigerants being
used in the formulation. Suva
®
404A (HP62) tests
with common POE lubricants indicate that chemi-
cal stability of Suva
®
404A (HP62) with common
metals used in refrigeration systems is acceptable.
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