Alternative Refrigerants / Lubricants / R-134a
g...@worldserver.com
It is well known from the literature, that chlorine adversely
affects the stability of Polyalkylene Glycol (PAG) oils used in
R-134a systems, both new and retrofit. The chlorine may come from
residual R-12 (or R-11 flush), or aluminum chloride coatings (not
possible to flush out) formed on the inside of aluminum parts from
when R-12 was previously installed in the system. If small amounts
of R-11 (more active than R-12 in the destruction of PAG oils) after
an R-11 flush when retrofitting (or from prev R-12 servicing) to
R-134a, engineering test stands have had compressor failues in as short
as a week from PAG oil breakdown. Residual chlorides from R-12 and
pipe coatings may not destroy PAG oil in a week, but often after
several months it will begin to break down. There is only one new
PAG oil on the market (recent times), which claims they can tolerate
large amounts of chlorides, I think it's brand name is "Daphne".
I have no actual test results, either way on it though. When you
service a R-134a car, the chances are that it does not contain Daphne
oil though.
Literature ref. to some papers about effects of chlorides on
PAG oils. This list is by no means complete, but can serve as
a starting point.
S. Yokoo, K. Doi, T. Takano (Nissan Motor Company, Limited, Japan),
and T. Kaimai (Kyodo Oil Technical Research Center Company, Limited,
Japan), "Development of a Lubricant for Retrofitting Automotive
Air Conditioners for Use with HFC-134a", Climate Control and Automotive
Cabin Air Filtration, publication SP-1040, Society of Automotive
Engineers (SAE), Warrendale, PA, pages 57-61 1994; republished as paper
940594 (SAE International Congress and Exposition, Detroit, MI, 28
Feb - 3 Mar 1994), SAE, 1994.
C. Powers (Robinair Divison of SPX Corp) and S. Rosen (Consultant),
"Compatibilty Testing of Various Percentages of R-12 in R-134a and
PAG Lubricant", unpublished presentation at the International CFC and
Halon Conference, Washington, DC, 30 September 1992.
"Polyglycol Sealed-Tube Tests", Carrier Corporation, Syracuse, NY,
September 1989. [reported that R-134a and two PAG lubricants
(Nippon RS680 and Glygoyle 11) that no decomposition was detected
for R-134a, but R-12 decomposition was 75-90% with both lubricants]
A. D. Nickens, G. F. Brunner, and D. L. Hamilton (US Navy),
"Navy Investigations of HFC-134a as a Replacement for CFC-12 in
Shipboard Applications", Naval Engineers Journal, pages 98-103,
May 1992.
"Factors Affecting the Copper Plating Phenomena with HFC-134a/
Polyalkylene Refrigeration Fluids (Focus: Mobile Air Conditioning)",
report ARTD-32 (H-35800), DuPont Chemicals, Incorporated,
Wilmington, DE, undated circa 1993.
S. Corr, E. Goodwin, R. D. Gregson, A. Halse, A. Lindley (ICI Chemicals
and Polymers, Limited), S. H. Colmery, T. W. Dekleva, and R. Yost
(ICI Americas, Incorporated), "Retrofitting Mobile Air Conditioning
Systems with HFC-134a", seminar presentation at the Society of Automotive
Engineers (SAE) Passenger Car Meeting and Exposition (Nashville, TN),
ICI Americas Incorporated, New Castle, DE, USA, 18 September 1991.
---
Any refrigerant or blend containing a "CFC" or "HCFC" (stands for
Chlorofluorocarbon and Hydrochlorofluorocarbon) contains chlorine
atoms and may be detrimental to PAG lubricants used in R-134a systems.
"HFC" means hydrofluorocarbon (e.g. HFC-134a) and contains no
chlorine. In order to use a chlorinated refrigerant (see below
table) in a R-134a system containing PAG oil (unless you have
Daphne PAG), one must take apart the system, and use a suitable
flush to remove *ALL* the PAG oil. Then remove the compressor and
place it on the bench, and dribble mineral oil (Ford part # YN9
is a good choice) into the compressor intake while turning it over
40 or 50 times to work out the PAG oil. The drier should be changed
to XH5 or XH9 desiccant if it is XH7 (134a only) desiccant.
Recharge with a chlorinated blend or R-12.
The following refrigerants and blends contain chlorine, components
(weight %)
name
R12 CFC-12 100%
(dichlorodifluoromethane)
R22 HCFC-22 100%
(chlorodifluoromethane)
R142b HCFC-142b 100%
(chlorodifluoroethane)
R124 HCFC-124 100%
(chlorotetrafluoroethane)
R406A/Autofrost-X3 HCFC-22 55% / HCFC-142b 41% /
Isobutane 4%
R414A/Chill-it/Autofrost-X4/GHG-X4 HCFC-22 51% / HCFC-124 28.5% /
HCFC-142b 16.5% / Isobutane 4%
FRIGC FR-12 HFC-134a 59% / HCFC-124 39% / Butane
2%
FREE ZONE RB-276 HFC-134a 79% / HCFC-142b 19% /
lubricant 2%
Freeze 12 HFC-134a 80% / HCFC-142b 20%
HOTSHOT/R-414B HCFC-22 50% / HCFC-124 39% /
HCFC-142b 9.5% / Isobutane 1.5%
Compositions listed on the US EPA web page
http://www.epa.gov/ozone/title6/snap/macssubs.html
In addition, the ARTI refrigerant database (see www.ari.org for info)
lists an "unassigned blend" of composition
HCFC-22 55% / HCFC-124 24% / HCFC-142b 18% / Isobutane 3%
and states "This blend was marketed by ICOR International,
Incorporated (Indianapolis, IN, USA) and others from late 1995
through March 1996 under the name "HOT SHOT". This product was
reformulated to settle a claim of patent infringement".
Now, look at the composition of R-414A / GHG-X4.
Some manufacturers and sales reps claim that their chlorinated
refrigerant blends can be "dropped into" R-134a systems without
regard or concern for the breakdown of PAG oils used in R-134a
systems. Nor do they say anything about removing said PAG oils
before installing their products.
------
Oil miscibility (in mineral oil).
A refrigerant and oil must be "miscible" in each other
(dissolve in each other) to a degree such that mineral oil
(as found in R-12 systems) circulates through the system correctly
and returns to the compressor. Using HFC-134a refrigerant in mineral
oil (R-12 systems), without changing the oil, results in a
non-miscibile condition, and the oil will eventually migrate to
the evaporator in a large number of systems and starve the compressor
for oil, and it will fail.
R-406A (Autofrost) and R-414A (Chillit / Autofrost-X4) were developed
and extensively tested for oil return capabilities using standard
mineral oils as used in R-12 systems (no oil change is needed).
Stationary systems were tested down to about -50 F and Automotive
systems down to about 0F for oil return and found to work fine
in engineering oil test stands and real life systems. Development
on what became R-406A was begun in August 1990. Both Isobutane
and HCFC-142b were needed to achieve proper operation of
returning mineral oil to the compressor so an oil change was not
needed. It was discovered during testing in 1990, that lowering
the isobutane content below 2.5% or so, did not provide adequate
oil return, and this is reflected in the claims of (my) US Patent No.
5,151,207 which covers R-406A and R-414A. Some manufacturers have
chosen to sell products which operate just outside the limits of
the above patent by having less than 2% isobutane and less than
15% HCFC-142b needed to adequately return mineral oil to the
compressor in all systems. Refrigerants with less than 2% isobutane
and less than 15% HCFC-142b may work fine in *SOME* or *MOST*
systems, depending on how much oil is present, the diameter of
the suction lines, and the length and whether or not the suction
line is level, uphill or downhill to the compressor. One will not
know if these refrigerants will work in the long term (it may take
a month or two for oil to migrate out of the compressor) until
a compressor failure occurs and a teardown shows a "dry" compressor.
These refrigerants will generally work ok, if most or all of the
oil is changed to alkylbezene type oil, which is miscibile in
R-124 and R-22, whereas mineral oil is only mediocre in R-22 and
very poor in R-124.
Without R-142b, even 5% isobutane does not provide sufficient
oil miscibility to return oil to the compressor. A test was tried
with R-134a and mineral oil, and 5% isobutane was added, and
oil return was still miserable. (525 SUS viscosity Automotive
compressor oil)
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Performance
R-134a has a couple of problems, when used in a system designed
for R-12.
Firstly, the boiling point of R-134a is about -15F compared to
R-12 at -21.6F. (at one Atmosphere).. This causes 4 or 5 degree
warmer duct temperatures unless the system is modified by setting
low pressure cutout lower to compensate. Variable displacement
compressors, such at the GM V5 are difficult or impossible to
modify, and always set the suction pressure at 28 PSIG.
R-134a has a lower "critical" temperature (214F) vs 233F for R-12.
The critical temperature of a gas is the the temperature at which
as gas will no longer condense to a liquid, no matter how much
pressure is placed upon it.
When under the hood/condenser temperatures approach the critical
temperature of a refrigerant, head pressures soar, and cooling
performance
goes down the tubes. Under the hood temps of 220F are not uncommon.
Other manufacturers market blends comprised primarily of R-134a
and are "cut" with either R-142b or R-124, both of which have
higher (warmer) boiling points than R-134a.
R-12 boiling point -21.6
R-134a boiling pt -15
R-124 boiling pt +10
R-142b boiling pt +14
So, how is adding 20% - 40% of R-124 or R-142b going to make
the refrigerant any colder than R-134a is already without
having a "balancing" ingredient in the colder direction?
R-406A contains 55% R-22, and R-414A contains 51% R-22
to produce a correct temperature-pressure relationship
which closely tracks R-12 and doesn't require changing the
oil nor the pressure controls. R-22 boils at -44F.
It has also been discovered, that blends with approximately
a "glide" of about 15 deg F, extend the "phase change" area
(the area where boiling or condensing is going on) in the
evaporator or condenser. These components are better utilized,
resulting in more heat transferred, which shows up as a faster
cooldown when starting up the A/C in a hot car.
One has to be sure their radiator/cooling system is in good shape
though, as the extra heat rejected out of the condenser with
R-406A/R-414A has caused radiator "boilovers" in cars with
dirty/plugged radiators, since the radiator is just behind
the condenser.
--George Goble (ghg), inventor of R-406A/R-414A/Autofrost/Autofrost-X4/
Chillit/McCool/GHG-HP refrigerants and holder of
US Patent no. 5,151,207.
President, GHG DEV Labs, Inc.
http://worldserver.com/autofrost
email: g...@worldserver.com
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