Date: Wed, 12 Jul 95 14:03:46 -0400
Sender: Vanagon Mailing List <vanagon@vanagon.com>
From: Bart Wineland <bwinelan@alleg.edu>
Subject: latest on Re: vanagon AC (long)
Sorry so long but addresses r-12 issue pretty well. I pulled this
from another list so can't answer for the content. The outlook for a
substitute for R-12 that doesn't involve a expensive retrofit looks
promising.
Bart
Here is the second version of the A/C FAQ. Please forward as
appropriate, and
send me any suggestions/comments.
--steve
sravet@bangate.compaq.com
0.........1.........2.........3.........4.........5.........6.........7.
...
Frequently asked questions about R-12 (Freon (c)) and alternatives.
This is my first attempt at a FAQ, so bear with me. You can reach me
via email at sravet@bangate.compaq.com if you want to comment, make
suggestions, etc.
Parts of this document are short, because I don't necessarily know the
whole answer to the question. If you know something about one of these
questions, feel free to email me with the information. If you have
suggestions for additional questions and answers, feel free to email me.
I will acknowledge up front that I view a lot of environmental
regulation as extremely suspicious. That viewpoint probably comes
across in this document. The point is, I welcome any comments about
this document, pro or con, as long as they contain factual data. Eco-
nazis and actors/actresses who are long on opinion but short on fact
need not bother writing to me.
DISCLAIMER:
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Please note that while I have tried to make this document as correct as
possible, there are inevetably going to be some errors. Something that
is legal today may very well not be legal tomorrow, and you are urged to
call the EPA and your state to verify the legality of any A/C service
you wish to perform. Some states have their own restrictions in
addition to the EPA guidelines. The EPA has an ozone hotline (run at a
profit by a private company, of course.) It can be reached at 1-800-
296-1996. Sometimes they have the correct answers to questions.
This FAQ is a source of facts on R-12, and other alternatives for mobile
A/C systems. It is not a tutorial on automotive A/C service. Fixing
your car's A/C is no more difficult and no more dangerous than changing
plugs, replacing a distributor, or any other type of service that people
typically do themselves to save money. You do, however, need to have
the proper tools and knowledge to work on A/C. There are many fine
books out there on this subject.
These opinions herein are mine, and although they are widespread, they
do not represent the opinions of anyone but myself.
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Table of Contents:
1) What is R-406a (aka GHG Refrigerant 12 substitute)?
2) What is HC-12a?
3) What is OZ-12?
4) What is R-134a?
5) How does R-12 hurt the ozone layer?
6) What about flammability?
7) Who is MACS?
8) How do the EPA regulations affect the A/C DIYer?
9) Numbers and addresses of the players.
10) Where can I get more infomation about this stuff?
Appendix A: People
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1) What is R-406a?
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R-406a, formerly known as GHG R-12 substitute, is an ozone friendlier,
R-12 compatible drop in refrigerant. It was invented by George Goble,
who has a couple of patents on it. (ghg@ecn.purdue.edu,
http://ghg.ecn.purdue.edu/). It is a three part blend of 55% HCFC-22,
41% HCFC-142b, and 4% isobutane. It is compatible with the rubber seals
and hoses, and with the mineral oils used in R-12 systems. In addition,
it offers somewhat better performance than R-12. It is 95% less ozone
depleting than R-12. (ODP of .05 vs. 1.0 for R-12).
R-406a was initially tested in August 1990 in three cars. By 1992,
approximately 500 vehicles had this blend installed. Out of 500 cars,
only one car suffered A/C system failure. Analysis showed that the
Teflon piston rings had failed, which is a common failure mode for this
particular compressor according to local mechanics.
R-406A may leak faster through "nitrile rubber" hoses, mostly found in
foreign made cars, and port-of-entry add-on A/C systems. Most American
cars, have used "barrier hoses" for years, and these work fine. All
replacement hoses are of the "barrier" type now.
R-406a yielded a 4 to 13 degree F decrease in discharge air temperature
over that of CFC-12 at ambient temperatures over 80 degrees F.
Compressor discharge temperatures were also approximately 20 degrees F
higher than comparable R-12 systems, but still low enough to prevent
refrigerant or oil breakdown.
R-406a has been tested with CRYO-SILANE, a commercial A/C system sealant
and was determined to be compatible. Cryo-Silane is effective at
stopping leaks that fall into the three week to one year leak rate.
Since R-406a is a blend, a system should be evacuated before filling.
The three components have different leak rates, so topping off would
result in altered concentrations. In addition, R-406A (and all other
blends) have to be charged as a LIQUID (yes, on the low-side, but bottle
upside-down) because each substance has a different vapor pressure (thus
different rate of release as a gas). But, you have to be careful to
monitor the suction pressure and ensure that the flow from the can is
gradual. If it gets above a certain point, you'll be sucking liquid and
the pump will fail.
This mix does contain Iso-butane, which is required to disolve the oil,
but has been shown to be non-flammable in this blend, or weakly
flammable in the worst case scenario. It has been classified as A1/A2
by ASHREA. Topping off could result in higher concentrations of
isobutane, which is why this practice should be avoided. Several things
should be noted here, namely that _any_ refrigerant can be "flammable"
if it contains dissolved oil and a rapid release occurs. The oil
atomizes and can be ignited. In addition, any refrigerant that contains
hydrogen atoms (HCFCs) can be flammable when mixed with large amounts of
air under pressure. This includes R-406a, the EPA approved R-134a, R-
22, etc. For this reason these refrigerants should not be mixed with
air under pressure.
This mixture is EPA approved as a drop in replacement for R-12 in a
variety of applications except automotive uses, and is approved for
automobiles in Canada and lots of other countries. The manufacturer has
not sought EPA certification for mobile applications in the US, which is
why it is not approved. See the question about EPA regulations for more
details. You do have to have a federal license to purchase R-406a, see
the question about MACS for details.
IT IS CURRENTLY ILLEGAL TO PUT R-406a INTO ANY MOBILE A/C UNIT.
R-406a can be purchased from:
Monroe Air Tech
Bloomington, IN
1-800-424-3836.
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2) What is HC-12a?
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HC-12a is manufactured by OZ Technology as a direct R-12 and R-134a
replacement requiring no retrofit. It is a second generation product
that replaces OZ-12. It is a patented hydrocarbon blend of unknown
composition. It has 0 ODP and 8 GWP. It is compatible with any system
containing R-12 or R-134a, including both mineral and synthetic oils,
rubbers, metals, etc. It is up to 30% more efficient than R-12, which
reduces load on the compressor and engine. Since it is a hydrocarbon
blend, it is flammable. It has had a strong odor added to help identify
leaking systems. DOE studies have shown that the risk of HC based
refrigerants in mobile A/C units is negligible.
The EPA banned it for use in mobile applications on June 2, 1995. The
ban will take effect 30 days after publication in the Federal Register,
which should be mid-July 1995. Approval was removed due to flammability
concerns. OZ technology has not done a risk assessment to determine if
there is a flammability hazard.
IT IS CURRENTLY LEGAL TO PUT HC-12a INTO A MOBILE A/C UNIT, BUT IT WILL
BE ILLEGAL TO DO THIS BY MID JULY 1995
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3) What is OZ-12?
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OZ-12 was the first-generation R-12 replacement from OZ Technology. It
is a hydrocarbon based refrigerant of unknown composition. It has been
supplanted by HC-12a. It has been banned by the EPA for over a year due
to flammability concerns.
IT IS CURRENTLY ILLEGAL TO PUT OZ-12 INTO ANY MOBILE A/C UNIT.
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4) What is R-134a?
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R-134a is the current replacement for R-12. Most new cars manufactured
now have R-134a in their air conditioning systems, and all manufacturers
plan to move solely to R-134a by the end of 1995. It is a retrofit
rather than a replacement, as it requires some parts to be replaced
before it can be placed into an R-12 system. R-134a is not compatible
with the mineral oil used in R-12 systems, and uses a PAG (polyalkylene
glycol) based oil instead. This oil is not compatible with the rubbers
typically used in an R-12 system, so at a minimum all O rings and hoses
must be replaced. In addition, R-134a has 20-30% less cooling capacity
than R-12. Newer systems are designed with this in mind, but older
systems just will not provide as much cooling capacity if they are
converted to R-134a. In addition, R-134a will react with the aluminum
chlorides left behind fron R-12 and form acids that eat at system
components. These chlorides form on the surface of aluminum parts that
are exposed to R-12.
There are other problems with the oils used with R-134a. PAG oils may
be destroyed from residual aluminum chloride coating the insides of
pipes, etc, left over from when R-12 was in the system. These chlorides
cannot be flushed out and are not present in "new cars". "Ester oils"
(POE) are more tolerant of the chlorides, but are still 10X more
moisture sensitive than R-12 mineral oil. PAG oil is about 100X more
moisture sensitive. Ester oils have less lubricity than PAG oils.
R-134a is flammable when mixed with air and placed under pressure, as
are all HFC refrigerants, including R-406a, R-22, and others. PAG based
oils are skin irritants and require impervious gloves to be worn when
handling. R-134a can irritate the eyes, nose and throat. Exposure to
R-134a has been shown to cause benign tumors in lab animals, under the
non-realistic conditions of 5% atmospheric content over 2 years.
Contrast this with R-12 and mineral oil, which are known safe under all
conditions.
IT IS CURENTLY LEGAL TO PUT R-134a INTO A MOBILE A/C SYSTEM
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5) How does R-12 hurt the ozone layer?
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The ozone layer is formed in the stratosphere when ultraviolet light
breaks apart normal oxygen molecules (O2) and causes them to form ozone
molecules (O3). In this process, the ultraviolet light is absorbed,
which is why the ozone layer helps protect the earth from ultraviolet
light. Exposure to ultraviolet light increases the chance of aquiring
skin cancer, and is thought to depress the immune system. So ozone in
the upper atmosphere is a good thing.
Current theory holds that chloro-fluoro-carbons (CFCs), once released,
work their way into the upper atmosphere (stratosphere), where the
chlorine atom is stripped from the CFC by the ultraviolet light. The
chlorine atom then reacts with the naturally occurring ozone and changes
it into normal oxygen. The chlorine is a catalyst in this reaction,
which means that it enables the reaction to take place, without actually
being used in the reaction. The chemical reactions that form and
deplete the ozone are:
Ozone forming (good)
(1) O2 + UV -> O + O (UV is ultraviolet light)
(2) O2 + O -> O3
Ozone depleting (bad)
(2) Cl + O3 -> ClO + O2
(3) ClO + O -> O2 + Cl
