Date:         Sun, 16 Apr 2006 22:09:18 -0700
Reply-To:     Robert Fisher <refisher@MCHSI.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Robert Fisher <refisher@MCHSI.COM>
Subject:      Re: AC convert
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
              reply-type=original

> You can legally use Duracool in R12 setups only after R134a conversion.
> Why?
> Because the EPA knows that "shops" don't do Duracool conversions and they
> know anyone who buys Duracool is venting the R12 into the atmosphere and
> not
> recycling the R12. Therefor they don't mind after a R134a conversion as
> they
> assume you had the R12 reclaimed via the a/c shop.

a.. What is a second-generation substitute? Does the SNAP program regulate
second-generation substitutes? Why can hydrocarbon refrigerants such as
HC-12aŽ and DURACOOL 12aŽ be used to replace HFC-134a in cars -- is using a
hydrocarbon replacement in an HFC-134a system safer than using it in a
CFC-12 system?
Under the SNAP rule, EPA regulates substitutes for ozone-depleting
substances. CFC-12 depletes the ozone layer, so EPA reviews substitutes for
CFC-12; acceptable alternative refrigerants used to directly replace
ozone-depleting substances such as CFC-12 are called "first-generation"
substitutes. Certain first-generation substitutes, such as HFC-134a, do not
threaten the ozone layer, and EPA was not directed by Congress to review
substitutes for these refrigerants. Substitutes for non-ozone-depleting
first-generation substitutes (such as substitutes for HFC-134a) are called
"second-generation" substitutes.
However, the fact that EPA does not regulate the use of second-generation
substitutes does not necessarily mean that such use is either legal or safe.
For example, EPA is aware that many states prohibit the use of flammable
refrigerants in automobiles. In addition, local fire codes may restrict the
use of hydrocarbon refrigerants.

Finally, the safety of using hydrocarbon refrigerants such as HC-12aŽ and
DURACOOL 12aŽ in a system designed for HFC-134a is not likely to be very
different from the safety of using it in a system designed for CFC-12. Since
no valid risk assessment addressing the safety of hydrocarbon refrigerants
in either type of system has yet been submitted under the SNAP program, EPA
does not believe that hydrocarbon refrigerants have been proven to be a safe
substitute for either CFC-12 or HFC-134a in motor vehicle air conditioning
systems.


> Otherwise it is a fine alternative as is HOTSHOT if you can get it. No
> neither is anymore combustible then R134a.

a.. Since the autoignition temperature of HFC-134a is lower than that of
hydrocarbon refrigerants such as HC-12aŽ and DURACOOL 12aŽ, doesn't that
mean that HFC-134a is more flammable than these hydrocarbons?
According to both Underwriters Laboratories and the American Society of
Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE), the main
standard-setting body for refrigerants in the U.S., hydrocarbons are
flammable materials. Flammability, as defined by the American Society for
Testing Materials (ASTM) E-681 standard test procedure for refrigerants,
means that a substance will ignite at atmospheric pressure when mixed in
some concentration in air at normal temperature and pressure. The minimum
and maximum concentrations at which ignition will occur are called the lower
and upper flammability limits in air. Hydrocarbons, like the components of
HC-12aŽ and DURACOOL 12aŽ, become flammable at concentrations as low as 2%
by volume. These values are well-established in published literature.
Autoignition temperature is a distinct measure from flammability limits in
air. Specifically, this test measures the temperature at which a substance
will spontaneously ignite, without any external ignition source like a match
or lighter.

Certain documents claim that because the autoignition temperature of
HFC-134a is below 750 degrees Celsius (1382 degrees Fahrenheit), it is
flammable, and because the autoignition temperature of hydrocarbon
refrigerant blends such as HC-12aŽ is above 750 degrees Celsius, it is
nonflammable. However, this statement misrepresents the procedure used by
Underwriters Laboratories to classify refrigerants.

UL first examines whether a refrigerant burns in air at some concentration
and normal pressure and temperature. If it does ignite under these
conditions, it is classified as flammable. Hydrocarbons, like the components
of HC-12aŽ and DURACOOL 12aŽ, are classified as flammable. (Note that
hydrocarbon refrigerant manufacturers recognize that their products are
flammable, and label containers for those products with the word
"flammable.")

If a refrigerant is not classified as flammable as a result of this test
procedure, UL then uses the autoignition temperature to distinguish between
practically nonflammable refrigerants (meaning the autoignition temperature
is below 750 degrees Celsius) and nonflammable refrigerants (meaning the
autoignition temperature is above 750 degrees Celsius). HFC-134a does not
ignite, regardless of concentration, at atmospheric temperatures and
pressures. This means that at atmospheric pressures and temperatures, if a
can of HFC-134a is opened and a lit match is placed in front of the can, the
HFC-134a will extinguish the match. HFC-134a is classified by UL as
practically nonflammable because its autoignition temperature is below 750
Celsius. Note that UL lists most alternative refrigerants as practically
nonflammable. HCFC-22, the refrigerant used in most home air-conditioning,
is also classified as practically non-flammable.



> OK all you haters let the tread begin!

Y'all can believe what you want to believe... no skin off me. You can put
these compounds in your car if you choose to... not gonna affect me any. I
have two issues here: One, people recommending products and procedures, or
advocating their use without mentioning that they have considerable baggage
to go along with them, for instance the possible legalities involved with
using hydrocarbon refrigerants in your car. I think mentioning the one
without mentioning the other is irresponsible.
Two, people come here to get and exchange information from and with the
supposedly well-informed. I realize that this can be vague by its very
nature but making statements such as yours above are misleading at best.

Here's the section addressing Kim Brennan's statement on retrofitting the
retrofit:

a.. What is a "sham retrofit" of a motor vehicle A/C system?
EPA does not regulate the use of hydrocarbon refrigerants such as HC-12aŽ
and DURACOOL 12aŽ as substitutes for HFC-134a in motor vehicles. Certain
materials have circulated claiming that by first converting a system from
CFC-12 to HFC-134a, the system may then be converted to use a hydrocarbon
refrigerant without violating the original prohibition against using
hydrocarbons as substitutes for CFC-12. Thus, the question arises about the
definition of a legitimate retrofit. This definition hinges on two distinct
principles: complying with the conditions placed on using HFC-134a under the
SNAP program, and the intent of the retrofit.
In accordance with the SNAP rules, a retrofit from CFC-12 to HFC-134a must
meet certain requirements. The CFC-12 must be completely recovered in
accordance with regulations issued under section 609 of the Clean Air Act.
Fittings designed for use with HFC-134a must be permanently attached to the
system. These fittings mechanically prevent the mixing of HFC-134a with
CFC-12 and other refrigerants. Finally, the system must be labeled, and the
label must contain detailed information as described by the SNAP rule. Some
vehicles also require the installation of a compressor shutoff switch.
Performing these activities complies with the letter of the SNAP
regulations.

Even such compliance may not, however, indicate a legitimate retrofit. For
example, HFC-134a should be used with a different lubricating oil from
CFC-12; if the lubricant is not changed, the air conditioner will not work.
Similarly, a vehicle must be charged with the correct amount of HFC-134a in
order for the air conditioner to work. Failure to take these steps indicates
that the technician does not truly intend to convert the vehicle's air
conditioner to work with HFC-134a, and the subsequent installation of a
hydrocarbon refrigerant such as HC-12aŽ or DURACOOL 12aŽ may violate the
prohibition against using hydrocarbon refrigerants as CFC-12 substitutes.

Other indications of a sham retrofit also exist, including the timing of the
retrofit. In general, if a car arrives in a repair shop containing CFC-12
and leaves containing a hydrocarbon refrigerant, it is likely that it
underwent a sham retrofit, regardless of what actually occurred in the shop.
Generally, if HFC-134a is charged into a system and then immediately
removed, such a temporary retrofit to HFC-134a was likely intended solely to
allow the use of HC-12aŽ, DURACOOL 12aŽ, or other hydrocarbon refrigerant in
a car designed to use CFC-12. EPA is currently investigating several
complaints, and believes indications such as those described above support
finding a Clean Air Act violation.

The whole of it can be read here:
http://www.epa.gov/ozone/snap/refrigerants/hc12alng.html

Like I said, it's no nevermind to me if you're gonna use this stuff... the
likelihood of you blowing yourself to that great Vanagon graveyard in the
sky (not the one in Pahrump) while next to me in traffic is nil... and I
seriously doubt the refrigerant police are waiting around to nail you on the
first hot day of the year, but- I think we should make an effort here to be
as complete and accurate in our information as we can be, so people can make
the best informed decision they can.

Cya,

Robert