Frequently asked questions about R-12
(Freon (c)) and alternatives.
This version updated 6-19-96
This FAQ can now be found on the
VetteNet home page,
Parts of this document are short,
because I don't necessarily know the whole answer to the question. 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.
People who are long on opinion but short on fact need not bother writing to me.
The EPA maintains a nice page listing the status of all refrigerants that have
been submitted for use in mobile systems.
So I am removing this information from the FAQ, as it was hard to keep
updated anyway.
See their page at http://www.epa.gov/ozone/title6/snap/macssubs.html At this site, the EPA also provides a
classified ad service for speculators buying and selling R-12. The EPA notes that prices of R-12 have skyrocketed
lately, they suppose that the following might be reasons:
o the end of production of R-12
on January 1, 1996.
o supplies being withheld for
future years.
o lack of information preventing
buyers from finding sellers.
o difficulties in moving
existing stocks around the
What they forgot to include were the
following:
o $5.45/lb federal tax on R-12
in 1995, increasing each year.
o Government bans always create
high prices/black markets.
DISCLAIMER:
Please note that while I have tried
to make this document as correct as possible, there are inevitably 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.
Some procedures and products in this
document may be illegal and/or dangerous depending on the context in which they
are used. Specifically, replacing R-12
with an unapproved substance is illegal and can get you up to a $25,000 fine,
with a $10,000 reward for whoever turns you in.
That’s nice, huh? This purpose of this document is expressly stated to
be a source of facts. It is not intended
in any way to encourage violating the law or other civil disobedience.
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. Purchase the factory service manual for your
car. You will be better off for having
spent the money.
Issues discussed within this document
apply to the
Any opinions herein are mine, and
although they are (or should be :-) widespread, they do not represent the
opinions of anyone but myself.
-----------------------------------------------------------------------
Table of Contents:
1)
What is R-406a (aka GHG Refrigerant 12 substitute)?
2)
What is GHG-X4?
3)
What is HC-12a?
4)
What is OZ-12?
5)
What is R-134a?
6)
What is
7)
How does R-12 hurt the ozone layer?
8)
It's a patent scam by DuPont!
9)
What about flammability?
10) Who is MACS?
11) How do the EPA regulations
affect the A/C D.I.Y. er?
12) Numbers and addresses of the
players.
13) Where can I get more information
about this stuff?
14) How can I make my own recovery
equipment?
15) What is that white vapor coming
out of the vent?
16) What is the two step upgrade?
17) How could I make an HC based replacement
if I wanted to?
Appendix A: People
1)
What is R-406a?
-----------------------------------------------------------------------
Newsflash: George Goble has filed for EPA approval on
R-406a in mobile applications. Normally,
it becomes legal to sell a refrigerant 90 days after application, even if there
is no word on approval from the EPA.
This is to encourage the EPA to act quickly since any refrigerant will
be legal to sell by default after 90 days.
The EPA has REVOKED this in the case of R-406a, since it is "weakly
flammable" in the worst leakage case.
In this case weakly flammable means that it can be ignited by a flame,
but will not actually sustain a flame on it's own. It is self-extinguishing.
This rule was passed in July
‘95. George made his application in June
‘95, but the EPA is still applying the rule.
This means that R-406a will have to successfully complete EPA approval
before it will be legal to sell. You can
voice you opinion on this to the EPA.
The EPA web site is listed at the end of this document, and they have a
feedback page for comments. EPA certification typically takes a year, so look
for R-406a to be available in the summer of ‘96.
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% isobutene. 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 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 compressor will fail.
This mix does contain Isobutene,
which is required to disolve the mineral 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 ASHRAE. Topping off could
result in higher concentrations of isobutene, 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.
See the WWW
page:http://worldserver.com/R-406A/
R-406a can be purchased from: Monroe
Air Tech Bloomington, IN1-800-424-3836.
IT IS CURRENTLY ILLEGAL TO USE
R-406a AS A REPLACEMENT FOR R-12 IN
-----------------------------------------------------------------------
2)
What is GHG-X4?
-----------------------------------------------------------------------
GHG-X4 is a reformulated version of
R-406a. GHG-X4 is nonflammable as formulated, and does not become flammable
after leaking and recharging (the refrigerant by itself). R-406a, upon which this blend is based, is
classified as non-flammable in it’s original blend, and weakly flammable after
the worst case leakage.
Under the 1990 Clean Air Act as
amended, GHG-X4 is legal to sell in the
GHG-X4 is made from the following
components and weight percentages:
R-600a 4% (R-600a is isobutene - carries oil)
R-142b 16.5%
R-124 28.5
R-22
51%
GHG-X4 works with mineral or AB oils
found in R-12 systems, no retrofit needed.
However, old "nitrile" rubber hoses should be changed to the
newer "barrier" (nylon lined) hoses as R-12 and GHG-X4 leak faster
thru nitrile hoses. Most American cars
have used barrier hoses for years, so no change is needed. Do not use with "PAG" or
"POE" oils (R-134a systems). Many times it will work in R-500 systems
unmodified, TXV systems might need a new "power-head" on the TXV.
R-500 cap tube systems should be ok. We
have even had customers (with R-406A) "retrofit" R-502 systems
(refrig transport) to R-406A which is very similar to GHG-X4 by only changing
the expansion valve.. This should not work, but we have several customers who
swear on a stack of Bibles that it works.
I would expect only 50% of original R-502 capacity.
Cooling performance is equal to or
better than R-12. (similar to R-406A)
GHG-X4 was unveiled Jan 18, 1996 at the MACS meeting/show (Mobile Air
Conditioning Society) booth 106 in
Call 1-800-424-3836 (Monroe Air Tech)
or 1-800-669-5730 (McMullen Oil Products) or see the WWW page. The WWW page has a more extensive GHG-X4
FAQ. Available in 25 lb cylinders (equiv
to 30 lbs of R-12) or in 9.6 oz cans (equiv to 12oz R-12). Contains EPA class
II substances (HCFCs), and must be recovered and not vented to the
atmosphere. Currently marketed under the
name "AutoFrost" and "Chillit".
http://worldserver.com/GHG-X4
IT IS CURRENTLY LEGAL TO USE GHG-X4
AS A REPLACEMENT FOR R-12 IN
-----------------------------------------------------------------------
3)
What is HC-12a?
-----------------------------------------------------------------------
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 ILLEGAL TO USE
HC-12a AS A REPLACEMENT FOR R-12 IN
4)
What is OZ-12?
-----------------------------------------------------------------------
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.
Report EA94-006 from DOT Auto safety
hotline
IT IS CURRENTLY ILLEGAL TO USE
OZ-12a AS A REPLACEMENT FOR R-12 IN
5)
What is R-134a?
-----------------------------------------------------------------------
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.
R-134a currently does not require a
license to purchase, but the EPA is considering requiring one. The initial rule will be published in August
1995. 90 days of public comment will be
accepted, then the final rule will be published in November 1995.
IT IS CURRENTLY LEGAL TO USE r-134A
AS A REPLACEMENT FOR R-12 IN MOBILE SYSTEMS
6)
What is
-----------------------------------------------------------------------
"
DuPont has also announced SUVA MP-36
and -39 which are "almost drop-ins"
for R-12 in automotive A/C. They are blends of R-22/R-152a/R-124 which
closely simulate the temp/pressure curve of R-12. I have heard that one will need to change out
the oil (need to use alkyl-benzene oil instead of mineral oil) and to use a new
drier with XH-9 desiccant instead of the standard XH-5 desiccant (the R-152a
attacks XH-5).
-----------------------------------------------------------------------
7)
How does R-12 hurt the ozone layer?
-----------------------------------------------------------------------
There are different wavelengths of
UV called UVC and UVB. UVC is higher in
energy (shorter wavelength) than UVB.
Oxygen absorbs UVC, and ozone absorbs UVB. It is true that normal molecular oxygen
absorbs UVC, and it is also true that it's not likely that UVC levels will
climb because of ozone depletion.
Current theory holds that
chloral-fluorocarbons (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 + UVC -> O + O (UV is ultraviolet light)
(2)
O2 + O -> O3
Ozone depleting (good)
(1)
O3 + UVB -> O2 + O (This
reaction protects us from UVB)
Ozone depleting (bad)
(1)
Cl + O3 -> ClO + O2
(2)
ClO + O -> O2 + Cl
Notice that after both the depletion
reactions occur, the chlorine atom that started the whole thing is still
hanging around to cause problems. This
is why the CFCs are bad for the ozone.
The chlorines cause the ozone to be destroyed, but aren't used up in the
process.
Other references on ozone are:
Description of how chlorine affects
the stratosphere http://icair.iac.org.nz/ozone/ozone.html
Greenpeace Ozone crisis page http://www.cyberstore.ca/greenpeace/ozone/ozonehome.html
There is a very good FAQ on ozone
depletion posted periodically to news answers.
It is very readable and provides much more information than I have
provided here. It is also available
online at:http://www.cis.ohio-state.edu/text/faq/usenet/ozone-depletion/top.html
Ozone Depletion Thematic Guide"
produced by CIESIN: http://www.ciesin.org/TG/OZ/oz-home.html
"US EPA Stratospheric Ozone
Home Page" http://www.epa.gov/docs/ozone/
-----------------------------------------------------------------------
8)
It's a patent scam by DuPont!
-----------------------------------------------------------------------
No it's not. R-12 was invented in the 1930s. The patent is long gone.
-----------------------------------------------------------------------
9)
What about flammability?
-----------------------------------------------------------------------
Most of the proposed drop-in
alternatives for R-12 contain flammable materials. In November of 1991, the DOE commissioned a
preliminary study of the risks involved.
The conclusion of the report is that the risk of fire and/or explosion
is very remote. The full text if
available from NTIS. I quote relevant
portions of the document below:
"Non-inert Refrigerant Study
for Automotive applications "Prepared for US Dept of Energy by Arthur D
Little, John Dieckmann, Jeffrey Bentley Page 36
"The event of most concern
involve a rapid release of refrigerant into the engine or occupant
compartment. Vehicle crashes are the
only likely source of a significant number of accidental releases."
"The risk of injury from leaks
into the occupant compartment is likely to be very small with current designes
because
1)
the interior A/C components are robust and well isolated from front/side
crashes;
2) no credible ignition sources were
found _inside_ the occupant compartment;
3) window blowout is predicted to
occur before explosive overpressures reach the level required for injury; and
4) the thermal pulse from an explosive event would have insufficient energy to
cause life threatening injuries. With a
conventional A/C system, the risk of refrigerant release and ignition in the
occupant compartment appears to be very small, approximately 3x10^7 such
incidents per automobile, per year. With
approximately 140 million passenger vehicles in service, approximately 40 incidents
per year would occur if no A/C system design changes were made. As discussed in section 6.3, we believe that
this estimate may overstate the risk considerably, as no evidence was developed
that indicates that evaporators and connecting lines within the passenger compartment
are damaged to the point of leakage in even the most severe collisions."
"For engine compartment leaks
in an A/C system of conventional design we estimate:
- Engine refrigerant leakage will occur in a
significant number (17%) of "tow away accidents."
- Jet mixing and dispersion will limit the
probability of formation of a flammable mixture in the vicinity of an ignition
source.
- Only high energy ignition sources (broken
battery cables, overheated catalyst jacket) are likely to cause ignition
- Explosive overpressures in the engine
compartment will be limited below levels of concern (<<1 psi) due to
venting out the bottom of the engine compartment.
- Conventional systems will have an incidence
of fire on the order of 14 to 50 per million vehicles resulting primarily from
ignition of refrigerant while it is leaking."
"With relatively minor redesign
we estimate the annual incidence of engine compartment fire will be reduced to
less that one fire per million cars."
The authors do CYA by stating that
the study is preliminary and more in-depth research is needed before flammable
refrigerants become widespread.
-----------------------------------------------------------------------
10)
Who is MACS?
-----------------------------------------------------------------------
MACS is the group mostly responsible
for the current state of affairs in mobile A/C.
MACS stands for Mobile Air Conditioning Society. They are the group that petitioned the EPA to
outlaw alternatives, in spite of the fact that the EPA admitted that there was
no environmental reason to ban the alternatives. As if that wasn't enough, you now have to pay
MACS for the privilege of buying the freon and alternatives that they were so
successful at driving the price of up.
Note that you need a license to purchase any sort of refrigerant these
days. Here's how to get the your very
own federal license to purchase refrigerants:
1:
Send $20 to MACS.
2:
In a couple days you'll get a test and study materials in the mail. Read the study guide (27 pages), take the test
at your leisure (it's open book, but you can't get help from anyone else.)
3:
Send the test back in. If you
answered 21 of the 25 questions correctly, then you are smart enough to buy
refrigerants and they will send you a license in 4-6 weeks.
This test only covers EPA
regulations. It is not intended to teach
you anything about A/C systems. Duh,
that makes sense.
There are other companies as well,
but I do not have any information on them.
-----------------------------------------------------------------------
11)
How do the EPA regulations affect the A/C D.I.Y. er?
-----------------------------------------------------------------------
The short answer is: Other than the need for an easily obtained
license, and the 900% increase in the price of R-12, there is very little
impact on the D.I.Y. er. "Topping
off" known leaking systems is perfectly legal, although it is logically
inconsistent with the EPA’s stated purpose.
First, there has been some comment
on the "service for consideration" loophole. This clause is only in, and only applies to,
Section 609 of the Clean Air Act.
Section 609 deals with the various certifications needed by technicians
and the equipment they use. This
"loophole" simply states that anyone providing A/C service for free does
not have to meet the certification requirements set forth in section 609. This means that D.I.Y. ers do not have to be
certified technicians, and do not have to use approved equipment for
refrigerant extraction. D.I.Y. ers must
use extraction equipment, but it can be a home-built system. Specifically, this clause does not apply to
alternative refrigerants. It is illegal
to use anything except approved refrigerants as a replacement for R-12. Please note that the EPA only regulates
replacements for R-12. There are no
restrictions on what may be introduced into an R-134a system, or what may be
introduced into a system that has been converted to R-134a.
The ban on venting refrigerants with
a non-zero ODP still stands and applies to everyone. Starting in November 1995, no replacement for
class I or class II refrigerants can be vented.
This will include hydrocarbon based replacements if they ever achieve
permanent approval. What if these HC
based replacements are vented from a grill?
It's unclear what the penalties will be for a person whose torch fails
to light on the first spark.
The ban on non-approved alternatives
still stands, and applies to everyone.
Only alternatives listed by the EPA’s SNAP (significant new alternatives
program) may be used in cooling systems.
This section used to maintain a list
of available alternatives and their status, but there are too many to keep up
with now. The EPA has a very nice HTML
formatted document that shows all substitutes and their current status. Please see this WWW page at http://www.epa.gov/ozone/title6/snap/macssubs.html
The bottom line is that D.I.Y. ers
can continue to service their air conditioners with only minor additional
headaches (other than the 800% increase in the cost of R-12, courtesy of the
-----------------------------------------------------------------------
12)
Numbers and addresses of the players
-----------------------------------------------------------------------
EPA Ozone hotline: 1-800-296-1996 http://www.epa.gov
MACS
OZ Technology 1 208 664-6196
Socity of Automotive Engineers (SAE)
1 412 776-4841
Greenpeace ozone crisis page http://www.cyberstore.ca/greenpeace/ozone/ozonehome.html
NTIS, National Technical Information
Service US Dept of Commerce
Cryo-Chem Intl. (makers of Cryo-Silane)1-800-237-4001
Intermagnetics (FRIGC) 1 800 555
1442
-----------------------------------------------------------------------
13) Where can I get more infomation
about this stuff?
-----------------------------------------------------------------------
Here are references for material
about the information in this FAQ. I
have not read/looked at all of these. I
make to claims as to their factual validity.
Trashing the Planet : How Science
Can Help Us Deal With Acid Rain,
Depletion of the Ozone, and Nuclear Waste (Among Other Things) by Dixie
Lee Ray , Lou Guzzo Published by Harperperennial Library Publication date: May
1, 1992
The Holes in the Ozone Scare : The
Scientific Evidence That the Sky Isn't Falling by Rogelio A. Maduro , Ralf
Schauerhammer Published by Twenty First Century Science Publication date: July
1992 ISBN: 0962813400
"Atmospheric ozone" http://icair.iac.org.nz/ozone/ozone.html A brief description of how ozone depletion
occurs.
"US EPA Stratospheric Ozone
Home Page" http://www.epa.gov/docs/ozone/
"Usenet FAQ on ozone
depletion" http://www.cis.ohio-state.edu:80/text/faq/usenet/ozone-depletion/top.html This is a FAQ that exhaustively covers
questions and answers on ozone depletion.
It is also posted regularly to news answers
"Government Publications
Online" http://thorplus.lib.purdue.edu:80/gpo/ Electronically
searchable index of government publications.
Searches may be performed on House and Senate bills, the Federal
Register, US Code, etc.
"Ozone crisis page" http://www.cyberstore.ca/greenpeace/ozone/ozonehome.html A WWW page sponsored by Greenpeace about
ozone depletion.
-----------------------------------------------------------------------
14) How can I make my own recovery
equipment?
-----------------------------------------------------------------------
Some easy ways to recover
refrigerant are to take a recovery cylinder (or even a propane BBQ grill tank -
it is DOT legal) and pull a vacuum on it just before the first use.
A "50lb" recovery cyl is
the same size as the 20lb propane BBQ grill tank. For these purposes, a 30lb recovery cylinder
would work better (don’t use a DOT39 "throw away" refrigerant
cylinder). Get a Rubbermaid
5 gallon water cooler, and stick the
30lb cylinder in it, and add dry ice around the edges. This cools the cylinder so both R-12 and R-22
can be removed, and it will draw a vacuum on the system if left on long enough.
If you can get it, liquid nitrogen works nicely also (-312F). Both dry ice and liquid nitrogen are very
cold and can cause frostbite burns. Be
careful.
Pre-cooling a cylinder in a freezer
is usually not sufficient, it has to be colder than -21F to extract a charge
from an R-12 system down to 0 PSIG. The
cylinder will warm up as the charge is removed.
Wrapping a recovery cylinder with
slightly flattened 3/8" copper tubing (on the outside), slowly venting
liquid CO2 through the tubing would also be cold enough.
Be very careful not to
"overfill" the cylinder, use scales and don't exceed 70% of the
"water capacity" (marked as WC), typically a BBQ grill tank will be
WC 47.7, subtract out the tare weight (listed as TW), typically 12-13 lbs on a
BBQ grill tank. JC Whitney sells propane
level gauges which are temp strips which stick on the side of the tank, pour
hot water on it, and the liquid level becomes visible.
If the cylinder is overfilled,
thermal expansion may result in 100% liquid full, when the cylinder warms up,
causing the safety (popoff) to vent or the cylinder to explode.--ghg
You can also build a recovery system
out of an old fridge or electric A/C compressor. I removed the compressor from a 4 ft^3 (dorm
style) refrigerator. The fridge was
given to me as it no longer cooled. The
compressor relay was bad, but the compressor itself was perfectly good. $10 worth of brass fittings and some teflon
tape from the hardware store enabled me to connect a line from the gague set to
the compressor intake. Running this
compressor for approximately 30 mins drew over 30” of vacuum. Another set of fittings allows the compression
side to be connected to a BBQ grill tank, thus resulting in a DIY evacuation
system that is perfectly legal for DIY (unpaid) use. Pull a vacuum on the BBQ tank first.
Note that the fridge compressor got
very hot during use, hot enough to burn skin.
I suspect it’s not designed to run for half an hour at a time. Next time I will place a fan blowing on
it. A compressor from a house or window
A/C unit would be a better choice as a vacuum pump, but the price was right for
this one.--author
-----------------------------------------------------------------------
15) What is that white vapor coming
out of the vent?
-----------------------------------------------------------------------
Water vapor. You can see this any time the relative
humidity is high outside and the A/C is not on "recirculate". It's not freon, or plutonium, or anything
else.
-----------------------------------------------------------------------
16) What is the two step upgrade
-----------------------------------------------------------------------
Here in
Ba dum bump.
All hilarity aside, section 612 of
the Clean Air Act gives the EPA a mandate for regulating Class I and II
refrigerants, and replacements for them.
The EPA does not regulate other refrigerants, or replacements for
non-Class I or II refrigerants. In other
words, the ban on HC based or other refrigerants is only in the context of
using them to replace R-12. While it is
illegal to replace R-12 with HC-12a (for example), it is not illegal to replace
R-134a with HC-12a. A two step upgrade
can be done to convert an existing R-12 system to the refrigerant of your
choice. First convert the system from
R-12 to R-134a, or another EPA approved non-class I or II substitute for
R-12. Since the EPA doesn’t regulate
your substitute, you can leave it in there or convert to any other refrigerant
of your choice. You are free from all
the other EPA regulations, such as the type of fitting, etc. It is left as an exercise to collapse this
process to the minimal number or steps required to achieve the final objective,
using a non-EPA approved R-12 substitute.
The EPA has stated that they will vigorously prosecute anyone they
suspect of performing a "sham switch". So try the replacement for a while, and if it
doesn’t perform to your satisfaction feel free to replace it.
17) How could I make an HC based
replacement if I wanted to?
-----------------------------------------------------------------------
So you’ve done the first step of the
two step upgrade, at least in theory, and now you are ready to upgrade to an HC
based refrigerant for better performance.
But you don’t want to send a lot of money to OZ technology, or you can’t
find them. This section is for you. It describes how you can make your own
refrigerant from commonly available hydrocarbons. The procedures described in this section were
taken from rec. auto. tech archives, dating from June 1991 to the present. Most of the text can be attributed to either
George Goble or John DeArmond.
************************************************************************
Disclaimer
Some of the procedures described in
this section may not be legal.
Refilling some types of pressurized
containers is illegal, as is replacing R-12 directly with a non EPA approved
substitute.
Several states have banned flammable
refrigerants outright. The current list
is:
Check with your state to see what
the exact restrictions are, if any.
Hydrocarbons weight much less than
CFCs, consequently much less mass is required to achieve the same
pressures. Always charge using gauges to
prevent overfilling. Check the pressure
and temperature of your blend if you pre-mix and store. The pressure should be the same as R-12 at
the same temperatures. Adding propane
will increase the pressure at a given temperature, adding iso-butane will
reduce it.
************************************************************************
The most commonly asked about
hydrocarbon mix is 21% isobutane, 79% propane, by weight. Note that is isobutane, not butane or
n-butane. This mix has the same
temperatures and pressures as R-12, but performs better in your A/C system,
partially due to being a blend.
Hydrocarbons weigh less than CFCs, so you will need about half the
weight of hydrocarbons to achieve the same performance. The paragraphs below describe how to charge
this mix directly into your A/C system from the can, and how to pre-mix it in a
large container for future use. Be sure
to charge with gauges so you can stop at the appropriate pressure. Do not add the same weight as you would if it
were R-12.
Side tappers are available from JC
Whitney and other places. A side tapper
is a device that taps a can by piercing the side of the can, rather than the
top. It will work on the small cans of
refrigerants as well as cans containing other substances, whereas the standard
A/C tapper will only work on refrigerant cans.
In a ruling from the summer of 1995, the EPA ruled that it is illegal to
use side tappers on cans of approved refrigerants. Use them on R-12, or on your custom blend,
but it’s illegal to use them on R-134a or any other approved R-12
substitute. You’re supposed to use the
fitting on top of the can.
HOW TO GET IT
-------------
Isobutene is available as the fuel
used in Gaz brand camping stoves. Read
the label to make sure you are getting isobutene and not n-butane. isobutene is generally used in stoves
designed for low temperature use. Gaz
sells both plus a propane/butane mix so read the label. Propane is conveniently available in propane
torch cylinders. The odorant does not harm
its use as a refrigerant. Don't use gas
grill propane. This stuff is generally
fairly wet.
HOW TO PRE-MIX IT
-----------------
You’ll need two old torch bodies
fitted with refrigeration flare fittings, an empty propane torch cylinder, a
side tapper, and some standard refrigeration service hose.
An empty propane torch cylinder
makes a very good mixing container, particularly the large fat ones. An old torch valve fitted with a
refrigeration flare fitting lets you use it with A/C equipment. The procedure is simple and requires only a
scales of some sort. A postage scale
will work fine. Evacuate the propane
cylinder if you have a vacuum pump. Then
using a side tapper for blow-off cans (the type that punches a hole in the side
of the can), introduce the correct weight of isobutane from the Gaz cylinder. Then top the cylinder off with the required
weight of propane from another propane torch cylinder. Warming the donor cylinder will drive the
process. A second torch body fitted with
a refrigeration flare will let you hook the two cylinders together with a
refrigeration service hose. Be sure not
to overfill the recipient cylinder.
Check this by slightly lifting the safety valve with the cylinder
sitting upright. If liquid comes out
(white mist, real cold), bleed the cylinder until the liquid is below the
bottom of the safety valve. Needless to
say, do all this outside.
Before using the mix, double check
the accuracy of the blend by comparing the vapor pressure in the cylinder to
its temperature. This is easily done
using refrigeration gauges. The vapor
pressure should agree with that of R-12 +- 10 psi or so. When using your mix, charge with the bottle
upside down, ie liquid into the system.
Otherwise the propane will charge first due to it’s higher
pressure. Charging as a liquid ensures
that both the propane and isobutene charge according to their proportions. Be careful to charge slowly, however, because
if the liquid gets back to the compressor it can destroy it.
When you modify a torch body, you'll
need to find and drill out all restrictions that limit the propane flow to the
torch. Typically there is a restriction
and/or a check valve in the barb that taps the cylinder and another one
downstream of the control valve.
BTW, propane torch cylinders make
convenient replacements for blow-off cans.
They are much more gas-tight than the typical disposable Freon cylinder
so transferring valuable R-12, GHG-12 or whatnot makes real good sense. And they are more reliable. Instant sickness is dropping a 30 lb can of Freon
onto something that punctures it. :-( Be
sure to label the cylinder contents.
It is illegal to refill and
transport disposable containers. BBQ
grill containers are legal to refill, but are much less convenient. Be sure whatever container you use is clean
initially.
HOW TO CHARGE DIRECTLY INTO THE A/C
SYSTEM
------------------------------------------
Go get a 6oz can of "isobutene"
camping fuel. Charge that into the
evacuated system first. Next follow up
with 16 oz of propane (you will have to crock up a fitting to mate with a 16 oz
torch tank). That should be close to
correct blend and amount of charge to run a typical car A/C. It will be slightly lower in capacity then
R-12. This mix will be 27% isobutane,
73% and will cause lower pressures than R-12, but should be close enough to
work. The best mixture is 21% isobutene,
79% propane, so adding less isobutene and more propane will help. When it is time to recharge again, vent the
remaining charge, and start over with a new fresh charge as the isobutene and
propane will leak at different rates.
HOW TO CLEAN BBQ PROPANE TANKS
------------------------------
You can clean the tanks by removing
the valve, inverting them and blowing them out with 1,1,1-trichloroethane with
an automotive power sprayer (like used for degreasing engines and about 200
PSIG air pressure. Next, install the
valves, and pump them down to 400 microns of vacuum (an hour or so), and fill
them with dry nitrogen for storage.
On a propane tank, DO NOT USE WATER.
K-Mart "brake cleaner" is 111-trichloroethane/perchlorethylene which
would work fine. AN easier way, may be
to just get it filled with propane, and invert the tank (in some field away
from fire, sparks, (unless you want to participate in rec. pyrotechnics)), and
open the valve all the way, and shake the tank.
This should blow the shit/crud out. 5 or 6 seconds should get most of
it.