This thread taken from http://www.aircondition.com/wwwboard/alternative/messages/1995.html

DANGER! R134a is not as safe as many believe. Posted by C.J. on February 27, 1999 at 00:40:05:

I am constantly being told how dangerous hydrocarbon refrigerents are because they are flammable.

I admit they are flammable but so is HFC-134a. Maybe not at atmospheric pressure but it does'nt take much to make it burn.

I have before me a copy of DuPont's own M.S.D.S. for "SUVA"134a.

The first thing I see is that it contains ETHANE (a flammable hydrocarbon).

The second thing I see is a caution to doctors about "possable disturbances of cardiac rhythm".

Next is a statement saying "HFC-134a has been shown to in tests to be combustable at pressure as low as 5.5 psig at 177 c (351 F) when mixed with air at concentrations of generally more than volume % air".

Aren't all A/C systems under much more than 5.5 psig?

If a leak were to occur would'nt it leak into more than 60 volume % of air?

After a paragraph on fire and explosion hazzards it says "HFC-134a SHOULD NOT be mixed with air for leak testing or USED FOR ANY OTHER PURPOSE ABOVE ATMOSPHERIC PRESSURE".

Are'nt all A/C systems above atmospheric pressure?

The next thing that cought my attention is a section called "INCOMPATIBILITY WITH OTHER MATERIALS" and what a suprise I got when I saw "powered aluminum" as one of the materials it is incompatible with.

Is'nt aluminum the major material used in A/C systems?

Next comes "Decomposition products are hazardous". It says that HFC-134 "can be decomposed at high temperatures (open flames, glowing metal surfaces, etc.) forming HYDROFLOURIC ACID and possibly CARBONYL FLOURIDE.

So if I am reading this correctly, if your A/C lines, which are only inches away, develop a leak and it sprays onto the exhaust manifold (glowing metal surfaces) it will form HYDROFLOURIC ACID?

THIS IS A VERY DANGEROUS CHEMICAL even in concentrations as low as 1%!

If this is'nt enough to get you "guys" having second thoughts then you should read the next section.

"In a two year study, HFC-134a, at a concentration of 50,000 ppm, produced an increase in late occuring benign TESTICULAR TOUMARS, TESTICULAR HYPERPLASIA and TESTICULAR WEIGHT".

I don't know if it has the same effects on humans but "This is one male who dos'nt want to find out".

All of this information is available to anyone including the EPA and it's FREE.

If you can't read then just call your local posin controal center and ask them what would happen if you were to inhale HFC-134a?

I did-- and they told me "DON'T DO IT--RAPID HEART RATE--SUDDEN DEATH".

Just look at all the warnings they are putting on the NEW cans of HFC-134a and see for yourself.]

I believe the EPA is trying to look out for the safty of consumers by not approving hydrocarbons until they are proven to be safe but I also think they overlook the obvious dangers of HFC-134a because someone else has already said it is ok to use.

If safty is a real concern of the EPA, they should look alot harder at HFC-134a and not let DuPont and all their money have any affect on their decisions.

C.J.

C.J
Interesting story unfortunately this MSDS was in circulation since (I thought) 1994 so you have not told us much new.
What may be interesting is your local poison centre's expression of "sudden death" try to get a statement on paper.
They may have looked in George Gobles website (www.autofrost.com).
If you do same you may learn a lot more about refrigerant toxicity in general and r134a in particular.

NB R134a is only flammable at the conditions you stipulated + oxygen and spark.

NB Anybody able to direct me to Toxicity studies (min 150 pages) of R134a, have so far not seen any of them. Recent TNO study Netherlands
is as far as I know not yet released to customers "Elf Atochem et al"
but small publications predict --no harm when using R134 within the 1000 ppm limit.

Jg/oz
 
 

R134 refrigerants, CryoChem, and moisture problems [ALL] ... posted by michael in sydney  on Saturday, 18 August 2001, at 9:52 p.m.
 

                        I haven't had a prob with the evap on my 95 850, so can't speak from experience, but I have seen
                        plenty of people on this forum discussing theirs. Has anyone seen this url/product:

                       http://www.autofrost.com/

                        Here's an excerpt from the site;

                        "New cars (R-134a) use PAG oils, that may absorb moisture 1,000 to 10,000 times more than the
                        mineral oils used in the older R-12 cars. Moisture entering during system service can easily lead to
                        corrosion and expensive system failures several months down the road. GHG-X8 contains Dry-Pak®
                        system dehydrant from Cryo Chem. Dry-Pak® reacts with any moisture found and converts it into a
                        harmless silicone oil that will not take part in refrigerant breakdown/corrosion reactions. This may greatly
                        extend system life to many years instead of a few months due moisture getting in during service. We
                        have had testing labs measure moisture content in unopened containers of GM PAG oil and found them
                        to be in the range of 800-900ppm, far more than enough to cause corrosion in just a few weeks and
                        system failures. Anything over 50-100ppm is trouble. The moisture standard for refrigerants is 10ppm."

                        I don't know much about the topic but thought the info might be of interest. Can anyone tell us about
                        experiences they have had with this product? Maybe the GHG-X8 is a solution - or maybe just another
                        marketing illusion...???

                        --
                        michael in Sydney
 

                        The only thing that comes to my mind is that after replacing a componant in the A/C system, it is
                        vacuumed for at least 30 minutes, sometimes an hour if the systems open for more than 10 minutes or so
                        to eliminate the moisture. So my concern is; even if the newly opened oil did have a high moisture
                        content, the real test would be to measure the moisture content after it had been under a vacuum for 30
                        minutes to an hour. The product sounds like hype to me. I'd want to see some relevant information
                        before I'd consider modifying what the A/C engineers have designed.

                        --
                        Rich K.

 The vacuum will boil out most of the free water in the system. However, it doesn't do a good job at removing water that's been entrained in a
 synthetic oil that absorbs moisture. That water only comes out with heat. That's the job of your reciever/drier or accumulator/drier. It removes
 any moisture that comes out during the gas/liquid phase shift.

 George Goebbel, who invented Autofrost, is a college professor at a large midwestern university. He served on most of the alternative
 refrigeration groups that were formed as R12 was banned. He's presented a lot of papers on alternative refrigerants. Ever see the web site
 (the humorist Dave Barry did a column on it) where a college professor uses liquid oxygen as a barbeque starter? That was George, the
 merry prankster.

 Moisture in PAG/PAO oils has been a hot topic on aircondition.com for the last few months. R134a systems use these oils because they are
 readily circulated by the refrigerant. However, they are extremely hygroscopic (they absorb water like a sponge). When moisture laden oil
 contaminates the system, it reacts with R134a and forms hydrochloric acid.

 George (and a lot of other people) think that the moisture/R134a connection is a huge problem. They think the acid formed tends to
 accumulate in the evaporator where the refrigerant shifts phase from liquid to gas. Hydrochloric acid loves aluminum and will eat a hole in a
 new evaporator. Usually within 5 years after installation. Sound familiar, 850 folks? There's been a lot of dialog recently in automotive A/C
 circles that maybe replacing R12 with R134a wasn't the best idea. George has licensed a air/gas supplier in Indiana to manufacture his
 favorite blend (autofrost). It's a "drop in" replacement for R12 and carries the mineral oils used in R12 systems very well.

 So why do we use R134a? Well, it's what most of the car manufacturer's standardized on. And our EPA has mandated that folks who repair
 our A/C systems have to recover the refrigerant on whatever they work on. And they aren't allowed to mix refrigerants. So, most A/C shops
 have a recovery machine for R12, one for R-134a, and they don't care to mess with a car that's charged with anything else.

 It's only natural that he'd expand his business to include a better moisture removal system for existing R134a systems.

 Just my two cents. I am not connected with George or his company, nor have I purchased Autofrost. I've just been a keen observer of the
 alternative refrigerant soap opera for the last few months.

 Bob Mohr

GHG-X8
High Performance Refrigerant for R-134a Systems.
currently marketed as COOL TOPTM refrigerant.
by ATC Specialists, Inc.
 

 Substitute for R-134a in almost all cases, US patent no. 6,056,891 (5/2/00)
 NO OIL CHANGE required - uses standard R-134a PAG or POE (ester) oils. DO not use to replace R-12 or in mineral oil systems.
 EPA SNAP listing not required, since this product contains no ozone depleting substances
and the substance being replaced (R-134a) contains none as well, it falls outside EPA SNAP
Jurisdiction.

 Technical help - 1-888-AUTOFROST (1-888-288-6376). Ask for code 10 [service provided by MEA]

 Performs equal to or BETTER THAN R-134a, often 10 degrees F lower duct temps or more.

 Question and Answer sheet for Autofrost GHG-X8

 Zero Ozone depletion.

 Currently, GHG-X8 may be sold to the public without EPA 609 certification, just like R-134a. The EPA is proposing to restrict the sale of R-134a to certified technicians only, in the future. GHG-X8 will be restricted to certified technicians when the R-134a rule becomes effective.

 Available this spring/summer time frame. Call Bobbie Burke, ATC, at 1-800-622-5008.
Autofrost GHG-X8 will replaceAutofrost GHG-X7. X8 has slightly better performance and COSTS MUCH LESS to make.

 New cars (R-134a) use PAG oils, that may absorb moisture 1,000 to 10,000 times more than the mineral oils used in the older R-12 cars. Moisture entering during system service can easily lead to corrosion and expensive system failures several months down the road. GHG-X8 contains Dry-Pak® system dehydrant from Cryo Chem. Dry-Pak® reacts with any moisture found and converts it into a harmless silicone oil that will not take part in refrigerant breakdown/corrosion reactions. This may greatly extend system life to many years instead of a few months due moisture getting in during service. We have had testing labs measure moisture content in unopened containers of GM PAG oil and found them to be in the range of 800-900ppm, far more than enough to cause corrosion in just a few weeks and system failures. Anything over 50-100ppm is trouble. The moisture standard for refrigerants is 10ppm.

 MUST be charged into system as liquid to prevent composition change

 When first charging into an evacuated system at over 80F or so, high head pressures (340-360 PSIG) and poor cooling may be noticed. (It will act like an R-134a charge). If this happens, just take a garden hose or flower watering pot, and pour some cool water on the condenser/radiator for a few seconds. The head pressure will often drop to 180 PSIG from 360 PSIG, then rise to around 220 PSIG after the water has evaporated. The AC ducts should now be delivering air in the 30's F to low 40's (it will be in the 60's before wetting the condenser/radiator). This watering only needs to be done once, to allow the blend to recombine after being charged into (and partially separated) by the initial vacuum. Letting the car cool down for a couple of hours also works.

 CANNOT BE VENTED (in the USA) - must be recovered (contains HFCs)

 DO NOT USE IN R-12 systems. Mineral oil will not return to the compressor, failing it.
 
 

Phone: 800-424-3836
Fax: 800-691-4996

 Autofrost GHG-X8 TM    R-134a Replacement Q & A's 11-08-98

Q. What is Autofrost X8 refrigerant?

A. Autofrost X8 is a non-flammable, high performance refrigerant that is
designed for the R-134a system and will result in 10o F colder duct
temperature. Autofrost X8 must have PAG or POE (ester) oils commonly used
with R-134a.  DO NOT use X8 to REPLACE R-12. R-12 systems will have
compressor failure will result from no oil return, (use Autofrost X3 /
R-406A to replace R-12 in systems using mineral oil ).
Autofrost X8 wll replace Autofrost X7 spring 2000. X8 performs slightly
better and is MUCH LESS EXPENSIVE to make. Autofrost X8 is made
from hydrofluorocarbons ( HFCs) and offers zero ozone depletion.  Autofrost
X7/X8 and Autofrost X3 / R-406A are marketed by Monroe Air Tech,
1-800-424-3836   web: www.autofrost.com

Q. Are these products legal to use?

A. Yes. Autofrost X8 is not governed by EPA SNAP rules since no ozone
depleting substances are being replaced. (Not EPA SNAP legal to replace R12).

Q. Does this refrigerant have to be charged as a liquid?

A. Yes.  This refrigerant and all other zeotropic blends (R-400 series)
must be charged as a liquid to prevent change in composition. Autofrost X8
is supplied in 12 ounce small cans which are equivalent to 14 ounces of
R-134a.  These are  the same cans that are used for R-134a and are packaged
twelve cans to a case. One case will service approximately six vehicles.
There are also plans to market X8 in 25 pound cylinders.  The 25 pound
cylinders contain a "dip" tube to withdraw the product as liquid with the
cylinder upright.  If charging from an 12 oz small can, make sure you
withdraw the product as liquid.

Q. How much Autofrost X8 do I need to charge in?

A. If you are using scales to weigh it, then start with 90% of the R-134a
weight amount. If you are using a liquid charging cylinder such as
DIAL-A-CHARGE TM, use the same liquid amount as you would R-134a. Some
systems will perform better with less than the recommended charge. A few
will work best with 93% of the R-134a charge.  It is better to use a heat
blanket on a supply cylinder to fill a DIAL-A-CHARGE rather than venting
the DIAL-A-CHARGE.

Q. What is the best procedure for charging?

A. Before starting engine, charge up to 90% (2.5 lb. R-134a X .90 = 2.25
lb. Autofrost X8) of determined amount through the low or high side port as
a liquid only. DO NOT TURN CYLINDER UPSIDE DOWN! (Cyl. has a pickup tube
and must remain "valve up" ). Allow the system to stabilize for 3 minutes,
then start engine. Turn A/C on Max., wait 3 more minutes and then add up to
20% (2.5 lb. R-134a X .20 =3D .5 lb.  ) more Autofrost X8 through low side
port only.  Performance may be acceptable at less than 90%. Total maximum
charge is 93%! (2.5 lb. R-134a X .93 = 2.325 lb. Autofrost X8)
DO NOT OVER CHARGE!!!    TOO MUCH IS WORSE THAN TOO LITTLE!!!

Q. Do any valve, switches or other sensing devices need to be changed or
adjusted?

A.  Autofrost was blended to operate in R-134a systems under about the same
pressures and temperatures as R-134a. Therefore no switch changes or
adjustments are necessary. Autofrost is one of the only replacements that
will work properly in a system with a variable displacement compressor such
as the Harrison V5 found on 1988 and newer GM's. These systems are
non-adjustable and will often offer better performance with Autofrost than
with R-134a. Late model Fords have been experiencing  leakage or premature
release of refrigerant through their "pop off valve". We have seen three
designs of this valve that have been defective. The best solution to the
problem is to use a GM valve, part # 6552743 or A C Delco part # 15-5415.
Q. Should I always vacuum the system before charging?

A. YES! Air will not condense and will cause excessive high side pressures!
This can cause damage to the system, especially the hoses. Moisture is also
very damaging to the system. When mixed with refrigerant, it becomes very
acidic and will eat away at system components. Always pull a vacuum at 29.9
inches of mercury for at least 30 minutes before charging. 45 min. to 1hr
is better. The preferred method of getting a good known vacuum is to use a
"micron" gauge.  A micron reading of 700-1000 microns (with the pump
blanked off from the system) indicates a good "dry" system.  Higher than
1500 microns, all the moisture won't be removed. If your pump cant make
1000 microns, then change the oil one or more times.  Many compressor
manufacturers specify about 700 or lower micron vacuums for warranty
coverage.

Q. Which of the three oils available in the automotive industry is the
best, PAG, POE (also known as ester), or mineral?

A. The oils used by R-134a, both PAG and POE (ester) are much less stable
than R-12 mineral oil and are very hygroscopic, (absorb moisture 10-10000
times more than R-12 mineral oil).  Autofrost X8 will not solve the
moisture problems of "wet" systems.  Extreme service vigilance is required
to keep R-134a systems "dry".  Cryo-Chem, Inc., offers a product called
"DRY-PAK(R)" or "Tune-Air(R)" that may be charged into R-134a systems (and
Autofrost X8 systems) to remove moisture to stop corrosion and acids. Cryo
Chem's toll free phone number is 1-800-237-4001. Web: www.cryochem.com. We
have seen many R-134a (factory systems just off 3yr warranty) fail from PAG
oil breakdown (from moisture), and have seen condensers and evaporators
with as many as eight holes eaten in them.  Failed/wet PAG oil is typically
bright orange in color.  Although POE oil, (also known as ester oil) works
with most any refrigerant, it is known to break down easily into fatty
acids and alcohol=92s from high temps, and possible exposure to steel.  POE
oils do not "foam" for good lubrication and provide less lubricity than PAG
or mineral oils. This is one reason the OEMs use PAGs. Another reason that
OEMS (new car makers) might use PAGs is that the extra moisture they draw in during
service down the line (after warranty), to induce more and faster major system
failures such as repeated acid eat throughs of evaporators and condensers.
Vacuums, used to "dry out" R-12 systems (mineral oil) are not very effective
on PAG oil systems, and one compromised, many R-134a systems will continue to
have a long strings of major failures for the life of the car due to the inability
to have the moisture removed.  Currently, we plan to offer Autofrost-X8
already premixed with Cryo-Chem Dry-Pak(R) to combat this extreme moisture problem.
 
 

There are several
vehicles running both Autofrost X3 / R-406A and Autofrost X8 in POE (ester)
oils and no problems have been reported to us, however, if system life or
longevity is a priority, then change to R-12 mineral oil and charge the
system with Autofrost X3 / R-406A. Duct temperature will still be at
least 10 F colder.

Oil should be changed to about a 300 viscosity mineral oil, such as Ford
Part # YN9.  Some R-134a compressors are too "tight" for the usual 525
viscosity oil and will immediately fail.  To flush the compressor, it must
be removed and put on the bench, and turned over by hand for 40-50 turns
while pouring mineral oil into the intake to wash out any PAG/POE oil. Use
a good high power liquid flush to clean all other components.  Recharge
system with Autofrost X3 / R-406A.  Any PAG oil remaining (unless Daphne
brand) will be destroyed by this process and could cause system problems if
not completely flushed out. (See the Autofrost X3/406A info packet)  Some
technicians see this as a big hassle, labor intensive and is the very
reason Autofrost X8 was developed. A fast and simple improvement in
performance (10o F colder air), no ozone depletion, and system
compatibility (PAG and POE oils).

Autofrost X8 is miscible in PAG (poly alkylene glycol) and POE (polyol
ester).
Autofrost X3 / R-406A is miscible in R-12 mineral oil and POE (polyol
ester).

Q. How should the system perform?

A. If you did a performance check on the same system with R-134a and
Autofrost, you would see a ten degree improvement with Autofrost. No two
systems will perform exactly the same, but the readings will be very close
on the suction side. High side pressures will be within 15% of R-134a
pressures depending on condenser design, airflow and ambient temperature.
If you experience excessive head pressure, check for a dirty radiator.
Small debris can get through condenser fins, get caught in the smaller fins
of the radiator, and is undetectable without removing top covers and
visually inspecting. Dirty radiators, inside and out will cause heat to
soak into the condenser and cause excessive pressure in the system even
after the vehicle is parked! It is wise to always measure refrigerant
charge. If using 25lb. cylinders, something as simple as a digital bathroom
scale will be closer than guessing. Also, check the fan-clutch if present.
A number of high head pressure problems were traced to worn out fan
clutches that caused the fan to spin slowly. Remember too much can do
damage!

Q. What about the old "feel the evaporator outlet line" and charge "until
it gets cold" method of charging?

A. Blends such as Autofrost sometimes need two or three minutes (at idle
speed) to become thoroughly mixed throughout the system. Often, when the
evaporator outlet line begins to get cold, the system will be overcharged.
 Solution: as you near the end of charging, stop charging for 2 or 3
minutes and let the system continue to run at idle before performing
further charging or diagnosis. If a large part of the initial charge is
dumped into a suction (low side) accumulator, such as on a typical GM CCOT
system, the higher boiling components of the blend will hang around in the
accumulator longer than R-134a would. Please take an extra 2 to 3 minutes
to let the blend mix completely before proceeding.
 

Q. What is the best procedure for leak checking a system?

A. Most any leak detector currently on the market will sense Autofrost.
Leak detection methods are the same, however there is one procedure that is
superior to any other which involves the use of dry nitrogen. The vehicle
should be emptied of all refrigerant and a vacuum pulled for at least five
minutes to remove air. Three or four ounces of refrigerant should then be
installed as a tracer for the leak detector to pick up on, and then the
system pressurized to 175-200 psi with dry nitrogen. After all the leaks
have been located the charge can then be released into the atmosphere
making leak checking less expensive and much quicker.
Dry nitrogen is non-flammable and is  available at any welding shop. It
comes in tanks similar to oxygen and acetylene that can be purchased or
leased and are very cheap to have refilled. This is a very important tool
that every A/C shop should have.

Q. Can I use automatic charging equipment with Autofrost?

A. Autofrost X8 is only packaged in small cans at this time and can be used
with your R-134a gauges and can taps. When packaging of cylinders begins,
you will be able to use most equipment.

Older type automatic charging equipment, which uses a FLOW METER to meter
in R-134a at a fixed rate should be checked with a scale. For example, pull
a vacuum on an empty recovery tank and place it on a scale. Program 3 lb.
on your charging station and note the weight added to the empty tank when
the machine stops charging. The number scale on your machine can be altered
to the correct amount.

 Newer type equipment, which contains a set of scales to weigh in a
measured charge (remember to only use 90% as much Autofrost as you would
R-134a)  to a holding tank before charging should work all right. Remember
to use the same liquid (level or volume) here as you would for R-134a.

Also, most R-134a automatic charging equipment withdraws the product
(R-134a) from a 25 lb. cylinder as a liquid, and the R-134a cylinder must
be mounted upside down when attached to charging equipment. Autofrost X8 25
lb. refrigerant cylinders contain a "pickup-tube" much like a can of spray
paint, such that you get liquid out when the can is upright. Autofrost
cylinders MUST BE INSTALLED UPRIGHT when used in charging equipment that is
designed to have R-134a cylinders installed upside down. You may have to
lengthen or splice in a small piece of hose if needed. Also, use only
automatic charging equipment that withdraws the product from the
refrigerant supply as a liquid.

Q. Does this refrigerant need to be recovered (captured)?

A. Yes. Under US EPA rules and regulations, all CFC, HCFC, HFC refrigerants
and just about anything else needs to be recovered and not be vented into
the atmosphere. Refrigerants which require recovery are R-12, R-22, R-134a,
Autofrost, and all the other current "legal" R-12 replacements at the
current time. The only refrigerants which may be vented are air (nitrogen),
water, CO2, ammonia, and pure hydrocarbons according to US EPA rules. You
are not likely to encounter any of these, as they will not work and will
damage the system. Autofrost X8 consists of 100% hydrofluorocarbons, so it
must be captured and returned to a reclaimer.
 

Q. What are EPA retrofit fittings?

A. The US EPA is requiring special "uniquely threaded" fittings to be
attached to all R-12 service ports. These fittings provide threads which
are unique to each type of alternative refrigerant. These fittings are
required by law (only for the automotive sector, does not apply to
stationary equipment) for refrigerants which have completed the entire EPA
approval process and are listed as "acceptable" for mobile A/C.
Refrigerants MUST be properly labeled somewhere under the hood. These
labels are packaged with Autofrost. All other refrigerant labels must be
removed or rendered unreadable. Retrofit fittings for Autofrost-X3 / R-406A
are available from suppliers of Autofrost.

Since Autofrost X8 is not under the jurisdiction of the EPA SNAP rules, no
unique fittings are required by law. However, it is strongly recommended
that Labels and service port caps be installed to identify the Autofrost X8
charge and prevent mixing with R-134a.

Q. Are compressor seal kits and system o-rings compatible with Autofrost
X8?

A. We have seen no problems in original factory R-134a cars changed over to
Autofrost X8.  Older cars, retrofitted from R-12 to R-134a should have
barrier (nylon lined) hoses installed as these were designed to contain
R-134a and they work fine on all blends.
 
 
 

Q. What about "topping off" systems low on charge?

A. Current EPA SNAP rules only permit "topping off" with the same type of
refrigerant which is already installed in an automotive system. For systems
charged with zeotropic refrigerants such as Autofrost-X3/R-406A, or almost
all other "blends", the recommended procedure is to first remove (recover)
the charge and recharge with fresh virgin material. As zeotropic blends
vapor leak, they change composition (pressures get lower), and a recharge
will result in lower pressures, and some reduced capacity. However, many
technicians have topped off Autofrost systems and report no problems. The
property which makes Autofrost change composition (called fractionation) as
it vapor leaks, is also responsible for a big performance gain over single
component refrigerants such as R-12 or R-134a. Zeotropic refrigerants
exhibit a temperature "glide" (about 16 degrees F for Autofrost), which
causes the refrigerant to boil (evaporate) or condense over a range of
temperatures instead of a single temperature, thus increasing the heat
rejecting capacity of the condenser and increasing cooling performance over
R-12 and R-134a.

Since Autofrost X8 is not covered by EPA SNAP rules, it may freely be mixed
with R-134a. Adding an 12oz can of X8 to a low-on-charge R-134a system,
will often produce 10o F colder air.  Remember to label what you did.
EPA SNAP rules prohibit mixing X8 with R-12 or their substitutes (if
substitutes contain chlorine atoms i.e. they have a small "ODP" ozone depletion
potential.)

Q. What do I do with used refrigerant?

A.  Providing you are an Autofrost customer, you can return any used
refrigerants that are collected. Cylinders will be sent to USA Distributors
at 1-800-898-4872, freight prepaid. Product in cylinder will be tested for
composition and you will be given credit towards the purchase of new virgin
Autofrost. Credit will range from $1.65 to $7.00 per lb. depending on
percentages of components. Cylinders will be purged with nitrogen and
checked for certification. There is a date stamped on all cylinders and are
only good for five years. Your cylinder can be recertified for $20.00
before it is returned if you wish. Cylinders will be returned within two
weeks.
 This procedure allows you to empty every vehicle that enters your shop and
fill with a known product so that you may make a proper diagnosis. If you
use Autofrost to make your diagnosis, you may want to recover, recycle, and
reuse this charge you just put in, provided there was no excessive loss due
to vapor leaking.
 Another legal, lower cost alternative to the high price of refrigerant
recovery cylinders, is to use NEW BBQ grill propane tanks. These are DOT
rated at 240 PSI and are legal for shipping R-12 and similar pressure
alternatives. A 20 lb. BBQ grill propane tank typically may be purchased at
places such as Sam's Club or other wholesale buyers clubs. Be sure you only
use NEW tanks. If propane was ever in the tank, it will "stink" for
eternity from the mercaptain odorant. The reclaimer will get extremely mad
at you and you will have to pay upwards of $10/lb. to have the refrigerant
burned if you do not use a new tank. Adapters are available from Autofrost
suppliers for adapting R-12 and R-134a hoses to these tanks. The 20 lb.
propane tank will hold 37 lb.. of Autofrost (the 80% fill level). Larger,
100 lb. propane tanks may be purchased new for around $80, and the hold 185
lb.. of refrigerant. If you do use propane tanks, be sure to contact your
reclaimer first to make sure it is all right. Contact your reclaimer or
refrigerant supplier for proper shipping instructions on used refrigerant.
A $10 or so "hazmat" fee (all compressed gases are shipped as hazardous)
will usually be charged in addition to the normal shipping charges. The
tank will have to be properly marked for shipment and need "diamond"
stickers, and other labels.