GOLFMK8
GOLFMK7
GOLFMK6
GOLFMKV

Charging your A/C with refrigerant grade propane; cooler, slightly more explosive!

timb

Passed Driver's Ed
Location
Hampton Roads, VA, USA
Car(s)
2007 Volkswagen GTI
Summer is coming, this means hot temperatures. Let's face it, the A/C system in most of our MKV GTIs is less than perfect.

The compressors are inefficient and prone to flat out blowing up.

The evaporators are small, the cooling fans smaller and to top it off it has to put up with heat soak from the radiator and intercooler.

What to do? Well, if your A/C isn't blowing cold, you might need a recharge. Systems lose refrigerant naturally over time. With the seals on our compressors, you could lose up to 25 grams over 3 years. That's about the threshold for the system to stop blowing cold.

Now you could just recharge with R-134a, but let's be honest, that shit just sucks. It's 30% less efficient than the old (and now banned, thanks EPA) R-12. This means your A/C won't blow as cold, and has to work harder.

But, you say, isn't R-134a my only option? Oh no, no, no!

There is another option. A little thing called R-12a. It's a hydrocarbon blended refrigerant. No license is required, and it's legal per the EPA. (If you have an existing R-134a system, it's legal to convert it to R-12a.)

What is a "hydrocarbon blended refrigerant" you might ask? Well, I'm not going to sugar coat this: It's propane.

Now, this isn't the same propane you use to burn steaks or heat your home with. Unlike Hank Hill's propane, this stuff has gone through extra refining to remove stuff like methane. We call this refrigerant grade propane.

The most popular version of this for cars is sold under the name Duracool R-12a.



It's sold in 6oz cans and 30lb cylinders.

To recharge the system in our GTIs, we'll need exactly 7.4oz, or 210g.

"Hold on a second," you're saying, "the sticker under my hood says 525g!"

Yes, that's for R-134a, but R-12a is 40% more efficient, this means you need 40% less!

So you'll need two cans. You can pick it up on eBay, it runs about $10 a can.

At this point, I think you're still stuck on the fact that we're going to be pumping propane into our A/C system, so let's go over some safety facts!

What is the difference between regular propane and the refrigerant propane that is used to manufacture the DURACOOL® products?
The propane that is regularly used for barbecues, and general consumer or commercial use is a by product or deritive of the hydrocarbon manufacturing process (the production and refining of raw oil products). The propane used for standard applications (such as your home barbecue). In order to utilize the product as "refrigerant grade" the product is further refined to render out methane gases and other impurities. This refrigerant propane is different in many ways, most notably is the disparity in the auto ignition. Essentially this refining makes the product safer and more stable. The Auto ignition for regular grade propane is ~842 F., while the DURACOOL® products auto ignition is ~1635 F.

Why does DURACOOL® have the scent of propane?
The additive "ethyl mercaptin" is actually a stenching agent that is added for safety reasons. Mercaptan, as it is commonly known, is added to natural gas, propane, butane and virtually all gases as an agent that will alert the user to any leakage. The addition of mercapan should be viewed as a safety feature (see below). Mercaptan is also condensable in the AC system and can not limit performance in any way and will not negatively impact components. The mercaptan smell is not detectable under regular working conditions or under normal install conditions.

Have there been studies to determine the potential level of incidence, in terms of ignited automobile compartment leakage?
Internationally respected risk assessors Arthur D. Little, in a detailed UK-based study, estimated the risk of an ignited refrigerant leak in the passenger compartment of a motor vehicle as being in the area of 3 in 10 million. Their findings, from a local perspective, mean that if every car in the USA (some 50 to 60 million vehicles) were to use a hydrocarbon refrigerant such an accident might occur once in every 50 years.

What would the impact of and "incident level, once every 50 years" ignited automobile compartment leakage actually be?
In terms of the "impact", it is important to recognize that automobiles generally have 12-15 ounces of DURACOOL® refrigerant. If there were a full amount leak into an automobile compartment and it ignited, it would theoretically create a "flash" which would last 1-1.5 seconds.

There are eminent Risk Assessment Reports available which document the safety of hydrocarbon refrigerants in motor vehicle air conditioning systems.

Duracool has an auto ignition of 1635°F, which is actually higher than the auto ignition of R134a (1328°F).

Also, you need to take into account that your car has 75 pounds of highly flammable gasoline, a sump full of oil and a 1 gallon tank full of methanol. I think 7.2 ounces of propane is the least of our worries.

Okay, now that we've got that out of the way, let's get to some data points!

R-134a Data
Ambient Temperature: 70°F
Compressor Load: 12Nm
Vent Temperature: 64°F
Condensor Temperature: 40°F

R-12a Data
Ambient Temperature: 70°F
Compressor Load: 7Nm
Vent Temperature: 46°F
Condensor Temperature: 30°F

Look at the change in compressor load; that's almost 40% more efficient! This translates to colder air and improved gas milage; plus less wear on the compressor and related parts.

The conversion to R-12a requires no parts to be swapped out. It uses existing R-134a fittings. All you have to do is evacuate the existing system, pull a 30inHg vacuum, then charge the low side with liquid R-12a (invert the can while charging).

It's best to charge by weight, so go ahead and put a full 6oz can in, then use a small postal or food scale to charge an additional 1.4oz.

That's all there is to it!

Hopefully this thread has been an informative introduction to hydrocarbon based refrigerants. If you have any questions, I'd be more than happy to answer them.

 
Last edited:

Tip-C

Ready to race!
Location
Montreal, Canada
Wow...I'm very interested in doing this. Can you elaborate a little more on the process...????

What to connect where and so on. A DIY would be great!

Thanks
 

timb

Passed Driver's Ed
Location
Hampton Roads, VA, USA
Car(s)
2007 Volkswagen GTI
Wow...I'm very interested in doing this. Can you elaborate a little more on the process...????

What to connect where and so on. A DIY would be great!

Thanks

Sure thing! I'll get a nice little DIY written up tomorrow. Should be sunny so I can get some clear pictures.
 

Speeddemon96

Go Kart Champion
Location
South Florida
Hmm I like this...what's the catch or the cons of doing this? How do I know how much to add of the new stuff? Do I need to take out the oil and put new oil in the compressor?
 

gadgetpup

Passed Driver's Ed
Location
CENCAL
Taken from EPA website.

What are HC-12a® and OZ-12®?
HC-12a® and OZ-12® brand hydrocarbon refrigerant blends are flammable refrigerants. Their primary components are hydrocarbons, which are flammable substances such as propane and butane. HC-12a® and OZ-12® are registered trademarks of OZ Technology, Inc. HC-12a® has been marketed since 1994. OZ-12® was a similar blend marketed until the introduction of HC-12a® . Both products have been reviewed by EPA under the Significant New Alternatives Policy (SNAP) program. More information about the SNAP program is available from the hotline listed at the top of this page.

Note that EPA refers to the chemical composition of HC-12a® as Hydrocarbon Blend B. EPA considers any substance with that chemical composition, no matter what its trade name is, to be Hydrocarbon Blend B and to have the same legal status that HC-12a® has.

In order to meet Department of Transportation requirements for shipping HC-12a® in six-ounce cans (DOT refers to these cans as DOT 2Q containers), OZ Technology reduced the vapor pressure of HC-12a® in June, 1998. In order to reduce the vapor pressure, OZ Technology changed the composition of HC-12a®. EPA does not consider this reformulated HC-12a® to be the same as Hydrocarbon Blend B. The reformulated HC-12a® has not been submitted for SNAP review, and thus cannot be marketed or used as a substitute for ozone-depleting substances.
What is DURACOOL 12a®? Is there a difference between HC-12a® and DURACOOL 12a®?
DURACOOL 12a® has the same chemical composition as the HC-12a® formulation that was submitted for SNAP review as Hydrocarbon Blend B. Both HC-12a® and DURACOOL 12a® are different than the new formulation of HC-12a® in six-ounce cans. DURACOOL 12a® is the registered trademark of Duracool Limited, the Canadian company that has manufactured DURACOOL 12a® since 1997. Duracool Limited and OZ Technology, the manufacturer of HC-12a®, are separate, unrelated companies with their own manufacturing facilities and distribution mechanisms.
What is the legal status of hydrocarbon refrigerants such as HC-12a® and DURACOOL 12a®?
It has been illegal since July 13, 1995 to replace CFC-12 with the HC-12a® formulation that was submitted for SNAP review in any refrigeration or A/C application other than industrial process refrigeration. The same prohibition for OZ-12® took effect on April 18, 1994. Because DURACOOL 12a® has the same chemical composition as the HC-12a® formulation that was submitted for SNAP review (i.e., Hydrocarbon Blend B), DURACOOL 12a® is also subject to the same restrictions.

HC-12a®, as reformulated to meet DOT requirements, is not the same as Hydrocarbon Blend B and has not been submitted for SNAP review. OZ Technology is therefore prohibited from marketing this blend as a substitute for any ozone-depleting substance. In addition, any use of this blend as a substitute for CFC-12 or any other ozone-depleting chemical, in industrial process refrigeration or any other refrigeration or A/C end use, is prohibited under the Clean Air Act.

Since HC-12a® as submitted for SNAP review, is chemically different from HC-12a®, as reformulated to meet DOT requirements, and since it has a different legal status under the Clean Air Act, users of any substance marketed as HC-12a® should be aware of which HC-12a® they have purchased.

Note that the Clean Air Act does not regulate the use of any of these hydrocarbon refrigerants when they are used as replacements for non-ozone-depleting chemicals such as HFC-134a. However, many states prohibit using flammable refrigerants in motor vehicles, regardless of which original refrigerant was used in the vehicle.

How did EPA make this determination?
The Clean Air Act, as amended in 1990, required EPA to establish a program to review substitutes for ozone-depleting substances, including refrigerants. EPA's Significant New Alternatives Policy (SNAP) program carries out this mandate. Manufacturers of substitutes must submit information to EPA about the products, including ozone depletion potential, global warming potential, and toxicity and flammability data. EPA then compares these characteristics to both the refrigerant being replaced and the other available substitutes.

Most refrigerants submitted to EPA for review under SNAP have been found acceptable, often subject to certain conditions. A full list of alternatives is available online. In particular, several refrigerants have been listed acceptable for use as CFC-12 substitutes in motor vehicle air conditioning, subject to certain conditions on their use. Each acceptable alternative refrigerant has been demonstrated to a) be safer for human health and the environment than the original refrigerant, and b) pose a level of risk similar to that of other acceptable alternatives.

Flammable refrigerants pose a special challenge, because air conditioning and refrigeration systems in the US have been designed to use nonflammable refrigerants. They are not designed to protect users, service technicians, and disposal personnel from the possibility of fire. Therefore, the use of flammable refrigerants in existing systems may pose a risk not found with nonflammable fluids.

Although new systems may be designed to provide that protection, they are not specifically designed so today. Demonstrating that a flammable refrigerant can be used safely in current systems, whether existing or new, requires a comprehensive, detailed, scientifically valid risk assessment. EPA has required a risk assessment for flammable refrigerants since the inception of the SNAP program in 1994. An assessment must address potential leak scenarios such as collisions, servicing errors, and disposal procedures. In addition, it must consider ignition sources ranging from cigarette lighters or matches to sparks caused during a collision.

OZ Technology has submitted reports that it states demonstrate the safety of using OZ-12® and HC-12a® in systems not designed to use such flammable refrigerants. However, after careful review of each document, EPA determined that none of the reports represented valid a risk assessment. Until such assessments are performed, EPA believes that flammable refrigerants like HC-12a®, OZ-12® and DURACOOL 12a® may pose potential risks not present when using nonflammable refrigerants. For these reasons, EPA does not allow the use of HC-12a®, OZ-12® or DURACOOL 12a® as substitutes for CFC-12 outside of industrial process refrigeration. (Note that HC-12a®, as reformulated to meet DOT requirements, is not permitted to be sold or used as a substitute for ozone-depleting chemicals in industrial process refrigeration, since it has not been submitted to SNAP for review.)

Cont. on next post...
 

gadgetpup

Passed Driver's Ed
Location
CENCAL
Gasoline and brake fluid are flammable, but they're allowed in cars. Why not hydrocarbon refrigerants?
Because EPA has been directed by Congress, under the SNAP program, to consider the safety aspects of alternative refrigerants for CFC-12 (as well as their environmental characteristics), it is necessary to address the safety aspects of using a flammable refrigerant in motor vehicle A/C systems originally designed for CFC-12, before that refrigerant can be approved.

There are good reasons why gasoline and other fluids may be used safely while the use of hydrocarbon refrigerants in A/C systems may not be safe. Gasoline and other flammable substances are used in systems designed specifically for flammable fluids. A gas tank is deliberately placed in the middle of the rear part of a vehicle to protect it against collisions. Air conditioner condensers, in contrast, are placed at the very front of the car to maintain good air flow. Unfortunately, this location means that condensers may be punctured during a front-end collision. Another difference is that unlike gasoline lines, air conditioners include lines that provide cooling directly to occupied areas -- in this case, passenger compartments. Flammability risk is extremely dependent on the specific system being considered; the simple presence of other flammable fluids in a car does not address the safety of using hydrocarbon refrigerants in an automobile air conditioner.
Is sale of hydrocarbon refrigerants legal?
Sale of subtitute refrigerants listed under the SNAP program is not regulated under SNAP. However, statutes and regulations issued by other federal, state, or local agencies may control the sale of these products, including illegal advertising.
Since the autoignition temperature of HFC-134a is lower than that of hydrocarbon refrigerants such as HC-12a® and DURACOOL 12a®, 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-12a® and DURACOOL 12a®, 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-12a® 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-12a® and DURACOOL 12a®, 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.
May hydrocarbon refrigerants be vented?
No. The Clean Air Act prohibits the venting of any refrigerant during the service, maintenance, repair, or disposal of air conditioning and refrigeration systems. When working on a system containing a hydrocarbon refrigerant such as HC-12a® or DURACOOL 12a®, the technician must recover the refrigerant into a suitable container and safely dispose of it.
What other regulations restrict the use and handling of hydrocarbon refrigerants?
In addition to the prohibition on use described above, and the federal law banning the venting of all refrigerants, there are also state and local statutes and regulations that relate to certain uses of hydrocarbons. As of the printing date of this fact sheet, EPA is aware that the following states prohibit the use of flammable refrigerants in automobile air conditioners: Arkansas, Arizona, Connecticut, Florida, Idaho, Indiana, Iowa, Kansas, Louisiana, Maryland, Nebraska, North Dakota, Oklahoma, Texas, Utah, Virginia, Washington, Wisconsin, and the District of Columbia.

Local fire codes also often restrict the storage of flammable materials. In addition, other federal, state, and local regulatory agencies may have regulations related to flammable refrigerants. Check with these authorities for more information.
Are there any advantages to using flammable hydrocarbon refrigerants?
Many flammable refrigerants offer potential energy efficiency savings, lower global warming potentials, low toxicity, and low cost. EPA believes that, with responsible development, flammable refrigerants have a role to play in the transition away from ozone-depleting substances. However, such development must adequately address safety concerns associated with manufacturing, use, servicing, and disposal of these new products. EPA is aware of several successful uses of flammable refrigerants, and welcomes future development of systems designed to be used with them.

The primary drawback to the use of flammable refrigerants today is that most existing systems are not designed to protect people from that flammability. In order to find a flammable refrigerant acceptable, EPA requires the completion of a risk assessment to determine the additional hazard posed by that flammability and necessary steps to mitigate any additional hazard. EPA believes hydrocarbons and other flammable refrigerants offer the potential to be good substitutes for ozone-depleting refrigerants. The best possibilities exist in the design of new equipment that includes safety features to protect against a fire or explosion. Several such systems are now being sold and developed around the world. EPA has always encouraged U.S. businesses to consider using hydrocarbon refrigerants in such newly designed systems.
Has EPA found any flammable refrigerants acceptable under SNAP?
EPA found the flammable refrigerant HFC-152a acceptable for use in new household refrigerators and freezers. This determination was based on a detailed assessment of the risks posed by this flammable refrigerant in this particular application. Note that HFC-152a, which is a single chemical rather than a blend, is not a hydrocarbon. The fact that HFC-152a was found acceptable in refrigerators cannot be read as encompassing all hydrocarbon or other flammable refrigerants in all end-uses. A risk assessment relates only to the specific end-use and refrigerant.

Is it legal to replace HFC-134a in a motor vehicle with hydrocarbon refrigerants such as DURACOOL 12a® and HC-12a®?
In certain circumstances, the replacement of HFC-134a in a motor vehicle with hydrocarbon refrigerants might be permitted. At a minimum, in order to avoid violating the Clean Air Act, the motor vehicle A/C system must have either been originally designed for use with HFC-134a refrigerant, or must have been previously retrofitted from CFC-12 to HFC-134a refrigerant, AND no sham retrofit must have occurred to convert the system to the hydrocarbon refrigerant. In order to avoid violating other laws, the replacement of the refrigerant must not violate any state or local prohibition on the use of flammable refrigerants in motor vehicle A/C systems.

The following 19 states ban the use of flammable refrigerants such as HC-12a® and DURACOOL 12a® in motor vehicle air conditioning, regardless of the original refrigerant: Arkansas, Arizona, Connecticut, Florida, Idaho, Indiana, Iowa, Kansas, Louisiana, Maryland, Nebraska, North Dakota, Oklahoma, Texas, Utah, Virginia, Wisconsin, Washington, and the District of Columbia.

If you plan to change a car from HFC-134a to a hydrocarbon refrigerant such as HC-12a® and DURACOOL 12a®, you should consider that auto manufacturers have stated that changing the refrigerant in new vehicles designed for use with HFC-134a will void the warranty and may damage the system. If the air conditioner on a new car or truck is not working, consult a qualified mechanic or your dealer.
.
 

gadgetpup

Passed Driver's Ed
Location
CENCAL
And now the math:

If 525g of R-134a is 100%
then 525g of R-12a is 140%

so to find out how many grams of R-12a to equal 100%

525/140 = x/100

140x=52500

x=375g

375g is 71% of 525g, weird right? That's the way the math works folks. Just because something is 40% more effective doesn't mean you need 40% less.

So you'll need 375g or 13.23 ounces of R-12a to equal 525g of R-134a.
 

timb

Passed Driver's Ed
Location
Hampton Roads, VA, USA
Car(s)
2007 Volkswagen GTI
525g - 40% = 315g, not 210g, or 11.1 ounces.
And now the math:

If 525g of R-134a is 100%
then 525g of R-12a is 140%

so to find out how many grams of R-12a to equal 100%

525/140 = x/100

140x=52500

x=375g

375g is 71% of 525g, weird right? That's the way the math works folks. Just because something is 40% more effective doesn't mean you need 40% less.

So you'll need 375g or 13.23 ounces of R-12a to equal 525g of R-134a.

Wrong. Check the Duracool FAQ under the R-134a equivalency tables.

In addition, type "40% of 525g" into Google or Wolfram Alpha.

210g is the correct amount.

Good call on the EPA post. I forgot to mention those 19 states. (I'm in one of them, in fact.)

That said, it's also illegal to speed in all 50 states, and we still do it. ;)
 

gadgetpup

Passed Driver's Ed
Location
CENCAL
Ok you were right, the Duracool FAQ does say a only 40% charge is required.

But putting this in your post is a little misleading.
Yes, that's for R-134a, but R-12a is 40% more efficient, this means you need 40% less!

Duracool calculated the 40% charge rate possibly from the flow rate of R-12a or some other reason, it can't be due to efficiency, if it is then their math is fuzzy.

Oh, another good tradeoff of using R-12a is it has a global warming potential (GWP) of 8. R-134a has a GWP of closer to 1300! The E.U. is trying to phase out R-134a in all their cars and use stuff that's 150 GWP or less. Some states in the U.S. are working towards the same goal so it may not stay illegal for long.

Duracool R-12a is also less corrosive than R-134a so it will actually prolong the life of your A/C system, they are so confident that they will guarantee it in writing that it will not damage your A/C.

I can't see of a reason not to do this swap and I'm in one of the states that allows it!
 
Last edited:

nhbubba

CEL free until 48,398 mi
Location
Seacoast NH
I can't see of a reason not to do this swap and I'm in one of the states that allows it!
Does your state allow it? Or does your state not outlaw it?
The difference worth noting. I know NH (also not listed) is very slow to pick up emissions and environmental protection laws. Often we do not require something unless doing so is tied to receiving federal highway funding.
 

gadgetpup

Passed Driver's Ed
Location
CENCAL
My state CA doesn't 'allow' it but isn't one of the ones that bans it. Considering it has some of the strictest air quality controls in the nation, the fact that it isn't banned says a lot.
 
Top