I've often wondered why we don't go back to ammonia as a refridgerant. It couldn't be much more dangerous than some of the substances that have already been mentioned. It seemed to work very well in ice plants and such.

I think that the EPA's record on refridgerants has been poor or worse anyway. I believe that 134 will be gone before long. It required a lot to do a successful conversion and didn't work all that well anyway.

David Duffield

Andy:

I realize that everyone has added their two cents worth. But if you read the thread, you will see that the original question evolved into many. Ed simply had many questions and not just one. We are all here to help one another, even if it is not as direct as some would like.

Peace brother.

Kobalt, I have that vacuum problem myself. I need a vacuum. I private messaged some propane pelicanhead here in Phoenix, but I got nothing in return. If only we could find some propane pelicanites in our neck of the woods with vacuum pumps.

I already drilled the propane tip like Steve said. Or maybe I kind of did like Steve said. Steve, give us a picture man. Jurgen, what did you use to put it in?

Ed, I'm sure you did alright. I just mic'd the hole I drilled at around 2 mm, although I don't think the size here matters too much. I think there's some kind of check valve at the tip, so drill it all the way through, and empty out the the metal shavings. On the bottle side of the torch adapter, you can screw off the port with an 8 mm socket. Then you can drill the check valve out of that. Don't make this hole too big, because it must be small enough to push the pintle valve on the propane bottle. Not sure if this is necessary though. It might work leaving this alone.

The threads on the end of the torch tip do not match those on a standard AC hose. Find the correct die, and rethread the brass threads to match your AC hose.

Making custom threads to subvert gas handling system safety features is a slippery slope. I hope you guys have the sense or the knowledge not to do this with acetylene or oxygen systems. Mess with these and they might not find enough of you to fill a shoebox. :eek: If you consult your local fire marshal you will likely find all these kludges are illegal and will void any insurance coverage of damage you may cause. I suggest you request more guardian angels!

Now to correct some errors stated above:
R134a refrigerant performance is only about 8% less than R-12 not 50%. Due to slightly lower and higher pressures in the cycle, R134a requires modestly stronger and more leak tight system components. Optimum performance with R-134a also means valves and switches should be recalibrated for the higher pressures. The higher pressures while the vehicle is idling also require either a bigger condenser or increased air flow across the condenser. A properly designed R-134a vehicle A/C system can freeze your ass off if required.

Cheers and many happy vapor compression cycles to you. Jim

Steve and Turbo, do you guys just pour out of the fresh bottle of propane? I am asking this because on another forum somewhere, someone mentioned running the propane torch for a couple of minutes to burn off any moisture content if present in the bottle. Just wondering.

How's this, Ed. My brother and father did the mods (I was responsible for vacuum, charging, and making a huge mushroom cloud explosion).

Remove the tip of the torch. Solder on a 1/4"-1/8" reducer fitting and a 1/8" to male refrigeration flare. On our torch, there was no hole in the tip to drill out. It was wide open. On the end that attaches to the torch, remove the prong fitting, drill out the torch really big, but don't drill out the prong fitting too big. If you do, the prong will not press down the pintle on the propane bottle.

Please don't mind the Porsche porn PolyBronze bushings in the background. They were posing, so I had to take their picture. ;)

Any other pictures you need?
Jürgen

http://forums.pelicanparts.com/uploa...1086228067.jpg
http://forums.pelicanparts.com/uploa...1086228083.jpg

Ed, moisture in a system with propane doesn't create the acidic byproduct, so a little moisture won't hurt. I charged from 2 used bottles (used digital scale to measure charge), so moisture probably wasn't an issue.

Just be aware, like mentioned before, 100% propane will give you mighty high pressures. If your system isn't in good shape, you might uncover its weakest link. I plan to vent the propane and recharge with isobutane/propane mix to reduce pressures before it gets really hot and high side pressures skyrocket.
good luck,jurgen

If your system is perfectly sealed, sure you can. However, when you connect your gauges, you will be letting in some outside air, until the hose to manifold is pulled to vacuum. I don't think this is a BIG problem.

The ideal circumstance would have you renting a vacuum pump from a rental store (if possible), and pulling a vacuum yourself to be absolutely sure your seals and hoses are fine. In my limited experience with older A/C systems, taking a few extra steps can yield big improvements or at least give clues to the condition of your existing system.
jurgen

Look at all Porsche junk yards, a lot are from rear engine fires. I will be installing Duracool in my 88 this weekend. I pasted the below info from thier web site. I have seen a lot of info about this stuff lately. Rarely have I heard anything about using propane.

EDUCATIONAL INFORMATION
DURACOOL® Refrigerants Inc. are the leading hydrocarbon refrigerant on the market today and that's because it provides consistently superior cooling capabilities and boasts all the qualities of a product that is not only safe and highly efficient but it is also NON OZONE-DEPLETING and NON GLOBAL-WARMING. Here are the facts:

NON CORROSIVE - WON'T HARM AIR CONDITIONING COMPONENTS:

Guaranteed in writing!

Over 10 million vehicles converted to date.

System head pressures greatly reduced from R134a systems - similar to R12 systems

MUCH COOLER & MORE EFFICIENT! VERY SIMPLE INSTALL!

Cools extremely better than R134a - Cools marginally better than FREON

Up to 35% more efficient than R134a - Moderately more efficient than FREON

VERY SIMPLE INSTALL!

Simple economical conversions of high/low screw on fittings - NO RETROFIT REQUIRED!

Compatible with mineral & synthetic oils including Pag & Ester - NO OIL CHANGE REQURED!

No special equipment required for installation. Use your R12 or R134a equipment and tools

Requires only 40% of charge by weight of R134a and 35% of FREON R12

BETTER PERFORMANCE AND SAFETY!

Patented hydrocarbon friction fighter enhances performances and safety

Auto ignition of 1635°F is ACTUALLY a higher auto ignition than R134a which is 1328°F

Absolutely non-toxic - 100% natural organic product

Only if you are damned sure your system is leak tight, otherwise you could have the " treat" of seeing (perhaps the last thing you see) your compressor explode as that air and propane/isobutane mixture detonates within.:eek: Jim

Not that there's anything wrong with Duracool, but Duracool 12a is just a marketing name for hydrocarbon refrigerants. If you look at the MSDS, it consists of 30-60% propane, with the remaining balance as methane.

DURACOOL 12a® ACGIH(2002)
COMPONENTS % CAS LD50 LC50 TLV
v/v inhalation (ppm)

--------------------------------------------------------------------------------

(rat)
methylethylmethane 15-40 106-97-8 n.ap. 276,000 ppm 800
4 hr
(mouse)
2-methylpropane 30-60 75-28-5 n.ap. 52mg/kg
1hr simple asphyxiant
dimethylmethane 40-70 74-98-6 n.ap. n.av. simple asphyxiant
Non Hazardous Ingredients =<2 n.ap. n.ap. n.ap. n.ap.

pulling vacuum
 

For those looking for the poor mans vacuum pump, look no further than the cast off refrigerator down the street on garbage day.

9 time out of 10 the pump is fine, people just remodel and get rid of the old unit, or something non mechanical breaks.

Remove the old compressor for the unit, take along any start solenoids that also may be attached. I've got my "vac pump" mounted to an old milk crate with a handy dandy on off switch, but no need to get fancy. A dollar or two worth of brass compression fittings will typically provide some attachment point for a set of manifold gauges.

The suction side of the generic fridge compressor I use as a vacuum pump easily draws my system down to 25 inches of mercury. I can keep the "vac pump" running for an hour or two easily, so long as I keep it parked in the shade. Be aware that it does begin to run a little hot, as there is no longer any fluid circulating through the unit, but for the price I'm willing to eventually burn one out. As an aside, I have been running this one off and on for years without a hiccup. For really pulling a deep vacuum, I run two cast off refrig pumps in parallel. Did I mention I tend to collect all sorts of junk?

As there is no longer any oil circulating through the compressor , occasionally suck up the smallest amount of mineral oil now and then to refill the compressor crankcase. Easy does it, as you dont want to slug the compressor with a incompressible liquid. Then again, for the price you can afford to accidentally do some damage.


Cheap and especially ugly, but it works surprisingly well. Also incredibly handy for all sorts of odd jobs. If your really desperate, they also make incredible air pumps, capable of 300-400 psi pressure, so be sure your pressure vessel is appropriatly rated.

vin

You would need oxygen in the proper and sufficient proportions to create a large combustion like that. There wouldn't be enough oxygen, in any in the system to create any explosion.

The atmosphere is about 20% oxygen and will fill any leaking vacuum system up to atmospheric pressure with air that is 20% oxygen. Add the fuel (propane and isobutane) as you charge the A/C system and you could be headed for a heartache. Jim

Turbo, what pressures are you talking about. R134 kind of pressures?

Duracool is good stuff. By that I mean it is basically a propane isobutane mix. No problem with that. The main advantages are that it comes in the nice cans which you just connect to a regular r134 charging hose. Make sure you put on a 134 adapter on your low pressure nipple. But chances are you will find yourself doing this rig we are talking about here with the propane. That's because if you want to see some better numbers out of the vents, you gotta do a propane boost. It's all about the percentages. I guess in the case of a 911, after a full vacuum, you would use maybe 2 cans of duracool and then top off with pure propane. Or if it is filled already on just 2 cans, then maybe vent just a bit and put in the propane.

Higher--like 50-80 psi higher on the high side.

See http://www.delphi.com/pdf/techpapers/1999-01-0874.PDF

Perhaps you should read 90% of the other threads on Pelican, or any other public forum for that matter. There are many aspects and considerations to a question of this nature. Realize that if someone merely answered your question and this thread is read by others without a full spectrum of considerations then they may make an uninformed choice.
IMO, there's nothing wrong with considering safety and legality here.

Certainly there are safety issues to consider with R12A...but don't for a moment think that the issue of a nearly-empty 22 gallon gas tank is any less safe. Want to calaculate the explosive value of a nearly-empty 22 gal gas tank with gasoline vapors above the liquid level ???

Don't.......

---Wil