Lots of Refrigeration Questions Today

[patkeefe]

Must be getting hot out west. I'm going to go take pictures of my aftermarket setup. I posted a couple of responses in the many threads going on simultaneously.

The summation is: Rubber hoses leak. Propane and Isobutane burn. R-12 doesn't burn. Make sure your condensers and evaporators are clean.

Pat

[patkeefe]

OK, that was easy. I have a Performance Aire system, installed in 1999 by PO. Couple of notes on the photos:
Compressor is rotary type, not the crappy York piston model. Uses very little HP.
Tracer dye is used in cars because they all leak.
The performance Aire system is an R-12 system. I would feel better about 134a, but I have enough R-12 to last a while. As I have a universal refrigerant license, choice of refrigerants is not a big deal
The undercarriage condenser has the first couple of tubes plugged, to absorb the rock damage without causing a leak.
Vent configuration is OK. I'm working on an improved ducting method, which I will post if it works.

Pat

[island911]

Originally posted by patkeefe
. .
Compressor is rotary type, not the crappy York piston model. Uses very little HP.. . ..

But wait; I just read the other day that a pump is a pump. . . if it Uses very little HP; it must pump very little amounts.

[patkeefe]

Dr Island:
So good to hear from you! I just heard today that Freon is Halon.
I believe what you heard the other day was that the RESULTS were the same. The working fliud is affected in the same way, thermodynamically.
Pat

[island911]

" Freon, Halon, whats the diff?" Yeah, that was a glib little joke. (note flaming smilie)

just razz'n ya . . .and feeling a bit defensive about my pathetic piston style compressor. ...which you so freely diss.

it's just as good thermodynamically . .. .it is, it is it is! (TIC)

[911pcars]

A couple of comments:

R12 doesn't burn. Yes, unlike hydrocarbon-based refrigerants (my friend calls these "rocket fuel"), but when exposed to an open flame, R12 (dichlorodifluoromethane) creates phosgene gas which can kill you if you happen to be so lucky as to do this in an enclosed area. Death is not cool.

Dye-Leak detectors. Not necessary. The A/C shop should have a refrigerant "sniffer" to locate system leaks. Dyes take up room in the system that should only have a measured amount of lube oil and refrigerant; no more, no less for optimum efficiency. Who knows how much dye is in a system over the years?

Hope this helps,
Sherwood

(sorry, fixed some spelling)

[patkeefe]

Just wait...I'll find a .gif for that one also.
I know you're razzing me...I am tuned in to that deadpan science humor.

[island911]

Originally posted by 911pcars
A couple of comments:

R12 doesn't burn. Yes, unlike hydrocarbon-based refrigerants (my friend calls these "rocket fuel"), but when exposed to an open flame, R12 (hydroflouromethane) creates phosgene gas which can kill you if you happen to be so lucky as to do this in an enclosed area. Death is not cool.
.. .

Do you mean it "doesn't burn." . . or "doesn't support combustion" . . .or maybe "pyrolyzes" ?

(not a smart-ass Q . .. I expect that it burns but don't know. That florine electronegativity trumps the oxygen . .. but there's only one florine stuck on that molecule, right?


edit: Ah; dichlorodifluoromethane (CCl2F2)

[patkeefe]

Sherwood:
In the amounts of refrigerants in automotive systems (mine is under three pounds), in an open environment, death would be highly unlikely. In my chiller plant, before I rebuilt it (the day job), I had 3300 lb of R-12. That will kill you. I now have all 134a machines, containing about 8500 lbs of gas. That could suffocate you. However, I did put in a leak detection and purge system. I have been in a room where the Halon was released. It was not fun, and I don't want any of my minions to experience that.

However slight the chance is, one could develop a leak in the refrigerant system of the car. Say the front seals wear out on the compressor, and it seizes, and the belt is now dragging at 3500 RPM over a locked pulley, and...The worry regarding propane or the flammables is not a health issue, it is a fire hazard. The PO had the retrofit of the Performance Aire system done; they put in the dye. I have since drained and refilled the system, it is dye free. As you stated, I much prefer the electronic leak detection systems. Also, most phosgene in refrigeration in due to electric compressor burnouts, such as in hermetic tin can compressors. So, phosgene generation in our open drive compressor systems is also unlikely. Open flame leak detection does work, but I would say it is highly improbable one of us is going to start probing around the 911 with a torch looking for leaks.

Kurt Cobain thought death was cool.
Pat

[patkeefe]

http://www.epa.gov/ozone/snap/refrigerants/hc-12a.html

[wholberg]

[QUOTE]Originally posted by island911
[B]. .. but there's only one florine stuck on that molecule, right?

I am a chemist and would like to correct some misinformation on this topic. I hope the information below is not too pedantic.

R12 is CCl2F2, dichlorodifluoromethane. It is not flammable, but when exposed to certain conditions, i.e., an electric arc, it may lose the fluorines and gain an oxygen to form COF2, phosgene, but this is highly unlikely. Carbon tetrachloride and chloroform also react in a like manner. I want to point out that gaining an oxygen is the opposite of combustion, in which oxygen is consumed and combines with hydrogen to form water as a by product.

There seems to be a lot of unnecessary concern about phosgene and R12. Yes, it was used as a poison gas in WWI, but since R12 began use as a refrigerant (1950's, I think) there has not been a rash of phosgene poisonings, so I don't believe it is a safety hazard. Incidentally, chlorine and carbon monoxide photochemically react in the presence of sunlight to form phosgene.

R12 is bad because it is destroying the ozone layer (as does Halon). The greatest danger to humans because of this is not skin cancer, but the effective destruction of all food-producing agriculture from high UV levels, should the ozone layer go away. Think death and starvation on a global scale.

R134a is a hydroxyfluoroalkane (HFA). It is mildly flammable. It is not believed to break down ozone, but may contribute to global warming. It may break down ozone, but has not yet been proven to do so. The alkane component degrades to methane in the upper atmosphere (methane is the culprit) Propane, isopropane, isobutane, isobutene are all going to do the same thing. So does raising cattle, who produce methane as a by product (all ruminants may do this, but I am not sure).

All this being said, I run 134a in my car. It is better for the environment than r12, it is less flammable than pure alkanes (i.e. propane) but more flammable than r12, and it is readily available. It is the most environmentally conscious refrigerant to run at this time.

OK, you can all wake up now!!!

[Rondinone]

[QUOTE]Originally posted by wholberg
[B]

Originally posted by island911
. .. but there's only one florine stuck on that molecule, right?

I am a chemist and would like to correct some misinformation on this topic. I hope the information below is not too pedantic.

R12 is CCl2F2, dichlorodifluoromethane. It is not flammable, but when exposed to certain conditions, i.e., an electric arc, it may lose the fluorines and gain an oxygen to form COF2, phosgene, but this is highly unlikely.

So you lose the fluorines but you're left with COF2?

You must have gone to to UNC!

[island911]

Originally posted by wholberg
.
I am a chemist and would like to correct some misinformation on this topic. I hope the information below is not too pedantic.
.. .

OK, you can all wake up now!!!

Not at all. (in fact it bugs me that some will pin a " too pedantic" lable on others here on this technical board.)

Anyway, that is precisely the type answer I was looking for.

So then, how is freon a problem for the O₃ if it (CCl2F2) is so dam stable?

Oh, btw, bad speelling and grammar-awkward help hedge that whole . .hole pedantic-image thing.

[Rondinone]

Most organic molecules have a relatively short half-life in the atmostphere, due to 1) UV and 2) oxygen is tough on carbon. For example, methanol or ethanol evaporated into the atmosphere will last just a few days. Freon is so stable that it survives until it floats up to the stratosphere, where it cleaves off a chlorine that reacts with and destroys the ozone. HCFC's are less destructive to ozone because they have a much shorter half life and don't make it up to where the ozone is located.

[patkeefe]

wholberg:
Thanks. That was enlightening. Your last sentence is a particularly appropiate double entendre. I run 12 because that's what it was fited with by the Performance Aire install people. Too bad the 134a will not drop in for an R-12 replacement without major modifications. One of my guys at work has done some drop in retrofits with one of the new blends, and says it's good to go on car systems and low temp refrigeration; I forget which number it is, since there's only a thousand of them. I, as should we all, try to remain conscious of the bad things we do as a society to poison the earth, our refusal to join in the Kyoto (?) protocol is sick.
Alas, I started out as a ChemE, but went to ME instead. If we could send the ground level ozone to the ionosphere, we'd be OK. Halon, incidentally, for new installations, has been replaced by FM-200, a carbon dioxide system for displacing oxygen. Halon, like R-12 is grandfathered in some applications
Pat

[island911]

Thanks Rondinone.

This tech board needs more tech like that.

. . .I mean; Seen any good personalized license plates on 911s?

[patkeefe]

Maybe we could petition our sponsors and hosts for a Conjecture Forum and a WAG Forum?

And, I nowe I can find a .gif of the ozone-r-12 interaction. I saw a cartoon type presentation at a symposium.

[ruf-porsche]

Does it really matter with this ozone depletion or global warming? I read that in 2010 the magenetic poles of the earth will reverse themselves. It is the magnetic poles that keep the atmosphere within our planet. Without the pole our planet would end up like Mars or the moon.

[wholberg]

Originally posted by Rondinone
So you lose the fluorines but you're left with COF2?

You must have gone to to UNC!

OK, OK, COCl2. Geez, one typo, you guys are a tough audience! And by the way, I went to Arizona, also home to a great basketball history (please don't ask me about their football team).

[wholberg]

Originally posted by island911
Not at all. (in fact it bugs me that some will pin a " too pedantic" lable on others here on this technical board.)

Anyway, that is precisely the type answer I was looking for.

So then, how is freon a problem for the O₃ if it (CCl2F2) is so dam stable?

The higher UV levels in the upper atmosphere, plus the fact that CFC's hang around up there for decades, result in photochemical reactions.

[/B][/QUOTE]Oh, btw, bad speelling and grammar-awkward help hedge that whole . .hole pedantic-image thing. [/B][/QUOTE]

Thanks. Hey, If I was a GREAT writer, I'de be a novelist!