Newsgroups: rec.autos.tech
From: ghg@noose.ecn.purdue.edu (George Goble)
Subject: Re: Freon R12 Regulation
Message-ID: <CrLDtA.CrA@noose.ecn.purdue.edu>
Organization: Purdue University Engineering Computer Network
Date: Sat, 18 Jun 1994 12:10:22 GMT
Lines: 49

In article <199406171910.OAA20404@cs.utexas.edu>
NRL6001@ccf3.nrl.navy.mil (EMAIL) writes:

>Oh, it doesn't end there. The proposed replacement technology--is it
>R134 or R143 or somesuch--is going to be phased out in a few years
>with no prospects of a "drop-in" there either.

There WERE quite a few viable DROP-IN or "near" drop-in alternatives
developed for automotive A/C.. The auto industry and MACS managed to
get them all banned or boycotted onto the shelf.

Only the auto industry "requested" R-134a is allowed or marketed now.

Automotive PAG oils used for R-134a are very sensitive to moisture and 
chloride (from R-12 prev in the system).  PAG oils are fine for "new"
manufacture (== new car or complete new A/C system), but conveniently
fail after 6mo-yr if R-11/R-12 was ever in the system. Ester based
R-134a oils may do better, but are EXTREMELY moisture sensitive and
may be lower lubricity than PAG or mineral (R-12) oils.  The right 
additives may eventually allow esters to make retrofits work and be
stable.

With approx 150 million R-12 cars out there, needing recharges every
1-2 years, say if 2/3 of them "sweat" when the R-12 is gone, and
around 1/3 of them "trade early" for a new car (to get factory
R-134a), this amounts to 50,000,000 X $10,000 or around $1/2 trillion
in extra new car sales.. You go figure why there are no substitutes
anymore..

Wonder if anybody has tried to take an R-12 system, leave in the
R-12 "mineral oil" (which is stable), add an oil separator to 
the system and charge it with R-134a?  R-134a needs special oils
since mineral oils do not dissolve (miscible) in R-134a, and the
oil gets stranded in the evaporator (cooling coils) and does not
make it back to the compresor which fails from lack of oil. An
oil separator captures the oil spray off the compressor and
returns it to the compressor, so it does not get trapped in
the evaporator.  They have been used for years on oil immiscible
systems such as CO2 and Ammonia refrigerants. Temprite makes
a very good separator, the 900 series.  There are about $65,
qty one, and would drop to $35 or so if mass produced in qty.

The only problem I see with this "solution" is that there is almost no
money to be made (except by Temprite) by service shops or
the auto-industry. Why use a $35 (+ labor) oil separator to get R-134a
when they should be able to snooker you into a new car instead?

--ghg
[Inventor of GHG R-12 substitute (R-406A), originally developed
for Auto A/C drop-in, now only available for stationary A/C systems]

From: ghg@freedom.ecn.purdue.edu (George Goble)
Newsgroups: rec.autos.tech
Subject: Re: A/C converson from Freon to R134- Necessary?
Message-ID: <3888q8$s2n@mozo.cc.purdue.edu>
Date: 21 Oct 1994 11:31:20 GMT
Organization: Purdue University Engineering Computer Network
Lines: 75

In article <dougm.47.0015ABDB@wimsey.com> dougm@wimsey.com (Gordon
McKenzie ) writes:

>>> >What is a typical conversion cost from R12 capable to R134 capable?
>>> >What parts are replaced?
>>> 
>>> Basically, you need a larger compressor, and EVERY piece of rubber has to
>>> be replaced with neoprene because R134 is big-time corrosive.  You'll also
>>> nee a larger condenser and evaporater.  The cost may well approach that of
>>> a decent used car.
>
>I've been told that EVERY piece of the system nust be replaced.  The reason 
>given is that the R12 and the R134 are violently incompatible.
>
>Now, having said that, I can't remember where I heard that, so please take it 
>with a grain of salt.

Most of this is BS from people who want to sell you new parts or new
cars.. R12 and R134a can even be mixed and work fine. (in an R12 system
with mineral oil).. you should have at least 30% R12 to provide oil
return though.  The auto industry had lobbied to get new laws (now in
proposed rule making @ EPA) which will soon make it illegal to mix refrigerants
for automotive use.  Don't put any R-12 in a native R-134a system or
the PAG oil will self-destruct. 50-70% R-134a in an R-12 system with
mineral oil should be ok.

If the system has 100% R-134a in it, mineral oil won't work, since
it doesn't dissolve in the refrigerant (miscibility) and may not
return to the compressor correctly.

The auto industry mostly uses "PAG" oils for new and retrofit
R-134a systems.. This oil is quickly destroyed by residual CFCs
(like R-12 and R-11 "flush")..  Even small traces of "chlorides"
left on the inside of pipes, etc, of an R-12 system, can destroy
the PAG oils.. The oils are destroyed, not the R-134a.. so this
is the reason to change all the parts.. (most people will trade for
a new car when they see the estimate.. probably the intended goal).

POE (polyol ester) oils are more tolerant of residual chorides,
but they are VERY moisture sensitive and offer less lubricity
than R-12 mineral oils.. The stationary industry is using POEs
for R-134a..  some segments of the stationary industry are
doing massive recalls on newly built  R-134a equipment, others
are doing fine..  Lots has to do with the variety of oil, and
cleanliness of assembly, moisture present, etc.. Some of the automotive
R-134a retrofit kits use POEs.. they should do better than PAGs.

POE oils are catalyzed into breakdown by steel and heat.. so
inhibitors are added to try to prevent this.. so now all these
secret proprietary "additive" packages are showing up in
various oils.. some work, some don't.. it will be a few
years before this is all sorted out.  This is why R-406A
was designed to run in simple mineral (R-12) oils.. no
oil changes needed.

R-134a has a lower "critical" temp than R-12. Critical temp
is the temp (and above) at which a gas cannot be liquified
or condensed, no matter what the presure is.  Critical temp
for R-12 is 234F.. and R-134a is 214F.  At critical temp,
the corresponding critical pressure (if you have liquid
present) will be in the range of 580-600 PSIG for both of them.

From doing experiments, I have found that automotive A/C
condenser temps of around 212F do happen.. since it is bolted
on the the radiator.. which gets hotter than that.

Car not moving, poor air flow, etc... all kill a
R-134a system much more than R-12 (or other refrigerant)
system.  At 214F, R-134a will not even  condense and be
at 588 PSIG or such.. so the system will pretty much
cease to function, bust hoses, compressor valves, etc.
R-134a needs a much bigger condenser, higher air flow rates,
and ways of getting cooler air due to the low critical temp.
--ghg

From: ghg@cidmac.ecn.purdue.edu (George Goble)
Newsgroups: rec.autos.tech
Subject: Re: air conditioning installation
Message-ID: <3qldhp$26q@mozo.cc.purdue.edu>
Date: 1 Jun 1995 22:04:41 GMT
Organization: Purdue University Engineering Computer Network
Lines: 36

In article <3qkvot$fvb@roadrunner.CS.Arizona.EDU> jhh@CS.Arizona.EDU
(John Hartman) writes:

>Several years back someone suggested a few books on installing
>air conditioning in your car. Of course, now that I need the
>information I can't find it. Basically, I want something that
>will explain how to go about assembling a custom system.
>
>Also, at one point someone (ghg?) was experimenting with putting an
>oil trap downstream of the compressor, thus eliminating the need
>for the compressor oil to dissolve in the refrigerant. Was
>this successful?

It was probably me.. I never made a R-134a auto A/C system with
an oil separator.. but it should work.. "Temprite" (Chicago?)
makes very good separators (9000 series, you would probably want
the 9002 or 003).. these are intended for "fixed" refrigeration
systems.. so you would have to solder (braze?).. aluminum to
steel (intended to be brazed to copper in fixed system)...,
I think the sep was copper plated steel... needs proper fluxing, etc..
The sep  holds about 16oz of oil as a baseline... any more
is sent back to the compressor...

I have built 3 or 4 pieces of "recovery" and special purpose
things which use 1-3 ton sizes.. they work very well.. You 
can take liquid refrigerant off the condenser, and spray it
on white paper.. no oil stain.. A car compressor is
in the 3-5 ton size range..

I dunno if the sep could take the road vibration.. you 
might want to call temprite..

Any refrigeration wholesaler should be able to get info
for you from Temprite..
--ghg

From: ghg@cidmac.ecn.purdue.edu (George Goble)
Newsgroups: sci.engr.heat-vent-ac
Date: 30 Oct 1995
Message-ID: <46rths$rv@mozo.cc.purdue.edu>
Subject: Re: testing oil miscibility/oil return
Organization: Purdue University Engineering Computer Network

In article <46pcg8$ekt@Twain.MO.NET> aschoen@mo.net (Andy Schoen) writes:
>In <46amuk$h1q@mozo.cc.purdue.edu>, ghg@cidmac.ecn.purdue.edu (George
>Goble) writes:
[snip]
>>
>>Operating temps on the evap, with R-12-like refrigerants will be -30 to -40F,
>>so the 2 ton med temp compressor will be delivering less than 1/2
>>ton effective.  This should further magnify the effect of the
>>large diameter suction line on poor oil return.
>>
>
>George, curious to know what you are expecting to find with this
>apparatus.  Are you attempting to determine minimum refrigerant
>velocities for oil return?  I've wondered about 'rules of thumb'
>recommendations like 700 ft/min for horizontal runs, 1500 ft/min
>for vertical risers.  How appropriate are these recommendations?
>Should they vary with refrigerant and oil used?

Thanks for the 'ruls of thumb'.  This test stand is for testing
oil return/miscibilities of various refrigerant blends I am
concocting up.  Managed to get -50F on the evap, and 4 inch diameter
frost jackets on the evap and part of suction line.

R22 has always had more oil miscibility problems and oil return
problems than R12.. I have heard early R-22 systems often used
R12 line sizes, [which were larger], and thus lower gas velocities,
and oil return problems.  By decreasing suction and evaporator 
line sizes, gas velocities went up (slight drop in efficiency),
but mineral oil returned well.

I put R22 in the test system, and ran for 8 hours.. whole evap [-40F] and
vertical suction line full of white globs of "solid paraffin wax,
just starting to melt", which was the oil (Suniso 3GS)..New blend
did not do this and left minimal oil in evap after a slow pumpdown
to boil off the refrigerant.  Had to wait for a cold day to do the
R22, to keep the compression ratio down, still had about 210F
discharge temps, ambient in the 40's, head approx 100 PSIG. Evap at
18 in vacuum.

Running R-134a (with 3GS mineral oil),
did manage to get SOME oil return, but "by force", formed oil
slugs and "oil bullets" in the suction lines.. and a sudden heat
load in the evap (or cycling on after being off), could easily
oil slug a compressor and bust valves, etc.. I have a ball  valve
in the suction line, so when the evap is full of refrigerant & oil,
and compressor is started, this valve is opened slowly, while observing
slugs in the sight glasses. R-134/oil in the liquid line and evap
looks like "milk"..forcibly mixed refrigerant & oil, but not really
"dissolved".

R-12 & R-406A worked well down to the -40 to -50 F range with
no oil return problems.. Have a jug of FX-56 (R-409A) on order,
still looking for FRIGC FR-12..

>Btw, kudos on your home page mention in the Nov 7th issue of PC
>Mag.

Thanks.. maybe I should submit the homepage to www.ashrae.org
to see if they assign at an R-number, and classify it A3/A3 :) ?
[starting a BBQ grill in 3 seconds with liquid oxygen]
PC mag listed it under "flammable web sites", part III...


--ghg
http://ghg.ecn.purdue.edu
http://worldserver.com/R-406A

From: ghg@cidmac.ecn.purdue.edu (George Goble)
Newsgroups: sci.engr.heat-vent-ac
Subject: Re: testing oil miscibility/oil return
Message-ID: <47497t$9nv@mozo.cc.purdue.edu>
Date: 31 Oct 1995 04:38:21 GMT
Organization: Purdue University Engineering Computer Network
Lines: 153

In article <4740rg$3jt@Twain.MO.NET> aschoen@mo.net (Andy Schoen) writes:

>George, I doubt you are going to make many friends among the 
>compressor manufacturers with your testing.   :-)

Compressor mfgrs already hate me, for inventing R-406A..
probably means less new 134a compressors for them to sell..

[ghg wrote]
>>R22 has always had more oil miscibility problems and oil return
>>problems than R12.. I have heard early R-22 systems often used
>>R12 line sizes, [which were larger], and thus lower gas velocities,
>>and oil return problems.  
>
>Same issue with the many R-12 (and R-502) systems being converted
>to R-22.  R-22 is inexpensive, plentiful, and well understood.
>As a result, it is still a popular refrigerant for converting
>systems away from CFCs.

22 has a very high heat of compression (reason 502 was invented)
that low and medium temp will generate refrigerant and maybe
oil brakedown.. and "coke" the valves, discharge line.. failure
being carbonized cap tubes (plugged), "wire drawing" on compressor
discharge valve plates, etc..  Home freezers used to use R22, but
not anymore..  

Some method is needed to deal with this, such as liquid injection,
two stages of compression (with cooling between), etc... I think
a lot of converted to R22 systems will fail in a year  or so.

I would be willing to take my chances with  10% CO2/ 90% propane
(if conditions permitted a flammable refrigrant), it should
perform well into lowtemp, no breakdown like R22.


>>I put R22 in the test system, and ran for 8 hours.. whole evap [-40F] and
>>vertical suction line full of white globs of "solid paraffin wax,
>>just starting to melt", which was the oil (Suniso 3GS)..New blend
>>did not do this and left minimal oil in evap after a slow pumpdown
>>to boil off the refrigerant.  Had to wait for a cold day to do the
>>R22, to keep the compression ratio down, still had about 210F
>>discharge temps, ambient in the 40's, head approx 100 PSIG. Evap at
>>18 in vacuum.
>
>Interesting.  Waxing problems are normally associated with low temp
>R-502 systems running mineral oil.  Older R-12 low temp systems never
>seemed to have waxing problems.  With low temp R-22 systems, high
>discharge temperatures causing oil breakdown problems seemed to be
>the major problem.  I have not seen major waxing problems with
>R-22 systems.

The "wax" was just partially frozen oil.. it cleared up when
system was turned off (i.e. melted).  Good refrigerant miscibility
would impede "wax" formation I would think.

>Btw, the reasons why wax forms in a refrigeration system would be a
>great area of study.  It is known that filter-driers with activated
>charcoal will remove wax from systems.  However, no one has any real
>definitive explanations why wax is more of a problem with one
>refrigerant than another.

R12 is totally miscible in mineral, R22 is only partially miscibile.

>The move to POE oils, however, may make this issue irrelevant.

POE's dont foam, so R-12 compressors may have lube problems,
if the foaming was relied on to cover some parts.. steel is
a breakdown agent for POEs, so there must be passivators to
prevent this, etc, etc, etc..

>>Running R-134a (with 3GS mineral oil),
>>did manage to get SOME oil return, but "by force", formed oil
>>slugs and "oil bullets" in the suction lines.. and a sudden heat
>>load in the evap (or cycling on after being off), could easily
>>oil slug a compressor and bust valves, etc.. I have a ball  valve
>>in the suction line, so when the evap is full of refrigerant & oil,
>>and compressor is started, this valve is opened slowly, while observing
>>slugs in the sight glasses. R-134/oil in the liquid line and evap
>>looks like "milk"..forcibly mixed refrigerant & oil, but not really
>>"dissolved".
>
>This is essentially what I've heard from others who have run
>similar tests with R-134a and mineral oil.
>
>>
>>R-12 & R-406A worked well down to the -40 to -50 F range with
>>no oil return problems.. Have a jug of FX-56 (R-409A) on order,
>>still looking for FRIGC FR-12..
>
>Just found out about FRIGC FR-12.  It's a ternery blend of 
>R-134a/R-124/R-600 (59/39/2) by weight with a reasonably low
>temperature glide (approx 3F).  My guess would test similar to R-134a
>with your tests.  Marketed at the automotive market.  UHaul seems
>to like it.  You can obtain it from Intermagnetics Corp.

FRIGC admitted to me a year ago, that they took the oil miscibility
idea from R-406A.  Intermagnetics wont sell us any, wonder why.
I saw the UHAUL yea FRIGC press release.. They said FRIGC had
good performance compared to a R-12 car that had been retrofitted
to 134a. Nothing was said about FRIGC to R-12 comparison.

Only advantage I can see in FRIGC is the raising the critical
temp of the refrigerant compared to 134a.. should help out in
"hot idle" (gridlock).. Their patent 5,425,890 claims the above
3 components..

With all the bitching going on about flammability, even "weak"
flammability, what happens if a car sets parked with FRIGC, 
with a vapor leak, at an ambient temp of 15F..BP of 
of R-124 is 8.26F and R-134a is -15.07F and BP of R-600 (n-butane)
is 31.03F.  All the R-134a and R-124 will leak off, (15F ambient),
and R-600 (BP 31.03) will be left as liquid.. and could
concentrate to "3" flammability???  Wonder why they don't submit
to ASHRAE for an R-number and safety classif?  They would have
to do low temp leakdowns?

Jim Calm's June 1995 ARTI Refrigerant Dbase lists the above
formulation also (bet that is where you saw it?), however
there are rumors that FRIGC reformulated some.. changing
the R-600 to R-600a (n-butane to isobutane, BP 10.83).
I have no hard evidence of this though.. Using isobutane
would cause FRIGC to infringe on US patent 4,482,465 (Gray),
which has claims of "bracketing" (by boiling point) a
hydrocarbon with two nonflammable halocarbons.

None of FRIGC's components has a boiling point less than (colder
than) R-12.. (-21.something F), so barring an azeotrope formation,
how is FRIGC going to provide proper suction pressures?

Calculations with NIST REFPROP V4.0 show suction pressure
at 32F would be about 21 PSIG for FRIGC, not 29-30 PSIG
as R-12 would do.  That is going to result in low capacity,
and problems with low pressure cutout switches.. so the
compressor would probably cycle off and back on every
few seconds, further reducing delivered capacity, and
causing excessive compressor clutch wear.. Variable displacement
automotive compressors, such as the GM V-5 vary their displacements
to hold suction at 28-30 PSIG.. so when they see 21 PSIG
suction (FRIGC).. they will go to nearly 25% or so displacement,
causing very poor performance and almost no capacity.

Someone might want to suggest to FRIGC (Intermagnetics?) to try

R-600a/124/134a/22  4/28/40/28

That should fix both the low pressure and oil miscibility problems.


--ghg

From: ghg@cidmac.ecn.purdue.edu (George Goble)
Newsgroups: sci.engr.heat-vent-ac
Message-ID: <4hd3mh$6ge@mozo.cc.purdue.edu>
Subject: Re: Refrigerant 404A - Is it Ester Oil Compatible?
Date: 3 Mar 1996 21:41:37 GMT

In article <4hcu1k$ifm@dfw-ixnews1.ix.netcom.com> Robert W. Bass writes:
 >A client wishes to use Refrigerant 404A (a tri-blend of R125, R143A and 
 >R134A) for a freezer system as a replacement for R502.  I have heard that 
 >R404A is not as compatible with ester oils as other refrigerants. Can anyone 
 >verify or refute this?  I would appreciate any information and/or
 >operational experience using R404A.  Thank you

The only oils I know of which would work are POEs (esters) or PAGs..
You want to avoid PAGs, since the chlorides (coatings) from the 
R-502 will cause the PAGs to break down.

Suggest you call the equipment mfgr and ask them which POE they
reccommend..  POEs have a multitude of possible problems also.
POEs dont foam, and can cause possible compressor lube problems, depending
on the type of the compressor. Wax from winding the motor windings is
insoluable in POEs and may turn to solids, and plug the expansion device.
POEs are very sensitive to moisture andd can break down from this
and sometimes steels (catalyst) back into their consitituant fatty acids and
alcohols. Various mfgrs have secret additive packages to try to 
combat these problems.  Also, if the compressor needs to be removed
to change the oil, stirring up the sludge/metal flakes in the bottom
as well as extra contamination from brazing comes into play.

There are number of R-502 replacements available.. If it were me, I
would chose one with HCFCs or a small amount of propane (HP80)
and use alkylbenzene (AB) (Zerol brand) oil, as that is just
synthetic mineral oil and will avoid the POE problems.

--ghg

From: ghg@cidmac.ecn.purdue.edu (George Goble)
Newsgroups: sci.engr.heat-vent-ac
Message-ID: <4n5cdv$96r@mozo.cc.purdue.edu>
Subject: Re: Oil harvesting (defrosts) >Marc O'Brien<
Date: 12 May 1996 18:59:11 GMT

In article <4n54c5$ogd@dub-news-svc-2.compuserve.com>
<100737.1611@compuserve.com> writes:

>A normal recip compressor can pump all its oil out in about an hour. Then
>with a non spiral oil sepperator of 60 % efficiency this is near 3 hrs or
>so. So you can see that if there is no return at all the comp will fail
>soon.

WOW.. which kind/brand of compressor can pump all it's oil out in an hour?
I made an oil miscibility test stand from a Copeland Med temp 2Ton (R12)
semi-hermetic compressor, with an oil sight glass.  It holds about 64
Fl Oz oil.  Evap is just a 50' coil of 5/8 tubing, with the loops
vertical (to trap oil).

Even when running R-134a in there with mineral oil (no oil return at normal
mass flows), it appeared it would take 2 or 3 days to pump out 1/2
to 3/4 of the oil.  I have seen automotive systems with approx 10%
oil in a liquid line sample from a running system.

--ghg
http://worldserver.com/R-406A
http://ghg.ecn.purdue.edu


>Marc O'Brien
>Ind.Ref.Mech.
>http://ourworld.compuserve.com/homepages/marc_vicky

From: ghg@cidmac.ecn.purdue.edu (George Goble)
Newsgroups: sci.engr.heat-vent-ac
Message-ID: <4n5cns$9dv@mozo.cc.purdue.edu>
Subject: Re: Oil harvesting (defrosts) >Marc O'Brien<
Date: 12 May 1996 19:04:28 GMT

In article <4n54c5$ogd@dub-news-svc-2.compuserve.com>
<100737.1611@compuserve.com> writes:

>A normal recip compressor can pump all its oil out in about an hour. Then
>with a non spiral oil sepperator of 60 % efficiency this is near 3 hrs or
>so. So you

Have you ever heard of the Temprite 9000 series of oil separators?
The ULT (ultra low temp folks) told me they are the  best.. nearly
100% oil removal..I build 3 or 4 pieces of recovery equipment, using 9000 seps
(back when it was legal to do so).. the largest being a 3-1/2 ton
scroll..  Blowing some liquid out of the condenser onto a sheet of fine
typing paper, showed NO oil stain at all.
--ghg

From: "George H. Goble" <ghg@worldserver.com>
Newsgroups: sci.engr.heat-vent-ac,alt.hvac
Subject: R-401A vs R-409A
Message-ID: <335F69AE.530B@worldserver.com>
Date: Thu, 24 Apr 1997 07:09:50 -0700

Marc O'Brien wrote:
> 
> redo@mhv.net wrote in article <5irhil$u5n$5@news.mhv.net>...
> :
> : I tried MP-39
> : 1. MP-39 not compatible with mineral oil, R-409 is no problem with
> any oil.
> 
>         Generally yes but I remember here earlier in the year George Goble
> mentioning some peculiarity about R409a with one of the oil types ?

FX-56 (R-409A) is composed of   R22/R142b/R124    60/15/25 (by weight %)
MP-39 (R-401A) is composed of   R22/R152a/R124    53/13/34

Oil miscibility of a refrigerant and oil is the ability of the oil
and refrigerant to dissolve in each other.

R22 only has "mediocre" miscibility in mineral oils.  Early R22 systems
had failures due to improper oil return to the compressor.  Good oil
miscibility in the refrigerant (such as R12 and mineral oil) are needed
to assure proper oil return to the compressor from the evaporator.
Changes were made, such as downsizing suction lines, which raised the
gas velocity, which aided in proper oil return in R22 systems and largly
solved the problem.  R12 systems may not have "downsized" suction lines
or have them run uphill back to the compressor.

R124 has real bad mineral oil miscibility, and R142b is similar to
R22 (slightly better).  Both of the above blends are going to be marginal
at returning mineral oil to the compressor, with problems getting worse
as the evaporator temps drop.  Changing some or all of the oil to alkyl-
benzene (a form of mineral oil) will make both of these blends return
oil properly. The mfgr of R-401A states this clearly up front.  Unlike
unstable POE or PAG oils, AB oils are very similar to and may be mixed
with mineral oils.  "Zerol" is a common brand of AB oils in the US.
R152a has zero miscibility with mineral oil.

I have run FX-56 in an oil miscibility engineering test stand with
standard 150 SUS viscosity mineral oil.  At evaporator temps below
around 32F, oil return dropped off dramatically.  The liquid refrigerant
(in the evap) turned "milky" white, a sign that the oil are refrigerant
are not dissolved in each other, but are forming a fine "dispersion"
instead (R-134a in mineral oil does this also).  Milky white 
liquid refrigerant is an almost sure sign the oil return problems are 
about to happen.

This test stand was designed to simulate "worst case" conditions of
oil return.  The large diameter suction line (7/8 inch), for 1.5 tons
capacity, and a 6 foot uphill (vertical) return from the evaporator.
Not all real life systems will be this bad, so the above blends may
work (with mineral oil) in some systems, depending on suction line size
(return gas velocity) and whether or not the suction line is
uphill, level or downhill.. One never knows beforehand until losing
a compressor.

One additional point.. when using blends with high percentages of R22,
one must carefully monitor compressor discharge temperatures.  R22 has a
very high "heat of compression".. This is why R-502 was invented for low
temp use.  As evaporator temps drop, the compression ratio increases and
large amounts of R22 contribute to high compressor discharge temps.  
Discharge line temps must stay below about 250 F (at the compressor) as
at that point the discharge valve temps may be at 300F, the point at
which refrigerant breakdowns begin.

--ghg (inventor of R-406A & R-414A)
http://worldserver.com/ghg  && http://ghg.ecn.purdue.edu/

Subject: Re: An Alternative to Retrofitting to R-134a - why blends work
From: ghg@worldserver.com
Message-ID: <867154574.12014@dejanews.com>
Date: Jun 24 1997
Newsgroups: rec.autos.tech

In article <867058008.7729@dejanews.com>,
  fred@inti.net wrote:

[snip]
>   The question is not one of these refrigerants working well.  I'm sure
> they do at least over the short term. But the question remains on
> long-term durability of blends, especially R-22 based ones. Will the

R-406A/Autofrost has been run in many cars since 1990, which is longer
than R-134a and 134a blends. The stability of the lubricant is more
critical than that of the refrigerant.	Mineral oils (used in R-12
systems) are very stable and much more resistant to moisture than the PAG
or POE oils needed by R-134a.

PAG (Polyalkylene Glycol) oils are good lubricants and used by OEMs for
new car mfgr.  They are about 100X more sensitive to moisture than
mineral oils.  Pour some PAG oil to the top of a coffee cup (setting on a
saucer).  Go to lunch.. Come back, and the PAG will have absorbed so much
moisture, that the oil has overflowed into the saucer, the table, etc. If
you system is orig assembled "dry" and never serviced, it may run fine
for years (new systems).  This is often not the case.. Many "new" R-134a
cars are coming off warranty now, and have shown up at airshops with 6 or
8 holes in the evap and/or condensers (new + 3 years), the PAG oil having
turned bright orange and broken down.

Most brands of PAG used in retrofits (all but Daphne) are very sensitive
to "chlorides" left over from R-12 being in the system, residual mineral
oil, etc.  The inside surfaces (esp aluminum) are coated with aluminum
chloride from the R-12.  These chlorides don't hurt the R-12 system
(they decrease friction acutally), but they may cause the PAG oil to
break down, leading to compressor failures after a few months.  There are
many articles in the 1990-1993 time frame in the literature.  Traces of
R-11 (used to be a common flush) destroy PAG oils much faster than R12
chlorides, often in less than a week.  If a car is being serviced and
retro'd to R-134a, and previous service was flushed with R-11, it
may not last long.  If a R-134a system is "left open" for service
too long or has a blown hose or other breech, the system (PAG oil) will
be water logged and very difficult to get dry and stable again.

POE (Polyolester) oils. POE (Ester oils), can tolerate residual chlorides
much better than PAG oils. This is apparently why most retrofitters use
them.  However, POE oils have lower lubricity than PAG or mineral oils. 
Almost all POE oils do not "foam" like the mineral oils do. Some
compressors rely on the foaming oil to hit all the parts, and these mail
fail prematurely on POEs.  POE oils can also be "unstable", from heat,
and moisture (they are 10X more moisture sensitive than mineral oils). 
Steel can act as a catalyst to cause POEs revert to their components of
formation - fatty acids and alcohols.


> lighter components of the blend escape the system prematurely and degrade
> performance?

You probably mean "lower boiling" components (like the R-22). THis is
true, but not to the degree that MACS and competitors state.
Autofrost/R-406A have about a 15 degree "glide", which is the amount of
fractionation that takes place during the trip around the A/C circuit,
and creates quite a bit of performance boost.  When selective leaking
happens, the performance degrades as you say, but to about that of R12
(with some leaked out) since you had much more performance to start with.
 R-134a blends start out bad and get worse as they leak.  We originally
told airshops to "not top off" systems due to fractionation change, but
they did it anyway, and are still satisfied with the performace, and they
are way ahead of where they would have been with R-12.

> There is also been concerns about the compatibility of MVAC
> components with long-term exposure to R-22. Do you think that
> organizations like MACS have simply raised these issues to frighten
> people away from blended refrigerants?

YES.  MACS has an agenda.  Many of its higher up members are paid
lobbyists for the auto industry.  They dont want older cars left on the
road running good A/C.	Anything which can cause A/C failures or poor
performance is "good for business" by getting older cars off the road and
trading in for "new" cars.  Around 1994 there were about 150 million R-12
cars on the road.  If 1/3 of them need air and cannot get good
performance/ reliabiltiy out of R-134a, they may trade-in.. that is
50,000,000 cars X $10,000/car (low) which equates to 1/2 trillion $$$ in
new car sales. By trying to stop good performing replacements, the auto
industry generates much more business.

We haven't seen any long term compatibility problems from
R-406A/Autofrost. We have identified 2 or 3 seal types (pretty rare) and
have reccomendations on how to handle those.

> here is also the question of
> getting systems fitted these refrigerants serviced. The shop that
> originally fitted it probably could service it, but if you're out on the
> road somewhere and need repairs, you'll probably be out of luck. I doubt
> that very many A/C shops are going to go through the expense of setting
> up to service vehicles fitted with these refrigerants especially having
> just gone through expense of getting R134a stations. Interdynamics has
> done a little better in that regard by striking an agreement with
> Pennzoil to market FRIGC and making it available through Jiffy-Lube
> shops. People might be more willing to go with FRIGC if they can get it
> serviced at any Jiffy-Lube shop.

Pennzoil has lost their "exclusive" distribution agreement on Frigc we
have heard.  A number of Jiffy-Lubes are dropping Frigc and switching to
Autofrost due to the poor performance of FR-12 in hot weather.

> Pep-Boys on the other hand never
> embraced any alternative refrigerants but have gone in the direction of
> straight R134a retrofits. If a national chain like Sears, Wal-Mart,
> Western Auto, Target, or K-Mart supported R406a/Autofrost/Chill-it, then
> it may be an acceptable alternative if questions concerning its
> durability are answered. So far, they don't seem to be lined up to get
> it!

Many chains (esp Sears) have thrown in the towel and gotten out of A/C
service business altogether.  They dont want to get caught up in the
134a disaster.

>  ......Fred

--ghg

From: ghg@cidmac.ecn.purdue.edu (George Goble)
Newsgroups: rec.autos.tech
Subject: Re: Celebrate! AC retrofit debate now IRRELEVANT!
Date: 24 Jun 1995 10:50:28 GMT
Message-ID: <3sgqlk$pfo@mozo.cc.purdue.edu>
Organization: Purdue University Engineering Computer Network
Lines: 101

In article <DAo3oG.6qu@ridgecrest.ca.us> homer@owens.ridgecrest.ca.us
(Scot Homer) writes:

>Daniel J. Stern <Daniel_J._Stern@nile.com> wrote:
>
>> This is great news, people.  Rejoice.  And keep cool.   Can we quit talking
>> about R134a vs. R12 now?
>
>Weren't you having fun?  I'll agree to stop the R-12 vs. R134a debate
>provided you answer the following question:
>
>Should I retrofit my '94 Bronco (came w/R134a) to an R406a A/C system?
>;-)

This is a good (and very tough) question.  We (ghg) get hounded
with this Q all the time.  The answer is not definate yet.. Here is
what we have so far.

Many (newly built) R-134a systems and R-12->R-134a retrofit systems
have very poor performance due to a number of reasons.  R-134a
has a low "critical" temp (max temp a gas will liquefy) of only
214F (R-12 is 233F and 406A is 237F) which is the "crux" of this
mess.  Oversized systems (esp the condenser and maybe the compressor)
are needed to get R-12 performance with R-134a.

New R-134a automotive systems use PAG oil instead of mineral oil.
PAG oil is about 100X more sensitive to moisture than R-12 mineral
oil.  PAG oil is also decomposed by even traces of things with
chlorine in them, such as aluminum chloride coatings inside a
former R-12 system retro'd to R-134a, R-11 flush (very bad),
R-12, R-406A, FRIGC, R-176 or any refrigerant with a chlorine
atom.  Once a system has/had PAG oil in it about the only "easy"
alternative refrigerant is one which is total hydrocarbons
such as OZ-12 or HC-12a but they are highly flammable (similar
to propane).

TO use R-406A (or R-12), *ALL* of the PAG oil must be removed!
Reports I have read for R-12 -> R-134a retro's often call for
R-12 liquid to be circulated as a "flush" from a recycling machine.
These recycling machines more often than not use some wimpy
circulator pump, and often 50% of the oil remins (in the evap!).

The way I was taught to do a "good flush" was to use (back then)
R-11 in a BBQ grill propane tank, pumped up to 240 PSIG
(pressure rating of the tank) with dry nitrogen. This would
"kick" like a firehose.  Remove the orfrice, drier, compressor,
and blow out each section one at a time, followed by 200 PSI
nitrogen to get the R-11 out.  This generally left the parts
"bone dry" of oil.  Since R-11 is an "evil" CFC, and gone now,
we have switched to (nicknamed GHG R-11 substitute), isopentane.
This is a highly flammable hydrocarbon with a boiling point
of around 75F (like R-11), it boils if poured in your hand,
like R-11 did.  It is a very good solvent also.  One has
to use extra care (do work outside, disconnect battery cable,
have fire ext handy, etc).  Both R-11 and isopentane give 
a "real" flush when backed up with 200 psi dry nitrogen.

The last and biggest problem is how to get the PAG oil out of
the compressor.  Things suggested so far:

1) replace the compressor with an R-12 model, shipped with mineral oil.
   May not fit on R-134a mfgr system?? Less capacity, more expensive.

2) Take the R-134a compressor apart and wash in a bucket of isopentane
   This is probably beyond the means of anybody but a compressor
   rebuild shop.

3) Immerse the compressor in a bucket of isopentane and turn
   it by hand. - Unknown about how much PAG oil this will get out.

4) run R-134a compressor "in free air", pouring a small stream of
mineral oil into the intake to try to work out the PAG oil.
How long?  How much mineral oil used?  How much PAG still stuck
in the compressor?

Whatever method (change the drier.. to XH-9 desiccant), there
is going to be a small amount of PAG oil left.  You can bet
when the R-406A or R-12 or whatever hits this, all of  the
remaining PAG oil will destruct and turn into contaminates,
including water I am told.  If the water is small enough,
one might be able to adsorb it into the drier or neutralize
it with something like Cryo-Chem's Dry-Pak??

We have heard of one guy in Florida whom was ticked at his
R-134a new car performance, and "retrofitted" to R-406A
and it still works fine after a year. We have no details on
original oil type or how he flushed it.  It was reported to
have "awesome" cooling capacity (R-134a system must have huge
condenser and larger compressor to match R-12).

I suppose somebody will substitute "gasoline" for isopentane..
It might work.. Make sure it evaporates and leaves no residue...
Gasoline  will be harder to get a good vacuum (higher BP), and it will
trash the vac pump oil and require a vac pump oil change between 
initial and final pumpdowm.  Gasoline also contains "detergents",
benzene, and other nasties which are not in isopentane.. more
contaminates left in the A/C system.

Some DIYer will likely tinker and post something.

This is all I know.
--ghg

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Oil in propane
Date: Sat, 12 May 2001 18:23:46 -0400

Bill wrote:
>
> An additional comment:
> propane is an additive to several types of refrigerant ("freon") because it
> (the propane) has an affinity for oil and assists in lubricating system
> components in cooling systems, primarily low temperature systems used in
> laboratories, etc.
>  One of the  substitutes for the old R-12 freon used in automobile air
> conditioners (R-409) uses a mall amount of propane. R409 was held up in
> getting approval because of the possibilty of a fire hazard--a smoke screen
> by the makers/installers of retrofit kits for r-134, the freon now used in
> automobiles
>
> If clean propane is contained in,  passed through, or comes in contact with
> an oily surface, I think it would quickly "absorb" as much as it can hold,
> later to be released when temperature and pressure conditions are different
> (or when it evaporates, leaving the oil behind).

I am good friends with George Goble, the inventor of the above
refrigerant (R-406a not 409) and was involved in the project.  I've
spent a LOT of time studying oil transport by refrigerant, including
making and photographing glass evaporators and condensers.

You are absolutely correct that propane is an excellent oil solvent,
even in trace quantities.  However, the vapor cannot dissolve a
liquid - the other way around.  In a refrigeration system, the oil
and refrigerant are dissolved in one another in the liquid phase.
When the mix goes through the expansion device, the refrigerant
boils and aerosolizes the liquid stream.  The oil is broken up into
a very fine fog.  Most of it remains in this form as it passes
through the evaporator and back to the compressor where the fog is
condensed again.  Some of the refrigerant and oil remain liquid and
flow along the walls of the evaporator.  The refrigerant evaporates
but not as rapidly as from the mist.  A small bit of refrigerant/oil
solution exits the evaporator and flows along the walls of the
suction line back to the compressor.  If the evaporator or suction
tubing is too large so that the gas velocity is too low, the oil
tends to puddle in low spots.  Some of this oil is swept away by the
passing gas.  A portion remains until the system is shut down.
Liquid refrigerant collects in the evaporator because it is usually
cooler than anywhere else in the system.  Upon startup, this
refrigerant/oil solution boils rapidly, flashing to mist and thereby
gets returned to the compressor.

Enough on refrigeration.  In the propane tank, unless something is
amiss, the propane is withdrawn as a dry gas.  It cannot transport
oil like in a refrigeration system.  There are some other mechanisms
for transport though.  The whole inside wall of the tank ends up
coated with a thin film of oil, from sloshing, from creep and from
boil atomization under high demand situations.  Some of this oil
film will end up in the valve where the gas flow will drag it along
via simple friction.  This is the major long term transport
mechanism of SMALL amounts of oil.  Under high demand conditions,
the propane liquid in the tank boils around the edges.  There is no
bulk boiling like in a pot of water.  This edge boiling throws up
droplets of propane and as it evaporates, whatever oil was in them
is left as tiny oil droplets.  This droplets can get swept out the
tank by the gas flow and into the gas system.  It would be hard to
imagine sufficient demand in an RV environment, except at the very
bottom of the tank, for this to be a significant factor.

When the tank is almost empty and there is moderate demand, the tiny
puddle of liquid propane boils vigorously.  At the same time
whatever oil/odorant remains is concentrated in the liquid.  This
vigorous boiling atomizes considerable oil and carries it out. That
is why you can frequently smell that "burned propane" smell when
your tank is almost empty.  In my glass shop, smelling that coming
from my burner tells me it is time to change tanks.

John