R-406A & 409A
Jimabate
From jim....@aol.com
Subject: R-406A & 409A
I converted 11 E-400 Manitowoc ice machines from r-12 air cooled to 409A
watercooled. The condenser water is a chilled water loop.
Anyhow, I noticed that the compressor discharge temperature and the
discharge superheat were very high. I assume, maybe wrongly, that the high
concentration of R-22 in this blend contributed to the high discharge
temps. I was able to lower the condensing temperature low enough to
mitigate the problem on the ice machines.
Then I converted 2 med. temp reach in boxes to r-406A. The line set was
about 30 feet to the remote condensing units. With normal pressures, these
air cooled units had discharge temps approaching 220 degrees, and over 100
degree discharge superheat on both units.
The compressors were practically glowing hot. I adjusted the TXV valves to
obtain the lowest suction superheat possible without killing the
compressors. Only when the valve was adjusted so low that a "wet" vapor
returned to the compressor, did the discharge temperature (and superheat)
come down to acceptable levels.
It has run for 3 months like this and seems OK.
With the wet return there was a considerable increase in run time, I
assume again, that the compressors must be refrigerated along with the
box.
No, I did not charge the refrigerant in as a vapor causing fractionization
of the blend.
I'm not bad mouthing these refrigerants, just looking to start a thread so
I can fully understand what operational quirks these refrigerants have.
If you really need exact temps & pressures I will pull out my reports.
My question is simply this:
Does anyone else experience simular problems with any of these blends?
g...@worldserver.com
In article <19970825030...@ladder02.news.aol.com>,
I am the inventor of R-406A. R-406A and similar blends have been in use
since Aug 1990. You are correct in the fact that R22 in blends cause an
increase in compressor discharge temps, a fact of life. That is why R502
was invented. You are also correct in that adjusting the TXV (or the
charge in cap tube units) to provide compressor cooling from the suction
return gas. You can even run ice machines and reach-ins, with frost
almost back to the compressor (but not covering the compressor shell).
This is good practice with R-12 and other refrigerants as well. As long
as the measured discharge temps at the compressor discharge line are less
than 240F, you should be ok. This equates into approx 280-290F in the
discharge valves. 300F starts approaching the temps where R22 will
breakdown and must be avoided. There is approx a 1 to 1 reduction in
discharge temp for each degree the suction gas temp is reduced (keep at
least 10-20F of suction superheat though)
On the systems with the 30 foot lines, the suction line should be
insulated. This way, you wont be wasting capacity cooling the room, while
still being able to cool the compressor.
The main advantage of R-406A is that is miscibile (dissolves in) mineral
oil and returns it to the compressor without problems down to at least
-50F. R-406A contains 55% R22 / 41% R142b / 4% isobutane (R600a), not
enough to be flammable, but this causes excellent oil return. FX-56
(R-409A), contains only 15% R-142b (60% R22, 25% R124) and does not
return mineral oil very well in all systems at all temperatures. Atochem
(FX-56 mfgr) states that Alkylbenezne oil (AB) may have to be added to
ensure oil return in some systems. R22 and R142b are at best only
"mediocre" at returning mineral oil. At least 15% R-142b AND 3%
isobutane are needed together to ensure good oil return it was discovered
in engineering oil-return test stands build for testing oil return
properties. This is a two ton low temp refrigeration circuit, with large
(vertical) suction lines and long line runs, with bunches of sight
glasses all over the evap and suction lines for observation. FX-56
(R-409A) offered almost no mineral oil return below 32F (150 SUS mineral
oil), whereas R-406A went down to -50F. A few degrees before oil return
starts to fail (oil return becomes more difficult as the evap temp
drops), the oil/refrigerant mixture in the evaporator starts to look
"milky". This is due to the oil not dissolving in the refrigerant
anymore, but forming a fine dispersion instead.
Some systems like refrigerators have a downhill run from the evaporator
to the compressor and may not need any oil miscibility to return the oil.
These systems will work even when charged with R-134a (in mineral oil!)
Other systems will just "log oil in the evaporator" and lose performance
if oil does not return properly. Still other systems, notably automotive
compressors only contain 5-8oz of (thick 525 SUS) oil, and a poor oil
return refrigerant will cause the compressor to lose all oil and fail
outright.
Lots of technical info on www.autofrost.com about R-406A
(Autofrost as the trade name for R-406A in the Automotive industry)
R-409A contains R-124 (R-406A does not), that was recently implicated
in a problem with human liver damage. See next post for more info on that.
--ghg, R-406A/R-414A/GHG-HP/GHG-X5 inventor.
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g...@worldserver.com
Jim's response didnt seem to make it out to all hosts (on 9/5), like
dejanews, I picked it up and reposted it here.. --ghg. Jim's response
lines will be preceeded with ">".. To save bandwidth, I will reply inline
(no >).
>From: jima...@aol.com (Jimabate)
>Newsgroups: sci.engr.heat-vent-ac
>Subject: R-406A & 409A
>Date: 5 Sep 1997 03:16:42 GMT
>Lines: 124
>Message-ID: <19970905031...@ladder01.news.aol.com>
>NNTP-Posting-Host: ladder01.news.aol.com
>X-Admin: ne...@aol.com
>Organization: AOL http://www.aol.com
>X-Newsreader: AOL Offline Reader
>
>
>From: jima...@aol.com
>Subject: Re: R-406A & 409A
>
>>>In article <19970825030...@ladder02.news.aol.com>,
>>> jima...@aol.com (Jimabate) wrote:
>>>
>>> From jim....@aol.com
>>> Subject: R-406A & 409A
>>>
>
>>>> Snipped<<<
>
>>> Anyhow, I noticed that the compressor discharge temperature and the
>>> discharge superheat were very high.
>
>...More Snipped...
>
>>> My question is simply this:
>>> Does anyone else experience simular problems with any of these blends?
>
>The following was the response from g...@worldserver.com
>
>>From: g...@worldserver.com
>>Date: Wed, 27 Aug 1997 06:11:21 -0600
>>I am the inventor of R-406A. R-406A and similar blends have been in use
>>since Aug 1990. You are correct in the fact that R22 in blends cause an
>>increase in compressor discharge temps, a fact of life.
>
> ..Snipped..
>
>>As long as the measured discharge temps at the compressor discharge
>>line are less than 240F, you should be ok. This equates into approx
>>280-290F in the discharge valves. 300F starts approaching the temps
>>where R22 will breakdown and must be avoided.
>
>OK is a relative term. Technically, yes at 200-239.9 degrees
>discharge temperature the unit should operate reliably. But as you
>know laboratory conditions seldom exist in the field. greased up
>condensers, slight undercharge and numerous other problems do exist.
>Any of these problems will push that discharge temp to an unacceptable
>temperature.
This is true. Important to have proper charge, so suction gas cools
compressor and reduces discharge temps.
>Compatibility does exist between all of the blends and R-12, but
>I'm not so sure that there exists suitability of all the blends as a
>replacement for
>R-12 for every temperature range encountered.
>
R-406A comes pretty close though. Numerous cases of MP-39 and MP-66
not cutting it in med and low temp, and 406A was dropped in and worked
fine.
>..Snipped..
>
>>On the systems with the 30 foot lines, the suction line should be
>>insulated. This way, you wont be wasting capacity cooling the room, while
>>still being able to cool the compressor.
>
>Agreed, and already done.
>
>>The main advantage of R-406A is that is miscibile (dissolves in) mineral
>>oil and returns it to the compressor without problems down to at least
>>-50F. R-406A contains 55% R22 / 41% R142b / 4% isobutane (R600a), not
>>enough to be flammable, but this causes excellent oil return.
>
>..Snipped..
>
>>At least 15% R-142b AND 3% isobutane are needed together to ensure
>>good oil return it was discovered in engineering oil-return test
>>stands build for testing oil return properties. This is a two ton
>>low temp refrigeration circuit, with large(vertical) suction lines
>>and long line runs, with bunches of sight glasses all over the evap
>>and suction lines for observation.
>>FX-56(R-409A) offered almost no mineral oil return below 32F
>>(150 SUS mineral oil), whereas R-406A went down to -50F.
>>A few degrees before oil return starts to fail (oil return becomes
>>more difficult as the evap temp drops), the oil/refrigerant mixture
>>in the evaporator starts to look "milky".
>>This is due to the oil not dissolving in the refrigerant
>>anymore, but forming a fine dispersion instead.
>
>I was taught that 3 things effect oil return.(in order of importance)
>
>1) Solubility of the oil with the refrigerant
>2) Mass flow of the refrigerant.
>3) Velocity of the refrigerant.
>
>Does this still hold true (or did it ever)?
These are certainly true. The suction layout, such as "up hill" to
the compressor have some effect also. Temperature has a great effect,
but this is covered mostly under your 1), and the oil gets thicker
when the evap is colder.
>What have you found to be the most important factor in oil return with
>the blends, particularly 406-A?
Since R-406A contains both R-142b and 4% R-600a (isobutane), not enough
to be flammable, we have never had anybody report oil return problems to
us. As above, I have run it down to -50F in an oil return test stand
that I built.
>Also, do you know where I can find any data on field conversions of R-12
>to R-406A?
Best bet is to contact Bill Hardaway, 1-765-762-2362, he has done to most
field installs with R-406A. He was the first one to install it in
stationary refrigeration systems, back in 1990 (my work started with
cars). You can also email him at BHard...@aol.com
Contact Monroe Air Tech for printed info, suppliers, etc (United refrig
carries it).. 1-800-424-3836.
>
>>Some systems like refrigerators have a downhill run from the evaporator
>>to the compressor and may not need any oil miscibility to return the oil.
>>These systems will work even when charged with R-134a (in mineral oil!)
>
>..Snipped..
>
>I remember a copeland representative, who's name I will not mention,
>stated that their engineers had found 134-A and mineral oil to be
>incompatible. He stated that when they tore down a test compressor that
>there was severe bearing damage. Also, and most interesting, was his
>claim that their engineers had theorized that the chlorine in R-12
>had somehow enhanced or assisited in the lubrication and without
>the chlorine being present, the oil was unable to sustain the bearing loads.
This is well known from 1990-1993 literature.. Chlorine forms chloride
films on parts and makes them very slippery. Not counting PAG oil
(automotive) breakdown from chlorides, automotive compressors which had
previously run in 12, had the chloride coatings, and lasted much longer
with R-134a than compressors starting out virgin with R-134a. The
stationary industry abandoned the PAG oils, since trace chlorides destroy
them and use POE (ester) instead. Ester oils are still unstable, very
moisture sensitive, and can revert back to their formation components
under some conditions (alcohols and fatty acids). "Steel" is a catalyst
that may cause POEs to break down. Different POEs contain different
"passivators" to try to slow this process down. POEs also dont "foam"
and some older compressors rely on foaming for the oil to cover all the
bases.
>Also the supply house scuttlbutt (for what it's worth) is that the R-134A and
>POE oil combination has been hard on the compressor reed valves and causes
>some premature failures.
>Any comments?
This happens during "flooded starts", from any refrigerant that may be in
the crankcase during at startup. The valves get pounded over 4X harder
than the same system with R-12/mineral oil. Copeland gave a talk at the
local United Refrig last summer, with graphs detailing this. Name avail
on request. This has caused significant failues in the field.
>
>>Lots of technical info on www.autofrost.com about R-406A
>>(Autofrost as the trade name for R-406A in the Automotive industry)
>
>That site came up as unavailable at this time.
www.autofrost.com is a pretty new name, maybe it hasnt propagated
everywhere yet. http://worldserver.com/Autofrost will get you to the
same place.
>
>>R-409A contains R-124 (R-406A does not), that was recently implicated
>>in a problem with human liver damage. See next post for more info on that.
>
>Too bad that was not found out earlier on some lab rat.
>
>
>>--ghg, R-406A/R-414A/GHG-HP/GHG-X5 inventor.
>
>
>George, I wanted to thank you for your response to my posting.
>Your help is sincerely appriciated.
> Jim Abate
You are welcome
--ghg