Posted by George Goble on October 26, 2000 at 14:07:03: via: or 128.211.159.12
In Reply to: Re: Moisture in oil, dryers, dry-eyes posted by Bob P. on October 23, 2000 at 18:42:28:
>Posted by Bob P. on October 23, 2000 at 18:42:28: via: or 157.238.208.241
>In Reply to: Re: Moisture in oil, dryers, dry-eyes posted by George Goble on
>October 22, 2000 at 21:07:54:
>George,
>Thanks for the information and the tip on www.sporlan.com. I'll check it out.
>I'll have to admit, I love to see a green dry-eye and show it to a customer even a
>years after it was installed.
You are welcome...
>From reading your posts on oil (great stuff I might add), when you continue to
>pull a vacuum on oil, once the minimum or "blanking" pressure is reached, does
>the oil just vaporize or does it separate changing the oil in some way? Is it
>different for mineral, PAG and POE?
The oil will continue to "boil", but very slowly, a few drops
may be lost after a day long vac, but the total amount is
not significant. Systems "flooded" with lots of water (i.e a water
cooled condenser failed), are best dried out with methanol flush
(anyhydrous) first, to get the "bulk" of the water out, then hot dry
nitrogen to dry out the methonal, then finally a deep vacuum, often
several days to get the remaining moisture out.
Compressor oil, will obviously boil out the lighter molecules first
(100-300 micron range), but for practical purposes, there is so much
oil, that any loss or fractionation will be neglagible.
Vac pump oil, a form of mineral oil, works down to about 20-50
microns..
Sorry, there are so many kinds of PAG and POE oil, that I haven't
messed much with them. Much of my vac data on them comes from others.
It would be real easy to take a vizi-vapor or dial-a-charge, and
a micron gauge and a pump and sort all this out. With the
exception of GHG-X7/X8 (Cooltop), everything else I worked with
was mineral oil based. I even "debugged" Cooltop in mineral oil
as to avoid putting POE/PAG in, and having to clean it out later.
After several hours of running Cooltop in mineral (mineral oil does
not return nor expected to in Cooltop), I added about 30% isobutane
and ran for a few mins and recovered the charge.. that returned the
MO for the next run!
>Do you know what is the lowest vacuum you can pull on POE oil before this
>happens? I read you post on PAG and mineral oil.
Sorry.. too many types of POE/PAG.. would be a good project.
maybe when I get caught up someday.
>I noticed the statment that the plastic oil containers are permiable. >Do you
>believe this is how the moisture is introduced into the sealed containers? Could
>we assume that the oil in metal cans (screw top) or the pressurized 2oz
>refrigerant/oil charge cans are dry? Will moisture damage the oil or form any
>acids while still in the bottle?
HVAC industry quickly figured out about moisture getting in via
plastic bottles and immed went to metal cans. I dont think moisture
"damages" either PAG or POE oil by itself.. Heat and moisture
MIGHT make POE revert to components of formation in the presence
of steel, but PAG should be OK. Acids come from the refrigerants
slowly breaking down due to the moisture, not the oil.
>I have used dry nitrogen along with vacuum and heat to remove >moisture from
>dryers. But, these were mainly the flare type liquid line dryers that >were easy to
>handle (for my reclaim unit). I haven't tried the dry nitrogen on an >auto
>accumulator/reciever dryer yet. I suppose that some heat could be >applied
>during a vacuum and the dry nitrogen pulled through from the opposite >side of
>the system though the dryer.
If pulling a vac, dry nitrogen is not needed.. heat will speed it up.
If drying in an oven, then some dry nitrogen flow is needed. This
is from UOP people, who make the mol sieve desiccants. I am currently
building a "dryer" out of a 1000lb recovery cylinder, using about
1000lbs of XH-9 desiccant.
>I'll try the micron gauge on the oil in the charging cylinder next >time and let it sit
>for a while to see what happens. I've generally just continued to >pull a vacuum
>until the bubbling was minimal.
>Micron vacumm gauges are a bit of a mystery. It's one area where a >
>lot of "trust"
>is involved. Do you know of a way to check a micron gauge other than >the
>calibration instructions in the lid?
Another micron gauge.. I have had good luck with JB, Robinair,
gauges.. Sensor must not get wet with oil, or it will give
bad readings.. sensors can be cleaned off with alcohol and work
ok again.
>Are you familiar or have you had any problems with the "Annie" micron
vacuum gauge?
never used an annie.
Thanks again for the information.
Bob
U R welcome
--ghg