Helical Oil Separator Experience with R508B
Kesselman
small cascade system (environmental chamber) and found it to be
completely ineffective under low mass flow conditions. Replacing it with
a similarly sized conventional oil separator (also from AC&R) solved the
oil logging problems which we were having under certain conditions on a
continual basis.
Does anyone else have experience with helical-style oil separators? I
would also be interested in sharing information with other OEM's about
R508B (SUVA95).
Peter Kesselman
George Goble
Kesselman <pk...@smartlink.net> wrote:
>I was using AC&R's Helical Oil Separator in the low-stage (R508B) of a
>small cascade system (environmental chamber) and found it to be
>completely ineffective under low mass flow conditions. Replacing it with
ULT companies have told me that there is no equal to the Temprite
900 series oil seps for ultra low temp systems. However, this is
back in the mineral oil days and CFCs. I have used 3 or 4 (medium temp)
and they worked fine.. Bleeding some liquid refrigerant (after the sep)
into a piece of typing paper, showed NO OIL.
Reclaimers tell me that POE oil is much harder to sep out of
refrigerant than was the mineral oil.
--ghg
Kesselman
R508B is extremely miscible with POE. That's good when things are
flowing. In my failure mode, things are barely flowing. A liquid-line
solenoid controls the flow to the evaporator TXV. The solenoid is
controlled by a time-proportioned signal from a PID controller which
senses the workspace temp (there is also a resistance heater which is
controlled by the heat output). This method is capable of achieving 0.1C
control tolerance throughout an extremely wide range of temperature/load
conditions. The application is an environmental chamber which has a
range of -75 to +175C. But to maintain relatively high temperatures of 0
to +55C (cooling is required even at +55C due to air movement of the
conditioner fan), the system requires occasional tiny pulses, <1%
on-time. Almost no mass flow, yet parts of the system under these
conditions still measure as low as -81degC! Interesingly enough, the
system worked flawlessly when trying to maintain low temperatures for
extended periods.
I'll look into the Temprite oil seps. Someone else told me that's all he
uses.
Peter
George Goble
Also, the ULT companies used to heat oil (over a flat plate) in
a vacuum at 300F for a week to try to drive out out any moisture
before charging it into compressors. Even a few ppm moisture
can freeze/plug the expansion device on a ULT and cause problems,
even below the amounts that cause corrosion, acids, etc.
There is an interesting product, call "DRY-PAK" made by Cryo-Chem,
Dry-Pak chemically reacts with the moisture and converts it to
some kind of "silicone oil", that at least in high/med temp systems
is "harmless". Dunno what this silicone oil would do in a ULT
though. See http://www.cryochem.com for more info.
After realizing that automotive dryers don't "suck" or "blow"
when popping off the caps (are probably already water logged
from breathing as atm pressure changes), and GM shipping PAG
oil (for R-134a A/C for cars), with 4200ppm moisture, I use
plenty of dry-pak in those systems.
--ghg