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  1. #1
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    Something in refrigerant oil

    Just swapped a compressor on a scroll chiller. Started evacuation after a pressure test and found this in the sight glass...
    It looks like liquid travelling up! This was factory charged with oil and still under pressure when I pulled the plugs. The evap was at room temp when we pulled it apart.
    I was at around 900 microns when that video was taken so I'm not so sure it was water and the vacuum pump oil was still clear. Maybe cleaning solvent?
    Any suggestions?
    https://youtu.be/y-9L8bfMs54

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  2. #2
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    Ok, after looking at my video again, I'm starting to feel kinda stupid....
    It looks like a clear cover over the motor wires with bubbles running up inside of it.
    When I first saw it, I thought it was on the OUTSIDE and wondered why it was moving so slow.

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  3. #3
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    Sou figure it was just nitro stuck in the insulation of the motor wires/windings? Weird one for sure....


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  4. #4
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    Quote Originally Posted by coolerik View Post
    Sou figure it was just nitro stuck in the insulation of the motor wires/windings? Weird one for sure....


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    The gas is coming out of the oil

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  6. #5
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    Quote Originally Posted by itsiceman View Post
    The gas is coming out of the oil
    So nitrogen entrained in the oil? Or is the oil itself “off gassing”?


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  7. #6
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    N2 and H2O would be my guess

  8. #7
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    Quote Originally Posted by itsiceman View Post
    N2 and H2O would be my guess
    But I thought you can’t get moisture out of POE...


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  9. #8
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    Quote Originally Posted by coolerik View Post
    But I thought you can’t get moisture out of POE...


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    Sure you can. Vacuum works it just takes a long time compaired to other ways.

    You know maybe its mostly H2O at lower vacuum since the bubbles seem to mostly originate from the bottom whenever I'm watching.

  10. #9
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    That brings up a thought I had about water and oil in a compressor. Ok so atmospheric pressure is 14.7 PSI and you pull a vacuum down to a few hundred microns to remove water. If the water is on the bottom of compressor ie oil on top of oil. The oil will add weight to the water below therefore it won't evaporate because the pressure is above the saturated point. So what is the weight of refrigerant oil per inch as it compares to the Micron scale??? Or said phrased simpler how much more vacuum do you need to boil water at lets say 60 degrees when it under the oil compared to sitting exposed in the lines.
    There is only one truly right way to do something, but there are thousands of wrong ways to varying degrees to do it.
    So the question is: If you don't do it right, then how wrong is it going to be???

  11. #10
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    I'm guessing it's probably moisture that was still in the oil boiling off up through a clear piece of insulation. Kinda freaked me out at the time.
    I'm sure there is a way to figure out when moisture will boil out underneath the oil. Just thinking, it would probably have to deal with ambient temperature, the specific gravity of the oil and the depth.

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  12. #11
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    If you add heat I know it speeds up

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  14. #12
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    Quote Originally Posted by itsiceman View Post
    If you add heat I know it speeds up
    Much more than one would think! I usually try to get the CCH going if it has one before I evacuate. Have used a heat gun if time is of the essence...

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  15. #13
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    Why wouldn't it be nitrogen forced into the oil that was 'boiling' off? That would be my first guess.

    I'm guessing it's POE oil (?).

    Here's something interesting that happened a week and a half ago. I get sent to change out a compressor because this will be a warranty call on us. New account. Customer told us not a good history. So there is no way I'm going to leave this compressor running after initial start up without me being right there.

    As chance would have it, running down to the truck to get something then back up to the roof, took a half hour. Probably got a couple of phone calls answering questions from the office or other techs. Anyway, when I left the roof, the oil was at the bottom of the sight glass. When I went to start it up, the level was over the top of the sight glass.

    In just half an hour, so much refrigerant migrated to the oil, that the level raised that much!

    Although I did just shut the unit down when I walked away from it, the crankcase heater was bad.

    So, if that much refrigerant can migrate into the oil in only half an hour, how much nitro do you think can be absorbed by that same oil in a month or two? Or more.


    Quote Originally Posted by BennyD View Post
    I'm guessing it's probably moisture that was still in the oil boiling off up through a clear piece of insulation. Kinda freaked me out at the time.
    I'm sure there is a way to figure out when moisture will boil out underneath the oil. Just thinking, it would probably have to deal with ambient temperature, the specific gravity of the oil and the depth.

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    I do a triple evac with nitro to remove non condensables.

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