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  1. #1
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    R22 Foaming reciprocating compressor crankcase oil



    Have a question on oil "foaming".
    What could be considered normal in real life practical terms.
    Why does it foam?

    Any good articles or previous posts appreciated.

    Thanks in advance



  2. #2
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    Re: R22 Foaming reciprocating compressor crankcase oil

    it may be refrigerant in the oil is the oil heater working

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    Re: R22 Foaming reciprocating compressor crankcase oil

    refrigeration oil can not foam on its own, it needs an other substance to foam.

    When liquid refrigerant gets into the oil in the compressor sump, it boils and what we call "foaming" are the refrigerant liquid bubbles that goes up and out of the oil.
    Time to check why refrigerant liquid return to the compressor.It shouldn't.

  4. #4
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    Re: R22 Foaming reciprocating compressor crankcase oil

    Is this an 06e compressor by an chance
    Carrier flowtronic

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    Re: R22 Foaming reciprocating compressor crankcase oil

    Hi Ranger
    Please pm your email and I’ll send you some articles on why compressors fail which explains this foaming or I think their still on the Danfoss web site . I wrote them due to the amount of Maneurop compressors I was getting back under warranty when they were obvious site issues

  6. #6
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    Re: R22 Foaming reciprocating compressor crankcase oil

    Glenn, thanks, sent you email.

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    Re: R22 Foaming reciprocating compressor crankcase oil

    Hi
    Refrigerant slove in the oil and when comparssor is start pressure comes down and gas goes to bubbleing inside oil

    To solve that we use heater to warm up oil and decrease refrigerant in oil

  8. #8
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    Re: R22 Foaming reciprocating compressor crankcase oil

    Hi Ranger
    When CFC/HCFC refrigerants are used with Mineral or Alkylbenzene Oils, foam in the sight glass normally indicates
    serious liquid flood back or the running gear is hitting the oil due to a very high oil level
    very high oil level can be due to either too much oil or excessive liquid refrigerant in the crankcase
    what i would do is carry out 2 or 3 pump downs to remove any liquid refrigerant in the crankcase
    then recording the suction pressure and suction super heat and crankcase temperature at 100% RLA
    this will confirm if the circuit is flooding back.
    Also its possible that the incorrect oil has been used this would cause foaming

    not teaching you how to suck eggs Ranger as you appear to be a very competent engineer
    but ive had this issue many times on the 06E Compressors causing oil pressure issues due to liquid flood back


    this will indicate if the circuit is flooding back or not

  9. #9
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    Re: R22 Foaming reciprocating compressor crankcase oil

    Thanks for responses.
    In this case industrial compressor
    synthetic oil
    oil temperature in crankcase 45 to 50 degC
    SST -10 deg C
    sometimes foam on top of oil, if loads up or suction pressure suddenly drops all oil foams.
    oil pressure always good.
    flooded evaporator on R22
    Cylinder banks warm under/ around heads.

    discharge temperature 65 to 70 deg C

    All seems normal to me, others say floodback

    If liquid in sump, thought oil temperature would drop, oil pressure fluctuate, or trip on low oil pressure.
    Discharge would be cooler.
    Maybe I’m in denial

  10. #10
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    Re: R22 Foaming reciprocating compressor crankcase oil

    Would liquid coming through the oil seperator cause it to be less effected by the warm oil temp?

  11. #11
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    Re: R22 Foaming reciprocating compressor crankcase oil

    Quote Originally Posted by seanf View Post
    Would liquid coming through the oil seperator cause it to be less effected by the warm oil temp?
    Seanf,
    Thanks, I don't think oil separator oil return is an issue in this case, as it returns to pilot oil reservoir that is vented to a lower pressure.
    Oil return from oil separator can be an issue if discharge check valve leaks & condensed refrigerant ends up in oil separator in off cycle.
    If there was refrigerant in oil separator you would notice it expanding with refrigeration effect through oil return float.
    Open to any ideas, or theories.

  12. #12
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    Re: R22 Foaming reciprocating compressor crankcase oil

    Are you able to prove its not floodback?

    Would oil analysis be able to tell you anything? do refrigerant oils have anti foaming agents? is it actually the right oil?

  13. #13
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    Re: R22 Foaming reciprocating compressor crankcase oil

    Don't think it would be likely but. What if the oil separators valve is stuck open bubbling discharge gas into the cooler oil in the reservoir (a high level or inlet normally below the oil level).
    Last edited by seanf; 01-02-2020 at 12:12 AM.

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