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Thread: Oil Change

  1. #1
    Join Date
    Sep 2016
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    Oil Change

    Hi Guys

    Looking for Ideas on what I should use to drain oil to ,from large screw compressors after I have valved them down and reduced the refrigerant pressure.
    Im trying not to breath the refrigerant from the oil.

    Cheers

  2. #2
    Join Date
    Jan 2015
    Location
    Somewhere making cold water
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    246
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    Push pull into recovery tank and then pull vapor out of tank with recovery machine back into machine. Have had to it that way for a Gov. customer once.
    Good luck

    Sent from my SM-G950U using Tapatalk

  3. #3
    Join Date
    Sep 2002
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    27,171
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    I use a big oil transfer pump to pump it out and then to pump it back in with. Although you can ease it out under lowered refrigeration pressure. I had Smith-Koch out of Philadelphia PA build the pump for me - but I'm sure they are commercially available. You can also use a carbonator pump. There is a version which direct couples to a drive motor - so you don't need a mounting base or open coupling.

    Why are you changing the oil? Did the oil analysis tests from the oil test lab suggest it? And if so; why?

    I always prefer to keep the oil so long as the lab tests come back OK. As soon as you change the oil - you lose the historic wear metal, and other, trends and have to start over again in developing them.

    How large are these large screw compressors? Are they hermetic or open drive?

    PHM
    --------


    Quote Originally Posted by DLR_LWT View Post
    Hi Guys

    Looking for Ideas on what I should use to drain oil to ,from large screw compressors after I have valved them down and reduced the refrigerant pressure.
    Im trying not to breath the refrigerant from the oil.

    Cheers
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  4. #4
    Join Date
    Apr 2010
    Location
    California
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    658
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    Quote Originally Posted by DLR_LWT View Post
    Hi Guys

    Looking for Ideas on what I should use to drain oil to ,from large screw compressors after I have valved them down and reduced the refrigerant pressure.
    Im trying not to breath the refrigerant from the oil.

    Cheers
    Here are my ideas for you. Either use the on board oil pump, or a good external transfer pump. Shown is the type of bronze gear pump i recommend, if you do go that route. Of course you will need a small junk motor and lovejoy coupling to drive it.
    Attached Thumbnails Attached Thumbnails 4KHH1_AS01.jpg  

  5. #5
    Join Date
    Aug 2019
    Location
    LA
    Posts
    39
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    I use a recovery tank to push/pull then recover refrigerant. Also works to install new oil

  6. #6
    Join Date
    Jan 2015
    Location
    Iowa
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    Typically I will remove the refrigerant. Then add a small amount of nitrogen to bring the pressure slightly positive (2 -5 psi) and push the oil out of the sump and or any other low spot. Then I have nitrogen blanket in the machine and not just sitting open. Blow down the nitrogen when I'm ready to open the machine. Unless you have a problem with the oil (by analysis, acid test, water leak....) there is no reason why it can't be reused. I do have a small electric driven gear pump that has come in handy several times. Typically use the pump to put oil in. Sometime use a vacuum to drag the oil in

  7. #7
    Join Date
    Nov 2004
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    up in the hizzy
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    3,437
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    Quote Originally Posted by Answer-Man View Post
    Typically I will remove the refrigerant. Then add a small amount of nitrogen to bring the pressure slightly positive (2 -5 psi) and push the oil out of the sump and or any other low spot. Then I have nitrogen blanket in the machine and not just sitting open. Blow down the nitrogen when I'm ready to open the machine. Unless you have a problem with the oil (by analysis, acid test, water leak....) there is no reason why it can't be reused. I do have a small electric driven gear pump that has come in handy several times. Typically use the pump to put oil in. Sometime use a vacuum to drag the oil in
    Same here, I use my oil pump on centrifugal chillers only, screws dont hold much oil
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