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  1. #14
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    May 2014
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    Pentane is an additive to thin the oil.

    Ethane (R-170) all by itself makes a great low temp refrigerant. And brings back the oil with no effort.


    Quote Originally Posted by COOLJIM View Post
    You may see Pentane or Ethane as part of the refrigerant charge . think of the P or E , as an oil additive and not a refrigerant . Still manufacturers want a warm up every so often , to fully bring oil back from the evap.
    If you were a real tech, you'd solder a relay on that board and call it good to go.

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

    I use 56% silver on everything except steel.

    Did you really need the " If you were a real tech " ??

  2. #15
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    The way you fix that problem is put a timer on the system that shuts the compressors off for something like half hour to an hour once every 24 hours.

    What happens is the low stage refrigerant will migrate to the coldest spot, which is where the oil is getting trapped. Then, when that compressor starts back up, the violent boiling of the refrigerant in the oil disturbs the oil enough to get it moving again.

    I think I first saw that on the Ransco ultra low temps. You'll get a spike on the chart recorder, but you won't need to shut it down for 24 hrs.


    Quote Originally Posted by navyguy1 View Post
    Hi all,

    Can someone explain to me about the problem with oil circulation for the -80 freezers? I believe its called oil logging. I get several calls a year about a -80 freezer not maintaining temperature and will hover around -65 to -70. Shutting it down for a good 24 hrs seems to usually fix it. Just wondering why this is a problem that cannot be corrected by any other means.

    Thanks
    If you were a real tech, you'd solder a relay on that board and call it good to go.

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

    I use 56% silver on everything except steel.

    Did you really need the " If you were a real tech " ??

  3. #16
    Join Date
    Nov 2006
    Location
    connecticut
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    12
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    Your suppose to defrost these every year if you read maintenance service manual instruction on that model .Was in charge of (148# -80c ) (24# -140- to -150c ) some of the -80 do shut down for certain time every day but that not enough time.It's good time for the lab people to clean out the freezer by just shutting off the freezer. By putting a timer -80c very care full of samples that is store inside they could be very sensitive to temperature change only by a few degree there experiment which could cost $$$$ and the customer won't be happy. Many of the experiment takes years and time .

  4. #17
    Join Date
    Aug 2019
    Location
    Philippines
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    Hi sir, im newbie in refrigeration, and still learning by just reading in your inputs. What are the applications of this kind of -80deg freezer?

  5. #18
    Join Date
    Dec 2006
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    Vancouver, B.C.
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    Quote Originally Posted by C0olDude View Post
    Hi sir, im newbie in refrigeration, and still learning by just reading in your inputs. What are the applications of this kind of -80deg freezer?
    Typically used with immigration training procedures for those who want to move to Canada


    Sent from my iPhone using Tapatalk
    Quickly, I must hurry, for there go my people and I am their leader!

  6. #19
    Join Date
    May 2014
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    Bay Area California
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    One application is to cut people up into small pieces then store them before freeze drying.


    Quote Originally Posted by C0olDude View Post
    Hi sir, im newbie in refrigeration, and still learning by just reading in your inputs. What are the applications of this kind of -80deg freezer?
    If you were a real tech, you'd solder a relay on that board and call it good to go.

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

    I use 56% silver on everything except steel.

    Did you really need the " If you were a real tech " ??

  7. #20
    Join Date
    Jan 2010
    Location
    Sea to Sky
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    Quote Originally Posted by BBeerme View Post
    One application is to cut people up into small pieces then store them before freeze drying.
    Bite size?

    Sent from my SM-G965W using Tapatalk

  8. #21
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    May 2014
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    Quote Originally Posted by BALloyd View Post
    Bite size?

    Sent from my SM-G965W using Tapatalk
    Mostly bone. Things like skull plugs. Chips to pack into bigger bones after the cancer is removed.
    If you were a real tech, you'd solder a relay on that board and call it good to go.

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

    I use 56% silver on everything except steel.

    Did you really need the " If you were a real tech " ??

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