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  1. #1
    Join Date
    Oct 2005
    Location
    B.C. Canada
    Posts
    903

    Question -150 Degree Lab Freezer

    Get to work on one of these tomorow, just wondering if anyoe knows anything about them... Im basicly going in blind, i know its made by Fisher Scientific, but thats about it.. no model number or anything
    Ive worked on a few -80s but apperently this is a whole different animal. Noone else at my company or any other company in town wants to go near it, so i figured id give it a shot.
    Anyone know anything about these babys?
    Thanx

  2. #2
    Join Date
    Sep 2002
    Location
    Virginia
    Posts
    3,327
    Jeeeeeezus thats cold

    Is this one of them deals where you walk inside one freezer , then inside another , inside another , getting colder and colder

  3. #3
    Join Date
    Aug 2012
    Location
    Gainesville, FL
    Posts
    325
    Probably a small reach in or chest freezer. Probably a microprocessor controlled cascade system with two different refrigerant circuits (possibly running two different refrigerants) and a refrigerant to refrigerant heat exchanger. Stage one cools the box on the evap side and warms the hxe, and stage two cools the hxe and discards heat at the air side condenser. Low temp side maybe 404a or 508b, warmer side 134a.

    Here's a little background:
    http://www.ishrae.in/journals/2000july/article05.html


    ...Or it's liquid nitrogen.

  4. #4
    Join Date
    Dec 2008
    Location
    New York, ny
    Posts
    203
    Damn never seen these would love to put my hands on it...

    Sent from my SGH-T999 using Tapatalk 2

  5. #5
    Join Date
    Jan 2010
    Posts
    6,776
    Getting kinda close to cryogenics isn't it. Where do you put the dead people while your fixing it ?

  6. #6
    Join Date
    Jul 2009
    Location
    In a mechanical room....
    Posts
    1,888
    Ultra low temp its most likely cascade and will haveb134a and r23. The condenser from the 23 is cooled by the EVAP of the 134a. Try to rule out everything other than charge before you go jerking the 23 ckt around.
    “It takes courage to grow up and turn out to be who you really are.”

    - E.E. Cummings

  7. #7
    Join Date
    Oct 2005
    Location
    B.C. Canada
    Posts
    903
    Work on the -80s which are 404 on stage one and propane and 508b on 2nd stage... this one is different tho, 1 comp with a mix of about 12 diff gasses... 134,404,23,24,n2,600 etc.. they freeze human brains in it... einstiens mabey.. tomorow should be interesting

  8. #8
    Join Date
    Oct 2005
    Location
    B.C. Canada
    Posts
    903
    Just a reachin deal, glad its not a walkin....yikes

  9. #9
    Join Date
    Dec 2008
    Location
    New York, ny
    Posts
    203
    Nice good luck.. bring back a few pictures for a tease

    Sent from my SGH-T999 using Tapatalk 2

  10. #10
    Join Date
    Oct 2005
    Location
    B.C. Canada
    Posts
    903
    Ill samp some pics if im allowed....or noones around

  11. #11
    Join Date
    Oct 2005
    Location
    B.C. Canada
    Posts
    903
    Probley just needs z new a19

  12. #12
    Join Date
    Apr 2010
    Location
    San Diego, CA
    Posts
    228
    -150 is an autocascade. Single compressor (3HP scroll iirc) 4-5 different refrigerants in one system. The higher pressure gases act like non-condensibles in the air cooled condenser, after which liquid is dropped out through a cap tube to a heat exchanger that cools the vapor that didnt condense in the air cooled condenser, so on and so forth. At the end you have argon in a saturated vapor state going through the evaporator. I like working on them, most people run screaming. Mostly cause they don't want to do what the manufacturer says needs to be done to get it right...

  13. #13
    Join Date
    Dec 2012
    Location
    Spokane, Washington
    Posts
    124
    I work on walk-ins at Plasma Centers, only -40F though. Have worked on some -80 scientific cascades at universities, but damnit...-150...that's friggin colder than Duluth, MN! Thank goodness it's a reach-in. The worst headache (literally) I've ever had was working on -40F walk-in on a 108F day, going back and forth from evap to cond on a 38' roof top. To old for that sheet! Let us know what you find, good luck.

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