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Thread: R22 to MO 99

  1. #1
    Join Date
    Oct 2001
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    Stoney Creek, Ontario
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    885

    R22 to MO 99

    when this conversion is done on a rack, what effect is there on TX valves


    I think i know what will happen from literature I have read, but a case manufacturer is telling me different

  2. #2
    Join Date
    Jul 2000
    Location
    Guayaquil EC
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    Here's a Case History story from DuPont's website:

    http://www2.dupont.com/ISCEON/en_US/...igeration.html

  3. #3
    Join Date
    Jun 2009
    Location
    DFW, TX
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    680
    I have a question after reading that story: How on earth do you charge 2600 pounds of refrigerant into a system. With 87 drums holding 30# each? Does a helicopter fly in a massive tank of refrigerant? I only work on small stuff!

  4. #4
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    Aug 2010
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    Memphis
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    Is it on the ground or on a roof? Can use 125# or 1000# cylinders

  5. #5
    Join Date
    Jul 2009
    Location
    Delaware, USA
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    Total refrigerant MO99 charge was 2600 lbs for the entire store, which was probably 4 racks @ 600-700 lbs each. I have seen it done plenty of times using 110# cylinders.

  6. #6
    Join Date
    Jul 2009
    Location
    Delaware, USA
    Posts
    44

    MO99 to R22 - TXV sizing

    Quote Originally Posted by shaun66 View Post
    when this conversion is done on a rack, what effect is there on TX valves


    I think i know what will happen from literature I have read, but a case manufacturer is telling me different
    If the valves sizing and operation was good on R-22 there should be no need to change out since the mass flow rates of R-22 and MO99 are very close.

    Depending on desired superheat and where it was operating on R22, you may want to make a slight adjustment to individual cases.

  7. #7
    Join Date
    Jun 2002
    Location
    Delaware
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    350
    The area to watch our for with TXV sizing is if you are running the rack with a lot of sub-cooling. Many of the R-22 replacements will need higher mass flow rates at high sub-cooling values than the R-22 TXV valve can deliver. You may also have problems with distributor nozzles being undersized. In the worst cases you may possibly even have an undersized liquid line exiting the condenser with some alternatives like R-422D. These are some of the reasons why some R-22 alternatives are no longer favored in LT R-22 racks.

    The closest match to the mass flow rate of R-22 in low temperature refrigeration is R-407A or R-407F. R-407A also delivers all the capacity the R-22 system had, and is one of the favored options by Copeland.

    I have no problem with using R-438A (MO99), I just think it is not as close a match to R-22 as some of the other options. It does have the benefit of working well at high concentrations of mineral oil. Like Dr. Freon said, if you have some spare capacity available on the rack, it will do a good job.


    Rob Yost
    National Refrigerants
    Those that are unaware are unaware they are unaware.

  8. #8
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    Aug 2002
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    Southold.calm
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  9. #9
    Join Date
    Mar 2006
    Location
    New Zealand
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    304
    Quote Originally Posted by pecmsg View Post
    Welcome back Rob
    Ditto

    Really enjoy reading your comments. Straight forward, to the point and no BS.

  10. #10
    Join Date
    Mar 2008
    Posts
    257
    Quote Originally Posted by RobY View Post
    The area to watch our for with TXV sizing is if you are running the rack with a lot of sub-cooling. Many of the R-22 replacements will need higher mass flow rates at high sub-cooling values than the R-22 TXV valve can deliver. You may also have problems with distributor nozzles being undersized. In the worst cases you may possibly even have an undersized liquid line exiting the condenser with some alternatives like R-422D. These are some of the reasons why some R-22 alternatives are no longer favored in LT R-22 racks.

    The closest match to the mass flow rate of R-22 in low temperature refrigeration is R-407A or R-407F. R-407A also delivers all the capacity the R-22 system had, and is one of the favored options by Copeland.

    I have no problem with using R-438A (MO99), I just think it is not as close a match to R-22 as some of the other options. It does have the benefit of working well at high concentrations of mineral oil. Like Dr. Freon said, if you have some spare capacity available on the rack, it will do a good job.


    Rob Yost
    National Refrigerants
    Hi Rob ..I'm looking at new scrolls with 407 duel temp rack question is what type of discharge pressures should I run? currently (fan control at 190) ( hold back at 180 ) we have a receiver. This seems to work fine at this point.
    We have subcooler on LT liquid feed at 50f . Outdoor ambiant 84f daytime and 60f overnight currently.

    I just noticed the age of this post....anyone feel free to comment.

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