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  1. #1
    Join Date
    Jun 2004
    Posts
    55

    Question

    hi, just changed a freezer over from r12 to 401b the highside is 160 and low is 5psi does this sound about right subcooling is 27. also site glass is only .75 fullthanks ken ambeint is arond 90 to 95

    [Edited by kc8939 on 07-19-2004 at 05:36 PM]

  2. #2
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,076

    We Need More Info to Comment.......

    You don't say what kind of system this is, compressor model number, compressor SH, box temps, TXV or Captube, etc. There's really not enough to go on here.

    All I can say is if you're at the desired temperature with these numbers it looks OK except the subcooling would indicate an overcharge condition in most any scenario. The half-full SG with 27 Deg F SH doesn't make sense unless your taking that reading ahead of a plugged up filter.

    If you can provide a lot more information, you'll get a lot more response.

  3. #3
    Join Date
    Jun 2004
    Posts
    420
    How can you have 27 degrees subcooling if the sight glass isn't full? You have to actually condense all the refrigerant before you can subcool it. Granted, most of the Zeotropic blends will have some bubbles in the site glass, but it's usually a stream of tiny bubbles, not 1/2 full.

    Perhaps that's 27 degrees superheat instead? If so, I'd suspect an undercharge (assuming the box is near setpoint).

  4. #4
    Why 401b ?

    I mean .... it's NOT like we have any GOOD choices anymore to select from.... but WHY oh WHY of all that is out there ... would you settle upon that one?

  5. #5
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,076

    Why R401B?..........

    R401B is DuPont SUVA MP66.

    R12, I know you have no love for DuPont but within the realm of R12 low temp interim replacement refrigerants, this is the best there is.

    If I run across an old LT R12 reach-in that's lost its charge, I'll go with R401B (MP66) every time. Some of them are goin' on ten years now with that stuff.

    I don't love it either, but I've learned to live with it.

  6. #6
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,542
    MP-66 is the gas for R-12 L/T

  7. #7

    Re: Why R401B?..........

    Originally posted by icemeister
    R401B is DuPont SUVA MP66.
    Guys, honestly .... I just lost sight of that little detail for the moment.
    Thanks for correcting me.

    I checked several PT charts at my side here and I still did not recognise it for what it is.

    Oops .... again.


    And yes, I agree, MP-66 is the right blend of choice for low temp 12.

    (at least until we get 12 back again)
    I will be lobbying for that very soon) (just joking)

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