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  1. #1
    Join Date
    Dec 2014
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    Is nitrogen always necessary?

    Hi guys, just wondering if nitrogen is always necessary during brazing of small hermetic compressors?

    One of my refrigerated machines blew a compressor yesterday. I had a small compressor (also R134a) replaced on a commercial fridge last year and the tech said that there was no need to run nitrogen but having done some reading on here I'm wondering if it is best practice to run nitrogen even on small systems?

    Cheers,
    Adam
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  2. #2
    Join Date
    Mar 2008
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    kansas
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    It’s always best practice although I suspect lest than 50% actually do. Doesn’t make it right a lot of times filter driers and luck is all that stands in the way of metering device failure
    Honeywell you can buy better but you cant pay more

    I told my wife when i die to sell my fishing stuff for what its worth not what i told her i paid for it

  3. #3
    Join Date
    Aug 2013
    Location
    Templeton MA
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    I think sometimes trouble arises when the brazer is inexperienced and takes far too long on a joint building up excessive oxidation scale. Fast in fast out, with hot flame with oxy acetylene is best. That being said we always use nitrogen as we build and repair small cap tube systems, but I have seen mistakes made with no consequence.


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  4. #4
    Join Date
    Dec 2009
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    maroon lazyboy
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    134a Cap tubes get plugged by cooked POE oil more than anything.

  5. #5
    Join Date
    Aug 2002
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    Southold, NY
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    By the book yes.
    Im more concerned with a good drier being installed!

  6. #6
    Join Date
    Nov 2006
    Location
    Southeastern Pa
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    Since you are the equipment owner, you should be posting in the AOP Commercial Forum.

    This forum is for technicians' posts.
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    2 Tim 3:16-17

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  7. #7
    Join Date
    Jan 2010
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    Also depends on if the equipment your welding is still out gasing.

  8. #8
    Join Date
    May 2014
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    Bay Area California
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    The color of that label indicates the compressor has been running too hot. Unless that's the original color; but I don't remember ever seeing a new label that color.
    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.

  9. #9
    Join Date
    Mar 2013
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    Treasure coast, FL
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    Quote Originally Posted by BBeerme View Post
    The color of that label indicates the compressor has been running too hot. Unless that's the original color; but I don't remember ever seeing a new label that color.
    It looks like it was just yellow to begin with, the print on it looks to be in good shape.

    Sent from my Moto Z (2) using Tapatalk

  10. #10
    Join Date
    Dec 2009
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    maroon lazyboy
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    Im with Dr. BB, shes been cookin

  11. #11
    Join Date
    May 2019
    Location
    Kingston ma
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    Nitrogen is always used when brazing any kind of copper piping it helps with the black crap that you get when brazing that forms on the piping


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  12. #12
    Join Date
    Dec 2014
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    Thread Starter
    Quote Originally Posted by BBeerme View Post
    The color of that label indicates the compressor has been running too hot. Unless that's the original color; but I don't remember ever seeing a new label that color.
    I checked the temperature of the top of the compressor just after it started making nasty noises and it was around 85c (185F). The sticker was originally yellow/Orange though as you can see.
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  13. #13
    Join Date
    May 2014
    Location
    Bay Area California
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    If that was a scroll compressor, then a case could be made that it was acceptable.

    Being a recip, the dome should be only slightly above the suction temp.

    You have a serious problem with that compressor.

    Need to tell both the customer and your employer there is a problem.

    I handle things like this with an email, from my personal account, that way I have a record to defend my position that I told you so.


    Quote Originally Posted by Adammac View Post
    I checked the temperature of the top of the compressor just after it started making nasty noises and it was around 85c (185F). The sticker was originally yellow/Orange though as you can see.
    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.

  14. Likes lions_lair liked this post
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