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  1. #1
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    May 2008
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    Last moon off of Pluto
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    Nitrogen flow when brazing

    I've been told that you're a fool if you don't flow nitrogen when you do your brazing. The idea is that the nitrogen sheild the brazing process on the inside of the refrigrant line so no soot or impurities form, therefore keeping trash out of your refrigrant line.

    I wouldn't mind doing a little bench test. Brazing a line and the charging a some with nitrogen and do the brazing. Cut the (2) lines right down the middle long ways and compare the interior.

  2. #2
    Join Date
    Feb 2008
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    St. Louis, Missouri
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    33
    Quote Originally Posted by highlifesipper View Post
    I've been told that you're a fool if you don't flow nitrogen when you do your brazing. The idea is that the nitrogen sheild the brazing process on the inside of the refrigrant line so no soot or impurities form, therefore keeping trash out of your refrigrant line.

    I wouldn't mind doing a little bench test. Brazing a line and the charging a some with nitrogen and do the brazing. Cut the (2) lines right down the middle long ways and compare the interior.
    Yea nitrogen actually displaces the oxygen inside the line, which prevents oxidation, you can see this oxidation on the outside of the line when you are brazing. Thats what will happen to the inside without nitro. Then take your finger (after it cools)and watch it flake off.

  3. #3
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    May 2008
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    Last moon off of Pluto
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    Quote Originally Posted by lmark View Post
    Then take your finger (after it cools)and watch it flake off.
    Yes...that's what I was told. That stuff that flakes off you wouldn't want in your TX..right?


    After it cools....ahhhh yeah

  4. #4
    Join Date
    Aug 2007
    Location
    Clearwater, Fl
    Posts
    358
    I had never flowed nitro while brazing until a couple of years ago, I simply didn't know that it should be done. Also, as far as I know there was never an issue with not doing it.

    Since I have started installing 410, and it was recommended in the classes that I have been to, I have been doing every time I braze something.

    Not sure if it makes a big difference or not, but since I have been told by multiple manufacturer reps that it does, I do it. I don't want any possible warranty issues later.

    Also, I have always installed a filter/dryer on every system. Don't know if that has made any difference in using nitro or not.

  5. #5
    Join Date
    Dec 2003
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    107
    My son-in law is having a new Trane HVAC system installed starting today. Since he is getting a system using R410a, I cautioned him that he should insist that all brazing of copper lines be done with a nitrogen purge. When he talked with the salesman, who is the owner's son, my son-in-law told the salesman that he wanted all brazing done with a nitrogen purge and the wording to that effect was even included in the contract.

    Today, I received a phone call from my son-in-law and he asked me if I had any information about implementing the purging of the copper lines with nitrogen. The installer stated to my son-in-law, "I've never heard of this before, how do you go about purging the lines with nitrogen?" I did a quick Google search and found and printed out a few things, including a Trane installation manual, that talks about using a nitrogen flow and delivered them to my son-in-law who lives less than a mile from me.

    Upon my arrival on site, one of guys in the crew told me that the main installation guy has been installing system for 16 years and he has never before heard of using a nitrogen flow while brazing. I replied that that might be part of the problem, that if he only been installing for a couple of years then he may have been trained to use nitrogen. They said they use nitrogen as a leak test but never as a purge while brazing.

    Does anyone know of a guide, preferably one that is accessible online, that I can give to my son-in-law so he can give it to the installation crew on how to set up a nitrogen purge while brazing?

    I would appreciate any help. Thanks

  6. #6
    Join Date
    Jul 2008
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    7
    I've never heard of that before now either, but it makes perfect sense... But why should it matter more on the new 410 rather than say the r22? because of the pressure difference or what?
    You know what else is funny, I now an older tech who always puts a system under a vacuum to do his brazing(unless he's near a a capilory or something), yet they tell you not to do that at school now.

  7. #7
    Join Date
    Sep 2008
    Location
    arlington, tx
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    225
    Quote Originally Posted by mcginkleschmidt View Post
    My son-in law is having a new Trane HVAC system installed starting today. Since he is getting a system using R410a, I cautioned him that he should insist that all brazing of copper lines be done with a nitrogen purge. When he talked with the salesman, who is the owner's son, my son-in-law told the salesman that he wanted all brazing done with a nitrogen purge and the wording to that effect was even included in the contract.

    Today, I received a phone call from my son-in-law and he asked me if I had any information about implementing the purging of the copper lines with nitrogen. The installer stated to my son-in-law, "I've never heard of this before, how do you go about purging the lines with nitrogen?" I did a quick Google search and found and printed out a few things, including a Trane installation manual, that talks about using a nitrogen flow and delivered them to my son-in-law who lives less than a mile from me.

    Upon my arrival on site, one of guys in the crew told me that the main installation guy has been installing system for 16 years and he has never before heard of using a nitrogen flow while brazing. I replied that that might be part of the problem, that if he only been installing for a couple of years then he may have been trained to use nitrogen. They said they use nitrogen as a leak test but never as a purge while brazing.

    Does anyone know of a guide, preferably one that is accessible online, that I can give to my son-in-law so he can give it to the installation crew on how to set up a nitrogen purge while brazing?

    I would appreciate any help. Thanks
    these guys are idiots i am the guy that comes behind them and replaces the txv

  8. #8
    Join Date
    Sep 2008
    Location
    arlington, tx
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    225
    Quote Originally Posted by hvac1982 View Post
    I've never heard of that before now either, but it makes perfect sense... But why should it matter more on the new 410 rather than say the r22? because of the pressure difference or what?
    You know what else is funny, I now an older tech who always puts a system under a vacuum to do his brazing(unless he's near a a capilory or something), yet they tell you not to do that at school now.
    it does not matter more you should always do it i have changed many txvs because of poor brazing but according to daikin the reason 410 is so critical is the metering orifice is smaller

  9. #9
    Join Date
    Aug 2007
    Location
    Clearwater, Fl
    Posts
    358
    Quote Originally Posted by hvac1982 View Post
    I've never heard of that before now either, but it makes perfect sense... But why should it matter more on the new 410 rather than say the r22? because of the pressure difference or what?
    You know what else is funny, I now an older tech who always puts a system under a vacuum to do his brazing(unless he's near a a capilory or something), yet they tell you not to do that at school now.

    It should be done every time that brazing is done to the system regardless of the refrigerant.

    I started in this field in 1994 as a helper without any schooling. Not only did we not use nitrogen, I don't recall ever being tought to use a vacuum pump either. The system was always purged using 22. The lead installers would flow the 22 from the suction through to the liquid side and purge it through the the hoses. After a few minutes they would say "that should be good enough", stop the purge, and open the valves.

    The company sent me through an apprenticeship program a couple of years later and that was the first time that I was ever told of what the vacuum pump was, what it was used for, and learned what a micron gauge was.

    Still don't remember anything about a nitro purge while brazing. It wasn't until I went to a 410 class a few years ago that I had heard of purging with nitro while brazing, and the reason for it.

    It doesn't surprise me one bit that a lot of techs and installers still don't do it, or have never heard of doing it. I think that quite a few around here still don't think it is necessary, so they don't do it, ever.
    If people only focused on the important things in life there would be a shortage of fishing poles.

  10. #10
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    Aug 2004
    Location
    North Richland Hills, Texas
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    14,914
    Quote Originally Posted by mcginkleschmidt View Post
    Upon my arrival on site, one of guys in the crew told me that the main installation guy has been installing system for 16 years and he has never before heard of using a nitrogen flow while brazing.
    Nice, so he admits that in 16 years he has never read the installation instructions for any of the equipment he installs...

    I wonder what else he doesn't know to do because he has never read installation instructions...
    If more government is the answer, then it's a really stupid question.

  11. #11
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    Jun 2008
    Location
    LONDON
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    57

    Talking brazing

    Quote Originally Posted by highlifesipper View Post
    I've been told that you're a fool if you don't flow nitrogen when you do your brazing. The idea is that the nitrogen sheild the brazing process on the inside of the refrigrant line so no soot or impurities form, therefore keeping trash out of your refrigrant line.

    I wouldn't mind doing a little bench test. Brazing a line and the charging a some with nitrogen and do the brazing. Cut the (2) lines right down the middle long ways and compare the interior.

    Absolutely,especially when you braze VRV/VRF systems ,all joints and refnets must to be OFN blown while brazing.Otherwise you will end up with blocked strainers and fu**** up 4 way valve....then the warranty is void.
    Daikin f.e. comes to check the system they cut a refnet and see the black soot inside it ....and of course they leave site.........

    If you do a small split type system a few brazings doesn't matter too much.


  12. #12
    Join Date
    Feb 2007
    Location
    Dallas, Tx.
    Posts
    572
    Quote Originally Posted by highlifesipper View Post
    I've been told that you're a fool if you don't flow nitrogen when you do your brazing. The idea is that the nitrogen sheild the brazing process on the inside of the refrigrant line so no soot or impurities form, therefore keeping trash out of your refrigrant line.

    I wouldn't mind doing a little bench test. Brazing a line and the charging a some with nitrogen and do the brazing. Cut the (2) lines right down the middle long ways and compare the interior.
    Lack of proper knowlege does not make you a fool. Not learning from, or listening to an educated, experienced tech or tech support, will certianly make you a fool. Nitrogen purge while brazing is proper operating procedure.
    mike

  13. #13
    Join Date
    Dec 2007
    Location
    Tidewater VA area
    Posts
    3
    Before you heat the joint, it is good practice to introduce nitrogen into the system to purge the air (containing oxygen) and reduce the possibility of oxidation to a minimum. A pressure of 1 to 2 pisg is enough to purge the piping.

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