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  1. #1
    Join Date
    Aug 2011
    Location
    Salem Oregon
    Posts
    26

    Inside a pipe brazed with nitrogen

    Just a cool Pi I took on an install six months ago. It's a 2 1/8 return line on a Leibert XD system. They tell you in class that you flow Nitrogen to prevent oxidation on the inside of the pipe but it's pretty cool to see it for yourself. The picture shows a 10 foot length of pipe and a brazed 45.

    Name:  IMG00162-20110225-1457.jpg
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  2. #2
    Join Date
    Feb 2011
    Location
    Orange County, in a Galaxy far far away...
    Posts
    277
    This is exactly the reason why I use a flowmeter, 3 psi is all it takes for a couple of minutes and it'll save a call back later when drier's plugged or worse...
    You cannot cheat an honest man. But that doesn't stop people trying!

  3. #3
    Join Date
    Jan 2011
    Location
    Boston, MA
    Posts
    459
    Sweet pic for sure!

    I'd like to see the same shot but without nitrogen being purged through.

    Probably be a cool side by side comparison to show non believers.

  4. #4
    Join Date
    Feb 2010
    Location
    Calgary, Alberta
    Posts
    1,101
    Without nitrogen it looks the same as the outside of the pipe. In school my teacher had us do all types of brazing and soldering then cut our joints down the middle to check penetration and heat control. You could tell who used nitrogen and who didn't.

  5. #5
    Join Date
    Aug 2011
    Location
    Salem Oregon
    Posts
    26
    Quote Originally Posted by FrostyBeer View Post

    I'd like to see the same shot but without nitrogen being purged through.
    Not possible at the time. No room in the schedule for doing work twice. Not to mention the price of a wasted fitting. $$$

  6. #6
    Join Date
    Jan 2011
    Location
    Boston, MA
    Posts
    459
    I mean like on some scrap in some spare time

  7. #7
    Join Date
    Aug 2011
    Location
    Salem Oregon
    Posts
    26
    good point

  8. #8
    Join Date
    Mar 2005
    Posts
    56
    Quote Originally Posted by FrostyBeer View Post
    Sweet pic for sure!

    I'd like to see the same shot but without nitrogen being purged through.

    Probably be a cool side by side comparison to show non believers.
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  9. #9
    Join Date
    Jan 2011
    Location
    Boston, MA
    Posts
    459
    Quote Originally Posted by stopro1 View Post
    Name:  Pipes.JPG
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    Nice!! Did you take that pic?

  10. #10
    Join Date
    Aug 2012
    Location
    MA
    Posts
    39
    Awesome pic man... I remember learning about this is school, must admit I have never done it... ;/

  11. #11
    Join Date
    Apr 2005
    Location
    nyc
    Posts
    23
    The flow rate for pruging with nitrogen is 3-5 CFH----That's cubic feet per hour-----which is not alot of nitrogen. I usually go 10CFH.

  12. #12
    Join Date
    Aug 2011
    Location
    Salem Oregon
    Posts
    26
    How do you measure/calculate the CFH you are using? Is it the same flow rate for different pipe sizes?

    I always just put 2 or 4 psi on the gauge. That puts more CFH in a larger pipe than a smaller one.

  13. #13
    Join Date
    Apr 2005
    Location
    nyc
    Posts
    23
    Quote Originally Posted by Eric S View Post
    How do you measure/calculate the CFH you are using? Is it the same flow rate for different pipe sizes?

    I always just put 2 or 4 psi on the gauge. That puts more CFH in a larger pipe than a smaller one.
    Flow meters can be purchased at any welding supply house........you'll save a ton of money on nitrogen. As far as the flow rate for different size pipes, I would assume the larger the pipe the more flow you would need. The correct procedure is to put an oxygen sensor at the end of the pipe and when you 0% oxygen you start brazing. Oxygen sensors can be quite expensive though.

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