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  1. #40
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    Dec 2011
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    New Zealand
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    Do you guys use OFN (oxygen free nitrogen) or just Nitrogen?

  2. #41
    Join Date
    Jul 2011
    Location
    Lehigh Valley, PA
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    471
    I never heard of oxygen free nitrogen. We use 99.999 nitrogen pumped from a cryogenic tank.

    Maybe oxygen free nitrogen slightly less pure? Does it come from LIN (air separation)? Or does it come from swing absorb process?

    The only real difference between industrial grade nitrogen and spec grade nitrogen here in the states is the paper trail. Spec grade is tested and documented when filled. ind grade is not.

  3. #42
    Join Date
    Dec 2011
    Location
    New Zealand
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    We class OFN as higher purity, yes from LIN (not sure of the % sorry)

  4. #43
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    Jul 2011
    Location
    Lehigh Valley, PA
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    471
    Interesting...never heard OFN terminology.

    Here is an image of a fancy Pittsburgh Cup. Not what we used. Our tool, much more basic. A Pittsburgh Cup may have been a manufacture name rather than a trade name.

    Slowly purge test vapor thru inside of the chamber pass the mirror with dry ice in center of cup. Watch for dew. Observe temp. read chart.

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  5. #44
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    Dec 2011
    Location
    New Zealand
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    Quote Originally Posted by Capz View Post
    Interesting...never heard OFN terminology.

    Here is an image of a fancy Pittsburgh Cup. Not what we used. Our tool, much more basic. A Pittsburgh Cup may have been a manufacture name rather than a trade name.

    Slowly purge test vapor thru inside of the chamber pass the mirror with dry ice in center of cup. Watch for dew. Observe temp. read chart.

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    Where do think ASCO,s manufacturing plant is??

  6. #45
    Join Date
    Jul 2011
    Location
    Lehigh Valley, PA
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    ASCO CARBON DIOXIDE LTD, Romanshorn / Switzerland, Tel. +41 71 466 80 80 / Fax +41 71 466 80 66, e-mail: info@ascoco2.com, www.ascoco2.com

  7. #46
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    Dec 2011
    Location
    New Zealand
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    Quote Originally Posted by Capz View Post
    ASCO CARBON DIOXIDE LTD, Romanshorn / Switzerland, Tel. +41 71 466 80 80 / Fax +41 71 466 80 66, e-mail: info@ascoco2.com, www.ascoco2.com
    Na, just round the corner, Christchurch, New Zealand

  8. #47
    Join Date
    Jul 2011
    Location
    Lehigh Valley, PA
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    471
    Quote Originally Posted by barbar View Post
    Na, just round the corner, Christchurch, New Zealand
    Cool, send us out a co2 dew point tester! Thanks.

  9. #48
    Join Date
    Dec 2011
    Location
    New Zealand
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    Quote Originally Posted by Capz View Post
    Cool, send us out a co2 dew point tester! Thanks.
    No problems, for

    cccccccccccccccccccc.cccc.cc.c cash?

  10. #49
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,863
    Quote Originally Posted by Capz View Post
    co2 is inert at room temperature. But the question that needs answering, is at what temperature does it become reactive? I don't have the answer to this question. see pg12
    http://www.lincolnelectric.com/asset...ture/C4200.pdf

    My background is with BOC Gases as a field service tech on medical, industrial & the food industry. Our trainers taught us not to use co2 for purging. This is what I go by. Commercial grade co2 is not a pure gas. The cylinder of co2 on your truck is likely a by-product of the oil & gas industry and other places unless you have spec gas. What's the moisture content in co2 vs nitrogen? I don't know. I'll keep using nitrogen from an Airgas cylinder. Or maybe I'll sweat some coupons with co2 purge for inspection and document the outcome for my own good.

    And one more thing, go ahead and fill your refrig unit with co2 for pressure testing on a very cold day. Blow it out quick. What will happen to some of co2 inside the compressor? I guess a good vacuum will solve this issue but why bother using it in the first place? It's not a great gas for leak testing. Nitrogen is much lighter and a better gas for leak testing and easier to evacuate.
    We aren't talking welding, friend, so that information, while interesting, isn't really pertinent to the discussion we're having about using CO2 to prevent oxidation within a copper line being heated to 12-1400 degrees F.

    Please, do as you suggest and try a couple of joints with CO2 and post pictures showing us how different they are from one done with nitrogen.

    I'll be very interested to see the difference.

    In order for CO2 to flash-freeze to dry ice, you would have to have LIQUID CO2 in the system. Paying close attention to pressure/temperature relationship of CO2 would prevent that from happening.

  11. #50
    Join Date
    Feb 2010
    Location
    Newnan Ga,
    Posts
    177
    Why not just use Nitrogen? Its a known gas that has no effect by heat,does not hold or transfer h20
    And is simple to aquire,regulate,use...
    just sayin... why not use pure argon or Halon they both displace oxygen, and are odorless an contain no moisture.

  12. #51
    Join Date
    Feb 2008
    Location
    California
    Posts
    2,069
    Not interested in what the book says...I want to hear about real life experience.

    Has anyone ever ran into a system problem during service that you could 100% say was caused by brazing without flowing nitro/co2...whatever.

    I've never once flowed nitrogen during service repairs, don't even pressure test. (my welds don't leak)

    Just braze it up, pull a vacuum, and get it going.

    I've brazed in cap tubes, txv's, reversing valves, all kinds of valves, never had one fail to my knowledge.

    I've only been in the trade 9 years, so maybe not enough time has passed to tell yet.

  13. #52
    Join Date
    Sep 2008
    Location
    Western PA
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    25,863
    Quote Originally Posted by Phase Loss View Post
    Not interested in what the book says...I want to hear about real life experience.

    Has anyone ever ran into a system problem during service that you could 100% say was caused by brazing without flowing nitro/co2...whatever.

    I've never once flowed nitrogen during service repairs, don't even pressure test. (my welds don't leak)

    Just braze it up, pull a vacuum, and get it going.

    I've brazed in cap tubes, txv's, reversing valves, all kinds of valves, never had one fail to my knowledge.

    I've only been in the trade 9 years, so maybe not enough time has passed to tell yet.
    Yep.

    I've cleaned hundreds of plugged TEV screens on a store where I know the fitters did NOT use nitrogen.

    Last store I started, the fitters used nitrogen "wherever they could" and I haven't had to touch a screen in that store.


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