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  1. #1
    Join Date
    Feb 2002
    Location
    Oregon
    Posts
    299
    So how hot can your get txv's before you cause damage. I've seen people braze them in w/o wrapping them and counted them as foolish.
    Do it right the first time.

  2. #2
    Join Date
    Apr 2002
    Location
    Dallas, TX
    Posts
    2,987
    If you overheat the thermostatic charge, you can damage the valve diaphragm. For non-MOP type charges, it is a good idea to keep the power head/sensing bulb below about 150F or so. For MOP-type charges, temperatures up to about 250F should not be a problem.

    If you overheat the valve body, the concern here is the superheat spring. Overheating the spring can collapse it. The spring temperature should remain below 250F. This is part of the reason why you aim the torch tip away from the valve body.

  3. #3
    I err on the side of extreme (paranoid) caution.

    I cover the valve, including diaphram head, with heat paste. (yuckey stuff). Then I wrap a damp cloth around the entire assembly. Once in place and about to weld, I take a quart spray bottle and soak it down, but not to the point where moisture would enter the joints.

    And then I weld.
    Once visual inspection is over, I once again spray down the entire wraped up assembly and let it sit.



    I hear Danfoss has a new SS valve that requires no precaution whatsoever.
    I wonder how they conpensate for the heat being absorbed by the internals parts. Also that spring.


    I've never had trouble with the method I employ. Calling it extreme is an understatement.
    The next time though, I may begin embedding temp sensors next to the valve body just to monitor how hot I am getting it.
    And then adjust my techniqe as necessary.

  4. #4
    Join Date
    Jun 2004
    Location
    Baltimore
    Posts
    18
    Originally posted by R12rules
    I hear Danfoss has a new SS valve that requires no precaution whatsoever.
    I wonder how they conpensate for the heat being absorbed by the internals parts. Also that spring.
    We don't compensate for heat being absorbed into the internals because the heat doesn't get to the internals. Stainless steel conducts heat 11 times less than copper so the heat is simply not transmitted into the valve in the time it takes to braze one in. We've done demonstrations where we have someone holding the powerhead in their bare hands as the valve is sweated in (demonstration only, not recommended obviously).

    Danfoss AE

    [Edited by danfoss engineer on 10-07-2004 at 05:26 PM]

  5. #5
    Thank God your here!!!


    We truly need more factory reps who know the technical aspect of this industry.

    I've personally invited Tecumseh and Sporlan tech reps to come lurk and then field some questions pertaining to their products.... but alas .... they chickened out.


    Welcome aboard!!!

  6. #6
    Join Date
    Jan 2004
    Location
    Earth
    Posts
    4,879
    Originally posted by R12rules
    I've personally invited Tecumseh and Sporlan tech reps to come lurk and then field some questions pertaining to their products.... but alas .... they chickened out.

    Whats Andy chicken salad? I have seen him answer many sporlan component questions.
    A Diamond is just a piece of coal, that made good under pressure!

  7. #7
    Join Date
    Jan 2004
    Location
    Earth
    Posts
    4,879
    We don't compensate for heat being absorbed into the internals because the heat doesn't get to the internals. Stainless steel conducts heat 11 times less than copper so the heat is simply not transmitted into the valve in the time it takes to braze one in. We've done demonstrations where we have someone holding the powerhead in their bare hands as the valve is sweated in (demonstration only, not recommended obviously).

    Danfoss AE

    [Edited by danfoss engineer on 10-07-2004 at 05:26 PM]
    This is the very same reason they melt very quickly also. Still gotta be careful.
    A Diamond is just a piece of coal, that made good under pressure!

  8. #8
    Join Date
    Jan 2004
    Posts
    526
    The next time though, I may begin embedding temp sensors next to the valve body just to monitor how hot I am getting it.
    And then adjust my techniqe as necessary

  9. #9
    Join Date
    Apr 2002
    Location
    Dallas, TX
    Posts
    2,987
    Originally posted by frozensolid
    Whats Andy chicken salad? I have seen him answer many sporlan component questions. [/B]
    Yeah R12rules, am I chicken salad? ...

  10. #10
    Join Date
    Sep 2001
    Location
    East Stroudsburg, PA
    Posts
    13,215
    I think all yall have identity issues. At least I think I know who I am...................

  11. #11
    Join Date
    Jun 2004
    Location
    Baltimore
    Posts
    18
    Originally posted by frozensolid
    This is the very same reason they melt very quickly also. Still gotta be careful.
    You always have to be careful. If you're melting the connector you are putting way too much heat into that joint. It may be stainless on the outside but inside there is a copper surface so chemically it's a copper-copper braze joint and we recommend 5 or 15% silver content solder. That stuff melts at about 1200-1400F. Stainless melts somewhere around 3000F.

    I think what gets most people is that our connectors have much less mass than a typical solid copper connector and therefore end up putting too much heat into it. With ours you'd need to put more of the heat into the copper tubing rather than the TXV connector. The opposite would be true of out fractional compressors where the connection is copper coated steel (with a lot more mass of steel). There you need to put a lot more heat into that connection rather than the copper tubing.

    Danfoss AE

    [Edited by danfoss engineer on 10-08-2004 at 10:28 AM]

  12. #12
    Join Date
    Jun 2004
    Location
    Baltimore
    Posts
    18
    PS. Andy is indeed chicken salad

    Danfoss AE (Cobb Salad)

  13. #13
    [QUOTE]Originally posted by R12rules

    I've personally invited Tecumseh and Sporlan tech reps to come lurk and then field some questions pertaining to their products.... but alas .... they chickened out.


    Andy Schoen is definitely not chicken salad; more like lobster thermador. Talk about getting a response from factory people. Andy has worked for Sporlan for many years, posts on this site regularly, and has authored numerous trade publication articles to help educate us in the field.

    Go back and read some of his posts and you'll see the level of expertise he provides.

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