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Acoustic application

Last post 04-18-2008, 12:13 PM by John Snell. 3 replies.
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  •  04-18-2008, 6:07 AM 1373

    Acoustic application


    An idea has struck me for a novel application of thermal imaging. An acoustic problem was reported with a building, undesirable noise was entering the building through faulty double glazing seals. The cause was easy enough to diagnose but the next step is of course to try and identify which windows are faulty and which aren't, a big job in a large building. I am wondering whether a thermographic inspection might be more effective, or efficient than an acoustic inspection. I haven't used IR cameras for window inspection before, I am more concerned with calibration myself.

    So does anyone have any comments on the idea, or any tips for getting the best possible assessment of window seals, best time of day etc?

    Luke

  •  04-18-2008, 8:13 AM 1376 in reply to 1373

    Re: Acoustic application

    In fact there is a well documented relationship between air leakage and noise levels in buildings: the tighter the building the quieter it will be. i know of a number of projects that utilized blower doors and infrared as the core diagnostics for air sealing work which was actually being done for sound control, as an example for homes near airport runways. The air leakage pathways around windows are often in the window to envelope joint rather than the window seal itself.

     After the 1995 Murrah building bombing I did work on a nearby large federal office building where the windows had literally been pushed in by the blast. We used the buildings HVAC system to depressurize the entire building and successfully analyzed the extent of damage on all the windows.  


    Thermally Yours,

    John
    ASNT NDT Level III #48166
    The Snell Group
    www.thesnellgroup.com
    www.thermalsolutions.org
    800-636-9820
  •  04-18-2008, 10:00 AM 1377 in reply to 1376

    Re: Acoustic application

    Ah, very interesting. Did you have to do any specail work on the HVAC system to get enough depressurisation?

     

  •  04-18-2008, 12:13 PM 1381 in reply to 1377

    Re: Acoustic application

    Yes, in this case it took several weeks of investigation and planning and then about 12 hours of manipulation, including blocking off some ducts temporarily, to get good results. These techniques would be impossible to implement in many buildings with special needs, such as clean rooms or hospitals. At least several of the blower door manufacturing companies have products that can handle larger, non-residential buildings.
    Thermally Yours,

    John
    ASNT NDT Level III #48166
    The Snell Group
    www.thesnellgroup.com
    www.thermalsolutions.org
    800-636-9820
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