A preliminary air quality analysis of my shop

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  • cgallery
    Veteran Member
    • Sep 2004
    • 4503
    • Milwaukee, WI
    • BT3K

    #31
    Originally posted by gugie
    I would bet that the unit is not very efficient at picking up the smallest bin size (.5 micron). The only way to test that is to compare it side by side with an industrial airborne particle counter certified down to at least 0.5 micron (most go down to at least 0.3 micron).
    The developer was silultaneously using his models along with a $4500 six-channel particle counter. His background is in designing cleanroom monitoring equipment (that runs into the tens of thousands of dollars).

    Originally posted by gugie
    In addition, the actual size of the particle that is measured varies greatly depending on shape, angularity, etc. These units are calibrated using perfect spheres which are electrostatically sorted by size for accuracy.
    Electrostatically? Wouldn't that pull the particle in from the field towards the edge and make it impossible to count?

    I admit that I have absolutely no idea how the technology works.

    Originally posted by gugie
    All that said, what you're really looking for in this case is relative cleanliness, so it should work just fine, with a few caveats.

    First, the number of particles it counts will depend greatly on where the unit is placed. I'd put it about the same height and position of where you'll be working, since that's what you're really concerned about.

    Second, this unit has a very low sample rate. I have a small hand held unit at work (semiconductor cleanroom) that draws 0.1 CFM, while this unit is 0.01 CFM. A lot of you may have heard the term "Class 1 cleanroom". This refers to the number of particles >0.5 micron in a cubic foot of air. FED STD 209 (now obsolete, but still used) has a lot of statistical work behind it, and to say an area is class 1 with confidence you have to draw a cubic foot of air. For cleanroom certification work, a larger unit that draws 1.0 CFM or more is used to get the job done quicker. For the same confidence level, you would need to run this unit for 100 minutes, assuming it meets other requirements which I won't detail here. For your usage, I wouldn't run the thing for a few minutes and use that number. I'd recommend turning it on for the full 100 minutes. This will help eliminate variability in the test due to randomness. Bottom line, longer test times are better.
    The amount of airborne dusts varies greatly in a shop environment. There really is no such thing as eliminating variability. Walk around a little and your numbers can spike by 5x. Sweep the floor and within seconds you'll increase your counts by a factor of at least 10x (often quite a bit more).

    Originally posted by gugie
    Third, the federal standard assumes uni-directional flow (sometimes called laminar flow, although this is technically incorrect), whereas airflow in most workshops is typically random.

    All this said, I think this tool can be pretty useful. If one area rates as a "10" for example, and another is "8.5", and both measurements are done in the same manner as stated above, you can say that they are roughly the same cleanliness. If one is 10 and another is 100, you can probably safely say one is significantly cleaner than another.

    The best usage would be to determine if measures you take to improve quality of air are effective. For example, before and after dust collection devices are installed. Shop air cleaners can be very cost effective.

    Alternatively, copy exactly Rod's shop, I think you won't go wrong.
    I have the 1/5 model and will purchase the .5/2.5 as well. I am quite confident that the #'s reported are quite accurate as far as particle counter tolerances allow. He talked a little about the differences and variability in even the multi-thousand dollar units. It seems like he really has a handle on the technology and is delivering a product that will work very well in the shop.
    Last edited by cgallery; 01-19-2008, 02:20 PM. Reason: I wrote .5/3.5, shoulda been .5/2.5

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    • mpauly
      Established Member
      • Apr 2006
      • 337
      • NJ

      #32
      I just noticed you posted the form (i must have been snoozing) and want in on a 1/5 micron unit, but I won't have access to a fax till I get back to work on Tuesday. Can we email this in or phone it in?

      Michael

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      • cgallery
        Veteran Member
        • Sep 2004
        • 4503
        • Milwaukee, WI
        • BT3K

        #33
        Originally posted by mpauly
        I just noticed you posted the form (i must have been snoozing) and want in on a 1/5 micron unit, but I won't have access to a fax till I get back to work on Tuesday. Can we email this in or phone it in?

        Michael
        In that case E-Mail all the information on the form, except for CC information, to support@dylosproducts.com

        Then call them at 877/351-2730 and read them your credit card #.

        WHen you're done don't forget to E-Mail groupbuy@cgallery.com so we can make sure you're added to our list that we will share w/ Dylos to make sure nobody falls through the cracks.

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