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17025- uncertainty- (precludes rigorous evaluation)

Discussion in 'ISO 17025 - Calibration and Test Laboratories' started by John C. Abnet, Mar 14, 2019.

  1. John C. Abnet

    John C. Abnet Well-Known Member

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    Good day all;
    17025 clause 7, section 7.6.3 has some interesting language. Specifically..."where the test method precludes rigorous evaluation of measurement uncertainty, an estimation shall be made..."
    This appears to be a bit of loophole for non-calibration facilities. Specifically for established/common (yeah, sadly subjective terms, but as of now I have no better way to describe) methods.
    e.g. one could argue that fastener thread pitch measurements using pitch micrometers, "precludes rigorous evaluation", and, therefore the requirement to "evaluate measurement uncertainty" becomes an opportunity to do so via estimation only.
    What say all of you regarding the interpretation/application of this section?

    Thank you.

    Be well.
     
    John C. Abnet, Mar 14, 2019
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  2. Andy Nichols

    Andy Nichols Moderator Staff Member

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    Mmmm, I'm not sure I follow your thought regarding pitch micrometers, John. Can you provide some more insights?

    As far as I have considered this, I'd suggest that it is more applicable towards what might be "leading edge" measurement/testing, where the method is still new/under evaluation for its accuracy/precision etc. One thing which comes to mind is the use of the tobacco industry "smoking" machines. These test cigarettes with a standard "puff", but there's no national or international standard for calibration and, measurement uncertainty - especially regarding the "unit under test", environmental conditions etc which affect the results of the "puff" can really only be estimated. Does this help?
     
    Andy Nichols, Mar 14, 2019
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  3. John C. Abnet

    John C. Abnet Well-Known Member

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    That's good logic Andy. Thanks. (regarding the "pitch micrometers", I was simply randomly referencing an "old standard" that is common and well established within industry.)

    Anyone else have any thoughts on this ?

    Thanks again @Andy Nichols

    Be well.
     
    John C. Abnet, Mar 14, 2019
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  4. Andy Nichols

    Andy Nichols Moderator Staff Member

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    Incidentally, this type of equipment is subject to inter-laboratory comparisons or "round-robin" evaluations. Contrary to what others have stated about calibration, verification and the need for traceability to national or international standards, this is a classic case of the "work around" which avoids any one lab getting spurious results, by comparing them to everyone else's. That's all they can do...
     
    Andy Nichols, Mar 14, 2019
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  5. Miner

    Miner Moderator Staff Member

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    While this is not an area in which I am fully competent, I wonder if it could also apply to some old school technology. Zahn cups and rheometers come to mind as something in which it would be very difficult to assess the uncertainty.
     
    Miner, Mar 14, 2019
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  6. Andy Nichols

    Andy Nichols Moderator Staff Member

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    Good call, Miner. I'd overlooked that (simple) technology!
     
    Andy Nichols, Mar 14, 2019
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  7. John C. Abnet

    John C. Abnet Well-Known Member

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    So...maybe BOTH ends of the spectrum can apply this "opportunity" (i.e. leading edge AND simple). Good conversation...thanks to all .
     
    John C. Abnet, Mar 14, 2019
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