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Calibration of Resistivity Meter

Discussion in 'ISO 17025 - Calibration and Test Laboratories' started by Nikki, Sep 23, 2015.

  1. Nikki

    Nikki Well-Known Member

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    Hello All-

    We have a couple customers that have us produce a couple compounds, which require surface resistivity requirements.

    We purchased a resistivity meter and the calibration certificate states an annual calibration - it is stated as a "suggested" calibration date.

    We actually only use the unit maybe 4 times a year. I don't see how that warrants an annual calibration.

    I am thinking of changing the calibration requirement to every 2 years instead.

    Do you think this would be okay?

    Thanks!
    Nikki
     
  2. BradM

    BradM Moderator Staff Member

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    IMO, it's OK. A calibration interval is best established based on usage, risk, etc.; factors that can only be assessed by the customer.

    Now... two years is a long time. If the device is found out of tolerance, you will have two years worth of data/potential impact to assess. Will that be a problem?
     
    Mikishots likes this.
  3. hogheavenfarm

    hogheavenfarm Well-Known Member

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    How long have you had it/used it? I would think some history would be required before extending the calibration beyond its suggested interval. Without any performance data, you could find it needs calibration more often, not less, so some history to build on would be in order. I have things like this I have extended to three years, and some to 5, but I have extensive past logs to provide rationale for doing this.
     
  4. Nikki

    Nikki Well-Known Member

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    The unit came with a fixture, which has a known result. We could simply place the probe on the fixture and read the result. If it is in spec, I wouldn't see a problem continuing without sending it out to calibration. If it reads off, then obviously...

    We have a verification of calibration method, but we can't calibrate it ourselves. To save money, I figured why not expand the cal requirement.
     
  5. Nikki

    Nikki Well-Known Member

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    This is a new unit - just over a year old. In the past, we would visit another company and use their resistivity meter. For convenience we purchased one.
     
  6. BradM

    BradM Moderator Staff Member

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    Can you call the other company? I would find out what the history is on this thing. You want to get mileage out of the calibrations; but you don't want them failing either.

    What kind of impact would it be if in two years the meter is found out of tolerance?
     
  7. Nikki

    Nikki Well-Known Member

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    The impact would not be that vast actually.

    We really only make 1 product that requires this testing. Maybe 2 or three lots a year.

    By using that fixture to check the meter every 6 months or so (the verification takes seconds to conduct), I should be able to identify if the meter is reading correctly.
     
  8. BradM

    BradM Moderator Staff Member

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    OK. Just keep in mind that you're accepting risk when you extend the due date interval. If the meter is found to have exceeded tolerance, you will want to be able to document that the test performed with that meter since the last calibration is not impacted.
     
    Nikki likes this.
  9. Candi1024

    Candi1024 Well-Known Member

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    Maybe since you only use it 2-3 times each year, you can verify it before each use.

    Also be sure to store it in a safe container, in a safe place where it won't be bumped around.
     
    Jennifer Kirley and Nikki like this.

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