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TMP117: NIST recalibration cycle

user5880095
Prodigy 10 points
Part Number: TMP117

Hi, 

we're looking into using TMP117 for our medical fridge. How often will we have to recalibrate TMP117 or exchange it against a new TMP117 to maintain NIST traceablity?

I'm asking this question because I read the following here: https://www.nist.gov/pml/mercury-thermometer-alternatives-what-traceability

"3. I have purchased a calibrated thermometer. How often must I have it tested to maintain traceability?

Initial testing/validation/calibration intervals should be based on manufacturer's recommendations or past experience with a type of thermometer (typically one year). "

Best regards

Simon Ströder

  • 0
    TI__Mastermind 28070 points

    Hello Simon,

    The answer to your question is tricky. We are the manufacturer of the sensing element (the TMP117), but not the final system that the device is placed in to. Traditionally it is the system itself that will need to be calibrated, and it will need to be reliable in your specific environment and application. We know due to our testing that the TMP117 will typically drift around 30 m°C if subjected to 300 hours at the top of its operating range (150 °C). We can't say how it will drift in your application. 

    So for your purposes the TMP117 and whatever module you build around it for measurements inside your medical fridge would need to be calibrated. 

    The actual calibration interval you need will be dependent on how much drift you see in the final product. The NIST standards should have some type of guidance on this, but traditionally you would start with some reasonable interval, and if the sensing portion of your system is found to be outside your target accuracy at the time of calibration you would increase your frequency of calibration. Or if its found that calibration wasn't needed you can decrease the calibration frequency as well.

    For laboratory measurement purposes, there is a recommended initial interval in GMP 11 of 12 months for digital thermometers. I am unsure if this would be what applied for your application. You will need to check the NIST standards to be sure. 

    Please let me know if you have any other questions. 

    Best Regards,
    Brandon Fisher