Is Uncertainty Calculation Mandatory

[raghu_1968]

We are having a very small in-house calibration lab.

During one of our inspection, observation has given to calculate the uncertainty.

Even though it is good to calculate measurement uncertainty, is it mandatory to calculate uncertainties for the in-house calibrated equipments? (like sensors, balances etc.,)

If it is not mandatory, is there any justification to support?

Regards / Raghu

 

[Hershal]

For calibration, uncertainty is a requirement.

Justification is from ISO/IEC 17025 Clause 5.4.6.1; VIM 2003, and VIM 2008.

 

[step30044]

For calibration, uncertainty is a requirement.

Justification is from ISO/IEC 17025 Clause 5.4.6.1; VIM 2003, and VIM 2008.

Hershal is dead on with this one.

 

[George Weiss]

I would take it a step further and say uncertainty calculations are required in a proper manner. That complete and correct calculations need be performed. There are expected sources of uncertainty. Omitting a significant uncertainty source, which is expected by an auditor will trigger a finding.

 

[Radlerka]

Thanks to everybody.

 

[dv8shane]

I would say it is not required if your QMS or customers do not specify 17025 accredited calibration. Fluke even offers 2 levels of service one that is accredited and one that is performed to be compliant to ISO9001 type customers.
Fluke Canada | Test & Measurement Tools & Software

 

[George Weiss]

Point made. In a generic calibration, just a manufacturer's manual or procedure is needed. If the manufacturer has already offered the equipment needed to perform the calibration, then the idea of acceptable methods have been met. Wow, calibrating w/o uncertainty budgets, is a liberating thought. just like skinny dipping.

 

[Graeme]

We are having a very small in-house calibration lab.

During one of our inspection, observation has given to calculate the uncertainty.

Even though it is good to calculate measurement uncertainty, is it mandatory to calculate uncertainties for the in-house calibrated equipments? (like sensors, balances etc.,)

If it is not mandatory, is there any justification to support?

Regards / Raghu

If you are an accredited laboratory, calculating measurement uncertainty is mandatory.

If you are claiming traceability of your calibrations (to the SI units of measure through a national metrology institute), accounting for measurement uncertainty is necessary. That is because measurement uncertainty appears twice in the definition of calibration (VIM 3rd edition, definition 2.39). Proper calculation of measurement uncertainty is also good professional practice.

Download a free copy of the current edition of the VIM (JCGM 200:2008) from the BIPM web site. Then, look at the definitions of calibration (2.39), calibration hierarchy (2.40) and metrological traceability (2.41). The VIM contains the accepted technical definitions of terms associated with measurement in all areas of science and engineering.

By the way, you will also find a free copy of the GUM listed on the same web page!

 

[BradM]

Graeme, thank you for the excellent information.

 

[BradM]

We are having a very small in-house calibration lab.

During one of our inspection, observation has given to calculate the uncertainty.

Even though it is good to calculate measurement uncertainty, is it mandatory to calculate uncertainties for the in-house calibrated equipments? (like sensors, balances etc.,)

If it is not mandatory, is there any justification to support?

Regards / Raghu

Hello Raghu!

Now... there are still a lot of questions unanswered here. Including, what level of calibration you are performing, what industry, what standard, etc.

But.... if you are ABC company, and you are calibrating your own micrometers/calipers and such, you don't need to perform uncertainty calculations so that your work is considered a legitimate calibration. However, there are multiple considerations you must take into account, such as acceptable accuracy ratios, environment, etc. And... once you're done with all that, it's just as easy to throw it into a budget and calculate uncertainty anyway.

But.... honestly... I wouldn't feel comfortable one way or another, unless you might be at liberty to share a little more about your industry and the requirements. Whoever made this observation in your lab might have an awfully good reason for suggesting it.