ISO 17025:2017 Clause 7.7 Ensuring the Validity of Calibration Results

[Unie24]

Hi and Greetings,

Can anybody explain to me on the new requirement of Clause 7.7. Previous ISO 17025:2005 has 5 requirement on monitoring validity of calibration, while current version requires 12. I don't really understand on Clause 7.7.1:

b) use of alternative instrumentation that has been calibrated to provide traceable results
g) re-calibration of retained items
h) correlation of results for different characteristics of an item

I would really appreciate some feedback and answer since I'm really stuck with this part. Thanks

 

[AndyN]

Do you not understand these three items? I guess I don't understand what you are asking here.

 

[Unie24]

Yes. And would appreciate any explanation on those items..

 

[AndyN]

Yes. And would appreciate any explanation on those items..

What type of lab are you working in? What type of equipment is being used or measurements are being made? That helps with an explanation.

 

[Unie24]

Calibration lab emphasizing on force calibration (compression system-Load cell/proving ring), mass calibration (weighing balance & standard weight) and heat (PT 100/ Type K/ temperature controlled enclosure).

 

[dwperron]

Hi and Greetings,

Can anybody explain to me on the new requirement of Clause 7.7. Previous ISO 17025:2005 has 5 requirement on monitoring validity of calibration, while current version requires 12. I don't really understand on Clause 7.7.1:

b) use of alternative instrumentation that has been calibrated to provide traceable results
g) re-calibration of retained items
h) correlation of results for different characteristics of an item

I would really appreciate some feedback and answer since I'm really stuck with this part. Thanks

One of the requirements for 17025 has always been that you have a process to confirm that you are making good measurements. Section 7.7.1 says you will have a procedure on how you do this, you will record this data in a way that detects trends (they like to see graphs here), and your results are reviewed using statistical techniques. Simple enough, you must find ways that prove you are producing valid, repeatable results.

The next line is fuzzy: "shall include, where appropriate, but not be limited to:" and follows with the list of methods. "Shall include" would indicate that you must use one of these methods, but then "where appropriate" gives you a way out if none of these methods works in your particular case. They would like to see you use one or more of these methods in your process, instead of the 10 Commandments think of these as the 12 Recommendations.

As for the three methods you are having trouble with:
b) would be for you to perform the same calibration using different instruments and comparing the results
g) would be for you to perform the calibration again, maybe with another technician, and comparing the results
h) I don't see how this method would be useful in your situation, as your devices are really checked for a single characteristic.

 

[Unie24]

Thanks for the explanation

 

[Ashwin T Joseph]

I can help you understand Clause 7.7.1 h) correlation of results for different characteristics of an item with an example. Maybe you can correlate the same to your scenario.

This clause suggests that you can establish a connection between various parameters of the same sample. For example, there is a correlation between tensile strength of steel with its hardness and microstructure. So if you have a carbon steel specimen of 1400 MPa tensile strength, you can meet the requirement of this clause by simply performing hardness test or microstructure analysis on the sample. Hardness of about 410BHN or Hardened and tempered microstructure indicates that the tensile value is accurate and you have proved it by establishing a correlation of results for different characteristics of an item.

These days many ISO 17025 External Accessors are evaluating this clause during audits.

Hope this helps.