Hi to everyone,
I'm new in ISO17025 and I was thinking what could be the difference between a reference standard and working standard. :confused:What is the effect in a calibration services if they are using a working standard instead of a reference standard? :frust: Is it a requirement that whenever you calibrate one should refer to a reference standard? Please advise.
Thank you very much in advance for the usual kind attention you will give this request.:thanx:
Raffy:cool:

I've been in metrology/calibration nearly 30 years and I still get confused by some of these terms (and I don't like them very much).

I just looked in the ISO definitions (Guide 99:2007) and found that a reference measurement standard is normally used to calibrate other standards; and a working measurement standard is usually used to calibrate equipment.

However, for most smaller labs, I don't believe this is an issue (in my opinion). I normally (personally) just use the term measurement standard, and select the correct standard to use for a calibration based on adequate accuracy/uncertainty. That is (for most calibration labs) the more important detail: to use an adequate standard for the calibration.

If you need the official definitions, I recommend obtaining a copy of ISO/IEC GUIDE 99:2007(E/F) "International vocabulary of metrology - Basic and general concepts and associated terms (VIM)". This gives the official definition of such terms.

I just looked in the ISO definitions (Guide 99:2007) and found that a reference measurement standard is normally used to calibrate other standards; and a working measurement standard is usually used to calibrate equipment.

If you need the official definitions, I recommend obtaining a copy of ISO/IEC GUIDE 99:2007(E/F) "International vocabulary of metrology - Basic and general concepts and associated terms (VIM)". This gives the official definition of such terms.

Thanks for this clarification, Jerry! The purpose of a working standard is just that - used for performing the work of calibration. The master or reference standard is used not just for calibration of the working standard, but also those intermediate checks and verifications used to detect any wear/drift of the working items between times of full calibration.......

If you use the same item for both working standard and as the master (which is a bit oxymoronic) then you'll end up using an outside source to supply the intermediate checks, which may add up to more cost than a set of masters....

Reference standard :
Standard, generally having the highest metrological quality available at a given location or in a given organization, from which measurements made there are derived.

Working standard :

Standard that is used routinely to calibrate or check material measures, measuring instruments or reference materials.

A working standard is usually calibrated against a reference standard.

Hi Jerry,
Thank you very much for the reply. We have an in-house laboratory. Performing calibration of testers and handlers. But for measuring instrument, we outsource the service provider which, was ISO17025 Accredited. My concern right now is the calibration standard that we must put in our Calibration Certificate. One of our external auditors make a comment with regard to the Method of Calibration. Our Method of Calibration is based on the Original Equipment Manufacturer (OEM) Calibration Procedure. My concern: Is it valid to used such comment that our Method of calibration is based on the OEM Calibration Procedure? Please advise.

Hi Ajit,
Thank you very much for differentiating the meaning of reference standard against working standard.
Best regards,
Raffy

Hi Raffy,

If I understand the question correctly, you are asking only about the correct details to enter in the a Certificate of Calibration in regard to the procedure used.

If it were my Certificate of Calibration, and I were concerned to be sure that I specifically described the method used, I might be a little more specific than just to reference OEM method (although it is very common to do that).

If you want to specifically cover that detail very well, I recommend entering the exact procedure used. If it is the OEM method, perhaps enter the document number and revision date (or revision number/letter). As far as describing method used, this is the most unambiguous description (in my view). This does not guarantee it is the correct or adequate procedure. But in my view, does fully meet the requirement to tell what method is used.