Is a "certificate of accuracy" enough for a class f weight which is being used for calibration of our shipping as well as our digital gram scale, or are we required to have a "certificate of traceability" as well?

Hello! and welcome to the board!

By your post, I am not totally certain what the differences are between a certificate of accuracy, and a certificate of traceability. Can you specify what the differences are between these two documents?

Minimally, you need to have adequate compliance with whatever regulatory agency you are subjected to. What are your requirements for needing to have this weight "certified"?

If you could provide a little bit more information, it would be greatly appreciated.

The paper provided to you may not be enough, and here's why.....

If you want your calibration to be traceable to National standards (whether NIST or another NMI), then the internationally recognized requirements are:

An unbroken chain of comparisons to National or international standards, so the specific chain must be documented.....by that I mean the specific standards used to calibrate your weights have a certificate number from their calibration.....that certificate number needs to be included on the certificate provided to you as a part of the calibration standards reference.....

Stated uncertainties at each step.....that means the measurement uncertainty of the calibration of your weights must be specifically provided.....

If you are missing either of these components, the calibration of your weights is NOT traceable and therefore the certificate provided to you is worthless.....

It also means your internal documentation should strive to have the same criteria met, in order to be traceable.

Hope this helps.

Hershal

If you are missing either of these components, the calibration of your weights is NOT traceable and therefore the certificate provided to you is worthless.....


Point of clarification, please. If a cal certificate positively identifies standards that meet the criteria you cite (i.e., the certificate information may be used to positively identify the calibration provider's traceability data) is that not sufficient? In other words, is the ability to trace not considered traceability?

Hence the reason I posted for clarification. There are a lot of pieces of paper floating around out there, with multiple titles/labels. Some of them are excellent, and like Hershel posted, some of them are worthless.

For me, I need to know what the differences are between what the two certificates state was completed (who/what/when/where/how).

Unless we know where these certificates came from, and what they are espousing, I think we are guessing in trying to help the OP.

Maybe he/she can provide some more details.

OK, I thought a bit about what Jim posted. Is it accurate to state the assessment of uncertainties as a "must" everytime or can it be a "must" given your requirements?

Moderator's Note: I moved this post to the Calibration Forum, since it is more about calibration and certificates.

Point of clarification, please. If a cal certificate positively identifies standards that meet the criteria you cite (i.e., the certificate information may be used to positively identify the calibration provider's traceability data) is that not sufficient? In other words, is the ability to trace not considered traceability?

It is actually half of traceability.....stated uncertainty at each step is the other half.....both must be present in order to have traceability, according to VIM (International Vocabulary of General and Specific Terms in Metrology).....VIM is one of the main documents in metrology.

Hershal

Greetings Turk,

It is important for us to understand what the end use of the scale is.
Are you operating under a certain standard? ( Good Manufacturing Practices, FDA, FAA, any ISO/IEC etc…) Or is it your state weights and measures?

As you can tell, certificates come in all kinds of flavors depending on how much you spend. Only spend what you need to for your requirements. I reference Hershal’s previous posts for the definitions.

Are you doing your own calibrations? If so, do you have someone with the level of competence needed for the standards you operate by?
Shipping scale:
If you are just putting a weight on your scale for your own reference/verification in house, you may not need any certs at all. After all, if 50Lb does not read 50Lb, you are going to call the scale company. :notme: Right??
Gram scale:
Depending on the resolution of the scale you may not be able to use Class F weights at all. The scale may be sensitive enough to pick up the variance of the weight within its stated tolerance.