12 replies to this topic

[fsafety15]

Hi everyone,

I 'm confused about the term "calibration" for scales. I work for a seafood processor company and we have scales that are calibrated once a year (or as needed) by a third party company. In-house we check the scales to verify the accuracy. My question is, is calibration  the same as checking the scales?

 

[pooled]

Yes, you are verifying that they are accurate & functioning as they should be. Then if you are out of range will have either trained maintenance correct or call a certified contractor to come and correct it.

[fsafety15]

Ok so it means that in our procedure we are just checking the scales not calibrating them, right?

[Charles.C]

Hi everyone,

I 'm confused about the term "calibration" for scales. I work for a seafood processor company and we have scales that are calibrated once a year (or as needed) by a third party company. In-house we check the scales to verify the accuracy. My question is, is calibration  the same as checking the scales?

Calibration

 

A set of operations that establish, under specified conditions, the relationship between values of quantities indicated by a measuring instrument or measuring system, or values represented by a material measure or reference material, and the corresponding values realised by standards.

 

 

So it depends on what is being interpreted as "Calibration", "Accuracy" etc

 

A typical in-house calibration of a (basic) scale requires the use of officially certified standard weights and noting the readings at appropriate points in the operational range. The calibration is satisfactory if the difference (error) complies with the instrument's specification (or perhaps some operationally required tolerance).

 

The above may/may not be identical to an external "Calibration" procedure.

[Slab]

Hi, foodsafetytx;

 

Ok so it means that in our procedure we are just checking the scales not calibrating them, right?

 

 

 

I hate to be that guy to split legal hairs (U.S.), but by definitions there is only a legal term of 'calibration' as the comparative values of a measuring device under test to an applied value of a known reference. "Known" being the key definition here of the process.  Traceability certs to calibration standards by an authoritative body need to be applied. Normally (U.S.), this is managed by municipal authorities.

 

 

You need to have your scales under surveillance of local jurisdictions to satisfy U.S. commerce laws, and in the event of a device used to monitor a critical limit also satisfy USDA, USDC, and USFDA regulations for applied guidance documents.

 

I've attached a few files for you review provided by NIST which govern this topic:

 

 NIST Handbook 44.pdf   5.29MB   33 downloads

 NIST Handbook 133.pdf   3.79MB   23 downloads

 

 

Essentially in summary, there is no 'check'. Either a measuring device is verified calibrated to a known reference or it is not. 

[Charles.C]

Hi Slab,

 

Interesting Post. Thks.

 

Does the above apply to all types of scale / products / types of establishments/facilities/etc in US or is there a defined scope ?

 

I would anticipate that strict observance nationwide would mean that not possible to do in-house "calibration" of scales anywhere. Seems sort of Draconian.

[fsafety15]

^{Thank you all for your help. This is the first time I post something and I really appreciate all the info. Thanks again!}

[redfox]

Hello All,

 

That is also our dilemma on what to label our form on our in-house scale calibration? or verification?

 

Could I mention "accuracy" and "precision" which also contribute the reliability of the instrument. A precise scale could display data far from known value but will give almost the same result repeatedly. Can we apply correction factor on this and everything will be alright?

 

One thing is, who can decide that the instrument is already OOT? I have read some articles about OOT, but it only gave ambiguity to me, and as far as I understood, the burden is still passed on to the user to determine or to decide whether the instrument is already an OOT.

 

regards,

redfox

[Slab]

Hi Slab,

 

Interesting Post. Thks.

 

Does the above apply to all types of scale / products / types of establishments/facilities/etc in US or is there a defined scope ?

 

I would anticipate that strict observance nationwide would mean that not possible to do in-house "calibration" of scales anywhere. Seems sort of Draconian.

 

Hi, Charles;

 

Jurisdiction applies if measuring devices are engaged in the exchange of goods, i.e. trade

[Charles.C]

Hi, Charles;

 

Jurisdiction applies if measuring devices are engaged in the exchange of goods, i.e. trade

 

Hi Slab,

 

Thanks.

 

How about if you are shipping semi-finished product, ie is the jurisdiction only applicable to items intended for direct public commercialisation, ie retail/wholesale.?

[Slab]

Hi Slab,

 

Thanks.

 

How about if you are shipping semi-finished product, ie is the jurisdiction only applicable to items intended for direct public commercialisation, ie retail/wholesale.?

 

Hi, Charles

 

If you mean for internal use, then it does not apply. Normally those scales should be identified as 'not legal for trade'. However if the product enters into commerce then by law it requires a weights and measures seal. Of course this is one of those laws that are neglected either willfully or through ignorance.

[Charles.C]

Hi Slab,

 

Hard to believe but I was unable to find a single definition of "Calibration," per se, in either of the 2 NIST Handbooks in Post 5 ! Maybe it's there somewhere.

 

Regardless, I think my interpretation (BRC/Post4) probably differs to the US legal one described in Post 5.

 

Basically, assuming "checking" as mentioned in OP is carried out as per my Post 4, my generic answer to the OP's query is Yes, regardless of the "status" of the material involved. I think yr answer as legally elaborated in Post 5 for US would "generally" be No (?). (I'm unclear as to how the legal viewpoint compares to typical US Production practice).

 

"Calibration" is notorious for generating "Confusion."

[CMHeywood]

Usually 3rd party auditors are looking to see that your check weights would be traceable back to NIST or equivalent.

 

How do you know that your check weights are exactly the weight you assume they are and have not changed?