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Metal Detection Verification and Validation

Metal Detection Validation Verification SQF

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Posted 19 April 2022 - 07:39 PM

We are a dry blending plant that packages in bulk, pouch & bottles. We follow SQF Guidelines.


Previous year we received a nonconforming  ( metal detection) on the bottling line when the wands passed thru with no issue - but didn't  go off  when product was added to the bottles. It was given as Validation Failure.  Auditor gave " industry standard/best practice -that each wand be run thru. The add to bottle 1/3 full of product , 2/3 & full. We do this at the beginning & end of runs. We just test the wands during the run. 


My question is:

Bulk  (drop thru) we drop wands thru one at time. We "validate" monthly by putting the wands in food safe bags with product. Is this ok?- 

Pouch (conveyor) - we run the wands between 2 bags of product. Is the verification? What is the validation ? 







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Posted 19 April 2022 - 08:14 PM

My question is have you validated your metal detector???  


That means, have you intentionally added metal to your finished goods (in a controlled situation on marked containers) to see the rejection rate?  Have you done this for each and every item you produce?   Once done, did you compile all of those data points into a summary explaining what you did and what you found?  If you discovered that test pieces were not rejected under certain circumstances, what did you change?  did those changes prove effective?


Both of the scenarios you mentioned are verifications only---you are verifying that the metal detector is still functioning as intended


you've missed what "as intended" means in your facility


The only time wands should/could be passed without product is at the beginning and end of shift (preferably also with product at end of shift) and only done that way to ensure the detector is still working at end, and is working at start up BEFORE you run product

Please stop referring to me as Sir/sirs


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Posted 19 April 2022 - 08:19 PM

Hi Buddha321,


In regards to putting the wand in the package with your product, why not just place the package on top of the wand? Less chance for contamination that way. 


For verification and Validation I think of it like this (and someone please correct me if I am wrong). I verify that the metal detectors are working at set times throughout the day as the production lines run. Then, the calibration company validates it once a year with their "calibrated" test pieces. 

Nicole Farmer



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Posted 19 April 2022 - 08:41 PM




The answer is no - but doing that makes sense as validation.  My confusion remains - for bottling adding the wands  to the filled product was counted as validation ( or lack of) by the auditor. So this is validation?


For pouch if we run every product with the wands inside a actual pouch is this verification or validation? For validation would we be using an actual piece of metal that is not the wands? 


Bulk - can we put the wands in a scoop of product & drop thru the metal detector or will it need to be in a bag? 


Basically  if we test the wands at the beginning and end of each run ( every 3 hours, after lunch, breaks or machine is turned off)  this is verification. i we add the wands to product ( no matter how often we do it) this is validation? Or does it need to be something besides the wands.


Thank you so much for your help!


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Posted 20 April 2022 - 12:19 AM

It's ideally about the relevant Standard and its interpretation -


FWIW here is SQF's ver 8.1 Guidance (to 11.7.6) -


What do I have to do?

Specific work instructions must be written on the monitoring of foreign material detection and prevention devices.  The frequency of monitoring such devices, the criteria used in monitoring, and the corrective actions to take when foreign materials are discovered, or issues are discovered with the effectiveness of the prevention device must be defined within the methods.  For example, if a metal detector must reject three wands (2.0 Fe, 2.5 non Fe, 3.0 SS) to pass, then when all three wands are not rejected, the site must have defined criteria for how such an incident will be handled including product identification and disposition (i.e., if the detector should fail, all product since last good check is placed on hold and must be re-run through a working metal detector).

Metal detectors, x-ray, color sorters (if used for defects or foreign material) and all other detection devices must be validated to ensure that they can effectively detect a foreign object within the packaged product that is passed through the device. 
The passing of wands through the device to ensure that it is working is verification.
An example of a means for validation of a metal detector could be the placing of a piece of metal within the package of product (product would be marked to ensure it does not enter market).  All types of packaging and sizes of product that are passed through the device must be validated as well as all new packaging or size of product.


(the above interpretation of Va/Ve  is IMO incomplete, eg  compare the examples attached below) (and "Monitoring" = ?)


In the above, "Validation" (and thereby "Verification") is operationally interpreted as Validation of the Critical Limit for the MD (if a CCP).


Illustrative SOPs for Validation and Verification could be -

Attached File  Validation Study for MD - CCP.pdf   90.24KB   52 downloads

Attached File  Verification of MD - CCP.pdf   35.96KB   49 downloads

Kind Regards,



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Posted 20 April 2022 - 02:00 PM

Thank you everyone! I am writing the new procedures for validation & starting testing tomorrow.

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