Is calibration of test weight required

[AstorBannerman]

Hi
At our comp[any we made changing tables, shower trolleys etc. for adults who need assistance during hygiene tasks.
Part of the testing procedure is placing weights onto the support surface for a period of time, the tolerance on weights in the relevant standard is +5% -0%.
My question is this,
Each weight can be up to 40kg grouped together to reach 200kg or above. we have a certified scale which is calibrated yearly and verified before use. In 9001 7.1.5.2 it says verified, calibrated or both. Are we OK to say the weights are verified using the certified scales and recorded. These weights are simply standard cast iron weights, no means of calibrating simply lumps of metal that have a certain mass. As far as I can see as long as this mass is verified using the scales all should be fine.
Is my assumption correct.
Thanks

 

[Tagin]

Yes, that's ok. You'll want to be able to show an auditor how the calibrated scale will suffice (precision, range, etc.) for this purpose. You'll also want to have ID tags on each weight to match to a calibration record entry for that weight.

 

[AllTheThings]

If you are referring to those gold or silver Troemner/rice lake weights, the other thing I do is note an inspection interval. Calling out inspection for paint damage, damage to the lead slugs, etc. is a good way of checking the mass hasn't changed between some kind of more formal verification/calibration. Right now, I have mine on 2 year intervals for external 17025 cal, but may stretch to 5 if an auditor lets me get away with that interval and the inspections I noted.

 

[Jen Kirley]

Good day AstorBannerman, welcome to the Cove!

What you are describing is called a self-certified "transfer" instrument and is not very different from the massive rail car weights used to check scales used for rail transportation of chemicals. You've received good advice here about the care of those weights that I hope you will heed. The point is that test weights do change and need to be periodically verified, especially for sensitive industries like personal care. J.A. King describes it in their article Proper Storage and Handling of Test Weights.

I hope this helps!

I am not affiliated with J.A. King.

 

[QChas]

Yes, that's ok. You'll want to be able to show an auditor how the calibrated scale will suffice (precision, range, etc.) for this purpose. You'll also want to have ID tags on each weight to match to a calibration record entry for that weight.

This is the same approach we use with weights being calibrated every 5 years.