Auditor interpretation of PO data - PO submitted for outside calibration


Mark Bidinger

A friend I know just went through a 1st time registration and were given a minor due to the fact that the PO submitted for outside calibration did not specifically call out the test method and criteria for each type of measurement device they had in house, the PO merely stated that it was the suppliers repsonibility to know the appropriate ASI/ASTM/NIST test required and the subsiquent critiera. The Lead Auditor felt this was not enought, that all the specifics should be on the PO

Does this make sence to anyone. I can see having a master list on hand of the information, which is provided to the supplier, and referenced on the PO, but tohave to call them all out on the PO?

Any one else run in to this or have suggestions as to how to resolve?


Jim Triller

I suggest requiring in the PO that the device must be calibrated in accordance with the manufacturer's recommendations. Additionally, if the calibration supplier is ISO 9000 registered or has a Z540 system in place the PO should state that the calibration must be performed in accordance with the supplier's quality management system.


I have been involved with metrology labs for years. A few simple lines on a PO should satisfy an assessor. Are you sure your assessor understands metrology (calibration) enough to understand what should be on the po?

Every piece of equipment sent out should have on the PO for it:
1. Item, serial number, manufacturer (to conclusively and unambiguously identify the item) as well as any standard number you have assigned
2. What is required, for example: Calibration and certification in accordance with ISO 17025, ANSI/NCSL Z540-1, etc. with before and after data traceable to NIST or industry accepted standards.
3. If it is an electrical device or a device that can easily have the calibration tampered with, a statement such as "Tamper resistent seals required"
You are not requried nor should you be expected to know about every calibration. After all you are sending the equipment out of your facility. It is important that the person you send the calibration to is an 'Approved' source for calibrations and shows as such on your approved vendor list. It is also important to indicate, usually with initials, that after the calibration PO has been generated, someone has reviewed it for the required statements. This is not approval of the PO, just review that all the proper verbiage is present. A copy of this PO needs to be in the history folder for the equipment as well.
It is up to you also to review the Calibration Certificate and the Data supplied when the instrument returns. Evidence of this review is also necessary and initials at the bottom of each page should suffice.
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