General Metrology Forum

Accounting for Calibration Uncertainties not listed on Certificate

Picture of Shane Johnson
Re: Accounting for Calibration Uncertainties not listed on Certificate
by Shane Johnson - Wednesday, May 19, 2010, 9:58 AM
In my case I had to send my HP 3458A to Hydro Quebec. The only way I was able to claim the transfer uncertainty for my budgets was to have a number for the point claimed. I actually had to design the data form for testing and pay double the cost of standard accredited calibration. The standard procedures from the manufacturer did not cover all the ranges and the Calibration Laboratories Assessment Services from the National Research Council of Canada insisted on this as part of my budget.
In closing it is my opinion the ranges or points not calibrated do not have traceability and can not be used in your claims. You can not claim the number from the manufacturers scope or assume a worst case value because it was not tested at the points in question. If you want to make a true claim you are going to need the unit calibrated at the points you want to add to your scope.
NIST and VIM include in their definition of traceability: "the property of the result of a measurement or the value of a standard whereby it can be related to stated references, usually national or international standards, through an unbroken chain of comparisons, all having stated uncertainties."