MEASURING INSTRUMENTS CALIBRATION NEAR ZERO VALUE

Edi Kulderknup, Argo Pandis

Abstract

Problem of measuring instruments calibration near zero value exists by accreditation of calibration laboratories. Some calibration laboratories present its calibration capability minimum value as 0 [with measuring unit of quantity g] and others with some deviation &Delta;<i>g</i> from 0. Often it is given as &Delta;<i>g</i> &asymp; <i>U</i>(<i>g</i>), where <i>U</i>(<i>g</i>) is the expanded uncertainty. As concrete example can be given air relative humidity measuring instruments calibration, where measuring instrument has in the calibration certificate indication 0.3% relative humidity with expanded uncertainty <i>U</i> = 0.7% relative humidity, (<i>k</i> = 2).<BR />Taking account circumstances that expanded uncertainty <i>U</i> is typically shown with symmetrical distribution, but accordingly to the probability theory the negative probability can’t occur, exists disagreement.<BR />Above was the ground for this paper and presents propositions how the calibration scope is useful to present for minimum value taking account users’ needs and probability theory.

Keywords

calibration, accreditation, zero value

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IMEKO-WC-2012-TC11-P1.pdf

DOI

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IMEKO TC

TC11 - Measurement in Testing, Inspection and Certification

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