Calibration Standard
Technical guidelines published by regional metrology organizations establish harmonized procedures for verifying the accuracy of laboratory instruments. Within European metrology, euramet cg-17 defines the step-by-step methods for calibrating non-automatic weighing instruments such as analytical balances and platform scales. This document provides laboratories with a standardized framework to determine instrument errors and estimate measurement uncertainty.
Uncertainty Evaluation
Repeatability tests form the foundation of the evaluation process, requiring multiple measurements at a single load point to quantify random variations. These trials reveal the dispersion of indications under identical conditions.
Environmental Influence
Thermal drift poses a challenge to calibration validity, as changes in ambient temperature alter the sensitivity of the weighing cell. To maintain traceability, the guidance specifies temperature stability limits that must be observed during the test sequence. Drafts and floor vibrations must also be controlled because they introduce high-frequency noise that distorts the calibration curve.
Verification Protocol
Calibration certificates must record the measured errors alongside their expanded uncertainties to allow users to assess the instrument for its intended task. The resulting data enables the calculation of a minimum weight threshold below which the relative measurement uncertainty becomes unacceptably high. This threshold ensures that subsequent measurements remain within the specified tolerance limits of the laboratory.
