This Technical Report gives the detailed evaluation of uncertainty for volume measurements according to the

Guide to the Expression of Uncertainty in Measurement (GUM) [1]. It uses the gravimetric method specified in

ISO 8655-6 [2] as the reference method for calibrating piston-operated volumetric apparatus. It has been arranged

in paragraphs to facilitate direct access to different aspects of this kind of evaluation as follows:

_ modelling the measurement by describing the physical equations necessary to calculate the volume using the

gravimetric method of measurement;

_ determination of the standard uncertainty of measurement associated with the volume V20 by describing the

calculation procedure according to the GUM;

_ determination of the sensitivity coefficients with an example of the calculation of all sensitivity coefficients by

using complete equations, approximations of equations and by giving numerical values for standard

conditions;

_ determination of the standard uncertainty associated with the volume delivered by a piston-operated

volumetric apparatus giving the combination of the standard uncertainty associated with the volume V20

measured using the gravimetric measuring system and the experimental standard deviation associated with

the volume delivered by the apparatus;

_ determination of the standard uncertainties of measurement with a brief insight into the calculation of

uncertainties of measuring devices according to GUM;

_ determination of the expanded uncertainty of measurement associated with volume V20;

_ example of the determination of the uncertainty for volume measurements.