Determination of Air Density with Buoyancy Artefacts

Sari Semenoja, Kari Riski and Leena Stenlund

Abstract

When comparing mass standards with large volume differences the density of air is one of the largest uncertainty components for mass. The air density can be determined by direct weighing using buoyancy artefacts or it can be calculated from the CIPM 81/91 formula. A small relative difference (about 6·10^-5) between these two methods exists. The aim of the present work is to verify this difference and to gain experience on vacuum weighing and on the stability of weights. Two buoyancy artefacts with different volumes were utilized. The artefacts were compared in vacuum and in air. From the weighing results air density was calculated and compared with the CIPM formula. The following value for the relative air density difference was obtained 4 x 10^-5 (u=7 x 10^-5).

Keywords

air density, buoyancy artefacts, vacuum weighing

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IMEKO-TC3-2007-063u.pdf

DOI

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IMEKO TC

TC3 - Measurement of Force, Mass, Torque, and Gravity

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