Bilateral comparison of buoyancy artefacts between PTB and KRISS

Buoyancy artefacts (BAs) are used for the experimental determination of air density. The artefacts used for this comparison were manufactured at the PTB and the KRISS respectively and consist of one hollow cylinder and one bobbin. Mass differences of the PTB and the KRISS BAs in vacuum and in air are measured simultaneously by using the PTB prototype mass comparator.Results of the bilateral comparison including uncertainty budgets and the deviation between air densities obtained by the BAs and those calculated by the International Committee for Weights and Measures (CIPM) formula are presented. Additionally, a comparison with a correction of the CIPM formula based on recently measured values for the air composition is given.