Archimedes’ principle has long been applied for measuring density. If highest precision is required this buoyancy method is always used to determine for example reference densities of liquids, gases or solid sinkers under comparatively simple conditions.

The ability of weighing a sinker through a high pressure wall by means of a magnetic suspension balance enables us now to apply the most accurate density measuring method in a very wide temperature and pressure range and for aggressive fluids.

To obtain optimal conditions for measuring the density of fluids, fluid mixtures and two-phase equilibrium of fluids a special suspension coupling was developed. This very compact instrument is optimal for flushing and easy to thermostate. Here, the coupling housing and measuring cell including sinker perform as a unit.

Temperature range of the standard version is 190K up to 500K. Extended version ranges from 77K to 700K. Special versions for pressures up to 200MPa are available.

Density measuring range is up to 2000 kg/m3. Resolution reaches down to 0,00005 kg/m3 and an accuracy in density of 0,01 % +0,0005 kg/m3 is achievable. 

For the last 12 years magnetic suspension balances have been used at the Chair of Thermodynamics at the Ruhr University Bochum, Germany, to measure reference densities of most important pure fluids and natural gases with highest precision.

The world standard of density measurements uses this technology as do several national institutes of standards