National Physical Laboratory

Density of particulates and powders

Density of particulates & powders

NPL has developed a liquid pyknometry technique for the density measurement of particulates and powders. The technique is also suitable for the density determination of small artefacts that are not suitable for measurement by hydrostatic weighing (i.e. less than about 10 grams in weight). The certified density values are traceable to the national standard of mass and to the density of water and the density of the reference liquid used for the individual calibration (the liquid used will vary depending on the nature of the sample under test). The method has been validated by determining the density of samples of single crystal silicon.  

Typically, sample densities are determined at 20 °C but measurements can be made in the range 10 °C to 70 °C. The ability to precisely temperature control the samples additionally allows the accurate measurement of the coefficient of thermal expansion, which is difficult to determine using other measurement methods. Depending on the nature of the sample under test, uncertainties of the order of 0.1% can be achieved.

Where appropriate, NPL can also calibrate the density of particulates and powders by conventional helium pyknometry techniques.

The supplied certificate of calibration will give the measured density of the liquid, together with an associated uncertainty. If requested, the coefficient of thermal expansion will also be provided.


Customer Service tel: +44 20 8943 6245

Last Updated: 25 Mar 2010
Created: 25 Feb 2010


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