Comment fonctionne un pycnomètre à gaz ?
The principle of the gas pycnometer is to inject a known mass of sample into a cell. The gas is expanded. Mariotte’s law is then used to determine the volume of the sample being weighed: it relates the sample volume, the cell volume and the initial and final pressures. Several measurement cycles are performed on the same sample to obtain a reliable average.
This type of device is used to determine the skeletal density. This density corresponds to the volume without the pores open to the outside. It is greater than the so-called bulk density, the volume of which includes the volume of open pores.
The gas most commonly used for this type of measurement is helium. The latter is indeed small enough to explore the smallest pore diameters.
The gas pycnometer used by Calnesis allows measurements to be made at room temperature.