Helium Picnometry uses the gas displacement to determine the volume of the sample. The density is calculated using the sample weight, measured on an analytical balance. The instrument measures the volume of the sample, excluding the interstitial voids between the particles in the powders and any open porosity to which the gas has access in the individual particles. The internal porosity (closed) is instead included in the volume.
This test is normally performed at room temperature, but can also be performed between 0 ° C and 50 ° C (to be specified by the customer).