Density analysis by helium pycnometry (AccuPyc II 1340, Micrometrics) is used to obtain information on the true density or real density of solids. A gas pycnometry operates by detecting the pressure change resulting from displacement of gas by a solid object. Helium gas is used since it is inert to testing materials and can enter the smallest pores or voids. The pressures observed upon filling the sample chamber and then discharging it into a second empty chamber allows computation of the sample skeleton density. When combining the results with geometrical data information on the volume porosity can be obtained.
Reproducibility typically to within ± 0.01% of the nominal full-scale sample cell chamber volume, 1 cm3. Reproducibility guaranteed to within ±0.02% of the nominal full-scale volume on clean, dry, thermally equilibrated samples using helium in the 15 to 35°C range.