True Density is an important parameter to be measured. It is defined as the mass to the volume occupied by that mass. Therefore, contribution to the volume made by pores or internal voids must be excluded when measuring the true density. For non-porous material, it can be measured by fluid displacement method but for porous materials, where it is difficult to penetrate the fluid into the pores, gas displacement method is useful. The apparatus used to measure sample volume of such material is well known as 'pyknometers' or 'pycnometers' where 'pycnos' means 'thickness' or 'density'.

The instrument, Smart Pycno 32, is specifically designed to measure the true volume of powders, solids etc. It employes Archimedes Principle of gas displacement. Normally Helium gas is recommended since its small atomic dimension ensures penetration into finest pores. Its behaviour as an ideal gas is also desirable.

Smart Pycno 32 determines the true volume of powder or solid material. Different sample cell sizes are available to accommodate various samples. The Helium gas is pressurized in the known volume reference chamber. The sample cell is kept in the sample chamber. The pressurised gas is allowed to flow into this sample cell. Depending upon the sample volume, the initial pressure drops and becomes stable and that reading is noted. From these two pressure readings, true volume of sample is calculated. Finally the True Density of the sample is calculated by dividing the weight of the sample by its true volume. The reference chamber and sample chamber volume are initially calibrated by known volume stainless steel spheres.