The open porosity is defined as the fraction of volume that is occupied by the fluid in the interconnected porous network. Non-interconnected voids trapped in the solid phase are not part of the open porosity; they are part of the closed porosity. The true bulk density is in the vacuum density of the porous aggregate.
Equipment: Porosity and Density Meter
Method 1: Isothermal pressure/mass method 
Method 2: Missing mass method to measure open porosity of porous solid 
Properties: ϕ – open porosity; ρ – true bulk density (kg/m³)
 Y. Salissou and R. Panneton, “Pressure/mass method to measure open porosity of porous solids,” J. Appl. Phys. 101, 124913 (2007).
 R. Panneton and E. Gros, “A missing mass method to measure the open porosity of porous solids,” Acta-Acustica 91(2), 342-348 (2005).