Description

The mercury porosimeter accurately determines the bulk and pore volumes of core samples. The apparatus comprises a mercury cell capable of accommodating between 10 to 15 cm3 samples, and a manual, helical screw pump equipped with a volumetric Vernier calliper graduated in 0.01 cm3 increments. A pressure gauge located on the cell indicates the system pressure up to 100 bar. Initially, the closed cell is entirely filled with mercury by means of the pump’s rotary crank, and the corresponding volume is read from the calliper. Mercury is then removed, the cell lid unscrewed, and the sample, placed inside. The system is evacuated by connecting a vacuum pump to a port located on the cell. Once the vacuum has been established and the vacuum pump shut off, the mercury will flow back into the cell to restore atmospheric pressure. The difference between the first volume reading and the current one indicates the bulk volume. To obtain the pore volume, the system must be pressurized to its maximum, i.e. 100 bar, at which point, the mercury will have invaded all the interconnected pore space. The difference between the new volume reading and the previous yields the pore volume.