Mercury intrusion porosimetry is a well known technique that has been widely used for pore structure measurement. Mercury does not enter pores spontaneously, but can be forced in to pores. Pressure required to intrude mercury in to a pore is determined by the diameter of the pore. Measure intrusion pressure and intrusion volume yield diameter and volume of through and blind pores.

In the porosimeter, mercury is forced into pores of solid material. The pressure required to fill the pores completely is inversely proportional to the size of the pores.

Capillary flow porometry is a liquid extrusion technique in which the differential gas pressure and flow rates through wet and dry samples are measured. This technique detects the largest pore diameter (or the bubble point), the mean flow pore diameter, pore distribution and gas permeability are computed.

The porometer is used for measurement of pore size distribution by the liquid displacement method. First, the sample is immersed in a wetting liquid, which fills the sample pores the liquid. An increasing pressure of dry air is applied on top of the sample. The air displaces the liquid in the pores of the sample, and air starts to flow through the sample. Both the air pressure and airflow are continuously monitored.

At low air pressures the wetting liquid is displaced from the larger pores. When the air pressure increases, all the pores are opened, and air totally displaces the wetting liquid. Subsequently, a similar run is done with the dry sample (the sample is dried during the first run). The number of pores with a certain size is calculated from the differences in the airflow of the two runs.

The results are represented in various pore size distribution curves, median, maximum and minimum pore size values.