The Pore Analysis GeoApps section contains a GeoApp for the calculation of the ASTM pore size calculation factor according to the ASTM E3278-21 standard.

In this standard, the hydraulic diameter bubble point pressure, percolation path fitting particle diameter, and pore size calculation factor (CF) are generated using the PoroDict module of GeoDict. The CF is used to calculate the pore size of filter cloth from the measured bubble point pressure. These parameters are derived from the non-circular cross-section of the bottleneck through-path of the filter cloth.

This method employs a capillary flow technique in which air pressure is applied to drive a bubble through a flat specimen of industrial woven wire filter cloth wetted with a liquid of known surface tension. As the required pressure is inversely proportional to the pore size, the measured bubble point pressure is used to determine the pore size. The procedure defines the measurement and standardization of pressure and the calculation of pore size using the CF factor.

For further details, refer to the GeoDict website and ASTM E3278-21 standard.

The bubble point pressure calculation factor can be determined using only geometric information, i.e., pore throat area and pore throat circumference. To calculate the CF, a distance map and a percolation path are computed, and local minima in the distance map are used to identify candidate pore throat locations. At each candidate, cutting planes with varying orientations are evaluated using planar ray tracing to determine the cross-sectional area and circumference. The plane with the minimum area defines the effective pore throat, from which the CF is computed. This approach enables accurate bubble point estimation for complex, non-circular pore geometries.

The computation of the ASTM pore size calculation factor was tested and optimized on several metal wire weaves. In the ASTM test, the wire weaves are put in a containment filled with water, while air is injected from below the weave. The bubble point pressure is reached when the first air bubble pushes through the weave layer.

The available result files in the Data Visualization tab of the Result Viewer are the same as for the Bubble Point command.