Cover Factor Calculation Impact on Fluid Penetration Rates in Woven Fabrics
Accurate cover factor calculation defines interthread pore hydraulic radius, predicting hydrostatic penetration pressure and capillary wicking velocity in woven barriers.
Capillary Flow Porometry
Pore Diameter Analysis
Analytical techniques used to characterize the pore size distribution and permeability of porous materials allow manufacturers to optimize filtration performance. High-precision capillary flow porometry measures the pressure required to displace a non-reacting wetting liquid from the pores of a sample. This process provides data on the largest flow pores and the mean flow pore sizes within a textile structure.
Fluid Displacement Mechanism
Testing begins with the saturation of the material in a liquid of known surface tension. Compressed gas gradually increases in pressure until it overcomes the capillary forces holding the liquid in the pores. Because capillary flow porometry relies on the relationship between gas pressure and pore diameter, it identifies the through-pores.
Gas cannot pass through blind or closed cavities during this test.
Characteristic Measurement
The instrument generates a curve representing the gas flow rate through both wet and dry samples. A bubble point indicates the first sign of gas flow through the largest pore. Capillary flow porometry results are derived from the calculation of the mean flow pore size where the wet flow reaches half of the dry flow value.
Smaller pores require higher pressure to empty. Additional calculations determine the overall pore size distribution by comparing the wet flow curve to the dry flow curve across the entire pressure range.
Fabric Validation
Production units for medical masks and high-performance filters rely on these results to ensure barrier efficiency. Success in capillary flow porometry confirms that the pore structure meets the required specifications for aerosol or liquid filtration. Precise pore control determines the ultimate breathability and safety of the finished product.