Permeability and Capillary Structure of Chinese Woods

Axial permeability measurements of Chinese spruce, pine, and birch were made over a range of average pressure from 1.6 to 54 cm Hg. Linear plots of permeability vs. reciprocal mean pressure were obtained for spruce and pine in agreement with the Klinkenberg equation. Pit-opening radii were calculated from the intercepts and slopes, and the number of openings per cm 2 of cross section were determined based on an assumed pit-membrane thickness of 0.1 μm. The plot of permeability vs. reciprocal mean pressure of the birch was curvilinear, indicating the presence of two conductances in series, which were assumed to be vessels and perforation plates. The calculated vessel radius and vessel concentration were in good agreement with data presented by Cheng (1980).