On the permeability of main wood species in China

This research dealt with the longitudinal air permeability of 40 important Chinese woods. The air permeabilities measured at about 10% moisture content for softwoods ranged between 0.00759 and 1.87130 darcy, while for hardwoods ranged between 0.00182 and 13.49867 darcy. The sapwood permeability of both softwoods and hardwoods was generally much higher than that of heartwood with 3 to 144 and 1 to 1302 times, respectively. The permeability values of wood were not affected by density between and within species. In all species studied, the permeability of heartwood of all softwoods, about 70% ring-porous and about 30% diffuse-porous or semi-diffuse porous hardwoods were below 0.1 darcy. The number of low permeability softwoods was higher than that of hardwoods. The number of low permeability ring-porous hardwoods was higher than that of diffuse-porous or semi-diffuse porous hardwoods. Finally, all the studied species were classified into five categories by their longitudinal permeabilities.