| 摘要 |
One or more logs are placed in a chamber (10) having a porous wall (13) which acts as a filter, one end of the logs being in contact with liquid in the chamber and the other end being in close contact with the porous wall and embedded in a filter cake (28) formed by filtering a slurry through the porous wall, and a difference in pressure is applied between the two ends of the logs such that liquid is forced longitudinally through the logs and out of the chamber through the porous wall. The pressure difference may be up to 1,000 psi. A positive and/or negative pressure, respectively, may be applied to the liquid and porous wall. The porous wall may consist of a layer of fabric supported on a porous plate. The filter cake may have a finer layer surrounded on a coarse layer to produce a good seal. The slurrying liquid may be the same as or different from the impregnating liquid. The method may be used for impregnating logs with liquid so as to proof them against fire, chemicals, decay, or physical distortion. In a modification, logs may be dried without impregnation by employing hot liquid at a pressure only sufficient to prevent vapour passing out into the liquid. In another embodiment (Figs. 6 and 7), one end only of a log is contained in a chamber (88), the intervening space being filled by a filter cake (99) which acts as a seal, the porous wall (97) being replaced by a cap (101) carrying an inlet pipe (102) for supply of the impregnating liquid. |
