Process and apparatus for impregnating wood

Claim 1

A PROCESS FOR IMPREGNATING WOOD IN WHICH THE WOOD AND THE IMPREGNATING LIQUID SUBSTANTIALLY SURROUNDING IT ARE SUBJECTED TO PRESSURE CHANGES IN A PERIODICAL COURSE CONSISTING OF CYCLES, CHARACTERIZED IN THAT EACH CYCLE CONSISTS OF A HIGH PRESSURE STAGE, SURING WHICH THE PRESSURE OF THE IMPREGNATING LIQUID IS MAINTAINED HIGHER THAN THE PRESSURE OF THE AIR WITHIN THE WOOD, BUT NOT HIGHER THAN ABOUT 18 KG/CM.2 ABSOLUTE PRESSURE, AND A LOW PRESSURE STAGE, DURING WHICH THE PRESSURE OF THE IMPREGNATING LIQUID IS MAINTAINED LOWER THAN THE PRESSURE OF THE AIR WITHIN THE WOOD, BUT NOT LOWER THAN ABOUT 0.03 KG/CM.2 ABSOLUTE PRESSURE; THAT THE CHANGES BETWEEN THE HIGH PRESSURE STAGES AND THE LOW PRESSURE STAGES ARE CARRIED OUT VERY RAPIDLY AND SUBSTANTIALLY INSTANTANEOUSLY; THAT THE LENGTH OF EACH CYCLE IS WITHIN THE RANGE OF ABOUT 10 SECONDS TO ABOUT 10 MINUTES; THAT THE RATIO WITHIN EACH CYCLE OF THE LENGTH OF THE HIGH PRESSURE STAGE TO THE LENGTH OF THE CYCLE IS FROM ABOUT 10% TO ABOUT 95%; THAT THE LENGTH OF EACH CYCLE AND THE RATIO WITHIN EACH CYCLE ARE SUCCESSIVELY INCREASED DURING THE IMPREGNATION BY STARTING THE IMPREGNATION WITH THE LOWEST VALUES AND TERMINATING IT WITH THE HIGHEST VALUES; THAT THE PRESSURE OF THE AIR WITHIN THE WOOD DOES NOT EXCEED APPROXIMATELY 1/4 OF SAID HIGH PRESSURE AND IS SUBSTANTIALLY EQUAL TO THE ATMOSPHERIC PRESSURE; AND THAT THE NUMBER OF CYCLES, WHICH STATES THE TOTAL DURATION OF THE IMPREGNATION, IS NOT LESS THAN OF THE ORDER OF ONE HUNDRED.