Drying Tests with a Weight-Actuated Lumber-Drying Control System

An experimental weight-actuated lumber drying control system using four 25,000-lb electric load cells is described. The operating principle is that the load cells sense the change in weight, and therefore water loss, of the lumber. The load cell signal is fed to a set of dry- and wet-bulb temperature controllers. Drying tests were made with both white fir sapwood-sinker and ponderosa pine corky comparing the time of drying and rate of water loss. The tests were made with commercial schedules using manual, cam, and the weight-actuated control system. Two further tests using the weight-actuated system were carried out using higher-and lower-than-commercial starting temperatures. Tests indicate that significant reductions in drying times and drying rates may be achieved with the weight-actuated system. Based on initial equipment costs, operating ease, and the observed reductions in drying time, this system shows promise of commercial application.

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