Report, Temas1661-1690U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, 1947 |
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17 laminations 90 percent adjacent to joint aspen groundwood birch Black tupelo butt joints cauls chemical coils columns Comp condensate control beams cross section curve delamination density diameter Douglas-fir beams dried dry kiln fans feet fiber Figure Forest Products Laboratory FOREST SERVICE freeness glued grinding groundwood pulps hardwoods header heartwood heat increase insulating board kiln kiln drying knots laminated beams laminations length load lower lumber material maximum method modulus of rupture molecular obtained Paper paper birch percent relative humidity pounds per square pressure PRODUCTS LABORATORY Madison proportional limit quaking aspen ratio red oak resorcinol samples sapwood scarf scarf joints series D softwoods southern yellow pine specific gravity specimens spruce square inch steam stone-surface condition strength stress sulfite pulps tanoak temperature tena tene tens tests thickness trap trees vapor waste weight Western hemlock width wood failure yellow birch
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Página 1 - An adequate rate of air circulation hastens the evaporation of moisture from the lumber and thereby shortens the drying time. The needed rate of circulation will, of course, depend upon the movement of moisture through the wood. For efficient drying, the more rapidly the moisture diffuses through the wood, the faster should be the air movement through the kiln charge.
Página 14 - ... relative conductivity. A qualitative demonstration of the ratios of radial to tangential diffusion in five hardwoods and Douglas fir confirmed the results found in the conductivity measurements and further supported the assumption that relative conductivities and relative diffusion constants are equal. Microscopical measurements of the number of fibers per centimeter in the radial and tangential directions, of the thickness of the double cell wall, and of the fractional pore volumes of hardwoods...
Página 1 - Ventilation of a kiln is important, especially in the early stages of drying green lumber. If the water evaporated from the wood had no way of escaping from the kiln, the kiln atmosphere would eventually become saturated with moisture and drying would stop.
Página 11 - Note; A relatively slow initial drying rate is needed. 1. Use wider piles or a double-pile on a common foundation. 2. Use minimum space between piles (2 feet). 3. Use minimum width of flues ( 1 inch ) . ty.
Página 1 - ... doors at both ends, the tracks are usually installed with a slight downgrade from the front (loading) to the back (unloading) end so that trucks, especially when moved by manpower, can be handled more easily. 3.4. HOW A KILN WORKS.— Lumber is kiln dried by circulating air controlled with respect to temperature and humidity through the kiln charge to evaporate the water contained in the wood and expel it from the kiln. Air circulation is required to convey the heat from the heating coils through...
Página 35 - Effect of elliptic or circular holes on the stress distribution in plates of wood or plywood considered as orthotropic materials.
Página 8 - ... freeness were generally higher and the strengths generally lower for the higher speed. A comparison of spruce and aspen ground under the same conditions showed a lower grinding rate, a higher energy consumption, higher strength, lower freeness, and shorter average fiber length for spruce than for aspen.