2936 Chapter 24 



STORAGE 



In many regions it is usual to convey acceptable flakes from the screening 

 operation to bulk interior storage in concrete-floored bins; in this arrangement 

 flakes are removed from storage by front-end loaders and introduced into con- 

 veyors leading to resin blenders. 



The frequent high humidity in the Southern States can dampen freshly dried 

 flakes — if stored for several days — to a moisture content exceeding the 2-6 

 percent desirable when they are admitted to the resin blender. 



Some plant designers feel that operations can be made less labor intensive, 

 and flake moisture pickup avoided, if screened flakes are deposited in moving- 

 bin storage (fig. 24-17), providing 1-1/2 to 2 hours of storage ahead of the resin 

 blender; such bins have floors that move, thereby continuously conveying flakes 

 to the blender. Power to drive bottom conveyor chains, picker rolls, and rake- 

 back conveyor totals about 10 hp. 



Designers concerned with flake transport should appreciate that thin, long, 

 hardwood flakes for face layers are particularly difficult to handle. Conveyors 

 must be of ample width, and with minimum discontinuities. Wide belts, de- 

 formed into semi-tubular shape, have proven effective. Bulk densities of 3-inch- 

 long, 0.020-inch-thick hardwood flakes are about as follows (condensed from 

 table 16-44): 



Red maple, sweetgum, 



and yellow-poplar Oak and hickory 



Condition Green Dry Green Dry 



Iblcu ft 



Loose 14.3 5.8 7.7 5.7 



Blown into van 6.2 2.0 5.3 3.4 



Settled in transport 18.4 — 10.5 — 



Settled by vibration 10.8 4.2 7.7 2.8 



Baled with pressures of 



12.5 psi 21.9 10.4 14.5 6.0 



50.0 psi 22.4 10.4 14.5 6.0 



100.0 psi 22.4 10.4 14.5 6.0 



A more complete discussion of handling and storing particles is given on 

 pages 264 through 281 of Maloney (1977) and in Moeltner and Young (1976). 



24-5 RESIN SELECTION AND APPLICATION 



Resin binders for structural flakeboards are in part determined by the condi- 

 tions to which the panels will be exposed. There is some doubt about the 

 suitability of resin-bonded flakeboard for long-term exterior application; shield- 

 ing flakeboard from the effects of weathering appears more promising than 

 attempts to greatly improve its resistance. Performance standards for sheathing 

 and for combination subfloor and underlayment (see sec. 24-2) recognize two 



