A NOTE ON THE ESTIMATION OF BASIC DENSITY OF FRESH WOOD CHIPS

The basic density of wood chips is an important economic consideration in several industrial operations, e.g., pulp production, particleboard manufacture, and the transport of wood in chip form. Various methods have been proposed for measurement of chip density (Smith 1961; Harder 1976; Balodis et al. 1980) and international standards have been developed (Tappi T18 m-53 and Appita Pls-79). Most methods have been designed to cope with wood at various moisture contents from air-dry to green, and thus require that the material be soaked before wet volume determination. This procedure usually involves a vacuum treatment and a soaking period of several days, after which the samples are centrifuged or hand-dried to remove excess surface water. After volume measurement by water displacement the chips are oven-dried and re-weighed. At the Forest Research Institute (FRI) wood billets for pulping studies are normally chipped when green and the wood is used almost immediately in experiments. Chip densities derived by the soaking and oven-drying process were found to be consistently 2- 8 % lower than solid wood densities from the same billets. An investigation of th