| accuracy | The closeness of the agreement between the result of a measurement and the true value. |
| aerosol | A dispersion of fine particles (solids or liquids) suspended in a gas. |
| adsorbed water | Water attracted to the particle surface by physiochemical forces, having properties that may differ from the pore water at the same temperature and pressure due to the altered molecular arrangement. Adsorbed water does not include water that is chemical combined within the particles. |
| aeration | The action of injecting gas, usually air, to a bulk material to weaken the particulate structure by dilatation. The process induces the material to adopt a fluid or highly agitated state. (See quiescent and boiling bed). |
| anistropic | Not of the same composition, structure or condition in all axial directions. |
| attrition | Unwanted reduction in particle size caused by the collision of particles with other particles or with a surface, resulting in abrasion, causing fines, or fracture that creates ‘mother’ and ‘daughter’ particles. |
| barrel section | The upper, parallel section of a circular storage hopper. See body section. |
| bed | An assembly of particles in a contained state. |
| biaxial compression | Compression of a bulk mass by the application of normal stresses in two directions at right angles to each other |
| biaxial state of stress | State of stress in which one of the three principal stresses is zero |
| big bag | See FIBC |
| bin | A bulk storage container, usually of small or medium size. Synonymous with hopper and, to a limited extent, with silo. May be mobile or transportable, See IBC |
| binder | An additive that coheres a loosely assembled particulate mass. |
| Bingham plastic | A form of deformation that exhibits Newtonian behaviour once a threshold shear stress is exceeded. |
| body force | A force, such as gravity, magnetic force or inertia, whose effect is distributed throughout a material body by direct action on each elementary part of the body independent of others. |
| body section | The upper, parallel part, of largest cross section, of a storage container. |
| bunker | Generic term for a fixed container for bulk storage. Typically of shallow construction with a large, open top. See hopper, bin. |
| capillarity | A phenomenon associated with surface tension and angle of contact that leads to the migration of fluids through narrow channels, as the interstitial voids of closely packed particulate beds. |
| cavitation | The formation of a cavity. |
| clean room | A room with control of particulate contamination to a defined level. |
Glossary of Terms in Powder & Bulk Technology
1.3 General Terms
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