AMETEK Brookfield Page 63
Manual No. M09-1200-F1016
Appendix C: Glossary
Angle of Wall Friction:
Represents the friction between the sliding powder and the wall of the
hopper or chute at the onset of flow.
Arching Dimension
:
Minimum hopper outlet size needed to insure that the powder will
discharge in Mass Flow instead of forming a stable arch across the
opening.
Axial Distance:
Distance between the lid and the bottom of the trough, indicating the
depth of the powder.
Bin Diameter
:
Maximum internal diameter of the storage vessel. For square or rectangle
vessels, the equivalent bin diameter should be used.
Bulk Density:
The mass of the powder divided by its total volume.
Cohesion
:
A measure of the strength retained by a powder after if has been
compacted to a given Consolidation Level.
Consolidation:
The process of applying a Normal and a Shear stress to a bulk solid
to move the particles together, in order to observe any increases in its
Cohesion, Bulk Density, etc.
Core-Flow
:
A first-in last-out discharge pattern where the powder flows from the top
of the vessel through a vertical channel above the outlet. Powder that is
near the walls of the vessel remains stagnant until the level descends to
the point where that powder is at the top surface.
Critical Arch:
The largest arch span that a given powder can support before collapsing
under its self weight.
Critical Consolidation Stress
:
For Arching:
The Major Principal Consolidating Stress acting on the powder in the
hopper at critical arching dimension during mass flow.
For Rat-Hole:
The Major Principal Consolidating Stress acting on the powder in the
region of the outlet due to the head of powder in a core flow hopper.
Critical Density:
The Bulk Density of the powder forming the Critical Arch or the
Critical Rathole. This is determined by taking the Bulk Density at the
corresponding Critical Consolidation Stress.
Critical Internal Friction Angle
:
The Internal Friction Angle of the powder forming the Critical Arch or
the Critical Rathole. This is determined by taking the Internal Friction
Angle at the corresponding Critical Consolidation Stress.
Critical Rathole:
The largest Rathole diameter a powder can support before collapsing in
a Core Flow regime.
Critical Stress
:
The Unconfined Failure Strength of the powder forming the Critical Arch
or the Critical Rathole. This is determined by taking the Unconfined
Failure Angle at the corresponding Critical Consolidation Stress.
