Trajectories: Classification Table

Classification Table

The angle of repose of a material is that angle to the horizontal assumed by the stir-face of a freely formed pile, The angle of surcharge is that angle to the horizontal assumed by the surface of a material at rest on a moving conveyor belt. The surcharge angle may be anything up to 20 less than the angle of repose. The flowability chart on sheet 2 shows the general relationship between the angles of repose and surcharge.
The classification table below and the material characteristics tables which follow, are based upon nvrm4e conditions and typical materials. The determination of angles of repose and surcharge and maximum recommended conveyor inclination must be considered with due regard to such properties as size and shape of fine particles and lumps, roughness of the surface of the particles, proportion of fines and lumps present, moisture content, dustiness, stickiness, abrasiveness, corrosive action, etc. Materials or characteristics omitted from the tables may be roughly appraised by comparison with similar listed materials.
References:
C.E.M.A. Handbook
UNIROYAL Conveyor Belt Selection Guide
PROK Handbook

Size	MATERIAL CHARACTERISTICS	CLASS
Size	Very fine-under 100 mesh Fine-under 3mm Granular-Under 12mm Lumpy-containing lumps over 12mm Irregular-stringy, interlocking, mats together	A B C D E
Flowability Angle of Repose	Very free flowing of repose less than 20 degrees Free flowing-angle of repose 20 - 30 degrees Average flowing-angle of repose 30 - 45 degrees Sluggish-angle of repose 45+ degrees	1 2 3 4
Abrasiveness	Non-abrasive Abrasive Very abrasive Very sharp-cuts or gouges belt covers	5 6 7 8
Miscellaneous Characteristics (sometimes more than one of these characteristics may apply)	Very dusty Aerates and develops fluid characteristics Contains explosive dust Contaminable affecting use or saleability Degradable, affecting use or saleability Gives off harmful fumes or dust Highly corrosive Mildly corrosive Hydroscopic Interlocks or mats Oils or chemical present-may affect rubber products Packs under pressure Very light and fluffy-may be wind swept Elevated temperature	L M N P Q R S T U V W X Y Z

Example: A very fine material that is free flowing, abrasive, contains explosive dust would be designated: Class A26N