Duty class
Trade shorthand for the thickness band of a refuse sack — light, medium, heavy, extra heavy, rubble grade.
Also called: sack duty, grade
It is convention, not a standard. Nothing defines the bands, so “heavy duty” means whatever a supplier decides it means until a micron figure and a polymer are attached to it.
EN 13592 is sometimes invoked here and it does not settle the question either. It classifies by drop test rather than by thickness, and its scope is narrower than the way it is quoted: sacks whose first use is household waste collection, explicitly not sacks that line a bin and are not lifted when the bin is emptied. Ask for microns, polymer and seal type. See the sack duty selector.