In rubber conveyor belts there are indeed DIN and ISO standards, but many conveyor belt suppliers interpret - especially the testing - rather freely. Learn all about the standards and the tests.
DIN 22102 and ISO 10247 - Rubber Conveyor Belts - Classes
The sober figures about the DIN 22102 and ISO 10247 standard. Type W is almost always the best choice. For very sharp, irregular product, type X can be the best choice. Type Y is average.
Are you going to make drums yourself (or have them made)? Then be sure to follow the guidelines in these tables for the curvature, so that the conveyor belts steer well.