Sch 1B para 3
(1) The pressure accessories defined in paragraph 6, are classified on the basis of: (a) their maximum allowable pressure PS; (b) their volume V or their nominal size DN, as appropriate; (c) the group of fluids for which they are intended. (2) The appropriate table for vessels or piping is to be used to determine the conformity assessment category. (3) Where both the volume and the nominal size are considered appropriate in subparagraph (1)(b), the pressure accessory shall be classified in the highest category.