If the duct system will remain exposed, system designers can choose the white or black PSK facing for aesthetics ... the use of substantially more metal. As HVAC system designers consider their ...

black iron, aluminized type 1 steel, 3003-H13 aluminum, 304 stainless steel or 316 stainless steel. Metal shells can be spiral duct or longitudinal seam welded duct, in a thickness from 10 gauge ...