Foam plastic used as duct coverings and linings must conform to the requirements of which section?

Foam plastic used as duct coverings and linings must conform to Section 604. This section specifically addresses the standards and requirements for materials used in ducts, including insulation and coverings that may be made from foam plastic. The guidelines outlined in this section ensure that materials not only provide thermal performance but also meet fire safety and health standards appropriate for building applications. It's essential for ductwork to be constructed from materials that will not contribute to fire hazards or emit harmful gases when exposed to high temperatures, which is why adherence to the stipulations in Section 604 is critical for safety and compliance in mechanical installations.