1.1 These requirements cover factory-built grease ducts, and grease duct assemblies that are intended to be installed at reduced clearances where 18 inch (457 mm) clearance is specified in the Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations, NFPA 96, and the International Mechanical Code.

1.2 These requirements also cover modular grease duct assemblies, unwelded connections between adjoining duct parts, fittings, access doors, and the like intended for use with grease ducts installed in accordance with NFPA 96 and the International Mechanical Code.

1.3 These requirements do not address NFPA 96 and the International Mechanical Code requirements for grease duct enclosures. Grease ducts covered only by these requirements are intended to be installed in a fire resistive enclosure when required by NFPA 96 or the IMC.

1.4 Requirements used to evaluate the effectiveness of the combination of a grease duct and an enclosure as a fire rated enclosure system and through penetration firestop system, as well as the enclosure's effect on the grease duct are contained in Standard for Tests of Fire Resistive Grease Duct Enclosure Assemblies, UL 2221, and ASTM E 2336, Standard Test Methods for Fire Resistive Grease Duct Enclosure Systems.