Cooking equipment that produces smoke or greaseladen vapors shall be equipped with an exhaust system that complies with all the equipment and performance requirements of this standard. All such equipment and performance also needs to be maintained per the requirements of this standard during all periods of operation. Specifically, the cooking equipment, hoods, ducts, fans, fire suppression systems and special grease collection or energy control equipment are to be kept in good working condition.
Airflows throughout all components of the system must be maintained at intervals necessary to keep the operating conditions of the equipment at the proper levels. All interior surfaces of the exhaust system shall be reasonably accessible for cleaning and inspection purposes. Except where enclosures are required, hoods, grease removal devices, exhaust fans, and ducts shall have a clearance of at least 18 inches to combustible material, 3 inches to limited combustible material and 0 inches to non-combustible material. (See Fig. 1a – 1e.) This is only a guideline and there are several exceptions to these.
Ultimately, the authority having jurisdiction (AHJ) has the final say in the acceptance or rejection of the installation. In the event of a fire within the exhaust system, the system must be inspected by qualified personnel and approved by the AHJ to determine whether the system is structurally sound, capable of maintaining their fire protection function, and suitable for continued operation. Clearances can be reduced by the installation of field applied or factory built grease duct enclosures. These must demonstrate that they provide sufficient mechanical and structural integrity, resiliency and stability when subjected to expected building environmental conditions, duct movement under general operating, and fire conditions. A drawing of the exhaust system installation along with a copy of operating instructions for subassemblies and components used in the exhaust system, including electrical schematics, shall be available on the premises.
Upblast fans with the motors surrounded by the airstream shall be hinged, supplied with a flexible weatherproof electrical cable and a hold open retainer for servicing and cleaning, and be listed for this use. Inline fans shall have the motor located outside of the airstream and have the belts and pulleys protected from the airstream by a greasetight housing. The fan must be securely bolted to the flanges of the exhaust duct using stainless steel bolts, nuts, lock washers and gasketing rated for 1500 deg F. Flexible connectors are not be used. If the design or positioning of the fan allows grease to be trapped, a grease drain directed to an accessible grease receptacle, not exceeding 1 gal, must be supplied.