507.2.4.3 The following clearance options for which field-applied grease duct enclosures and factory-built grease duct enclosures have been successfully evaluated shall be clearly identified in their listing and installation documentation and on their label [NFPA 96: 4.3.4]:
Open combustible clearance at manufac- turer’s requested dimensions. [NFPA 96: 4.3.4(1)]
Closed combustible clearance at manufacturer’s requested dimensions, with or without specified ventilation. [NFPA 96: 4.3.4(2)]
(3) Rated shaft clearance at manufacturer’s requested dimensions, with or without s p e c i f i e d v e n t i l a t i o n . [ N F P A 9 6 : 4 . 3 . 4 ( 3 ) ] 5 0 7 . 2 . 5 A d u c t s h a l l b e p e r m i t t e d t o c o n t a c t noncombustible floors, interior walls, and other noncombustible structures or supports, but it shall not be in contact for more than 50 percent of its surface area per each lineal foot of contact length. Where such direct contact is made, the duct shall be protected from corrosion due to this contact.
Exception: When the duct is protected with a material or product listed for the purpose o f r e d u c i n g c l e a r a n c e t o z e r o . 5 0 7 . 2 . 6 C l e a r a n c e s b e t w e e n t h e d u c t a n d interior surfaces of enclosures shall meet the r e q u i r e m e n t s o f S e c t i o n 5 0 7 . 2 . 5 0 7 . 3 A d r a w i n g ( s ) o f t h e e x h a u s t s y s t e m i n s t a l l a t i o n along with a copy of operating instructions for subassemblies and components used in the exhaust
FIGURE 5-1 Typical Section of Eyebrow-Type Hood.
507.2 – 508.2
system, including electrical schematics, shall be a v a i l a b l e o n t h e p r e m i s e s . 5 0 7 . 4 I f r e q u i r e d b y t h e A u t h o r i t y H a v i n g Jurisdiction, notification in writing shall be given of any alteration, replacement, or relocation of any exhaust or extinguishing system or part thereof or cooking equipment. Satisfaction shall be provided to the Authority Having Jurisdiction that the complete exhaust system as addressed in this standard is installed and operable in accordance with the approved design and the manufacturer’s instructions.
508.1 Where Required. Hoods shall be installed at or above all commercial-type deep fat fryers, broilers, fry grills, steam-jacketed kettles, hot-top ranges, ovens, barbecues, rotisseries, dishwashing machines, and similar equipment that produces comparable amounts of steam, smoke, grease, or heat in a food-processing establishment. For the purpose of this section, a food- processing establishment shall include any building or portion thereof used for the processing of food, but s h a l l n o t i n c l u d e a d w e l l i n g u n i t . 5 0 8 . 1 . 1 C o n s t r u c t i o n . T h e h o o d o r t h a t p o r t i o n of a primary collection means designed for collecting cooking vapors and residues shall be constructed of and be supported by steel not less than 0.043 inch (1.09 mm) (No. 18 MSG) in thickness, stainless steel not less than 0.037 inch(0.94 mm) (No. 20 MSG) in thickness, or other approved material of equivalent strength and fire and corrosion resistance.
(1) Listed exhaust hoods with or without exhaust dampers.
Type II hoods shall be constructed of at least
inch (0.61 mm) (No. 24 gauge) steel. Hoods constructed of copper shall be of copper sheets weighing at least twenty-four
ounces per square foot (7.32 kg/m2).
Joints and seams shall be substantially tight. Solder shall not be used except for sealing a joint or seam.
All hoods shall be secured in place [For OSHPD 1, 2 & 4] to resist the lateral loads given in the Califonria Building Code, Title 24, Part 2 by n o n c o m b u s t i b l e s u p p o r t s . 5 0 8 . 2 A l l s e a m s , j o i n t s , a n d p e n e t r a t i o n s o f t h e h o o d enclosure that direct and capture grease-laden vapors and exhaust gases shall have a liquidtight continuous external weld to the hood’s lower outermost perimeter. Internal hood joints, seams,