The hood or that
portion of a primary collection means designed for collecting
cooking vapors and residues constructed of steel shall be not
less than 0.048 of an inch (1.219 mm) (No. 18 MSG), stainless
steel not less than 0.036 of an inch (0.914 mm) (No. 20
MSG) in thickness, or other approved material of equivalent
strength and fire and corrosion resistance. [NFPA 96:5.1.1]
Wall-mounted exhaust hood
assemblies shall be tight fitting against the back wall as
to not permit passage of grease vapor behind the hood, or
between the back wall and the hood assembly. [NFPA
96:5.1.13]
Seams,
joints, and penetrations of the hood enclosure that direct
and capture grease-laden vapors and exhaust gases shall
have a liquid-tight continuous external weld to the hood's
lower outermost perimeter. [NFPA 96:5.1.2]
Exceptions:
Seams, joints, and penetrations of the hood shall be
permitted to be internally welded, provided that the
weld is formed smooth or ground smooth, so as to
not trapgrease, and is cleanable. [NFPA 96:5.1.3]
Penetrations shall be permitted to be sealed by
devices that are listed for such use and whose presence
does not detract from the hood's or duct's structural
integrity. [NFPA 96:5.1.5]
Internal hood joints, seams, filter support frames, and appurtenances attached
inside the hood shall be sealed or otherwise made
greasetight. [NFPA 96:5.1.4]
Eyebrow-type hoods
over gas or electric ovens shall be permitted to have a
duct constructed as required in Section 510.0 from the
oven flue(s) connected to the hood canopy upstream of
the exhaust plenum, as shown in Figure 508.3.3. [NFPA
96:5.1.8.1]
Insulation materials other than
electrical insulation shall have a flame spread index of
not more than 25, where tested in accordance with
ASTM E84 or UL 723. Adhesives or cements used in the
installation of insulating materials shall be in accordance
with this section where tested with the specific insulating
material. [NFPA 96:5.1.9, 5.1.10]
The construction and
size of exhaust hood assemblies with integrated supply
air plenums shall be in accordance with the requirements
of Section 508.1 through Section 508.5. [NFPA 96:5.3.1]
A fire-actuated damper
shall be installed in the supply air plenum at each
point where a supply air duct inlet or a supply air
outlet penetrates the continuously welded shell of
the assembly. [NFPA 96:5.3.4.1]
Supply air plenums
that discharge air from the face rather than from
the bottom or into the exhaust hood and that are
isolated from the exhaust hood by the continuously
welded shell extending to the lower outermost
perimeter of the entire hood assembly
shall not require a fire-actuated damper. [NFPA
96:5.3.4.4]
Internal hood joints, seams, filter support frames, and appurtenances attached
inside the hood shall be sealed or otherwise made
greasetight. [NFPA ...
