3.1.5.3
Light Duty Corrosive Exhaust Ductwork
Light duty corrosive exhaust ductwork shall be PVC plastisol coated
galvanized steel with PVC coating on interior [surfaces.] [and exterior
surfaces] [and epoxy wash primer coating on exterior surfaces].
3.1.6
Fibrous Glass Ductwork
Installation shall be according to the manufacturer's written
recommendations unless otherwise required in NAIMA AH116. Duct supports
for fibrous glass ductwork shall conform to NAIMA AH116. In those cases
not covered in NAIMA AH116, the written recommendation of the fibrous duct
manufacturer shall be followed.
3.1.7
FRP Ductwork
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NOTE: Study characteristics of exhaust stream
constituents and contaminant materials to determine
service life and safety controlling parameters.
Consider that constituents concentrate upon
evaporation of carrier. Some concentrates detonate
upon impact. Design to preclude concentrate
high-out water washing may be necessary. Review
fire protection provisions, and the need for fire
stops. The manufacturer cannot be held responsible
for performance of his product, unless the
specification delineates product exposure. Modify
or supplement specification criteria as necessary.
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Fibrous glass reinforced plastic ducting and related structures shall
conform to SMACNA Industry Practice. Flanged joints shall be provided
where indicated. Crevice-free butt lay-up joints are acceptable where
flanged joints are not indicated. When ambient temperatures are lower than
10 degrees C 50 degrees F, joints shall be heat cured by exothermic
reaction heat packs.
3.1.8
Kitchen Exhaust Ductwork
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NOTE: The requirements in NFPA 96 pertaining to
enclosures around kitchen exhaust ducts shall be
shown on the drawings.
The referenced SMACNA HVAC Duct Construction Manual
does not cover negative pressures in excess of 3
inches water gauge. If the static pressure within
the duct will exceed 3 inches negative, then the
spacing and duct thickness must be indicated on the
drawings and the paragraph accordingly.
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3.1.8.1
Ducts Conveying Smoke and Grease Laden Vapors
Ducts conveying smoke and grease laden vapors shall conform to requirements
of NFPA 96. Seams, joints, penetrations, and duct-to-hood collar
connections shall have a liquid tight continuous external weld. Duct
material shall be [minimum 1.3 mm 18 gauge, Type 304L or 316L, stainless
SECTION 15895
Page 57
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