2.10.1.3
General Service Duct Connectors
A flexible duct connector approximately 150 mm 6 inches in width shall be
provided where sheet metal connections are made to fans or where ducts of
dissimilar metals are connected. For round/oval ducts, the flexible
material shall be secured by stainless steel or zinc-coated, iron
clinch-type draw bands. For rectangular ducts, the flexible material
locked to metal collars shall be installed using normal duct construction
methods. The composite connector system shall comply with UL 214 and be
classified as "flame-retarded fabrics" in UL Bld Mat Dir.
2.10.2
Fibrous Glass Ductwork
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NOTE: Fibrous glass ducts will not be used in
ductwork systems for medical facilities or in clean
rooms with requirements equal to or exceeding Class
100. Refer to AFR 88-15 for use on Air Force
projects.
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Fibrous glass ductwork may be provided in lieu of sheet metal ductwork
except that fibrous glass ductwork will not be allowed in fan and equipment
rooms, where subject to traffic or weather damage, for outside air intakes,
for risers of more than two stories, in kitchen or fume exhaust ducts, to
convey solids or corrosive gases, in concrete, for burial below grade, as
casings or housings, or in systems used for life support systems. Fibrous
glass ductwork, including components, shall be fabricated in accordance
with NAIMA AH116 where the velocity and the static pressure are within its
scope. Where the velocity or static pressure exceeds these limits, the
ductwork manufacturer shall certify that the ductwork is intended for the
velocities and pressures to be encountered, and that the proposed
installation meets all performance criteria specified herein for metal
ductwork. Fibrous glass ductwork shall have the thermal equivalent of the
insulation specified for metal ductwork in Section 15080A THERMAL
INSULATION FOR MECHANICAL SYSTEMS. Field or factory fabricated fibrous
glass ductwork shall conform to UL 181, Class 1. Duct wall penetrations,
traverse joints and longitudinal seams shall be sealed as instructed by the
manufacturer by one of the methods prescribed by NAIMA AH116, where
applicable, except that pressure sensitive tape shall not be used as a
sealant. All items necessary for a complete installation shall be provided
as specified for sheet metal duct systems.
2.10.3
Ductwork Accessories
2.10.3.1
Duct Access Doors
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NOTE: Provide duct access doors at regular
intervals to facilitate the cleaning of duct systems
for applications requiring clean air supplies, such
as hospitals, laboratories, electronics servicing
and similar activities.
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Access doors shall be provided in ductwork where indicated and at all air
flow measuring primaries, automatic dampers, fire dampers, coils,
thermostats, and other apparatus requiring service and inspection in the
duct system, and unless otherwise shown, shall conform to SMACNA HVAC Duct
SECTION 15566A
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